U.S. patent application number 13/178016 was filed with the patent office on 2011-11-03 for imaging lens, imaging device, and mobile terminal.
This patent application is currently assigned to Konica Minolta Opto, Inc.. Invention is credited to Yusuke HIRAO, Keiji Matsusaka.
Application Number | 20110267709 13/178016 |
Document ID | / |
Family ID | 39709926 |
Filed Date | 2011-11-03 |
United States Patent
Application |
20110267709 |
Kind Code |
A1 |
HIRAO; Yusuke ; et
al. |
November 3, 2011 |
IMAGING LENS, IMAGING DEVICE, AND MOBILE TERMINAL
Abstract
The present invention provides an image pickup lens, an image
pickup apparatus, and a mobile terminal. The image pickup lens
includes a lens group. The lens group includes a lens substrate
which is a parallel flat plate, and lenses are formed on an object
side surface and image side surface of the lens substrate, where a
lens with a positive refractive power formed on the lens substrate
has an Abbe number of .nu.p and a lens with a negative refractive
power formed on the lens substrate has an Abbe number of .nu.n. The
difference between the Abbe number .nu.p and the Abbe number of
.nu.n satisfies 10<|.nu.p-.nu.n|.
Inventors: |
HIRAO; Yusuke; (Sakai-shi,
JP) ; Matsusaka; Keiji; (Osaka-shi, JP) |
Assignee: |
Konica Minolta Opto, Inc.
Tokyo
JP
|
Family ID: |
39709926 |
Appl. No.: |
13/178016 |
Filed: |
July 7, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12522580 |
Jul 9, 2009 |
8000038 |
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PCT/JP2008/052036 |
Feb 7, 2008 |
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13178016 |
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Current U.S.
Class: |
359/795 |
Current CPC
Class: |
G02B 13/006 20130101;
G02B 13/0085 20130101; G02B 13/0025 20130101; G02B 13/003 20130101;
Y10T 29/49826 20150115; Y10T 156/1052 20150115; G02B 7/028
20130101; G02B 13/0035 20130101; B82Y 20/00 20130101 |
Class at
Publication: |
359/795 |
International
Class: |
G02B 9/04 20060101
G02B009/04 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 19, 2007 |
JP |
2007-038221 |
Claims
1.-34. (canceled)
35. An image pickup lens comprising: a lens group arranged at a
closest position to an object side in the image pickup lens,
comprising: a first lens substrate being a parallel flat plate, a
first lens with an Abbe number .nu.1 and a positive refractive
power, formed on an object side surface of the first lens
substrate, and a second lens with an Abbe number .nu.2 and a
negative refractive power, formed on an image side surface of the
first lens substrate, wherein a difference of the Abbe numbers
.nu.1 and .nu.2 satisfies the following expression (1):
10<(.nu.1-.nu.2). (1)
36. An image pickup lens of claim 35 comprising of: a lens group
comprising: a first lens substrate being a parallel flat plate, a
first lens with an Abbe number .nu.1 and a positive refractive
power, formed on an object side surface of the first lens
substrate, an object side surface of the first lens being a convex
surface facing the object side, and a second lens with an Abbe
number .nu.2 and a negative refractive power, formed on an image
side surface of the first lens substrate, an image side surface of
the second lens being a concave surface facing the image side,
wherein a difference of the Abbe numbers .nu.1 and .nu.2 satisfies
the following expression (2): 10<(.nu.1-.nu.2)<70. (2)
37. An image pickup lens of claim 35 comprising: a lens group; and
a lens A arranged at an image side of the lens group with a
predetermined distance, wherein the lens group comprises: a first
lens substrate being a parallel flat plate, a first lens with an
Abbe number .nu.1 and a positive refractive power, formed on an
object side surface of the first lens substrate, an object side
surface of the first lens being a convex surface facing the object
side, and a second lens with an Abbe number .nu.2 and a negative
refractive power, formed on an image side surface of the first lens
substrate, an image side surface of the second lens being an
concave surface facing the image side, the lens A is a lens or a
lens group and has a positive or negative refractive power, and a
difference of the Abbe numbers .nu.1 and .nu.2 satisfies the
following expression (2): 10<(.nu.1-.nu.2)<70. (2)
38. An image pickup lens of claim 37 further comprising: a lens B
arranged at an image side of the lens A with a predetermined
distance, wherein the lens B is a lens or a lens group and has a
positive or negative refractive power.
39. An image pickup lens of claim 35 comprising: a lens group; and
an optical member being a parallel flat plate, arranged at an image
side of the lens group with a predetermined distance, wherein the
lens group comprises: a first lens substrate being a parallel flat
plate; a first lens with an Abbe number .nu.1 and a positive
refractive power, formed on an object side surface of the first
lens substrate, an object side surface of the first lens being a
convex surface facing the object side; and a second lens with an
Abbe number .nu.2 and a negative refractive power, formed on an
image side surface of the first lens substrate, an image side
surface of the second lens being a concave surface facing the image
side, a difference of the Abbe numbers .nu.1 and .nu.2 satisfies
the following expression (2), and the optical member satisfies the
following expression (6): 10 < ( v 1 - v 2 ) < 70 , ( 2 ) D g
f .gtoreq. 0.1 , ( 6 ) ##EQU00025## where Dg is a thickness of the
optical member, and f is a focal length of a total lens system of
the image pickup lens.
40. The image pickup lens of claim 35, wherein the lens group
satisfies the following expression (2): 10<(.nu.1-.nu.2)<70.
(2)
41. The image pickup lens of claim 35, further comprising: a second
lens substrate being a parallel flat plate, arranged at an image
side of the first lens substrate with a predetermined distance, and
a lens or lenses with a positive or negative power formed on at
least one of an object side surface and an image side surface of
the second lens substrate.
42. The image pickup lens of claim 41, further comprising: a third
lens substrate being a parallel flat plate, arranged at the image
side of the second lens substrate with a predetermined distance,
and a lens or lenses with a positive or negative power formed on at
least one of an object side surface and an image side surface of
the third lens substrate.
43. The image pickup lens of claim 35, further comprising: an
aperture stop formed on a surface of any one of a lens substrate or
lens substrates in the image pickup lens.
44. The image pickup lens of claim 35, wherein each of the first
lens and the second lens comprises a resin material, and inorganic
fine particles with a size of 30 nanometers or less are dispersed
into the resin material.
45. An image pickup apparatus comprising: an image pickup lens of
claim 35; and an image sensor photoelectrically converting an
object image formed by the image pickup lens.
46. A mobile terminal comprising: an image pickup apparatus of
claim 45.
47. The image pickup lens of claim 35, wherein the first lens is
arranged at a closest position to the object side of the image
pickup lens.
Description
TECHNICAL FIELD
[0001] The present invention relates to an image pickup lens for an
image pickup apparatus that employs a solid-state imaging device
such as an image sensor of a CCD type and an image sensor of a CMOS
type and that is capable of being mounted on a mobile terminal.
BACKGROUND ART
[0002] A small-sized and thin-type image pickup apparatus has been
mounted on a mobile terminal representing a small-sized and
thin-type electronic instrument such as a cell-phone and a PDA
(Personal Digital Assistant), which has made it possible to
transmit not only voice information but also image information to
the remote place one another.
[0003] As image sensors used for these image pickup apparatuses,
there are used solid-state imaging devices including an image
sensor of a CCD (Charge Coupled Device) type and an image sensor of
a CMOS (Complementary Metal-Oxide Semiconductor) type. As a lens
for forming a subject image on the image sensor, lenses which are
made of resins on a mass production basis at a low price come to be
used for achieving a reduced cost.
[0004] As an image pickup lens used for such the image pickup
apparatus (which is called also as a camera module, hereafter) that
is built in a mobile terminal, an optical system of the type of
three-element structure composed of three plastic lenses and an
optical system of three-element structure composed of one glass
lens and two plastic lenses are widely known. However, there are
technical limitations for achieving a good balance between further
downsizing of these optical systems and mass productivity required
for mobile terminals.
[0005] To solve the aforesaid problems, there has been proposed a
method for mass production of camera modules (see Patent Document
1) wherein a large amount of lens elements are formed
simultaneously on a wafer with a dimension of several inches in a
parallel flat plate shape, through a replica method, then, the
wafer and a sensor wafer are combined and are cut. Lenses
manufactured through this manufacturing method are sometimes called
wafer scale lenses, and the camera modules manufactured through
this manufacturing method are sometimes called wafer scale camera
modules. Patent Document 1 discloses an image pickup lens that
makes it possible to correct aberrations by simultaneously forming
a diffractive surface and a refractive surface on a lens
substrate.
[0006] However, it is not easy to simultaneously form a diffractive
surface and a refractive surface on a lens substrate, and a
thickness at the center on the refractive surface becomes extremely
thin in the lens system in which an optical total length (a
distance from an incident surface arranged at the closest position
to the object side in the lens system, to an imaging plane of CCD)
is small. Further, when the diffractive surface is employed, a
diffraction efficiency for a wavelength other than a design
wavelength is lowered, and an angle of light entering the
diffractive surface is greatly restricted due to bad angle
characteristics of an incident light entering the diffractive
surface, which cause a problem that a wide angle of view is hardly
secured. [0007] Patent Document 1: Unexamined Japanese Patent
Application Publication No. 2006-323365
DISCLOSURE OF INVENTION
Technical Problems
[0008] The present invention is achieved in view of the aforesaid
circumstances, and an object of the present invention is to provide
a wafer scale lens and an image pickup lens equipped with the wafer
scale lens, wherein the wafer scale lens is an image pickup lens
equipped with a lens substrate and a lens formed on the substrate
and exhibits a property that a diffractive surface is not used, a
total length of the optical system is short compared with an image
height, and aberrations can be corrected favorably, especially,
chromatic aberration can be corrected in a good condition.
Solution to Problem
[0009] The above object is achieved by an invention described in
any one of Items 1 through 34:
1. An image pickup lens, where a lens group is assumed to comprise
a lens substrate being a parallel flat plate and a lens or lenses
formed on at least one of an object side surface and image side
surface of the lens substrate, the image pickup lens
comprising:
[0010] the lens group in which lenses are formed on both sides of
the lens substrate, which satisfies a condition of the following
expression (28):
[Math. 1]
10<|.nu.p-.nu.n| (28)
[0011] In the expression, .nu.p is an Abbe number of a lens with a
positive refractive power formed on the lens substrate, and .nu.n
is an Abbe number of a lens with a negative refractive power formed
on the lens substrate.
2. An image pickup lens, where a lens group is assumed to comprise
a lens substrate being a parallel flat plate and a lens or lenses
formed on at least one of an object side surface and image side
surface of the lens substrate, and a first lens substrate is
assumed to be a lens substrate being a parallel flat plate and be
included in a lens group arranged at a closest position to an
object side, the image pickup lens comprising:
[0012] the first lens substrate;
[0013] a first lens with an Abbe number .nu.1 and a positive
refractive power, formed on an object side surface of the first
lens substrate; and
[0014] a second lens with an Abbe number .nu.2 and a negative
refractive power, formed on an image side surface of the first lens
substrate,
[0015] wherein a difference of the Abbe numbers .nu.1 and .nu.2
satisfies a condition of the following expression (1).
[Math. 2]
10<(.nu.1-.nu.2) (1)
3. An image pickup lens, where a lens group is assumed to comprise
a lens substrate being a parallel flat plate and a lens or lenses
formed on at least one of an object side surface and image side
surface of the lens substrate, the image pickup lens consisting
of:
[0016] a lens group comprising [0017] a first lens substrate,
[0018] a first lens with an Abbe number .nu.1 and a positive
refractive power, formed on an object side surface of the first
lens substrate, an object side surface of the first lens being a
convex surface facing the object side, and [0019] a second lens
with an Abbe number .nu.2 and a negative refractive power, formed
on an image side surface of the first lens substrate, an image side
surface of the second lens being a concave surface facing the image
side,
[0020] wherein a difference of the Abbe numbers .nu.1 and .nu.2
satisfies a condition of the following expression (2).
[Math. 3]
10<(.nu.1-.nu.2)<70 (2)
4. An image pickup lens, where a lens group is assumed to comprise
a lens substrate being a parallel flat plate and lenses formed on
an object side surface and an image side surface of the lens
substrate, the image pickup lens comprising:
[0021] a first lens group; and
[0022] a lens A arranged at an image side of the first lens group
with a predetermined distance,
[0023] wherein the first lens group comprises [0024] a first lens
substrate, [0025] a first lens with an Abbe number .nu.1 and a
positive refractive power, formed on an object side surface of the
first lens substrate, an object side surface of the first lens
being a convex surface facing the object side, and [0026] a second
lens with an Abbe number .nu.2 and a negative refractive power,
formed on an image side surface of the first lens substrate, an
image side surface of the second lens being an concave surface
facing the image side,
[0027] the lens A is a lens or a lens group and has a positive or
negative refractive power, and
[0028] a difference of the Abbe numbers .nu.1 and .nu.2 satisfies a
condition of the following expression (2).
[Math. 4]
10<(.nu.1-.nu.2)<70 (2)
5. An image pickup lens, where a lens group is assumed to comprise
a lens substrate being a parallel flat plate and lenses formed on
an object side surface and an image side surface of the lens
substrate, the image pickup lens comprising:
[0029] a first lens group;
[0030] a lens A arranged at an image side of the first lens group
with a predetermined distance; and
[0031] a lens B arranged at an image side of the lens A with a
predetermined distance,
[0032] wherein the first lens group comprises
[0033] a first lens substrate,
[0034] a first lens with an Abbe number .nu.1 and a positive
refractive power, formed on an object side surface of the first
lens substrate, an object side surface of the first lens being a
convex surface facing the object side, and
[0035] a second lens with an Abbe number .nu.2 with a negative
refractive power, formed on an image side surface of the first lens
substrate, an image side surface of the second lens being a concave
surface facing the image side,
[0036] each of the lens A and the lens B is a lens or a lens group,
and has a positive or negative refractive power, and
[0037] a difference of the Abbe numbers .nu.1 and .nu.2 satisfies a
condition of the following expression (2).
