U.S. patent application number 12/478560 was filed with the patent office on 2009-10-08 for integrated optical system and method of manufacturing the same and information recording and/or reproducing apparatus using the integrated optical system.
This patent application is currently assigned to Samsung Electro-Mechanics Co., Ltd.. Invention is credited to Eun-hyoung Cho, Mee-suk Jung, Hae-sung Kim, Jin-seung Sohn, Sung-dong Suh.
Application Number | 20090252023 12/478560 |
Document ID | / |
Family ID | 34941379 |
Filed Date | 2009-10-08 |
United States Patent
Application |
20090252023 |
Kind Code |
A1 |
Sohn; Jin-seung ; et
al. |
October 8, 2009 |
INTEGRATED OPTICAL SYSTEM AND METHOD OF MANUFACTURING THE SAME AND
INFORMATION RECORDING AND/OR REPRODUCING APPARATUS USING THE
INTEGRATED OPTICAL SYSTEM
Abstract
An optical system and an information apparatus using the optical
system are provided. The optical system includes an optical bench
on which a light source and a photodetector including a main
photodetector receiving the light are mounted. A lens unit is
coupled to the optical bench, and an optical path separating member
separates an optical path of light emitted from the light source
and propagating toward the lens unit and an optical path of light
incident from the lens unit. The optical system may include a
monitor photodetector and/or an optical path forming unit coupled
to the optical bench. The monitor photodetector receives a portion
of the light emitted from the light source. The optical path
forming unit includes a first mirror reflecting the light emitted
from the light source and a second mirror reflecting the light
incident from the lens unit and reflected by the first mirror.
Inventors: |
Sohn; Jin-seung; (Seoul,
KR) ; Suh; Sung-dong; (Seoul, KR) ; Jung;
Mee-suk; (Suwon-si, KR) ; Cho; Eun-hyoung;
(Seoul, KR) ; Kim; Hae-sung; (Hwaseong-si,
KR) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W., SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
Samsung Electro-Mechanics Co.,
Ltd.
Suwon-si
KR
|
Family ID: |
34941379 |
Appl. No.: |
12/478560 |
Filed: |
June 4, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11141052 |
Jun 1, 2005 |
7558161 |
|
|
12478560 |
|
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|
Current U.S.
Class: |
369/112.23 ;
156/250; G9B/7 |
Current CPC
Class: |
G11B 7/123 20130101;
G11B 7/1353 20130101; G11B 7/131 20130101; G11B 7/1362 20130101;
G11B 7/1263 20130101; Y10T 156/1052 20150115; G11B 7/22
20130101 |
Class at
Publication: |
369/112.23 ;
156/250; G9B/7 |
International
Class: |
G11B 7/00 20060101
G11B007/00; B32B 38/00 20060101 B32B038/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 1, 2004 |
KR |
10-2004-0039627 |
Claims
1. An integrated optical system comprising: an optical bench on
which a light source for generating light and a monitor
photodetector that receives a portion of the light from the light
source are mounted thereon; a lens unit coupled to the optical
bench; and an optical path separating member separating an optical
path of light emitted from the light source that propagates toward
the lens unit and an optical path of light incident from the lens
unit.
2. The integrated optical system of claim 1, wherein the monitor
photodetector is disposed on a bottom surface of the optical bench,
and the light source is mounted on a mount and spaced apart from
the bottom surface of the optical bench.
3. The integrated optical system of claim 2, wherein the monitor
photodetector is disposed to be parallel to the light source,
slanted toward the light source or spaced from the bottom surface
of the optical bench.
4. The integrated optical system of claim 1, wherein the light
source is mounted on a mount.
5. The integrated optical system of claim 1, further comprising: a
main photodetector mounted on the optical bench; and connection
elements for electrically connecting the light source, the main
photodetector, the monitor photodetector and external circuits,
wherein the connection elements are disposed on a bottom surface of
the optical bench.
6. The integrated optical system of claim 11, wherein the lens unit
comprises at least one of a refractive lens, a diffractive lens and
a gradient index (GRIN) lens.
7. The integrated optical system of claim 6, wherein the lens unit
comprises a hybrid lens comprising the refractive lens and the
diffractive lens.
8. The integrated optical system of claim 6, wherein the lens unit
comprises the refractive lens and the diffractive lens, wherein the
refractive lens functions as an objective lens and the diffractive
lens functions as a collimating lens.
9. The integrated optical system of claim 6, wherein the lens unit
uses the refractive lens, the diffractive lens or the GRIN lens
functioning a collimating lens so that the integrated optical
system can be used as an optical module for an optical pickup.
10. The integrated optical system of claim 6, wherein the lens unit
comprises the diffractive lens, functioning as a collimating lens,
disposed at one surface of a lens holder and transitioning between
an optical module for an optical pickup and an optical pickup is
performed by selectively inserting the refractive lens functioning
as an objective lens into the lens holder.