[Math. 5]
10<(.nu.1-.nu.2)<70 (2)
6. The image pickup lens of Item 1, wherein at least one lens group
in which lenses are formed on both sides of the lens substrate,
satisfies a condition of the following expression (29).
[Math. 6]
10<|(.nu.p-.nu.n)|<70 (29)
7. The image pickup lens of Item 2,
[0038] wherein at least one lens group in which lenses are formed
on both sides of the lens substrate, satisfies a condition of the
following expression (2).
[Math. 7]
10<(.nu.1-.nu.2)<70 (2)
8. The image pickup lens of Item 2, 4, 5, or 7, further
comprising:
[0039] a second lens substrate being a parallel flat plate,
arranged at an image side of the first lens substrate with a
predetermined distance, wherein a lens or lenses with a positive or
negative power is formed on at least one of an object side surface
and an image side surface of the second lens substrate.
9. The image pickup lens of any one of Items 2 through 5, 7, and
8,
[0040] wherein an image side surface of the second lens is in an
aspheric shape.
10. The image pickup lens of Item 8, further comprising:
[0041] a third lens substrate being a parallel flat plate, arranged
at the image side of the second lens substrate with a predetermined
distance, wherein a lens or lenses with a positive or negative
power is formed on at least one of an object side surface and an
image side surface of the third lens substrate.
11. The image pickup lens of Item 8 or 10,
[0042] wherein at least one m-th lens selected from a third lens
and lenses arranged at a closer position to the image side than the
third lens, has a negative power and has a focal length fm
satisfying a condition of the expression (25).
[ Math . 8 ] - 0.7 .ltoreq. f 1 fm < 0 ( 25 ) ##EQU00001##
[0043] In the expression, m satisfies m.gtoreq.3, and f.sub.1 is a
focal length of the first lens.
12. The image pickup lens of Item 11,
[0044] wherein an Abbe number .nu..sub.m of the m-th lens satisfies
a condition of the expression (26).
[Math. 9]
20.ltoreq..nu.m.ltoreq.50 (26)
13. The image pickup lens of Item 11 or 12,
[0045] wherein a lens substrate arranged at a closest position to
the image side comprises a lens on an image side thereof, and an
image side surface of the lens has a negative refractive power.
14. The image pickup lens of any one of Items 8, and 10 through 12,
further comprising:
[0046] a third lens with a negative refractive power, arranged on
an object side surface of the second lens substrate.
15. The image pickup lens of any one of Items 8, and 10 through
14,
[0047] wherein a lens surface arranged at a closest position to the
image side is an aspheric surface, and
[0048] a value calculated by normalizing an amount of an aspheric
sag of the lens surface arranged at the closest position to the
image side by a maximum image height, satisfies a condition of the
following expression (5).
[ Math . 10 ] X - X 0 Y > 0.14 ( 5 ) ##EQU00002##
[0049] In the expression, X is a displacement amount of the
aspheric surface given by the expression (5.1), and is measured in
a perpendicular direction to an optical axis at a height of a
principal ray at a maximum image height. In the expression, X.sub.0
is a displacement amount of a component of a quadratic surface of
revolution in the aspheric surface, given by the expression (5.2),
and is measured in the perpendicular direction to the optical axis
at the height of the principal ray at the maximum image height. In
the expression, Y is the maximum image height.
[ Math . 11 ] X = h 2 / R 1 + 1 - ( 1 + K ) h 2 / R 2 + A i h i (
5.1 ) [ Math . 12 ] X 0 = h 2 / R 1 + 1 - ( 1 + K ) h 2 / R 2 ( 5.2
) ##EQU00003##
[0050] Herein, Ai is a i-th order aspheric surface coefficient of
the lens surface arranged at the closest position to the image
side, where i=2, 4, 6 . . . , R is a paraxial curvature radius of
the lens surface arranged at the closest position to the image
side, K is a conic constant at the closest position to the image
side, and h is a height of a principal ray at the maximum image
height and is measured in the perpendicular direction to the
optical axis.
16. The image pickup lens of any one of Items 8, and 10 through
15,
[0051] wherein a lens formed on the second lens substrate comprises
a resin material.
17. The image pickup lens of any one of Items 10 through 16,
[0052] wherein a lens formed on the third lens substrate comprises
a resin material.
18. The image pickup lens of any one of Items 2 through 5, and 7
through 17,
[0053] wherein a value calculated by normalizing a focal length
f.sub.s1 of an object side surface of the first lens by a focal
length f of a total lens system, satisfies a condition of the
following expression (3).
[ Math . 13 ] 0.6 .ltoreq. f s 1 f .ltoreq. 1.0 ( 3 )
##EQU00004##
[0054] In the expression, f.sub.s1 is a focal length of an object
side surface of the first lens, and f is a focal length of the
total lens system.
19. The image pickup lens of any one of Items 1 through 18,
[0055] wherein a Petzval's sum of a total lens system satisfies a
condition of the following expression (4).
[ Math . 14 ] j 1 f j n j .ltoreq. 0.14 ( 4 ) ##EQU00005##
[0056] In the expression, f.sub.j is a focal length of a j-th lens,
and n.sub.j is a refractive index of the j-th lens.
20. The image pickup lens of any one of Items 1 through 19, further
comprising:
[0057] an aperture stop formed on a surface of any one of a lens
substrate or lens substrates in the image pickup lens.
21. The image pickup lens of Item 20,
[0058] wherein the aperture stop is arranged at a position between
the first lens substrate and the first lens.
22. The image pickup lens of any one of Items 2 through 5 and 7
through 21,
[0059] wherein a refractive index n1 of the first lens and a
refractive index n2 of the first lens substrate satisfy a condition
of the following expression (9).
[Math. 15]
n.sub.1<n.sub.2 (9)
23. The image pickup lens of any one of Items 2 through 5 and 7
through 22,
[0060] wherein an Abbe number .nu.0 of the first lens substrate
satisfies a condition of the following expression (10).
[Math. 16]
.nu..sub.0.ltoreq.60 (10)
24. The image pickup lens of any one of Items 2 through 5 and 7
through 21,
[0061] wherein a refractive index n1 of the first lens, a
refractive index n2 of the first lens substrate, and an Abbe number
.nu.0 of the first lens substrate satisfy a condition of the
following expressions (11) and (12).
[Math. 17]
n.sub.2<n.sub.1 (11)
[Math. 18]
.nu..sub.0>50 (12)
25. The image pickup lens of any one of Items 2 through 5 and 7
through 24,
[0062] wherein each of the first lens and the second lens comprises
a resin material.
26. The image pickup lens of Item 25,
[0063] wherein the difference of the Abbe numbers .nu.1 and .nu.2
satisfies a condition of the following expression (8).
[Math. 19]
10<(.nu.1-.nu.2)<40 (8)
27. The image pickup lens of any one of Items 16 through 26,
[0064] wherein inorganic fine particles with a size of 30
nanometers or less are dispersed into the resin material.
28. The image pickup lens of any one of Items 16 through 27,
[0065] wherein the resin material is a curable resin.
29. The image pickup lens of Item 28, wherein the resin material is
a UV curing resin. 30. The image pickup lens of any one of Items 1
through 29,
[0066] wherein a surface coming in contact with the air of each of
lenses in the image pickup lens, is in an aspheric shape.
31. An image pickup lens, where a lens group is assumed to comprise
a lens substrate being a parallel flat plate and a lens or lenses
formed on at least one of an object side surface and image side
surface of the lens substrate, the image pickup lens
comprising:
[0067] a lens group; and
[0068] an optical member being a parallel flat plate, arranged at
an image side of the lens group with a predetermined distance,
[0069] wherein the lens group comprises: [0070] a first lens
substrate; [0071] a first lens with an Abbe number .nu.1 and a
positive refractive power, formed on an object side surface of the
first lens substrate, an object side surface of the first lens
being a convex surface facing the object side; and
[0072] a second lens with an Abbe number .nu.2 and a negative
refractive power, formed on an image side surface of the first lens
substrate, an image side surface of the second lens being a concave
surface facing the image side,
[0073] a difference of the Abbe numbers .nu.1 and .nu.2 satisfies a
condition of the following expression (2), and the optical member
satisfies a condition of the following expression (6).
[ Math . 20 ] 10 < ( v 1 - v 2 ) < 70 ( 2 ) [ Math . 21 ] D g
f .gtoreq. 0.1 ( 6 ) ##EQU00006##
[0074] In the expression, Dg is a thickness of the optical member,
and f is a focal length of a total lens system.
32. An image pickup lens, where a lens group is assumed to comprise
a lens substrate being a parallel flat plate and a lens or lenses
formed on at least one of an object side surface and image side
surface of the lens substrate, the image pickup lens
comprising:
[0075] a lens group; and
[0076] an optical member being a parallel flat plate, arranged at
an image side of the lens group with a predetermined distance,
[0077] wherein the lens group comprises: [0078] a first lens
substrate; [0079] a first lens with an Abbe number .nu.1 and a
positive refractive power, formed on an object side surface of the
first lens substrate, an object side surface of the first lens
being a convex surface facing the object side; and
[0080] a second lens with an Abbe number .nu.2 and a negative
refractive power, formed on an image side surface of the first lens
substrate, the image side surface of the second lens being a
concave surface facing the image side,
[0081] a difference of the Abbe numbers .nu.1 and .nu.2 satisfies a
condition of the following expression (2), and the optical member
satisfies a condition of the following expression (7).
[ Math . 22 ] 10 < ( v 1 - v 2 ) < 70 ( 2 ) [ Math . 23 ]
0.13 > 1 2 - 1 1 f ( 7 ) ##EQU00007##
[0082] In the expression, l.sub.1 is an optical path length of an
axial ray from the second lens to an image plane, l.sub.2 is an
optical path length of a principal ray at a maximum image height
from the second lens to the image plane, and f is a focal length of
a total lens system.
33. An image pickup apparatus comprising:
[0083] an image pickup lens of any one of Items 1 through 32;
and
[0084] an image sensor photoelectrically converting an object image
formed by the image pickup lens.
34. A mobile terminal comprising: an image pickup apparatus of Item
33.
Advantageous Effects of Invention
[0085] According to the present invention, there are provided a
first lens with positive refractive power formed on a surface of a
first lens substrate facing the object side and the second lens
with negative refractive power formed on a surface of the first
lens substrate facing the image side, wherein a difference between
Abbe numbers of the first lens and the second lens exceeds 10, by
which chromatic aberration is corrected satisfactorily and the
total length of the optical system is shortened, without employing
a diffractive surface.
BRIEF DESCRIPTION OF DRAWINGS
[0086] FIG. 1 is a diagram showing the structure of an image pickup
lens relating to First Embodiment and First Example.
[0087] FIG. 2 is an enlarged diagram of the first lens and the
second lens of the image pickup lens.
[0088] FIG. 3 is an aberration diagram of an image pickup lens
relating to First Example.
[0089] FIG. 4 is a diagram showing the structure of an image pickup
lens relating to Second Example based on Embodiment 1.
[0090] FIG. 5 is an aberration diagram of an image pickup lens
relating to Second Example.
[0091] FIG. 6 is a diagram showing the structure of an image pickup
lens relating to Third Example based on Embodiment 1.
[0092] FIG. 7 is an aberration diagram of an image pickup lens
relating to Third Example.
[0093] FIG. 8 is a diagram showing the structure of an image pickup
lens relating to Fourth Example based on Embodiment 1.
[0094] FIG. 9 is an aberration diagram of an image pickup lens
relating to Fourth Example.
[0095] FIG. 10 is a diagram showing the structure of an image
pickup lens relating to Fifth Example based on Embodiment 1.
[0096] FIG. 11 is an aberration diagram of an image pickup lens
relating to Fifth Example.
[0097] FIG. 12 is a diagram showing the structure of an image
pickup lens relating to Sixth Example based on Embodiment 1.
[0098] FIG. 13 is an aberration diagram of an image pickup lens
relating to Sixth Example.
[0099] FIG. 14 is a diagram showing the structure of an image
pickup lens relating to Seventh Example based on Embodiment 1.
[0100] FIG. 15 is an aberration diagram of an image pickup lens
relating to Seventh Example.
[0101] FIG. 16 is a diagram showing the structure of an image
pickup lens relating to Embodiment 2 and Eighth Example.
[0102] FIG. 17 is an aberration diagram of an image pickup lens
relating to Eighth Example.
[0103] FIG. 18 is a diagram showing the structure of an image
pickup lens relating to Ninth Example based on Embodiment 2.
[0104] FIG. 19 is an aberration diagram of an image pickup lens
relating to Ninth Example.
[0105] FIG. 20 is a diagram showing the structure of an image
pickup lens relating to Tenth Example based on Embodiment 2.
[0106] FIG. 21 is an aberration diagram of an image pickup lens
relating to Tenth Example.
[0107] FIG. 22 is a diagram showing the structure of an image
pickup lens relating to Eleventh Example based on variation
examples of Embodiment 1 and Embodiment 2.
[0108] FIG. 23 is an aberration diagram of an image pickup lens
relating to Eleventh Example.
[0109] FIG. 24 is a diagram showing the structure of an image
pickup lens relating to Twelfth Example based on Embodiment 1.
[0110] FIG. 25 is an aberration diagram of an image pickup lens
relating to Twelfth Example.
[0111] FIG. 26 is a diagram showing the structure of an image
pickup lens relating to Thirteenth Example based on Embodiment
1.
[0112] FIG. 27 is an aberration diagram of an image pickup lens
relating to Thirteenth Example.
[0113] FIG. 28 is a diagram showing the structure of an image
pickup lens relating to Fourteenth Example based on Embodiment
2.
[0114] FIG. 29 is an aberration diagram of an image pickup lens
relating to Fourteenth Example.
[0115] FIG. 30 is a diagram showing the structure of an image
pickup lens relating to Fifteenth Example based on Embodiment
2.
[0116] FIG. 31 is an aberration diagram of an image pickup lens
relating to Fifteenth Example.
[0117] FIG. 32 is a diagram showing the structure of an image
pickup lens relating to Sixteenth Example based on Embodiment
1.
[0118] FIG. 33 is an aberration diagram of an image pickup lens
relating to Sixteenth Example.
REFERENCE SIGNS LIST
[0119] 100 Image pickup lens [0120] 1 First lens substrate [0121]
1a Aperture stop [0122] 11 First lens [0123] 12 Second lens [0124]
2 Second lens substrate [0125] 23 Third lens [0126] 24 Fourth lens
[0127] 3 Third lens substrate [0128] 35 Fifth lens [0129] 36 Sixth
lens [0130] 4 Image sensor [0131] 7 Optical member [0132] 8 Lens A
[0133] 9 Lens B
BEST MODE FOR CARRYING OUT THE INVENTION
[0134] Preferred embodiments for a technology of an image pickup
lens relating to the invention will be explained specifically as
follows, referring to the drawings. Incidentally, the invention
will be explained based on the illustrated embodiments, to which,
however, the invention is not limited. Further, parts or sections
which are the same or which correspond to each other between
respective embodiments are given the same signs, and overlapping
explanations will be omitted.
Embodiment 1
[0135] FIG. 1 is a diagram showing an image pickup lens relating to
Embodiment 1.
[0136] Image pickup lens 100 is arranged in an image pickup
apparatus. In the image pickup apparatus, there is arranged an
image sensor of a CCD type or of a CMOS type. An image of an object
image is formed on image sensor 4 by the image pickup lens 100. The
image pickup apparatus is arranged in a mobile terminal such as a
cell-phone and a PDA.
[0137] In the image pickup lens 100 relating to the present
embodiment, first lens substrate 1 is arranged on the side of an
object representing a photographic subject, and second lens
substrate 2 is arranged on the image side that is behind the first
lens substrate 1. The first lens substrate 1 and the second lens
substrate 2 are arranged with the predetermined distance between
them. The first lens substrate 1 and the second lens substrate 2
are formed into parallel flat plates. On the image side of the
second lens substrate 2, there is arranged image sensor 4 of a CCD
type or of a CMOS type which photoelectrically converts an image of
the object.
[0138] There is formed first lens 11 on a surface of the first lens
substrate 1 facing the object side, and is formed second lens 12 on
a surface of the first lens substrate facing the image side.
Further, there is formed third lens 23 on a surface of the second
lens substrate 2 facing the object side, and is formed fourth lens
24 on a surface of the second lens substrate 2 facing the image
side. As a lens section, there are arranged first lens 11, second
lens 12, third lens 23 and fourth lens 24, in this order from the
object side. Each of the first lens 11, the second lens 12, the
third lens 23 and the fourth lens 24 employs a resin material as a
lens material. By using a resin material for each lens, it is
possible to lower the cost and to manufacture the lenses
easily.
[0139] These lenses 11, 12, 23 and 24 are formed on lens substrates
1 and 2 through a photo curing method and a heat curing method, by
using a mold. After that, a group of lenses integrated with lens
substrates is automatically mounted on a circuit substrate by the
following process: the lens group is combined with a wafer of a
solid-state imaging device and is cut. On an outer edge of the cut,
solder is arranged, where the outer edge is to come in contact with
a circuit substrate. Then, the lens group is subjected to a reflow
process which is operated at high temperatures such as 250.degree.
C. through 300.degree. C., to be automatically mounted on the
circuit substrate. A surface of each of the lenses 11, 12, 23 and
24 that is in contact with air, namely, a surface that is not in
contact with the first lens substrate 1 or with the second lens
substrate 2 is formed into an aspheric surface. By forming all
surfaces which are in contact with air into aspheric surfaces, it
is possible to realize an optical system having an aberration
property that is more excellent. The aspheric surface is made by
forming a dropped curable resin with an aspheric-surface mold into
an aspheric shape, and by hardening it. The curable resin in this
case includes heat curing resin and UV curing resin. When UV curing
resin is employed as a resin material, it is possible to make a
large number of lenses at one time when forming lenses on lens
substrates 1 and 2 and then radiating UV rays on the lenses. Such
the material is well matched with a replica method. In addition,
since UV curing resin is excellent in heat resistance property, an
image pickup lens 100 employing this resin can withstand a reflow
process. Therefore, the process can be greatly simplified and it is
suitable for mass production of inexpensive image pickup lenses
100.
[0140] Image pickup lens 100 relating to the present embodiment
controls a change in refractive index caused by temperature changes
by dispersing inorganic fine particles with a size of 30 nanometers
or less into such the resin material. The size is more preferably
20 nanometers or less, and is further more preferably 15 nanometers
or less, which does not cause a problem of stray light due to
nano-particles.
[0141] In this case, the change in refractive index due to a
temperature will be explained in detail. Refractive index change A
due to a temperature is indicated by the following expression (23),
by differentiating the refractive index n based on Lorentz-Lorentz
equation with temperature t.
[ Math . 24 ] n t = ( n 2 + 2 ) ( n 2 - 1 ) 6 n { ( - 3 .alpha. ) +
1 [ R ] .differential. [ R ] .differential. t } ( 23 )
##EQU00008##
[0142] In the aforesaid expression, a represents a linear expansion
coefficient, and [R] represents molecular refraction.
[0143] In the case of plastic materials, contribution of the second
term is smaller than that of the first term in the expression (23)
in general, and the contribution can be ignored. For example, in
the case of PMMA resins, the linear expansion coefficient .alpha.
is 7.times.10.sup.-5. When this is substituted in the aforesaid
expression, the equation of dn/dt=-1.2.times.10.sup.-4 [/.degree.
C.] is set up, which mostly agree with an actual measurement.
[0144] With respect to this refractive index change, it has been
found recently that a change of plastic materials due to a
temperature can be made small by mixing inorganic fine particles in
a plastic material. In the detailed explanation, when fine
particles are mixed in a transparent plastic material, light
generally scatters and transmittance is lowered. The material has
been difficult to use as an optical material. However, it is
possible to avoid light from scattering substantially, by making a
size of the fine particles to be smaller than a wavelength of a
transmitting light flux. The refractive index of a plastic material
is lowered with the temperature rise, but the refractive index of
inorganic particles is raised with the temperature rise. Therefore,
it is possible to control the refractive index change to be mostly
the same as an influence to the position of a paraxial image point
due to changes of a lens surface form. Specifically, by dispersing
inorganic particles with maximum size of 30 nanometers or less in a
plastic material representing a base material, it is provided a
plastic material with extremely low dependence of refractive index
on the temperature. For example, by dispersing fine particles of
niobium oxide (Nb.sub.2O.sub.5) in acrylic resin, it is possible to
make the refractive index change caused by temperature change to be
small. Further, there are known materials wherein a dependence of
the refractive index on the temperature is low by using
nanocompsite. When a difference in the linear expansion coefficient
between a lens holding plate (for example, the first lens substrate
1) and a lens section (for example, first lens 11 and second lens
12) causes a reduction of a paraxial curvature radius of the lens
section and it affects the position of the paraxial image point in
a lens holding structure in the embodiment relating to the present
invention, these technologies enable that a shift of the focus
point is satisfactorily corrected by employing a resin material
with the dependence of refractive index on the temperature in the
amount by which the effect to the position of the paraxial image
point can be canceled. For example, Unexamined Japanese Patent
Application Publication No. 2007-126636 discloses an optical
material that satisfies a condition of the following Expression
(24).
[Math. 25]
1300.times.10.sup.-7.gtoreq..alpha..gtoreq.250.times.10.sup.-7
(24)
[0145] By providing resin structure wherein a refractive index is
hardly fluctuated based on a temperature change, employing the
optical material satisfying the condition of Expression (24), it is
possible to realize an image pickup lens having strong durability
for temperatures.
[0146] Further, image sensor 4 is formed in a way where a plurality
of semiconductor elements having photoelectric conversion functions
are formed on one side of a disk-shaped wafer, and electrodes are
arranged on the other side so that voltage for driving an image
pickup apparatus and a supply of clocks may be received.
[0147] The image pickup apparatus can be obtained easily in the
matter that lens substrates 1 and 2 on which lenses 11, 12, 23 and
24 are formed are arranged to face image sensor 4, lattice-shaped
spacers are arranged between the first lens substrate 1 and the
second lens substrate 2 and between the second lens substrate 2 and
image sensor 4, and they are diced.
[0148] Further, between the first lens 11 and the first lens
substrate 1, there is arranged aperture stop 1a that shields
visible light contributing to image forming. This aperture stop 1a
is formed by a coating method such as a spreading method and a
vacuum deposition. This aperture stop 1a can be formed easily by
forming a film on the lens substrate. By forming aperture stop 1a
between the first lens 11 and the first lens substrate 1, it is
possible to realize an optical system that is more telecentric for
the image sensor 4. Further, on a surface of the lens substrate
representing either the first lens substrate 1 or the second lens
substrate 2, there is formed a film of an infrared-ray blocking
filter. By forming this film of an infrared-ray blocking filter on
a surface of the lens substrate, it is possible to easily form a
filter which blocks infrared ray.
[0149] The first lens 11 is convex and has positive refractive
power. The second lens 12 is concave and has negative refractive
power. The third lens 23 is convex and has negative refractive
power. The fourth lens 24 is concave and has positive refractive
power.
[0150] Lens materials for the first lens 11 and for the second lens
12 are selected so that both lenses may have different Abbe numbers
from each other. Abbe number is a constant indicating optical
dispersion of a lens material, and it shows an extent of refraction
of beams with different wavelengths in different directions.
[0151] Materials of image pickup lens 100 are selected so that a
difference between Abbe number .nu.1 of the first lens 11 and Abbe
number .nu.2 of the second lens 12 (.nu.1-.nu.2) may exceed 10.
[0152] FIG. 2 is an enlarged diagram of the first lens 11 and the
second lens 12 of the image pickup lens 100 whose materials are
selected so that the difference (.nu.1-.nu.2) between Abbe number
.nu.1 of the first lens 11 and Abbe number .nu.2 of the second lens
12 may exceed 10. Incidentally, FIG. 2 is shown exaggeratedly.
[0153] As for beams shown in FIG. 2a, when beams having plural
wavelengths enter the first lens 11 having positive refractive
power, beam P21 whose wavelength is shorter than that of beam P11
having a longer wavelength is much refracted toward the optical
axis P side. So, an optical path of the beam P21 having a shorter
wavelength appears at the closer position to the optical axis P,
and beam P11 having a longer wavelength appears to be outside the
aforesaid optical path. Namely, if beams having plural wavelengths
enter the first lens 11 having positive refractive power, the beams
are separated toward the optical axis P.
[0154] When second lens 12 having negative refractive power and
having a concave surface that faces the image side is arranged on
the image side of the first lens 11, beam P21 having a shorter
wavelength enters the second lens 12 to be closer to optical axis P
side, and beam P11 having a longer wavelength enters to be outside
of the beam P21, on the second lens. Then, the beam P21 having a
shorter wavelength is refracted to the outside of the optical axis
P more than the beam P11 having a longer wavelength. Namely, the
beams are separated toward the optical axis P once when entering
the first lens 11, then, they are collected rapidly toward the
outside of the optical axis P when entering the image side surface
of the second lens 12. Thereby, chromatic aberration caused when
the beams enters the first lens 11 having positive refractive power
can be corrected.
[0155] When a difference between Abbe number .nu.1 of first lens 11
and Abbe number .nu.2 of second lens 12 (dv=.nu.1-.nu.2) exceeds
10, an extent of the collection of beams in the second lens 12 with
negative refractive power is greater than that of separation of
beams in the first lens 11 with positive refractive power, thus,
the separated beams are collected rapidly and chromatic aberration
can be corrected through a shorter optical path.
[0156] Namely, it is preferable that the difference dv between the
Abbe number .nu.1 of the first lens 11 and the Abbe number .nu.2 of
the second lens 12 satisfies the following conditions.
[0157] When the difference dv in Abbe number between the first lens
11 with positive refractive power and the second lens 12 with
negative refractive power exceeds 10, chromatic aberration can be
corrected satisfactorily, but when the difference dv is 10 or less,
it is difficult to correct chromatic aberration. Meanwhile, when
the difference dv in Abbe number is 70 or more, it is difficult to
combine lens materials suitable for a mobile terminal, on the
points of cost and mass productivity.
[0158] When resin materials are used for the first lens 11 and the
second lens 12, it is necessary, from characteristics of resin lens
materials, that the difference dv in Abbe number is less than
40.