11. A method of manufacturing the integrated optical system of
claim 1, the method comprising: preparing an optical bench wafer on
which the optical bench is formed; preparing an optical path
forming unit wafer on which the optical path forming unit is
formed; bonding the optical path forming unit wafer to the optical
bench wafer; and dicing the bonded wafers to obtain an optical
bench and optical path forming unit assembly.
12. The method of claim 11, wherein the monitor photodetector is
disposed on a bottom surface of the optical bench, and the light
source is mounted on a mount and spaced apart from the bottom
surface of the optical bench.
13. The method of claim 12, wherein the monitor photodetector is
mounted to be parallel to the light source, slanted toward the
light source or spaced apart from the bottom surface of the optical
bench.
14. A method of manufacturing the integrated optical system of
claim 1, the method comprising: preparing an optical bench wafer on
which the optical bench is formed; attaching the optical path
forming unit to the optical bench formed on the optical bench
wafer; and dicing the optical bench wafer to which the optical path
forming unit is attached to obtain an optical bench and optical
path forming unit assembly.
15. The method of claim 14, wherein the optical path forming unit
is formed on a wafer.
16. The method of claim 14, wherein the monitor photodetector is
disposed on a bottom surface of the optical bench, and the light
source is mounted on a mount and spaced apart from the bottom
surface of the optical bench.
17. The method of claim 16, wherein the monitor photodetector is
mounted to be parallel to the light source, slanted toward the
light source or spaced apart from the bottom surface of the optical
bench.
18. A method of manufacturing the integrated optical system of
claim 1, the method comprising: preparing an optical bench wafer on
which the optical bench is formed; dicing the optical bench wafer;
and attaching the optical path forming unit to the optical bench to
obtain an optical bench and optical path forming unit assembly.
19. The method of claim 18, wherein the monitor photodetector is
disposed on a bottom surface of the optical bench, and the light
source is mounted on a mount and spaced apart from the bottom
surface of the optical bench.
20. The method of claim 19, wherein the monitor photodetector is
mounted to be parallel to the light source, slanted toward the
light source, or spaced apart from the bottom surface of the
optical bench.
21. An information recording and/or reproducing apparatus
comprising: the integrated optical system of claim 1, an
information storage medium rotating unit rotating an information
storage medium; a driving unit driving the integrated optical
system and the information storage medium rotating unit; and a
control unit controlling the driving unit to control focusing and
tracking servos.
22. The information recording and/or reproducing apparatus of claim
21, wherein the lens unit comprises a hybrid lens comprising a
refractive lens and a diffractive lens, and the integrated optical
system is used as an optical pickup.
23. The information recording and/or reproducing apparatus of claim
21, wherein the lens unit comprises a refractive lens functioning
as an objective lens and a diffractive lens functioning as a
collimating lens, wherein the refractive lens is disposed in a lens
holder, the diffractive lens is disposed at one surface of the lens
holder and the integrated optical system is used as an optical
pickup.
24. The information recording and/or reproducing apparatus of claim
21, further comprising an objective lens focusing incident light on
the information storage medium, wherein the lens unit functions as
a collimating lens and the integrated optical system is used as an
optical module.
25. The information recording and/or reproducing apparatus of claim
21, wherein the lens unit is structured such that a diffractive
lens functioning as a collimating lens is formed at one surface of
a lens holder.
26. The information recording and/or reproducing apparatus of claim
21, wherein the monitor photodetector is disposed on a bottom
surface of the optical bench, and the light source is mounted on a
mount and spaced apart from the bottom surface of the optical
bench.
27. The information recording and/or reproducing apparatus of claim
26, wherein the monitor photodetector is disposed to be parallel to
the light source, slanted toward the light source or spaced apart
from the bottom surface of the optical bench.
Description
[0001] This application is a divisional application of U.S.
application Ser. No. 11/141,052, filed on Jun. 1, 2005, which
claims priority to Korean Patent Application No. 10-2004-0039627,
filed on Jun. 1, 2004, in the Korean Intellectual Property Office,
the disclosure of which is incorporated herein in its entirety by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an information recording
and/or reproducing apparatus, and more particularly, to an
integrated optical system and a method of manufacturing the same,
and an information recording and/or reproducing apparatus employing
the integrated optical system.
[0004] 2. Description of the Related Art
[0005] In an optical recording and/or reproducing apparatus that
records arbitrary information on an optical information storage
medium and reproduces information recorded on the optical
information storage medium by focusing laser light using an
objective lens, the recording capacity is determined according to
the size of a focused light spot. The size (S) of a focused light
spot is determined according to the wavelength (.lamda.) of laser
light and the numerical aperture (NA) of an objective lens is
expressed below by Equation (1).
S.varies..lamda./NA Equation (1)
[0006] Therefore, in order to reduce the size of a light spot
focused on an optical information storage medium for a higher
recording density, research into an optical recording and/or
reproducing apparatus using a short wavelength light source such as
a blue laser and an objective lens having an NA of 0.6 or greater
has been conducted.