[0159] Further, the image pickup lens 100 corrects its chromatic
aberration by providing the first lens 11 with positive refractive
power on a surface of the first lens substrate 1 facing the object
side and the second lens 12 with negative refractive power on a
surface of the first lens substrate 1 facing the image side. In
other words, it has the structure to cancel chromatic aberration
caused by the first lens 11 with positive refractive power and
chromatic aberration caused by the second lens 12 with negative
refractive power each other. Since the first lens substrate 1 is a
parallel flat plate, chromatic aberration caused by the first lens
11 can be controlled to be small, as will be stated later. Such the
structure is most effective for correcting chromatic aberration,
when resins whose dispersion is extremely great or is extremely
small cannot be used for the lens system for the purpose of mass
production because the materials are expensive.
[0160] Now, there will be explained a mechanism to control
chromatic aberration caused by the first lens 11 to be small by the
first lens substrate 1. With respect to the first lens substrate 1,
it is preferable that refractive index n2 of the first lens
substrate 1 is greater than refractive index n1 of the first lens
11. As is shown in FIG. 2a, beam P22 having a shorter wavelength is
generally refracted more largely by the object side surface of the
first lens 11 with positive refractive power, than beam P12 having
a longer wavelength. In this case, with respect to beams entering
the object side surface of the first lens substrate 1, an incident
angle of the beam P22 having a shorter wavelength to enter the
object side surface of the first lens substrate 1, is greater than
that of beam P12 having a longer wavelength. Further, as for a
refractive index ratio of the first lens 11 with positive
refractive power to the first lens substrate 1, the refractive
index ratio for beam P22 having a shorter wavelength is also
greater than that for beam P12 having a longer wavelength. As is
understood from Snell's low, a difference between an optical path
of beam P22 having a shorter wavelength and an optical path of beam
P12 having a longer wavelength is made to be small by the effects
of both factors. In other words, chromatic aberration can be
controlled to be small. In addition, the first lens substrate 1 has
a prescribed thickness, and when beams having different wavelengths
pass the thickness in the condition that the dispersion is
controlled as described above, the dispersion is more controlled
compared with an occasion where the first lens substrate 1 is not
present.
[0161] Explaining in detail, beams are separated into the upper
part and the lower part (P21, P11) by the first lens 11 with
positive refractive power formed on the object side surface of the
first lens substrate 1 as shown in FIG. 2a. When there is no action
of a parallel flat plate (first lens substrate 1), the beam travels
straight to the image side surface of the second lens 12 to be
refracted on the image side surface of the second lens 12. On the
other hand, when refractive index n2 of the parallel flat plate
(first lens substrate 1) is greater than refractive index n1 of the
first lens 11 with positive refractive power (P22, P12), dispersion
of beams having different wavelengths is controlled by refraction
on the object side surface of the parallel flat plate (first lens
substrate 1), and the beams travel by an amount equivalent to a
thickness of the parallel flat plate (first lens substrate 1),
whereby, the dispersion is controlled to be smaller than an
occasion where the parallel flat plate (first lens substrate 1) is
not present.
[0162] More preferably, when refractive index n2 of the first lens
substrate 1 is greater than refractive index n1 of the first lens
11, it is preferable that Abbe number .nu.0 of the first lens
substrate 1 is small (for example, .nu.0.ltoreq.60). In other
words, it is preferable to be smaller than Abbe number .nu.1 of the
first lens 11. Abbe number is a number indicating dispersion
obtained from refractive indexes for F line, C line and d line. A
small Abbe number means a large difference in refractive indexes
between, for example, F line and C line, and it can increase an
effect that the aforesaid beam having a shorter wavelength is be
refracted further more greatly.
[0163] Further, when refractive index n2 of the first lens
substrate 1 is smaller than refractive index n1 of the first lens
11, it is preferable that Abbe number .nu.0 of the first lens
substrate 1 is great (for example, .nu.0>50). When refractive
index n2 of the first lens substrate 1 is smaller than refractive
index n1 of the first lens 11, the parallel flat plate (first lens
substrate 1) enlarges dispersion of beams having different
wavelengths caused by the first lens 11 with positive refractive
power as shown in FIG. 2b, which is not preferable. However, it is
possible to control chromatic aberration to be small by making Abbe
number .nu.0 of the parallel flat plate (first lens substrate 1) to
be great, namely, by selecting materials which make a difference in
refractive indexes between F line and C line to be small. Such the
structure represents a method that is effective in a wafer scale
lens.
[0164] Explaining in detail, beams are separated into the upper
part and the lower part (P21, P11) by the object side surface of
the first lens 11 with positive refractive power formed on the
object side surface of the first lens substrate 1 as shown in FIG.
2b. When there is no action of a parallel flat plate (first lens
substrate 1), the beams travel straight to the surface of the
second lens 12 to be refracted on the image side surface of the
second lens 12. On the other hand, when refractive index n2 of the
parallel flat plate (first lens substrate 1) is smaller than
refractive index n1 of the first lens 11 with positive refractive
power (P22, P12), dispersion of the beams having a different
wavelength is enlarged by their refraction on the object side
surface of the parallel flat plate (first lens substrate 1).
However, when refractive index n2 of the parallel flat plate (first
lens substrate 1) is smaller than refractive index n1 of the first
lens 11 with positive refractive power, and when Abbe number .nu.0
of the parallel flat plate (first lens substrate 1) is great (P23,
P13), dispersion is controlled to be smaller by the large Abbe
number .nu.0 than an occasion where Abbe number .nu.0 is small.
[0165] Further, since the first lens substrate 1 is a parallel flat
plate, the substrate is easily processed, and power is not present
on a boundary face between the first lens 11 and the second lens
12, thereby, an influence on a focal position on the image plane
caused by its surface accuracy is small. In addition, this
structure matches with a wafer scale lens. Owing to the aforesaid
structure, cost becomes low, and deterioration of MTF caused by
chromatic aberration can be controlled to be small.
[0166] In the image pickup lens 100 wherein there are provided
first lens 11 with positive refractive power and second lens 12
with negative refractive power, and the difference dv between Abbe
number .nu.1 of the first lens 11 and Abbe number .nu.2 of the
second lens 12 exceeds 10, it is preferable that a ratio of a focal
length of the first lens 11 to a focal length of the total lens
system is made to be from 0.6 to 1.0.
[0167] When a ratio f.sub.R of the focal length of the first lens
11 to the focal length of the total lens system is 0.6 or higher,
distortion is corrected satisfactorily. When the ratio is less than
0.6, correction of spherical aberration and astigmatism becomes
difficult. If the ratio of the focal length of the first lens 11 to
the focal length of the total lens system is 1.0 or lower, it is
possible to construct the total optical system to be short. If the
ratio is more than 1.0, the total optical system becomes long in
size. In each lens in the invention, a lens formed on the object
side surface of the lens substrate provides a focal length in case
that the object side of the lens is filled with air and the image
side of the lens is filled with the medium of the lens substrate.
Meanwhile, a lens formed on the image side surface of the lens
substrate provides a focal length in case that the object side of
the lens is filled with a medium of the lens substrate, and the
image side of the lens is filled with the air. As for a lens which
are not cemented with another, the focal length on the object side
surface represents a focal length in the case that the object side
of the lens surface is filled with air and the image side of the
lens surface is filled with a medium of the lens, and the focal
length on the image side surface represents a focal length in the
case that the object side of the lens surface is filled with the
medium of the lens and the image side of the lens surface is filled
with the air, so as to correspond to the above.
[0168] In the image pickup lens 100, the second lens substrate 2 is
arranged at the image side of the first lens 12, and a lens or
lenses with at least positive or negative refractive power is
arranged on one side or both sides of the second lens substrate 2.
Thereby, Petzval's sum can be controlled, and astigmatism can be
corrected satisfactorily. Further, when an additional lens
substrate is provided at the image side of fourth lens 24, it is
possible to control the Petzval's sum to be smaller and to correct
the astigmatism more satisfactorily, by forming at least a lens
with positive or negative refractive power on one side or on both
sides of the lens substrate.
[0169] The Petzval's sum represents an expression indicating
relationship between a planar object and a curvature of field for
the planar object. It is necessary to optimize combination of focal
lengths and refractive powers of lens materials of respective
lenses, to control the curvature of field. It is preferable that
the Petzval's sum of the image pickup lens 100 is made be 0.14 or
less. By making the Petzval's sum to be 0.14 or less, astigmatism
can be corrected satisfactorily even in an optical system with a
short total optical length. If the Petzval's sum exceeds 0.14, it
is difficult to correct astigmatism.
[0170] It is preferable that value Sv obtained by normalizing an
amount of an aspheric sag of the lens surface closest to the image
side in the image pickup lens 100, by the maximum image height,
namely, value Sv obtained by normalizing an amount of an aspheric
sag of the image side surface of fourth lens 24 in the present
embodiment by the maximum image height, is made to be 0.14 or more.
In this case, an amount of an aspheric sag means a value measured
at a height of a principal ray at the maximum image height and
measured at a height in the direction perpendicular to an optical
axis. The maximum image height means a half length of the diagonal
line of a solid-state imaging device in a rectangular shape.
[0171] By making this value Sv to be 0.14, it is possible to secure
an excellent aberration property in an optical system with the
short total optical length, and to keep an angle of incidence for
an image sensor such as CCD to be small, in an area where an image
height is great. If the value Sv is 0.14 or less, it is difficult
to correct distortion, and an angle of incidence for an image
sensor such as CCD becomes large in an area where an image height
is great, and shading is caused.
[0172] Further, when m.sup.th lens represents a lens at the
m.sup.th position (where, m.gtoreq.3) which is the third lens or a
lens arranged at the image side of the third lens in the image
pickup lens 100, it is preferable that the m.sup.th lens has
negative power, and that a ratio of focal length f.sub.1 of the
first lens to focal length f.sub.m of the m.sup.th lens is made to
be from -0.7 to 0.
[0173] As for axial chromatic aberration, it is given by the
following expression (27), and chromatic aberration can be
corrected by arranging the m.sup.th lens with negative power
wherein a ratio of focal length f.sub.1 of the first lens to focal
length f.sub.m of the m.sup.th lens satisfies the range which is
not less than -0.7 and not more than 0. If the ratio is less than
-0.7, it is difficult to correct chromatic aberration, and if the
ratio is more than 0, it hardly corrects chromatic aberration.
[ Math . 26 ] i ( h i h 1 ) 2 1 v i f i ( 27 ) ##EQU00009##
[0174] Further, it is preferable that Abbe number .nu..sub.m of
i.sup.th lens is made to be from 20 to 50. If it exceeds 50, it is
difficult to correct chromatic aberration, and if it is less than
20, excessive correction of chromatic aberration is caused,
depending on power of the lens with negative power, resulting in
difficult correction of chromatic aberration.
[0175] The image pickup lens 100 exhibits the total length which is
1.2 times or less as long as the focal length, and an excellent
aberration correction function even when the total optical length
is still shorter, by following the conditions: the difference in
Abbe number dv, relationship between the refractive index n1 of the
first lens 11 and the refractive index n2 of first lens substrate
1, value f.sub.R obtained by normalizing the focal length f.sub.s1
of the object side lens surface of first lens 11 by the focal
length f of the total lens system, Petzval's sum pn, aspheric sag
amount Sv on the surface closest to the image side, and a ratio of
the focal length f.sub.1 of the first lens to the focal length
f.sub.m of the m.sup.th lens.
[0176] Further, when the image side surface of the lens closest to
the image side has negative refractive power, it is possible to
arrange the position of a rear principal point closer to the object
side. In image pickup lenses having the same focal lengths, an
image pickup lens in which the image side principal point is
positioned at a position closer to the object side, becomes more
compact, which is preferable.
Embodiment 2
[0177] FIG. 16 is a diagram showing an image pickup lens relating
to Embodiment 2.
[0178] In image pickup lens 100 relating to Embodiment 2, there are
arranged an aperture stop 1a on the object side, first lens
substrate 1 on the image side and the rear of the aperture stop,
and optical member 7 in a form of a parallel flat plate on the
image side and the rear of the first lens substrate. On the first
lens substrate 1, first lens 11 and second lens 12 which are the
same as those in Embodiment 1 are formed. In image pickup lens 100
of such the structure, optical member 7 arranged at the closest
position to the image side causes negative distortion to reduce
positive distortion caused by the negative power of the second lens
12. Further, when curvature of field is caused, it keeps a sagittal
image plane and a meridional image plane in a balanced manner. The
wording saying that "when curvature of field is caused" in this
case means a situation wherein both of the sagittal image plane and
the meridional image plane are inclined toward the negative
direction.
[0179] The effect of the kept image planes in a balanced manner by
optical member 7 will be explained as follows. It is known that the
optical member 7 generates astigmatism based on the following
expression (13).
[ Math . 27 ] D g 2 n ( 1 - con 2 U con 2 U ' ) conU conU ' ( 13 )
##EQU00010##
[0180] In the aforesaid expression, U represents an incident angle
of a beam that enters optical member 7, U' represents an outgoing
angle of a beam that emerges from the optical member 7, Dg
represents a thickness of the optical member 7, and n represents a
refractive index of the optical member 7.
[0181] Owing to the foregoing, it is also known that the sagittal
image plane and the meridional image plane are changed at a ratio
of about 1:3. In other words, though there is generated a
difference between the sagittal image plane and the meridional
image plane, the sagittal image plane can be improved, and the
meridional image plane can be kept to be in a permissible level
that it can be regarded as an excellent image plane, because the
meridional image plane is covering the paraxial image plane.
[0182] In this case, it is preferable that the ratio of the
thickness of the optical member 7 to the focal length of the total
lens system is made to be 0.1 or more. The reason for this is that
positive distortion generated by negative power of second lens 12
is canceled with negative distortion generated by optical member 7.
In addition, if a thickness of the optical member 7 is greater, an
amount of negative distortions generated by the optical member 7 is
larger, and the cancelled amount becomes larger.
[0183] If ratio D.sub.R of a thickness of the optical member 7 to a
focal length of the total lens system is 0.1 or less, a thickness
of the optical member 7 is thin, which is unsuitable for
manufacturing. In addition, correction of distortion becomes too
small to be ineffective.
[0184] With respect to the optical member 7, it is preferable that
a ratio of a difference in optical path length between a principal
ray at the maximum image height and an axial ray to a focal length
of the total lens system is made to be less than 0.13. It provides
the optical member a function to reduce the difference in optical
path length between the axial ray and the principal ray of the
maximum image height to be small. In other words, a distance to
arrive at the image plane becomes short under Snell laws, which
means that distortion can be made small by refraction. If ratio
l.sub.R of the difference in optical path length between the axial
ray and the principal ray of the maximum image height to the focal
length of the total lens system is 0.13 or more, a function to
correct the distortion becomes small, or the distortion generated
by image pickup lens 100 in the present embodiment becomes still
greater.
[0185] It is possible for image pickup lens 100 to have excellent
property to correct aberrations by following various conditions
such as the ratio D.sub.R of the thickness of optical member 7 to
the focal length of the total lens system, and the ratio l.sub.R of
the difference in optical path length between the principal ray at
the maximum image height and the axial ray to the focal length of
the total lens system.
Variation Example
[0186] FIG. 22 is a diagram showing an image pickup lens relating
to a variation example of Embodiment 1 and Embodiment 2.
[0187] In image pickup lens 100 relating to the variation example,
there are arranged aperture stop 1a on the object side and first
lens substrate 1 on the image side and the rear of the aperture
stop. On the first lens substrate 1, first lens 11 and second lens
12 which are the same as those in Embodiment 1 and Embodiment 2 are
formed. There are not arranged the second lens substrate 2 shown in
Embodiment 1 and optical member 7 shown in Embodiment 2. Further,
the image side surface of the second lens 12 is formed into an
aspheric surface.
[0188] The image pickup lens 100 having such the structure can
controls axial chromatic aberration and magnification chromatic
aberration to be low in spite of its simple structure, by
satisfying a condition of the expression (1) or expression (2) of
the difference dv between Abbe number .nu.1 of the first lens 11
and Abbe number .nu.2 of the second lens 12, which is the same as
occasions of Embodiment 1 and Embodiment 2. Further, by forming the
image side surface of the second lens 12 into an aspheric shape,
distortion and a curvature of field can be controlled.
EXAMPLE
[0189] Data and measurement results of aberrations of respective
examples and variation examples of image pickup lens 100 relating
to Embodiment 1 and Embodiment 2 will be shown below. The examples
use the following signs. [0190] R: Curvature radius of lens (mm)
[0191] D: Axial distance of lens surfaces (mm) [0192] Nd:
Refractive index of lens [0193] .nu.: Abbe number of lens
[0194] In each example, a form of an aspheric surface is
represented by the following expression (14) which is an expression
of a displacement amount X of the aspheric surface, where a tip of
the surface is the origin, the X axis extends in a direction of the
optical axis, and h is a height along a perpendicular direction to
the optical axis.
[ Math . 28 ] X = h 2 / R 1 + 1 ( 1 + K ) h 2 / R 2 + A i h i ( 14
) ##EQU00011##
[0195] In the aforesaid expression, A.sub.i represents an aspheric
surface coefficient of i.sup.th order (where i=4, 6, 8 . . . ), and
K represents a conic constant.
[0196] Aberrations were measured and the difference dv between Abbe
number .nu.1 of the first lens 11 and Abbe number .nu.2 of the
second lens 12 was evaluated, based on a form of the aspheric
surface and on data of working examples. Namely, the following
expression (15) was evaluated for each example.
[Math. 29]
d.nu.=.nu.1-.nu.2 (15)
[0197] Further, in each example, the ratio f.sub.R was evaluated,
where the value of f.sub.R is a ratio of the focal length of the
first lens 11 to the focal length of the total lens system in image
pickup lens 100 wherein Abbe number of the first lens 11 is
different from that of the second lens 12. Namely, the following
expression (16) was evaluated for each example.
[ Math . 30 ] f R = f s 1 f ( 16 ) ##EQU00012##
[0198] In the aforesaid expression, f.sub.s1 represents a focal
length of the object side surface on of the first lens 11, and f
represents a focal length of the total lens system.
[0199] Further, in each example, Petzval's sum pn in image pickup
lens 100 wherein Abbe number of the first lens 11 is different from
that of the second lens 12, was evaluated. Namely, the following
expression (17) was evaluated for each example.
[ Math . 31 ] pn = j 1 f j n j ( 17 ) ##EQU00013##
[0200] In the aforesaid expression, f.sub.j represents a focal
length of j.sup.th lens, and n.sub.j represents a refractive index
of the j.sup.th lens.
[0201] Further, in Examples 1 through 7 and Example 16, value Sv
was evaluated, where the value Sv is calculated by normalizing an
amount of an aspheric sag of the lens surface arranged at the
closest position to the image side of image pickup lens 100 wherein
Abbe number of the first lens 11 is different from that of the
second lens 12, by the maximum image height. Namely, the following
expression (18) was evaluated for Examples 1 through 7 and Example
16.
[ Math . 32 ] Sv = X - X 0 Y ( 18 ) ##EQU00014##
[0202] In the aforesaid expression, X represents a displacement
amount of an aspheric surface given by the following expression
(19), and it is a value at a height in the direction perpendicular
to the optical axis of a principal ray at the maximum image
height.
[0203] X.sub.0 represents a displacement amount of a component of
quadratic surface of revolution of the aspheric surface given by
the following expression (20), and it is a value at the height in
the direction perpendicular to the optical axis of a principal ray
at the maximum image height.
[0204] Y represents the maximum image height.
[ Math . 33 ] X = h 2 / R 1 + 1 ( 1 + K ) h 2 / R 2 + A i h i ( 19
) [ Math . 34 ] X 0 = h 2 / R 1 + 1 - ( 1 + K ) h 2 / R 2 ( 20 )
##EQU00015##
[0205] In the aforesaid expression, A.sub.i represents i.sup.th
order aspheric surface coefficient of the lens surface closest to
the image side, Ro represents a curvature radius of the lens
surface closest to the image side, and Ko represents a conic
constant closest to the image side.
[0206] Further, in Examples 1 through 7 and Example 16, a ratio of
the focal length f.sub.1 of the first lens to the focal length
f.sub.1 of the i.sup.th lens was evaluated. Namely, the following
expression (25) was evaluated for Examples 1 through 7 and Example
16.
[ Math . 35 ] - 0.7 .ltoreq. f 1 fm < 0 ( 25 ) ##EQU00016##
[0207] Further, in Examples 8 through 10, Example 14 and Example
15, the value of D.sub.R was evaluated, where the value D.sub.R is
a ratio of a thickness of parallel flat plate 7 to the focal length
of the total lens system in image pickup lens 100 wherein Abbe
number of the first lens 11 is different from that of the second
lens 12. Namely, the following expression (21) was evaluated in
Examples 8 through 10, Example 14 and Example 15.
[ Math . 36 ] D R = D g f ( 21 ) ##EQU00017##
[0208] Further, in Examples 8 through 11, Example 14 and Example
15, the value of l.sub.R was evaluated, where the value l.sub.R is
a ratio of a difference between an optical path length of a axial
ray and an optical path length of a principal ray at the maximum
image height to the focal length of the total lens system in image
pickup lens 100 wherein Abbe number of the first lens 11 is
different from that of the second lens
12. Namely, the following expression (22) was evaluated in Examples
8 through 11, Example 14 and Example 15.
[ Math . 37 ] I R = I 2 - I 1 f ( 22 ) ##EQU00018##
First Example
[0209] Data of relating to the First Example of image pickup lens
100 based on Embodiment 1 are shown in Table 1 and Table 2. An
illustration of the image pickup lens 100 relating to the first
example will be omitted because it is the same as the image pickup
lens 100 relating to Embodiment 1 in terms of structure. Further,
an aberration diagram of the image pickup lens 100 providing the
data is shown in FIG. 3.
[0210] With respect to the image pickup lens 100 relating to the
first example, Abbe number .nu.1 of the first lens 11 is 54.00, and
Abbe number .nu.2 of the second lens 12 is 29.00, as shown in
Tables.
TABLE-US-00001 TABLE 1 Surface No. R D Nd .nu. 1* 0.911 0.290
1.50710 54.00 2(ape) .infin. 0.390 1.48749 70.44 3 .infin. 0.110
1.57370 29.00 4* 1.564 0.684 5* 3.611 0.115 1.50710 54.00 6 .infin.
0.304 1.48749 70.44 7 .infin. 0.355 1.50710 54.00 8* 5.353 0.928 9
.infin. BF Fno HFOV TL 0.928 2.8 30.63 3.177
TABLE-US-00002 TABLE 2 Aspheric surface coefficient ** K A B C D E
F G H I 1 6.08E-03 -4.68E-03 9.08E-02 -9.80E-02 -5.25E-01 -6.08E-01
5.71E+00 0.00E+00 0.00E+00 0.00E+00 4 5.15E+00 7.41E-02 1.47E-01
7.91E-02 1.48E-01 -1.24E+00 -1.42E+00 0.00E+00 0.00E+00 0.00E+00 5
-4.71E+01 -7.85E-02 -4.45E-02 -2.47E-02 -3.66E-06 1.20E-02 1.39E-02
0.00E+00 0.00E+00 0.00E+00 8 4.12E-01 -6.53E-02 -2.39E-02 -8.17E-03
2.68E-03 -1.28E-03 -5.39E-04 0.00E+00 0.00E+00 0.00E+00 **Surface
No.
[0211] In Table 1, Surface No. 1 represents the object side surface
of the first lens 11, Surface No. 2 represents the image side
surface of the first lens 11, Surface No. 3 represents the object
side surface of the second lens 12, Surface No. 4 represents the
image side surface of the second lens 12, Surface No. 5 represents
the object side surface of the third lens 23, Surface No. 6
represents the image side surface of the third lens 23, Surface No.
7 represents the object side surface of the fourth lens 24, and
Surface No. 8 represents the image side surface of the fourth lens
24. Further, mark * in the drawings shows an aspheric surface. Sign
(ape) in the drawings shows that aperture stop 1a is formed on the
lens surface indicated by that surface number.
Second Example
[0212] FIG. 4 is a schematic diagram relating to the second example
of image pickup lens 100 based on Embodiment 1.
[0213] An arrangement of lens substrates and lenses is the same as
that shown in Embodiment 1. Table 3 and Table 4 show data of a
working example of image pickup lens 100 including this optical
system. FIG. 5 shows an aberration diagram of the image pickup lens
including this optical system and providing data of the working
example.
[0214] With respect to the image pickup lens 100 relating to the
second example, Abbe number .nu.1 of the first lens 11 is 55.72,
and Abbe number .nu.2 of the second lens 12 is 30.23, as shown in
Tables.
TABLE-US-00003 TABLE 3 Surface No. R D Nd .nu. 1* 0.893 0.361
1.53048 55.72 2(ape) .infin. 0.302 1.49974 62.16 3 .infin. 0.159
1.58340 30.23 4* 1.459 0.508 5* 9.342 0.187 1.53048 55.72 6 .infin.
0.411 1.49974 62.16 7 .infin. 0.441 1.53048 55.72 8* 17.669 0.809 9
.infin. BF Fno HFOV TL 0.8086 2.8 30.96 3.177
TABLE-US-00004 TABLE 4 Aspheric surface coefficient ** K A B C D E
F G H I 1 -1.09E-02 -5.00E-03 9.04E-02 -1.75E-01 -3.06E-01
-1.32E-01 5.97E+00 -7.17E+00 5.00E+00 -6.89E-03 4 4.09E+00 1.01E-01
2.25E-01 1.25E-03 3.27E+00 -3.52E+00 2.75E-01 -8.80E-01 -4.84E+01
-2.70E+01 5 -3.70E+02 -1.60E-01 -1.94E-02 -2.97E-02 -6.92E-02
-9.81E-02 3.33E-02 3.63E-01 0.00E+00 0.00E+00 8 9.93E+01 -5.49E-02
-4.07E-02 -8.86E-03 1.03E-03 1.44E-03 -9.40E-05 -1.15E-03 0.00E+00
0.00E+00 **Surface No.
Third Example
[0215] FIG. 6 is a schematic diagram relating to the third example
of image pickup lens 100 based on Embodiment 1.
[0216] An arrangement of lens substrates and lenses is the same as
that shown in Embodiment 1. Table 5 and Table 6 show data of a
working example of image pickup lens 100 including this optical
system. FIG. 7 shows an aberration diagram of an image pickup lens
including this optical system and providing data of the working
example.
[0217] With respect to the image pickup lens 100 relating to the
third example, Abbe number .nu.1 of the first lens 11 is 54.00, and
Abbe number .nu.2 of the second lens 12 is 29.00, as shown in
Tables.
TABLE-US-00005 TABLE 5 Surface No. R D Nd .nu. 1* 0.938 0.310
1.50710 54.00 2(ape) .infin. 0.379 1.48752 70.42 3 .infin. 0.100
1.57370 29.00 4* 1.740 0.734 5* 3.356 0.124 1.50710 54.00 6 .infin.