[0007] Since the development of compact discs (CDs) that require
light with a wavelength of 780 nm and an objective lens having an
NA of 0.45 or 0.5 to record information thereon and/or reproduce
information therefrom, intensive research has been conducted into
increasing the recording density and information storage capacity
of the media. Digital versatile discs (DVDs), to/from which
information can be recorded and reproduced using light having a
wavelength of 650 nm and an objective lens having an NA or 0.6 or
0.65, were obtained as a result of the research.
[0008] Recently, there has been steady progress in research into
high-density information storage media using blue light having a
wavelength of, for example, 405 nm, and having a recording capacity
of 20 GB or greater.
[0009] There have been efforts to standardize high-density optical
information storage media using blue light having a wavelength of,
for example, 405 nm, and standards are being defined. A NA of an
objective lens for a high-density optical information storage
medium is 0.65 or 0.85, which will be described later.
[0010] The thickness of a DVD is reduced to 0.6 mm from 1.2 mm of a
CD to provide adequate tolerance for tilting of the optical
information storage medium because the NA of an objective lens is
increased to 0.6 for the DVD from 0.45 for the CD.
[0011] In a high-density optical information storage medium having
a higher storage capacity than a DVD, when the NA of an objective
lens is increased to, for example, 0.85, the thickness of the
high-density optical information storage medium must be reduced to
about 0.1 mm.
[0012] A high-density optical information storage medium that has a
reduced thickness and requires a greater NA objective lens is
referred to as a Blu-ray Disc (BD). According to the standard for
BDs, the wavelength of a light source is 405 nm, and the NA of an
objective lens is 0.85. The standard thickness of BDs is about 0.1
mm.
[0013] In addition to BDs, (high definition) HD DVDs are currently
under development as high-density optical information storage
media. HD DVDs have the same substrate thickness and require an
objective lens having the same NA as DVDs. Only the wavelength of a
standard light source, that is, a blue wavelength of, for example,
405 nm, matches the standard for BDs.
[0014] In addition to the requirement for high-density,
high-capacity optical information storage media, there is a need
for a slimmer, smaller optical system constituting an optical
pickup.
[0015] Along with the increasing need for the adoption of optical
recording and/or reproducing apparatuses in portable terminals,
such as personal digital assistants (PDAs), mobile phones, digital
cameras, portable disc players, camcoders, etc., there has been an
increasing need for slim optical pickups. For use in the field of
portable terminals, optical pickups should be slim and small and be
able to record and/or reproduce a large amount of information, such
as music, moving pictures, etc., at high density.
[0016] However, there are technical limitations in manufacturing a
small, slim optical system by reducing the sizes of optical
elements constituting a conventional optical pickup that is
currently used in optical recording and/or reproducing apparatuses
for CDs and/or DVDs.
[0017] Furthermore, a conventional optical pickup is constructed by
optically aligning and bonding a plurality of individually
manufactured optical elements. Therefore, due to possible
assembling errors in the assembling and aligning of parts, the
reliability of the assembled optical pickup and the degree of
automation are lowered.
SUMMARY OF THE INVENTION
[0018] Illustrative, non-limiting embodiments of the present
invention overcome the above disadvantages and other disadvantages
not described above. Also, the present invention is not required to
overcome the disadvantages described above, and an illustrative,
non-limiting embodiment of the present invention may not overcome
any of the problems described above.
[0019] The present invention provides an integrated optical system
that satisfies the requirements for small, slim device and can be
manufactured through a micro-electro-mechanical system (MEMS)
process, a method of manufacturing the integrated optical system
and an information recording and/or reproducing apparatus using the
integrated optical system as an optical module or an optical
pickup.
[0020] According to an aspect of the present invention, there is
provided an integrated optical system that comprises an optical
bench on which a light source generating light and at least one
photodetector comprising a main photodetector receiving the light
are mounted. The integrated optical system further comprises a lens
unit coupled to the optical bench, and an optical path separating
member separating an optical path of light emitted from the light
source and propagating toward the lens unit and an optical path of
light incident from the lens unit. The integrated optical system
also comprises an optical path forming unit coupled to the optical
bench. The optical path forming unit comprises a first mirror
reflecting the light emitted from the light source to the lens unit
and a second mirror reflecting the light incident from the lens
unit and reflected by the first mirror to the main
photodetector.
[0021] The at least one photodetector may further comprise a
monitor photodetector, which is disposed on the optical bench and
directly receives some of the light forwardly emitted from the
light source.
[0022] The main photodetector and the monitor photodetector may be
disposed on a bottom surface of the optical bench, and the light
source may be mounted on a mount and spaced apart from the bottom
surface of the optical bench.
[0023] The monitor photodetector may be mounted so as to be
parallel to the light source, slanted toward the light source or
spaced apart from the bottom surface of the optical bench.
[0024] The light source may be mounted on a mount.
[0025] The light source may be interposed between the first and
second mirrors.
[0026] The optical path separating member may comprise a
diffraction optical element. The optical path separating member may
comprise a polarization diffraction element and a quarter-wave
plate.