0.303 1.48752 70.42 7 .infin. 0.416 1.50710 54.00 8* 4.230 0.810 9
.infin. BF Fno HFOV TL 0.8105 2.8 31.15 3.177
TABLE-US-00006 TABLE 6 Aspheric surface coefficient Sur- face No. K
A B C D E F G H I 1 3.32E-03 -5.96E-03 9.10E-02 -3.15E-02 -3.97E-01
-4.04E-01 3.91E+00 0.00E+00 0.00E+00 0.00E+00 4 5.82E+00 1.04E-01
1.63E-01 -3.99E-02 1.97E-01 2.73E-01 -7.07E-01 0.00E+00 0.00E+00
0.00E+00 5 -4.41E+01 -6.96E-02 -2.97E-02 -9.84E-03 4.86E-03
7.38E-03 2.52E-03 0.00E+00 0.00E+00 0.00E+00 8 -5.87E+01 -3.94E-02
-7.25E-03 -1.25E-02 1.82E-03 -6.82E-04 1.41E-04 0.00E+00 0.00E+00
0.00E+00
Fourth Example
[0218] FIG. 8 is a schematic diagram relating to the fourth example
of image pickup lens 100 based on Embodiment 1.
[0219] An arrangement of lens substrates and lenses is the same as
that shown in Embodiment 1. Table 7 and Table 8 show data of a
working example of image pickup lens 100 including this optical
system. FIG. 9 shows an aberration diagram of an image pickup lens
including this optical system and providing data of the working
example.
[0220] With respect to the image pickup lens 100 relating to the
fourth example, Abbe number .nu.1 of the first lens 11 is 54.00,
and Abbe number .nu.2 of the second lens 12 is 29.00, as shown in
Tables.
TABLE-US-00007 TABLE 7 Surface No. R D Nd .nu. 1* 0.808 0.489
1.50710 54.00 2(ape) .infin. 0.300 1.64924 29.92 3 .infin. 0.080
1.57370 29.00 4* 2.301 0.373 5* -1.948 0.100 1.50710 54.00 6
.infin. 0.695 1.64924 29.92 7 .infin. 0.680 1.50710 54.00 8* 18.783
0.463 9 .infin. BF Fno HFOV TL 0.4625 2.8 30.56 3.179
TABLE-US-00008 TABLE 8 Aspheric surface coefficient ** K A B C D E
F G H I 1 -1.20E-01 1.30E-02 2.66E-02 1.51E-01 -1.54E-01 -2.05E-01
2.63E+00 -3.72E+00 3.33E+00 2.59E+00 4 1.63E+01 3.20E-02 2.71E-01
-9.96E-01 1.63E+00 -2.38E+00 7.12E+01 -3.52E+00 -4.13E+01 -5.28E+02
5 1.04E+01 -4.11E-01 3.07E-01 -4.63E+00 9.15E+00 -4.59E+00
-7.14E+01 -2.51E+01 -6.52E+01 -1.88E+02 8 -3.60E+04 -3.72E-02
-1.36E-01 5.58E-02 2.95E-03 -1.45E-02 -4.84E-03 4.32E-03 2.28E-03
-1.37E-03 ** Surface No.
Fifth Example
[0221] FIG. 10 is a schematic diagram relating to the fifth example
of image pickup lens 100 based on Embodiment 1.
[0222] An arrangement of lens substrates and lenses is the same as
that shown in Embodiment 1. Table 9 and Table 10 show data of a
working example of image pickup lens 100 including this optical
system. FIG. 11 shows an aberration diagram of an image pickup lens
including this optical system and providing data of the working
example.
[0223] With respect to the image pickup lens 100 relating to the
fifth example, Abbe number .nu.1 of the first lens 11 is 70.45, and
Abbe number .nu.2 of the second lens 12 is 31.16, as shown in
Tables.
TABLE-US-00009 TABLE 9 Surface No. R D Nd .nu. 1* 0.934 0.362
1.48749 70.45 2(ape) .infin. 0.427 1.68855 47.43 3 .infin. 0.074
1.68893 31.16 4* 2.194 0.726 5* 4.356 0.124 1.53048 55.72 6 .infin.
0.362 1.68855 47.43 7 .infin. 0.619 1.53048 55.72 8* 6.134 0.753 9
.infin. BF Fno HFOV TL 0.7526 2.8 30.43 3.448
TABLE-US-00010 TABLE 10 Aspheric surface coefficient ** K A B C D E
F G H I 1 1.78E-02 -2.99E-03 1.01E-01 -6.96E-03 -3.67E-01 -4.39E-01
3.39E+00 0.00E+00 0.00E+00 0.00E+00 4 6.32E+00 1.17E-01 2.15E-01
1.70E-01 1.01E+00 9.13E-01 -3.45E+00 0.00E+00 0.00E+00 0.00E+00 5
-4.52E+01 -7.05E-02 -2.74E-02 -9.45E-03 2.67E-03 6.76E-03 2.96E-03
0.00E+00 0.00E+00 0.00E+00 8 -9.45E+00 -3.51E-02 -7.32E-03
-1.25E-02 1.77E-03 -6.39E-04 2.11E-04 0.00E+00 0.00E+00 0.00E+00 **
Surface No.
Sixth Example
[0224] FIG. 12 is a schematic diagram relating to the sixth example
of image pickup lens 100 based on Embodiment 1.
[0225] In the image pickup lens 100 relating to the sixth example,
there are arranged a first lens substrate 1 at the object side, and
a second lens substrate 2 at the image side of the first lens
substrate. Further, there is arranged a third lens substrate 3 at
the image side of the second lens substrate 2. The first lens
substrate 1 and the second lens substrate 2 are arranged with the
predetermined distance between them. The second lens substrate 2
and the third lens substrate 3 are arranged with the predetermined
distance between them. Each of the first lens substrate 1, the
second lens substrate 2, and the third lens substrate 3 is a
parallel flat plate. Further, there is arranged an image sensor 4
of a CCD type or a CMOS type at the image side of the third lens
substrate 3.
[0226] The first lens substrate 1 includes a first lens 11 formed
on its object side surface and a second lens 12 formed on its image
side surface. Further, the second lens substrate 2 includes a third
lens 23 formed on its object side surface and a fourth lens 24
formed on its image side surface. The third lens substrate 3
includes a fifth lens 35 formed on its object side surface and a
sixth lens 36 formed on its image side surface.
[0227] As a lens section, the first lens 11, the second lens 12,
the third lens 23, the fourth lens 24, the fifth lens 35, and the
sixth lens 36 are arranged, in this order from the object side. A
surface coming in contact with the air of each of the lenses 11,
12, 23, 24, 35, and 36 is formed into an aspheric surface. Each of
the lenses 11, 12, 23, 24, 35, and 36 employs a resin material as
its lens material.
[0228] Further, there is arranged an aperture stop 1a between the
first lens 11 and the first lens substrate 1, where the aperture
stop shields visible light contributing to image forming.
[0229] The first lens 11 has a positive refractive power. The
second lens 12 has a negative refractive power. The third lens 23
has a negative refractive power. The fourth lens 24 has a positive
refractive power. The fifth lens 35 has a negative refractive
power. The sixth lens 36 has a positive refractive power.
[0230] The manufacturing method of the image pickup lens 100 is the
same as that of the first example.
[0231] Tables 11 and 12 shows data of a working example of the
image pickup lens 100 including this optical system.
[0232] FIG. 13 shows an aberration diagram of the image pickup lens
including this optical system and providing data of the working
example.
[0233] With respect to the image pickup lens 100 relating to the
sixth example, Abbe number .nu.1 of the first lens 11 is 54.00, and
Abbe number .nu.2 of the second lens 12 is 26.00, as shown in
Tables.
TABLE-US-00011 TABLE 11 Surface No. R D Nd .nu. 1* 0.758 0.360
1.50710 54.00 2(ape) .infin. 0.303 1.84078 40.83 3 .infin. 0.114
1.61000 26.00 4* 2.606 0.281 5* -1.751 0.095 1.61000 26.00 6
.infin. 0.360 1.84078 40.83 7 .infin. 0.198 1.61000 26.00 8*
-33.387 0.110 9* 7.682 0.110 1.53048 55.72 10 .infin. 0.312 1.84078
40.83 11 .infin. 0.510 1.53048 55.72 12* 5.749 0.528 13 .infin. BF
Fno HFOV TL 0.5282 2.8 30.64 3.28
TABLE-US-00012 TABLE 12 Aspheric surface coefficient ** K A B C D E
F G H I 1 1.52E-02 -8.73E-03 1.07E-01 -1.83E-01 6.94E-01 -2.14E+00
8.57E+00 0.00E+00 0.00E+00 0.00E+00 4 2.72E+01 3.43E-02 -4.99E-01
1.14E+00 -9.83E-01 -1.15E+01 -1.45E+01 -2.16E+02 8.29E+02 0.00E+00
5 1.11E+01 -1.82E-01 -1.14E+00 2.31E+00 -1.22E+01 3.69E+00 2.58E+01
-3.77E+00 -1.62E+03 -2.05E+03 8 0.00E+00 -7.36E-02 -2.57E-02
-1.62E-02 -2.96E-02 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 9
-5.44E+02 -1.09E-01 -2.61E-03 -8.62E-03 -1.58E-02 -1.89E-02
-1.65E-02 -1.02E-02 6.72E-04 1.60E-02 12 -1.31E+02 -1.39E-01
2.93E-02 -2.37E-02 -1.76E-02 8.83E-03 5.73E-03 -3.87E-03 5.37E-05
1.47E-04 ** Surface No.
[0234] In Table 11, Surface No. 9 represents the object side
surface of the fifth lens 35, Surface No. 10 represents the image
side surface of the fifth lens 35, Surface No. 11 shows the object
side surface of the sixth lens 36, Surface No. 12 shows an image
side surface of the fifth lens 35. Further, mark * represents an
aspheric surface.
Seventh Example
[0235] FIG. 14 is a schematic diagram relating to the seventh
example of image pickup lens 100 based on Embodiment 1.
[0236] As for the arrangement of lens substrates and lenses, there
are arranged a first lens substrate 1 at the object side, and a
second lens substrate 2 at the image side of the first lens
substrate. Further, there is arranged a third lens substrate 3 at
the image side of the second lens substrate 2. The first lens
substrate 1 and the second lens substrate 2 are arranged with the
predetermined distance between them. The second lens substrate 2
and the third lens substrate 3 are arranged with the predetermined
distance between them. Each of the first lens substrate 1, the
second lens substrate 2, and the third lens substrate 3 is a
parallel flat plate. Further, there is arranged an image sensor 4
of a CCD type or a CMOS type at the image side of the third lens
substrate 3.
[0237] The first lens substrate 1 includes a first lens 11 formed
on its object side surface and a second lens 12 formed on its image
side surface. Further, the second lens substrate 2 includes a third
lens 23 formed on its object side surface. The third lens substrate
3 includes a fifth lens 35 formed on its object side surface and a
sixth lens 36 formed on its image side surface. There is no lens on
the image side surface of the second lens substrate 2.
[0238] Tables 13 and 14 show data of a working example of the image
pickup lens 100 including this optical system. FIG. 15 shows an
aberration diagram of the image pickup lens including this optical
system and providing data of the working example.
[0239] With respect to the image pickup lens 100 relating to the
seventh example, Abbe number .nu.1 of the first lens 11 is 54.00,
and Abbe number .nu.2 of the second lens 12 is 29.00, as shown in
Tables.
TABLE-US-00013 TABLE 13 Surface No. R D Nd .nu. 1* 0.798 0.339
1.50710 54.00 2(ape) .infin. 0.308 1.55082 43.35 3 .infin. 0.109
1.57370 29.00 4* 2.618 0.207 5* -1.816 0.099 1.57370 29.00 6
.infin. 0.375 1.55082 43.35 7 .infin. 0.000 1.58749 30.07 8 .infin.
0.100 9* 3.325 0.104 1.50710 54.00 10 .infin. 0.304 1.55308 43.28
11 .infin. 0.572 1.50710 54.00 12* 3.856 0.658 13 .infin. BF Fno
HFOV TL 0.6582 2.8 30.88 3.176
TABLE-US-00014 TABLE 14 Aspheric surface coefficient ** K A B C D E
F G H I 1 1.95E-02 -7.50E-04 1.22E-01 -1.64E-01 8.90E-01 -2.19E+00
4.90E+00 0.00E+00 0.00E+00 0.00E+00 4 2.43E+01 1.22E-01 -4.91E-01
1.15E+00 2.30E-02 -8.87E+00 -3.57E+00 -1.85E+02 8.43E+02 0.00E+00 5
1.09E+01 2.12E-01 -1.32E+00 1.69E+00 -3.12E+00 2.70E+00 2.82E+01
4.19E+01 -1.28E+03 5.02E+00 9 -1.36E+02 -1.18E-01 -4.71E-02
l.00E-03 -3.52E-02 -6.31E-03 -2.61E-04 1.40E-02 3.75E-02 2.89E-02
12 -1.06E+02 -1.22E-01 1.34E-02 -1.88E-02 -1.51E-02 7.97E-03
4.14E-03 -3.86E-03 2.95E-04 7.25E-05 ** Surface No.
Eighth Example
[0240] FIG. 16 is a schematic diagram relating to the eighth
example of image pickup lens 100 based on Embodiment 2.
[0241] In the image pickup lens 100 relating to the eighth example,
there are arranged a first lens substrate 1 at the object side, and
an optical member 7 formed in a parallel flat plate and arranged at
the image side of the first lens substrate. The first lens
substrate 1 and the optical member 7 are arranged with the
predetermined distance between them. Further, there is arranged an
image sensor 4 of a CCD type or a CMOS type at the image side of
the optical member 7.