[0027] A receiving groove with an opening may be formed in the
optical bench, and the optical path separating member may be
inserted into the receiving groove.
[0028] The integrated optical system may further comprise
connection elements, such as wires and terminals, for electrical
connection between the light source and the at least one
photodetctor and external circuits. The connection elements are
formed on a substrate of the optical bench.
[0029] According to another aspect of the present invention, there
is provided an integrated optical system comprising an optical
bench on which a light source that generates light and a monitor
photodetector that receives some of the light emitted from the
light source are mounted. The integrated optical bench further
comprises a lens unit coupled to the optical bench and an optical
path separating member. The optical path separating member
separates an optical path of light emitted from the light source
that propagates towards the lens unit and an optical path of light
incident from the lens unit.
[0030] The monitor photodetector may be disposed on a bottom
surface of the optical bench, and the light source may be mounted
on a mount and spaced apart from the bottom surface of the optical
bench.
[0031] The monitor photodetector may be mounted so as to be
parallel to the light source, slanted toward the light source or
spaced from the bottom surface of the optical bench.
[0032] The light source may be mounted on a mount.
[0033] The integrated optical system may further comprise a main
photodetector mounted on the optical bench. The integrated optical
system may further comprise electrical elements, such as wires and
terminals, for electrical connection between the light source, the
main photodetector, the monitor photodetector and external
circuits, wherein the electrical elements are formed on a bottom
surface of the optical bench.
[0034] The lens unit may comprise at least one of a refractive
lens, a diffractive lens and a gradient index (GRIN) lens.
[0035] The lens unit may comprise a hybrid lens comprising the
refractive lens and the diffractive lens.
[0036] The lens unit may comprise the refractive lens and the
diffractive lens, wherein the refractive lens may function as an
objective lens and the diffractive lens may function as a
collimating lens.
[0037] The lens unit may be structured such that the diffractive
lens functioning as a collimating lens is formed at one surface of
a lens holder and conversion can be selectively made between an
optical module for an optical pickup and an optical pickup by
selectively inserting the refractive lens functioning as an
objective lens into the lens holder.
[0038] The lens unit may use the refractive lens, the diffractive
lens or the GRIN lens functioning a collimating lens so that the
integrated optical system can be used as an optical module for an
optical pickup.
[0039] According to still another aspect of the present invention,
there is provided a method of manufacturing an integrated optical
system. The method comprises preparing an optical bench wafer on
which the optical bench is formed and preparing an optical path
forming unit wafer on which the optical path forming unit is
formed. The method further comprises bonding the optical path
forming unit wafer to the optical bench wafer and dicing the bonded
wafers to obtain an optical bench and optical path forming unit
assembly.
[0040] According to yet another aspect of the present invention,
there is provided a method of manufacturing an integrated optical
system. The method comprises preparing an optical bench wafer on
which the optical bench is formed, attaching the optical path
forming unit to the optical bench formed on the optical bench wafer
and dicing the optical bench wafer to which the optical path
forming unit is attached to obtain an optical bench and optical
path forming unit assembly.
[0041] According to a further aspect of the present invention,
there is provided a method of manufacturing an integrated optical
system. The method comprises preparing an optical bench wafer on
which the optical bench is formed, dicing the optical bench wafer
and attaching the optical path forming unit to the optical bench to
obtain an optical bench and optical path forming unit assembly.
[0042] The optical path forming unit may be formed on a wafer.
[0043] According to another aspect of the present invention, there
is provided an information recording and/or reproducing apparatus
that comprises an integrated optical system as described above. The
apparatus further comprises an information storage medium rotating
unit rotating an information storage medium, a driving unit driving
the integrated optical system and the information storage medium
rotating unit, and a control unit controlling the driving unit to
control focusing and tracking servos.
[0044] The integrated optical system may be used as an optical
pickup.
[0045] The information recording and/or reproducing apparatus may
further comprise an objective lens focusing incident light on the
information storage medium, and the integrated optical system may
be used as an optical module.
[0046] Additional aspects and/or advantages of the invention will
be set forth in part in the description that follows and, in part,
will be apparent from the description, or may be learned by
practice of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] The above and other features and advantages of the present
invention will become more apparent by describing in detail
exemplary embodiments thereof with reference to the attached
drawings in which:
[0048] FIG. 1 is a schematic perspective view of an integrated
optical system according to an exemplary embodiment of the present
invention;
[0049] FIG. 2 is a side view of the integrated optical system of
FIG. 1;
[0050] FIG. 3 is a perspective view of an optical bench of the
integrated optical system of FIG. 1;
[0051] FIG. 4A is a cross-sectional view of an optical path
separating member of the integrated optical system of FIG. 1
according to an exemplary embodiment of the present invention;
[0052] FIG. 4B is a cross-sectional view of the optical path
separating member of the integrated optical system of FIG. 1
according to another exemplary embodiment of the present
invention;
[0053] FIG. 5 is a cross-sectional view of a lens unit of the
integrated optical system of FIG. 1 according to an exemplary
embodiment of the present invention;
[0054] FIG. 6 is a cross-sectional view of the lens unit of the
integrated optical system of FIG. 1 according to another exemplary
embodiment of the present invention;
[0055] FIG. 7 is a side view illustrating an example where the
integrated optical system of FIG. 1 including the lens unit of FIG.
5 is used as an integrated optical pickup;
[0056] FIG. 8 is a perspective view illustrating an example where
the integrated optical system of FIG. 1 comprising the lens unit of
FIG. 6 is used as an optical pickup module;
[0057] FIG. 9 is a diagram illustrating the case where a monitor
photodetector is disposed on a bottom surface of an optical bench
and parallel to a light source;
[0058] FIG. 10 is a diagram illustrating the case where a monitor
photodetector is slanted toward a light source;
[0059] FIG. 11 is a diagram illustrating the case where a monitor
photodetector is disposed on a portion protruding from a bottom
surface of an optical bench and parallel to a light source; and
[0060] FIG. 12 is a schematic diagram of an information recording
and/or reproducing apparatus employing the integrated optical
system according to an exemplary embodiment the present
invention.
DETAILED DESCRIPTION OF THE ILLUSTRATIVE, NON-LIMITING EMBODIMENTS
OF THE INVENTION
[0061] The present invention will now be described more fully with
reference to the accompanying drawings, in which exemplary,
non-limiting embodiments of the invention are shown.
[0062] FIG. 1 is a schematic perspective view of an integrated
optical system according to an exemplary embodiment of the present
invention. FIG. 2 is a side view of the integrated optical system
of FIG. 1. FIG. 3 is a perspective view of an optical bench 10 of
the integrated optical system of FIG. 1.
[0063] Referring to FIGS. 1, 2 and 3, the integrated optical system
according to an exemplary embodiment of the present invention
comprises the optical bench 10 on which a light source 15 and at
least one photodetector comprising a main photodetector 17 are
mounted. The integrated optical system further comprises a lens
unit 70 and an optical path forming unit 30 coupled to the optical
bench 10, and an optical path separating member 50 separating an
optical path of light emitted from the light source 15 propagating
toward the lens unit 70 and an optical path of light reflected by
an information storage medium 1 and then incident on the lens unit
70. The integrated optical system may be used as an optical pickup
module or an optical pickup according to the construction of the
lens unit 70. The at least one photodetector may comprise the main
photodetector 17 and a monitor photodetector 19 disposed on the
optical bench 10 to directly receive some of the light forwardly
emitted from the light source 15.
[0064] Referring to FIG. 3, the optical bench 10 of the exemplary
embodiment is a silicon optical bench (SiOB). The optical bench 10
comprises the light source 15, the main photodetector 17 and the
monitor photodetector 19, which are disposed on a substrate.
[0065] The substrate of the optical bench 10 may be a silicon
wafer. The optical bench 10 may be manufactured through a wafer
process in which an optical bench wafer is formed using a
micro-electro-mechanical system (MEMS) process.
[0066] The light source 15 is a semiconductor laser emitting light
of a predetermined wavelength. The light source 15 may be a
semiconductor laser emitting light having a blue wavelength, for
example, a wavelength of 405 nm. In this case, the integrated
optical system can record information on and/or reproduce
information from a blu-ray disc (BD) or a high definition (HD)
DVD.
[0067] Further, the light source 15 may be a semiconductor laser
emitting light having a red wavelength, for example, a wavelength
of 650 nm. In this case, the integrated optical system can record
information on and/or reproduce information from a digital
versatile disc (DVD).
[0068] In addition, the light source 15 may be configured to emit
light in another wavelength range. Also, the light source 15 may be
configured to emit light of a plurality of wavelengths such that
the integrated optical system is compatible with a plurality of
optical information storage media having different formats.
[0069] The wavelength of light emitted from the light source 15 may
vary according to the type of information storage medium that is
used. Therefore, the integrated optical system can record data on
and/or reproduce data from various kinds of optical information
storage media, for example, a CD-family optical disc, a DVD-family
optical disc, a BD and/or an HD DVD.
[0070] The light source 15 may be an edge emitting type
semiconductor laser that emits laser light in a direction parallel
to semiconductor material layers.
[0071] Considering the light emitting structure of this type
semiconductor laser, the light source 15 is mounted on a mount 13.
Consequently, the light source 15 is mounted apart from a bottom
surface 11 of the optical bench 10.
[0072] The light source 15 mounted on the mount 13 may be installed
on the optical bench 10. Alternatively, the mount 13 may be formed
to protrude from the bottom surface 11 of the optical bench 10 and
then the light source 15 may be mounted on the mount 13. In the
exemplary embodiment, the light source 15, which is a semiconductor
laser, may be directly formed on the optical bench wafer for
manufacturing the optical bench 10 using a semiconductor
process.