[0242] The first lens substrate 1 includes a first lens 11 formed
on its object side surface and a second lens 12 formed on its image
side surface. There are no lenses on the object side surface and
the image side surface of the optical member 7.
[0243] As a lens section, the first lens 11, and the second lens 12
are arranged, in this order from the object side. A surface coming
in contact with the air of each of the lenses 11 and 12 is formed
in an aspheric surface. Each of the lenses 11 and 12 employs a
resin material as its lens material.
[0244] Further, there is arranged an aperture stop 1a between the
first lens 11 and the first lens substrate 1, where the aperture
stop shields visible light contributing to image forming.
[0245] The first lens 11 has a positive refractive power. The
second lens 12 has a negative refractive power.
[0246] Tables 15 and 16 shows data of a working example of the
image pickup lens 100 including this optical system. FIG. 17 shows
an aberration diagram of an image pickup lens including this
optical system and providing data of the working example.
[0247] With respect to the image pickup lens 100 relating to the
eighth example, Abbe number .nu.1 of the first lens 11 is 54.00,
and Abbe number .nu.2 of the second lens 12 is 29.00, as shown in
Tables.
TABLE-US-00015 TABLE 15 Surface No. R D Nd .nu. 1(ape) 0.116 2*
0.730 0.050 1.50710 54.00 3 .infin. 0.570 1.52470 56.20 4 .infin.
0.050 1.57370 29.00 5* -1.816 0.100 6 .infin. 0.200 1.51633 64.10 7
.infin. 0.120 BF Fno HFOV TL 1.0258 2.8 30.81321 1.91
TABLE-US-00016 TABLE 16 Aspheric surface coefficient ** K A B C D E
F G H I 2 -6.46E-01 -6.59E-01 5.00E+01 -7.06E+02 3.16E+03 0.00E+00
0.00E+00 0.00E+00 0.00E+00 0.00E+00 5 -2.61E+04 2.50E+00 -1.16E+01
7.11E+01 -1.71E+02 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 **
Surface No.
Ninth Example
[0248] FIG. 18 is a schematic diagram relating to the ninth example
of image pickup lens 100 based on Embodiment 2.
[0249] An arrangement of lens substrates and lenses is the same as
that shown in Embodiment 2. Table 17 and Table 18 show data of a
working example of image pickup lens 100 including this optical
system. FIG. 19 shows an aberration diagram of an image pickup lens
including this optical system and providing data of the working
example.
[0250] With respect to the image pickup lens 100 relating to the
ninth example, Abbe number .nu.1 of the first lens 11 is 54.00, and
Abbe number .nu.2 of the second lens 12 is 29.00, as shown in
Tables.
TABLE-US-00017 TABLE 17 Surface No. R D Nd .nu. 1(ape) 0.116 2*
0.740 0.050 1.50710 54.00 3 .infin. 0.570 1.52470 56.20 4 .infin.
0.050 1.57370 29.00 5* -1.816 0.100 6 .infin. 0.994 1.51633 64.10 7
.infin. 0.120 BF Fno HFOV TL 1.0465 2.8 31.25937 2.17
TABLE-US-00018 TABLE 18 Aspheric surface coefficient ** K A B C D E
F G H I 2 -3.55E-01 -6.59E-01 5.00E+01 -7.06E+02 3.16E+03 0.00E+00
0.00E+00 0.00E+00 0.00E+00 0.00E+00 5 2.37E+03 2.47E+00 -1.88E+01
1.34E+02 -3.21E+02 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 **
Surface No.
[0251] The present example shows the case in which the optical
member 7 is thicker than that of the eighth example, which exhibits
an excellent function to control distortion of the optical member 7
to be small and corrects the distortion with keeping the better
aberration property than that of the eighth example.
Tenth Example
[0252] FIG. 20 is a schematic diagram relating to the tenth example
of image pickup lens 100 based on Embodiment 2.
[0253] An arrangement of lens substrates and lenses is the same as
that shown in Embodiment 2. Table 19 and Table 20 show data of a
working example of image pickup lens 100 including this optical
system. FIG. 21 shows an aberration diagram of an image pickup lens
including this optical system and providing data of the working
example.
[0254] With respect to the image pickup lens 100 relating to the
tenth example, Abbe number .nu.1 of the first lens 11 is 70.45, and
Abbe number .nu.2 of the second lens 12 is 31.16, as shown in
Tables.
TABLE-US-00019 TABLE 19 Surface No. R D Nd .nu. 1(ape) 0.116 2*
0.740 0.050 1.48749 70.45 3 .infin. 0.570 1.52470 56.20 4 .infin.
0.050 1.57370 31.16 5* -1.816 0.100 6 .infin. 1.200 1.51633 64.10 7
.infin. 0.120 BF Fno HFOV TL 1.1077 2.8 29.4479 2.33
TABLE-US-00020 TABLE 20 Aspheric surface coefficient ** K A B C D E
F G H I 2 -1.89E-01 -6.59E-01 5.00E+01 -7.06E+02 3.16E+03 0.00E+00
0.00E+00 0.00E+00 0.00E+00 0.00E+00 5 -2.61E+04 2.47E+00 -1.88E+01
1.34E+02 -3.21E+02 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 **
Surface No.
[0255] In the present example, distortion is controlled to be
smaller than that of the ninth example, by making thicker the
optical member 7.
Eleventh Example
[0256] FIG. 22 is a schematic diagram relating to the eleventh
example of image pickup lens 100 based on a variation example of
Embodiment 1 and Embodiment 2.
[0257] In the image pickup lens 100 relating to the eleventh
example, there is arranged just the first lens substrate. Further,
there is arranged an image sensor 4 of a CCD type or a CMOS type at
the image side of the first lens substrate 1.
[0258] The first lens substrate 1 includes a first lens 11 formed
on its object side surface and a second lens 12 formed on its image
side surface.
[0259] As a lens section, the first lens 11, and the second lens 12
are arranged, in this order from the object side. A surface coming
in contact with the air of each of the lenses 11 and 12 is formed
into an aspheric surface. Each of the lenses 11 and 12 employs a
resin material as its lens material.
[0260] Further, there is arranged an aperture stop 1a on the image
side of the first lens 11, where the aperture stop shields visible
light contributing to image forming.
[0261] The first lens 11 has a positive refractive power. The
second lens 12 has a negative refractive power.
[0262] Tables 21 and 22 show data of a working example of the image
pickup lens 100 including this optical system. FIG. 23 shows an
aberration diagram of an image pickup lens including this optical
system and providing data of the working example.
[0263] With respect to the image pickup lens 100 relating to the
eleventh example, Abbe number .nu.1 of the first lens 11 is 54.00,
and Abbe number .nu.2 of the second lens 12 is 29.00, as shown in
Tables.
TABLE-US-00021 TABLE 21 Surface No. R D Nd .nu. 1(ape) 0.116 2*
0.730 0.050 1.50710 54.00 3 .infin. 0.570 1.67700 56.20 4 .infin.
0.050 1.57370 29.00 5* -1.816 1.061 BF Fno HFOV TL 1.0258 2.8
30.81321 1.91
TABLE-US-00022 TABLE 22 Aspheric surface coefficient ** K A B C D E
F G H I 2 -6.46E-01 -6.59E-01 5.00E+01 -7.06E+02 3.16E+03 0.00E+00
0.00E+00 0.00E+00 0.00E+00 0.00E+00 5 -2.61E+04 2.50E+00 -1.16E+01
7.11E+01 -1.71E+02 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 **
Surface No.
Twelfth Example
[0264] FIG. 24 is a schematic diagram relating to the twelfth
example of image pickup lens 100 based on Embodiment 1.
[0265] In the image pickup lens 100 relating to the twelfth
example, there are arranged a first lens substrate 1 at the object
side, and a lens A 8 at the image side of the first lens substrate
1. The first lens substrate 1 and the lens A 8 are arranged with
the predetermined distance between them. Further, there is arranged
an image sensor 4 of a CCD type or a CMOS type at the image side of
the lens A 8.
[0266] The first lens substrate 1 includes a first lens 11 formed
on its object side surface and a second lens 12 formed on its image
side surface.
[0267] As a lens section, the first lens 11, the second lens 12,
and lens A 8 are arranged, in this order from the object side. A
surface coming in contact with the air of each of the lenses 11,
12, and 8 is formed into an aspheric surface. Each of the lenses 11
and 12 employs a resin material as its lens material.
[0268] Further, there is arranged an aperture stop 1a between the
first lens 11 and the first substrate 1, where the aperture stop
shields visible light contributing to image forming.
[0269] The first lens 11 has a positive refractive power. The
second lens 12 has a negative refractive power.
[0270] The refractive index n2 of the first substrate 1 is greater
than the refractive index of n1 of the first lens 11.
[0271] Tables 23 and 24 show data of a working example of the image
pickup lens 100 including this optical system. FIG. 25 shows an
aberration diagram of an image pickup lens including this optical
system and providing data of the working example.
[0272] With respect to the image pickup lens 100 relating to the
twelfth example, Abbe number .nu.1 of the first lens 11 is 70.45,
and Abbe number .nu.2 of the second lens 12 is 31.16, as shown in
Tables.
TABLE-US-00023 TABLE 23 Surface No. R D Nd .nu. 1(ape) 0.934 0.362
1.48749 70.45 2* .infin. 0.427 1.68855 47.43 3 .infin. 0.074
1.68893 31.16 4 2.194 0.726 5* 4.356 1.106 1.53048 55.72 6* 6.134
0.728 BF Fno HFOV TL 0.7275 2.8 30.48 3.42
TABLE-US-00024 TABLE 24 Aspheric surface coefficient ** K A B C D E
F G H I 1 1.78E-02 -2.99E-03 1.01E-01 -6.96E-03 -3.67E-01 -4.39E-01
3.39E+00 0.00E+00 0.00E+00 0.00E+00 4 6.32E+00 1.17E-01 2.15E-01
1.70E-01 1.01E+00 9.13E-01 -3.45E+00 0.00E+00 0.00E+00 0.00E+00 5
-4.52E+01 -7.05E-02 -2.74E-02 -9.45E-03 2.67E-03 6.76E-03 2.96E-03
0.00E+00 0.00E+00 0.00E+00 6 -9.45E+00 -3.51E-02 -7.32E-03
-1.25E-02 1.77E-03 -6.39E-04 2.11E-04 0.00E+00 0.00E+00 0.00E+00 **
Surface No.
Thirteenth Example
[0273] FIG. 26 is a schematic diagram relating to the thirteenth
example of image pickup lens 100 based on Embodiment 1.
[0274] In the image pickup lens 100 relating to the thirteenth
example, there are arranged a first lens substrate 1 at the object
side, and a lens A 8 at the image side of the first lens substrate
1. Further, there is arranged a lens B 9 at the image side of the
lens A 8. The first lens substrate 1 and the lens A 8 are arranged
with the predetermined distance between them. The lens A 8 and the
lens B 9 are arranged with the predetermined distance between them.
Further, there is arranged an image sensor 4 of a CCD type or a
CMOS type at the image side of the lens B 9.
[0275] The first lens substrate 1 includes a first lens 11 formed
on its object side surface and a second lens 12 formed on its image
side surface.
[0276] As a lens section, the first lens 11, the second lens 12,
lens A 8, and lens B 9 are arranged, in this order from the object
side. A surface coming in contact with the air of each of the
lenses 11, 12, 8, and 9 is formed into an aspheric surface. Each of
the lenses 11, 12, and 9 employs a resin material as its lens
material. The lens 8 employs a glass material as its lens
material.
[0277] Further, there is arranged an aperture stop 1a between the
first lens 11 and the first substrate 1, where the aperture stop
shields visible light contributing to image forming.
[0278] The first lens 11 has a positive refractive power. The
second lens 12 has a negative refractive power.
[0279] The refractive index n2 of the first substrate 1 is greater
than the refractive index of n1 of the first lens 11.
[0280] Tables 25 and 26 show data of a working example of the image
pickup lens 100 including this optical system. FIG. 27 shows an
aberration diagram of an image pickup lens including this optical
system and providing data of the working example.
[0281] With respect to the image pickup lens 100 relating to the
thirteenth example, Abbe number .nu.1 of the first lens 11 is
54.00, and Abbe number .nu.2 of the second lens 12 is 26.00, as
shown in Tables.
TABLE-US-00025 TABLE 25 Surface No. R D Nd .nu. 1* 0.758 0.360
1.50710 54.00 2(ape) .infin. 0.303 1.84078 40.83 3 .infin. 0.114
1.61000 26.00 4* 2.606 0.281 5* -1.751 0.652 1.61000 26.00 6*
-33.387 0.110 7* 7.682 0.820 1.53048 55.72 8* 5.749 0.546 BF Fno
HFOV TL 0.5458 2.8 30.54 3.186
TABLE-US-00026 TABLE 26 Aspheric surface coefficient ** K A B C D E
F G H I 1 1.52E-02 -8.73E-03 1.07E-01 -1.83E-01 6.94E-01 -2.14E+00
8.57E+00 0.00E+00 0.00E+00 0.00E+00 4 2.72E+01 3.43E-02 -4.99E-01
1.14E+00 -9.83E-01 -1.15E+01 -1.45E+01 -2.16E+02 8.29E+02 0.00E+00
5 1.11E+01 -1.82E-01 -1.14E+00 2.31E+00 -1.22E+01 3.69E+00 2.58E+01
-3.77E+00 -1.62E+03 -2.05E+03 6 0.00E+00 -7.36E-02 -2.57E-02
-1.62E-02 -2.96E-02 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 7
-5.44E+02 -1.09E-01 -2.61E-03 -8.62E-03 -1.58E-02 -1.89E-02
-1.65E-02 -1.02E-02 6.72E-04 1.60E-02 8 -1.31E+02 -1.39E-01
2.93E-02 -2.37E-02 -1.76E-02 8.83E-03 5.73E-03 -3.87E-03 5.37E-05
1.47E-04 ** Surface No.