[0073] During operation, the main photodetector 17 receives the
light reflected by the information storage medium 1 and detects an
information reproduction (RF) signal and an error signal (e.g., a
focusing error signal, a tracking error signal, and/or a tilt error
signal) used for servo driving. The main photodetector 17 may be
disposed on the bottom surface 11 of the optical bench 10.
[0074] The monitor photodetector 19 monitors the intensity of light
emitted from the light source 15. The monitor photodetector 19 may
be disposed in front of the light source 15 to receive some of the
light emitted from the light source 15 before the light passes
through a reflection mirror. In the exemplary embodiment, the light
emitted from the semiconductor laser used as the light source 15 is
a diverging light having a Gaussian distribution. In practice, only
central light in a predetermined center region of the diverging
light emitted from the semiconductor laser is focused by an
objective lens to be used for optical recording and/or
reproduction, and peripheral light is not focused by the objective
lens and is lost.
[0075] The monitor photodetector 19 receives part of the light with
low intensity that is not focused by the objective lens and
monitors the light output from the light source 15. The light
received by the monitor photodetector 19 is emitted from the light
source 15 and then directly impinges on the monitor photodetector
19 without passing through a separate mirror member.
[0076] As described later, although the monitor photodetector 19 is
disposed on the bottom surface 11 of the optical bench in front of
the light source 15, the monitor photodetector 19 can receive light
with sufficient intensity to monitor the operation of the light
source 15.
[0077] Accordingly, the monitor photodetector 19 can be disposed on
the bottom surface 11 of the optical bench 10, parallel to the
light source 15.
[0078] Alternatively, to increase the intensity of light received
by the monitor photodetector 19, the monitor photodetector 19 may
be slanted toward the light source 15 or may be disposed on a
portion protruding from the bottom surface 11 of the optical bench
10. This can be achieved by providing the optical bench 10 with a
slanted surface protruding from the bottom surface 11 on which the
monitor photodetector 19 is installed, or forming a mount
protruding from the bottom surface 11 and having a plane surface
parallel to the light source 15. Alternatively, a mount on which
the monitor photodetector 19 is mounted may be attached to the
optical bench 10.
[0079] The main photodetector 17 and the monitor photodetector 19
may be directly formed on the optical bench wafer on which the
optical bench 10 is formed, or may be separately manufactured and
then installed on the optical bench 10.
[0080] Wires and pads 23 for electrical connection between the
light source 15, the main photodetector 17, the monitor
photodetector 19 and external circuits may be formed on the bottom
surface 11 of the optical bench 10. The pads 23 are formed to make
electrical contact with the external circuits. When the main
photodetector 17 and the monitor photodetector 19 are directly
formed on the optical bench wafer, the internal wires 21 and the
pads 23 are formed on the optical bench 10 using a thin film
process.
[0081] A heating structure (not shown) for radiating heat generated
by an actuator (not shown) for driving the integrated optical
pickup and/or the light source 15 may be installed on a top surface
of the optical bench 10. In the exemplary embodiment, a heating
structure may be further installed on a side surface of the optical
bench 10, if necessary.
[0082] A receiving groove 25 with an opening 27 is formed at a side
of the optical bench 10. The optical path separating member 50 may
be inserted into the receiving groove 25.
[0083] The optical path separating member 50 separates the optical
paths of the light emitted from the light source 15 and proceeding
toward the lens unit 70 and the light incident from the lens unit
70.
[0084] As described above, the receiving groove 25 with the opening
27 may be formed in the optical bench 10, and the optical path
separating member 50 may be inserted into the receiving groove 25.
Alternatively, instead of forming the receiving groove 25 and
inserting the optical path separating member 50 into the receiving
groove 25, the optical path separating member 50 may be attached to
a surface of the optical bench 10 with no receiving groove, or the
optical path separating member 50 may be integrally formed with the
lens unit 70.
[0085] In the exemplary embodiment, regardless of the existence of
the receiving groove 25, the optical bench 10 has the opening 27
through which the light emitted from the light source 15 and then
reflected by a first mirror 31 of the optical path forming unit 30
can pass to propagate toward the lens unit 70.
[0086] In the integrated optical system according to an exemplary
embodiment of the present invention, the optical path separating
member 50 separates optical paths by transmitting light directed to
the information storage medium 1 without altering the light's path
and diffracting light reflected by the information storage medium
1. The optical path separating member 50 allows the detection of a
signal recorded on the information storage medium 1 and focusing
and tracking error signals by diffracting the light reflected by
the information storage medium 1 into a plurality of light beams,
or adjusting a shape of a light spot formed on the main
photodetector 17 and reflecting light to the main photodetector 17
for signal detection.
[0087] FIG. 4A illustrates an example where the optical path
separating member 50 has a diffraction optical element 51, for
example, a hologram optical element (HOE) or a diffractive optical
element (DOE).
[0088] When the optical path separating member 50 has the
diffraction optical element 51, the light reflected by the
information storage medium 1 is diffracted by the optical path
separating member 50 at an angle such that the light proceeds
toward the main photodetector 17 distanced from the light source
15.
[0089] The integrated optical system according to the exemplary
embodiment of the present invention may comprise a polarization
selectivity optical path separating member 150 as shown in FIG. 4B
instead of the optical path separating member 50 with the
diffraction optical element 51.
[0090] The polarization selectivity optical path separating member
150 comprises a polarization diffraction element 151, which is a
polarization holographic element that selectively linearly
transmits or diffractively transmits incident light depending on
the polarization of the incident light, and a quarter-wave plate
153, which changes the polarization of the incident light.
[0091] The semiconductor laser used as the light source 15 emits
laser light has a predominant linearly polarized component. Thus,
substantially s-polarized or p-polarized light may be emitted from
the semiconductor laser.
[0092] Accordingly, if the polarization diffraction element 151 is
configured to transmit linearly polarized light emitted from the
light source 15 without altering the light's path, the light
transmitted through the polarization diffraction element 151 is
changed into first circularly polarized light after passing through
the quarter-wave plate 153 and then into second circularly
polarized light, which is orthogonal to the first circularly
polarized light, after being reflected by the optical information
storage medium 1. The second circularly polarized light is changed
into another linearly polarized light after passing through the
quarter-wave plate 153 and then is diffracted by the polarization
diffraction element 151.
[0093] Accordingly, the optical path of the light proceeding toward
the optical information storage medium 1 and the optical path of
the light reflected by the optical information storage medium 1 can
be separated from one another by the polarization selectivity
optical path separating member 150. In this regard, the
polarization selectivity optical path separating member 150
diffracts only the light reflected by the information storage
medium 1, without affecting the light emitted directly from the
light source 15, thereby increasing efficiency.
[0094] The optical path forming unit 30 comprises the first mirror
31, which reflects the light emitted from the light source 15 to
the lens unit 70, and a second mirror 35, which reflects the light
incident from the lens unit 70 reflected by the first mirror 31 to
the main photodetector 17. The light source 15 may be disposed
between the first and second mirrors 31 and 35.
[0095] The optical path forming unit 30 comprises the two mirrors
31 and 35 as shown in FIGS. 1 and 2, and is adapted to control an
optical path of the light emitted from the light source 15 such
that a focal point is formed on the information storage medium 1
through the objective lens of the lens unit 70 and to transmit the
light reflected by the information storage medium 1 to the main
photodetector 17.
[0096] The optical path forming unit 30 may be manufactured using a
wafer process. That is, as described later, the optical path
forming unit 30 may be formed by processing a plurality of mirrors
on an optical path forming unit wafer. An optical bench and optical
path forming unit assembly may be formed by bonding the optical
path forming unit wafer on which the at least one optical path
forming unit 30 is formed to the optical bench wafer and dicing the
bonded wafers, or the optical path forming unit 30 may be formed by
dicing the optical path forming unit wafer by mirrors and then
attaching the mirrors at proper positions to the optical bench
10.
[0097] The lens unit 70 may be coupled to one side of the top
surface of the optical bench 10. The lens unit 70 may comprise at
least one of a refractive lens, a diffractive lens and a gradient
index (GRIN) lens.
[0098] Referring to FIG. 5, the lens unit 70 may comprise a hybrid
lens comprising a refractive lens 71 and a diffractive lens 73. In
the exemplary embodiment, the refractive lens 71 may be inserted
into a lens holder 75 and the diffractive lens 73 may be formed at
one surface of the lens holder 75.
[0099] Referring to FIG. 5, the lens unit 70 may be formed by
perforating a silicon substrate to form the lens holder 75 having
an opening to assemble the refractive lens 71, forming the
diffractive lens 73 on a glass substrate, inserting the refractive
lens 71 into the opening of the lens holder 75 and attaching the
diffractive lens 73 to one surface of the lens holder 75.
[0100] An objective lens focuses the light emitted from the light
source 15 and forms a light spot smaller than a diffraction limit
to record a signal on the information storage medium 1 and read the
recorded signal. The refractive lens 71 and the diffractive lens 73
may be designed to function as an objective lens for incident
diverging light. Accordingly, if the hybrid lens comprising the
diffractive lens 73 and the refractive lens 71 is used as the
objective lens, the refractive lens 71 can be easily manufactured
and better correction of chromatic aberration can be achieved. In
the exemplary embodiment, although the refractive lens 71 and the
diffractive lens 73 are independent parts in FIG. 5, the hybrid
lens comprising the refractive lens 71 and the diffractive lens 73
that are integrally formed with each other may be used as the
objective lens.
[0101] On the other hand, the diffractive lens 73, as shown in FIG.
5, may be formed at a bottom surface of the lens holder 75. The
diffractive lens 73 may be designed to collimate a beam.
[0102] In this case, if the refractive lens 71 is installed into
the lens holder 75, the diffractive lens 73 functions as a
collimating lens that collimates incident diverging light and the
refractive lens 71 functions as an objective lens that focuses the
light collimated by the diffractive lens 73.