Fourteenth Example
[0282] FIG. 28 is a schematic diagram relating to the fourteenth
example of image pickup lens 100 based on Embodiment 2.
[0283] An arrangement of lens substrates and lenses is the same as
that shown in Embodiment 2. Table 27 and Table 28 show data of a
working example of image pickup lens 100 including this optical
system. FIG. 29 shows an aberration diagram of an image pickup lens
including this optical system and providing data of the working
example.
[0284] With respect to the image pickup lens 100 relating to the
fourteenth example, Abbe number .nu.1 of the first lens 11 is
56.60, and Abbe number .nu.2 of the second lens 12 is 23.00, as
shown in Tables.
TABLE-US-00027 TABLE 27 Surface No. R D Nd .nu. 1(ape) 0.116 2*
0.730 0.120 1.43000 56.60 3 .infin. 0.500 1.51680 64.20 4 .infin.
0.050 1.63630 23.00 5* -1.816 0.100 6 .infin. 0.683 1.51680 64.20
0.447 BF Fno HFOV TL 0.447 2.8 31.187 2.017
TABLE-US-00028 TABLE 28 Aspheric surface coefficient ** K A B C D E
F G H I 2 -2.98E+00 -7.16E-01 8.71E+01 -1.17E+03 1.48E+03 1.39E+04
-4.55E+04 8.01E+06 1.43E+08 -2.37E+09 5 -9.70E+04 1.34E+00 2.96E+00
-2.42E+01 -3.78E+02 4.99E+03 -1.46E+04 1.61E+04 -7.20E+04 -2.65E+05
** Surface No.
Fifteenth Example
[0285] FIG. 30 is a schematic diagram relating to the fifteenth
example of image pickup lens 100 based on Embodiment 2.
[0286] An arrangement of lens substrates and lenses is the same as
that shown in Embodiment 2. Table 29 and Table 30 show data of a
working example of image pickup lens 100 including this optical
system. FIG. 31 shows an aberration diagram of an image pickup lens
including this optical system and providing data of the working
example.
[0287] With respect to the image pickup lens 100 relating to the
fifteenth example, Abbe number .nu.1 of the first lens 11 is 56.60,
and Abbe number .nu.2 of the second lens 12 is 23.00, as shown in
Tables.
TABLE-US-00029 TABLE 29 Surface No. R D Nd .nu. 1(ape) 0.116 2*
0.730 0.120 1.43000 56.60 3 .infin. 0.500 1.71300 53.90 4 .infin.
0.050 1.63630 23.00 5* -1.816 0.100 6 .infin. 0.683 1.51680 64.20
0.487 BF Fno HFOV TL 0.487 2.8 31.17 2.086
TABLE-US-00030 TABLE 30 Aspheric surface coefficient ** K A B C D E
F G H I 2 -2.98E+00 -7.16E-01 8.71E+01 -1.17E+03 1.48E+03 1.39E+04
-4.55E+04 8.01E+06 1.43E+08 -2.37E+09 5 -9.70E+04 1.34E+00 2.96E+00
-2.42E+01 -3.78E+02 4.99E+03 -1.46E+04 1.61E+04 -7.20E+04 -2.65E+05
** Surface No.
Sixteenth Example
[0288] FIG. 32 is a schematic diagram relating to the sixteenth
example of image pickup lens 100 based on Embodiment 1. An
arrangement of lens substrates and lenses is the same as that shown
in Embodiment 1. Table 31 and Table 32 show data of a working
example of image pickup lens 100 including this optical system.
FIG. 33 shows an aberration diagram of an image pickup lens
including this optical system and providing data of the working
example.
[0289] With respect to the image pickup lens 100 relating to the
second example, Abbe number .nu.1 of the first lens 11 is 56.60,
and Abbe number .nu.2 of the second lens 12 is 23.00, as shown in
Tables.
TABLE-US-00031 TABLE 31 Surface No. R D Nd .nu. 1* 0.791 0.250
1.43000 56.60 2(ape) .infin. 0.353 1.71300 53.90 3 .infin. 0.086
1.63630 23.00 4* 1.800 0.657 5* 2.636 0.060 1.63630 23.00 6 .infin.
0.300 1.71300 53.90 7 .infin. 0.256 1.63630 23.00 8* 4.696 1.213 BF
Fno HFOV TL 1.213 2.8 31.93 3.175
TABLE-US-00032 TABLE 32 Aspheric surface coefficient ** K A B C D E
F G H I 1 3.08E-02 -3.22E-03 1.89E-01 -7.70E-02 -7.65E-01 1.70E-01
9.73E+00 0.00E+00 0.00E+00 0.00E+00 4 7.54E+00 8.01E-02 2.89E-01
-7.98E-01 6.68E+00 -1.21E+00 -1.38E+00 0.00E+00 0.00E+00 0.00E+00 5
-1.82E+01 -6.35E-02 -4.50E-02 -2.63E-02 -2.41E-02 -1.38E-02
3.75E-02 3.43E-04 7.24E-04 1.24E-03 8 5.35E+00 -6.40E-02 -5.66E-02
4.65E-03 2.07E-03 -3.55E-03 -4.39E-04 2.67E-05 3.61E-05 3.13E-05 **
Surface No.
Results of Examples
[0290] As is shown in an aberration diagram of each example,
chromatic aberration is corrected satisfactorily in each example.
Table 33 and Table 34 show evaluation results in the present
examples: evaluation results in the difference dv between Abbe
number .nu.1 of the first lens 11 and Abbe number .nu.2 of the
second lens 12 (results of calculation of the expression 15),
evaluation results of the ratio f.sub.R of the focal length of the
first lens 11 to the focal length of the total lens system (results
of calculation of the expression 16), evaluation results of
Petzval's sum pn (results of calculation of the expression 17),
evaluation results of the ratio f.sub.1/f.sub.m of the focal length
f.sub.1 of the first lens to the focal length f.sub.m of M.sup.th
lens (results of calculation of the expression 25), evaluation
results of the amount Sv of aspheric sag of a surface arranged at
the closest position to the image side (results of calculation of
the expression 18), evaluation results of the ratio D.sub.R of a
thickness of optical member 7 to the focal length of the total lens
system (results of calculation of expression 21), and evaluation
results of the ratio l.sub.R of difference in optical path length
between a principal ray at the maximum image height and an axial
ray to the focal length of the total lens system (results of
calculation of the expression 22).
[0291] As shown in Table 33 and Table 34, chromatic aberration was
corrected satisfactorily when the difference between Abbe number
.nu.1 of the first lens 11 and Abbe number .nu.1 of the second lens
12 satisfied the following conditional expression (2).
[Math. 38]
10<(.nu.1-.nu.2)<70 (2)
[0292] Under the condition of using a resin material for each of
the first lens 11 and the second lens 12, chromatic aberration was
corrected satisfactorily when the following conditional expression
(8) was satisfied, owing to the characteristic of a resin lens
material.
[Math. 39]
10<(.nu.1-.nu.2)<40 (8)
[0293] As shown in Table 33 and Table 34, when a value obtained by
normalizing focal length f.sub.s1 of the object side surface of the
first lens 11 by the focal length f of the total lens system
satisfied the following conditional expression (3), the total
optical length was short, and excellent aberration properties were
obtained.
[ Math . 40 ] 0.6 .ltoreq. f s 1 f .ltoreq. 1.0 ( 3 )
##EQU00019##
[0294] As shown in Table 33 and Table 34, it is preferable that the
Petzval's sum satisfies the following conditional expression (4).
By satisfying the following conditional expression (4), astigmatism
was corrected satisfactorily in spite of its short total optical
length.
[ Math . 41 ] j 1 f j n j .ltoreq. 0.14 ( 4 ) ##EQU00020##
[0295] As shown in Table 33 and Table 34, when the ratio
f.sub.1/f.sub.n of focal length f.sub.1 to focal length f.sub.m of
i.sup.th lens satisfied the following conditional expression (25),
it was possible to obtain excellent aberration properties.
[ Math . 42 ] - 0.7 .ltoreq. f 1 fm < 0 ( 25 ) ##EQU00021##
[0296] As shown in Table 33 and Table 34, when a value obtained by
normalizing the amount of the aspheric sag of the surface arranged
at the closest position to the image side by the maximum image
height satisfies the following conditional expression (5), it
provides excellent aberration properties in spite of its short
total optical length, and an incident angle to an image sensor such
as a CCD can be kept to be small in the area where the image height
is great.
[ Math . 43 ] X - X 0 Y > 0.14 ( 5 ) ##EQU00022##
[0297] As shown in Table 33 and Table 34, when the ratio of a
thickness of optical member 7 to the focal length of the total lens
system satisfies the following conditional expression (6), it was
possible to obtain a short total optical length and excellent
aberration properties.
[ Math . 44 ] D g f .gtoreq. 0.1 ( 6 ) ##EQU00023##
[0298] As shown in Table 33 and Table 34, when the ratio of
difference in optical path between an axial ray and a principal ray
at the maximum image height to the focal length of the total lens
system satisfies the following conditional expression (7), it was
possible to obtain a short total optical length and excellent
aberration properties.
[ Math . 45 ] 0.13 > l 2 - l 1 f ( 7 ) ##EQU00024##
[0299] Further, when relationship between refractive index n1 of
the first lens 11 and refractive index n2 of the first lens
substrate 1 satisfied the following conditional expression (9), it
was possible to obtain a short total optical length and excellent
aberration properties.
[Math. 46]
n.sub.1<n.sub.2 (9)
TABLE-US-00033 TABLE 33 Example 1 Example 2 Example 3 Example 4
Example 5 Example 6 Example 7 Example 8 .nu.1 54.00 55.72 54.00
54.00 70.45 54.00 54.00 54.00 .nu.2 29.00 30.23 29.00 29.00 31.16
26.00 29.00 29.00 (**15) Results 25.00 25.50 25.00 25.00 39.28
28.00 25.00 25.00 f.sub.s1 2.670 2.525 2.751 2.627 3.237 2.753
2.439 2.170 f 2.955 2.918 2.895 2.964 2.979 2.954 2.927 1.475
(**16) Results 0.90 0.87 0.95 0.89 1.09 0.93 0.83 1.471 f.sub.s2
-2.730 -2.500 -3.033 -4.010 -3.185 -4.273 -4.564 -41.700 f.sub.s3
10.590 26.411 9.845 -6.336 13.866 -5.285 -4.909 f.sub.s4 -10.560
-33.308 -8.341 -37.041 -11.562 54.733 f.sub.s5 26.656 10.184
f.sub.s6 -10.838 -7.604 (**17) Results 0.167 0.153 0.170 0.067
0.188 0.077 0.056 0.434 f.sub.1/f.sub.3 0.252 0.096 0.279 -0.415
0.233 -0.521 -0.497 f.sub.1/f.sub.4 0.252 0.096 0.279 -0.415 0.233
-0.521 -0.497 f.sub.1/f.sub.5 -0.253 -0.076 -0.330 -0.071 -0.280
0.050 f.sub.1/f.sub.6 -0.254 -0.321 X -0.180 -0.397 -0.150 -0.484
-0.203 -0.400 -0.349 X.sub.0 0.154 0.057 0.116 0.006 0.147 0.078
0.093 Y 1.750 1.730 1.750 1.750 1.750 1.750 1.750 0.88 h 1.270
1.298 1.329 1.291 1.410 1.298 1.270 (**18) Results 0.191 0.262
0.152 0.280 0.200 0.273 0.253 (**21) Results 0.136 (**22) Results
0.107 **Expression
TABLE-US-00034 TABLE 34 Example 9 Example 10 Example 11 Example 12
Example 13 Example 14 Example 15 Example 16 .nu.1 54.00 70.45 54.00
70.45 54.00 56.60 56.60 56.60 .nu.2 29.00 31.16 29.00 31.16 26.00
23.00 23.00 23.00 (**15) Results 25.00 39.28 25.00 39.28 28.00
33.60 33.60 33.60 f.sub.s1 2.200 2.258 2.415 3.237 2.753 2.150
2.426 3.15 f 1.450 1.559 1.477 2.973 2.966 1.453 1.455 2.81 (**16)
Results 1.517 1.449 1.635 1.09 0.93 1.820 1.667 1.12 f.sub.s2
-41.700 -41.700 -41.700 -3.185 -4.273 -38.480 -38.480 -2.821
f.sub.s3 12.570 -4.620 7.0957 f.sub.s4 -11.562 54.733 -7.38
f.sub.s5 22.160 f.sub.s6 -10.838 (**17) Results 0.442 0.416 0.434
0.017 -0.058 0.465 0.465 0.087 f.sub.1/f.sub.3 0.444
f.sub.1/f.sub.4 0.444 f.sub.1/f.sub.5 -0.427 f.sub.1/f.sub.6 X
-0.06258 X.sub.0 0.14902 Y 0.88 0.88 0.88 1.75 1.750 0.88 0.88 1.75
h 1.298 1.1219 (**18) Results 0.1209 (**21) Results 0.624 0.770
0.683 0.683 (**22) Results 0.108 0.096 0.106 0.111 0.111
**Expression
[0300] The invention has been explained above, referring to the
embodiments and the examples. However, the invention should not be
construed to be limited to the embodiments and the examples, and it
is naturally possible to vary or improve the invention.
* * * * *