[0103] In the exemplary embodiment, when the lens unit 70 comprises
the hybrid lens in which the refractive lens 71 and the diffractive
lens 73 are combined, the hybrid lens can relieve aberration, such
as chromatic aberration and spherical aberration, whether the
hybrid lens acts as both an objective lens and a collimating lens
or acts as only an objective lens. For example, the diffractive
lens 73 has a greater diffraction angle with respect to longer
wavelength light, and the refractive lens 71 has a smaller
refraction angle with respect to longer wavelength light.
Accordingly, by combining the diffractive lens 73 and the
refractive lens 71, an occurrence of chromatic aberration due to a
variation in the wavelength of light can be suppressed.
[0104] When the diffractive lens 73 is designed to collimate a
beam, the lens unit 70 functions as a collimating lens in the state
where the refractive lens 71 is not assembled into the lens holder
75, as shown in FIG. 6.
[0105] Accordingly, when the refractive lens 71 is inserted into
the lens holder 75 of the lens unit 70, the integrated optical
system according to the present invention can be used as an
integrated optical pickup as illustrated in FIG. 7.
[0106] Further, when the refractive lens 71 is not inserted into
the lens holder 75 of the lens unit 70, the integrated optical
system according to the present invention may be used as an optical
pickup module for an optical pickup as shown in FIG. 8.
[0107] FIG. 7 is a diagram illustrating an example where the
integrated optical system according to the present invention is
used as an integrated optical pickup. Referring to FIG. 7, the lens
unit 70 comprises both the refractive lens 71 and the diffractive
lens 73 shown in FIG. 5.
[0108] When the integrated optical system is used as the integrated
optical pickup as shown in FIG. 7, the whole integrated optical
system is focused, tracked and/or tilted by the actuator.
[0109] FIG. 8 is a diagram illustrating an example where the
integrated optical system according to an exemplary embodiment of
the present invention is used as the optical module for an optical
pickup. Referring to FIG. 8, the lens unit 70 may include the
diffractive lens 73 designed to act as a collimating lens but not
include the refractive lens 71 designed to act as an objective
lens.
[0110] In the exemplary embodiment, the diffractive lens 73
designed to act as a collimating lens may be formed on a separate
substrate and attached to the opening of the optical bench 10 or
may be integrally formed with the optical path separating member
50.
[0111] In the exemplary embodiment, the lens unit 70 may use a
refractive lens, a diffractive lens or a GRIN lens as the
collimating lens, and in this case, the integrated optical system
can be used as an optical module for an optical module.
[0112] When the integrated optical system is used as the optical
module as shown in FIG. 8, the optical pickup may further comprise
a reflection mirror 81 reflecting light emitted from the optical
module and an objective lens 85 focusing the light reflected by the
reflection mirror 81 and forming a spot on the information storage
medium 1. In this case, only the objective lens 85 can be focused,
tracked and/or tilted by the actuator.
[0113] Therefore, the integrated optical system according to the
present invention can be easily converted between the optical
pickup and the optical module for an optical pickup during
manufacturing. That is, the integrated optical system can be
selectively used as the optical module for the optical pickup or
the optical pickup by selectively inserting the refractive lens 71
into the lens holder 75 having one surface on which the diffractive
lens 73 is formed.
[0114] Also, when the lens holder 75 is used as shown in FIGS. 5
and 6, the lens unit 70 can be easily coupled to the optical bench
10 by simply attaching the lens holder 75 to the optical bench
10.
[0115] Although the diffractive lens 73 is used in the above
description, a refractive lens functioning as a collimating lens
may be used instead of the diffractive lens 73.
[0116] In the integrated optical system according to the present
invention, some intensity portion of light emitted from the light
source 15, that is, from the semiconductor laser, is reflected by
the first mirror 31 and then focused on the information storage
medium 1 through the objective lens, that is, the refractive lens
71 functioning as the objective lens of the lens unit 70 or the
separate objective lens 85 (see FIG. 8). Some low intensity portion
of light emitted from the light source 15 and not collected by the
objective lens is transmitted to the monitor photodetector 19 to
monitor the intensity of light emitted from the light source
15.
[0117] Light reflected by the information storage medium 1 passes
through the objective lens, is divided into a plurality of beams or
is adjusted the shape of a spot focused on the main photodetector
17, and is changed proceeding direction by the optical path
separating member 50, is reflected by the first mirror 31, and
reaches the second mirror 35 without interfering with the light
source 15 and the sub mount 13 of the light source 15. Light
reflected by the second mirror 35 is formed on the main
photodetector 17 for signal detection to detect a signal recorded
on the information storage medium 1 and/or focusing and tracking
errors of the information storage medium 1.
[0118] Since the integrated optical system according to the present
invention has a simpler structure than a conventional optical
pickup, and a MEMS process can be used to manufacture most parts,
that is, the optical bench and the optical path forming unit of the
integrated optical system, a plurality of the integrated optical
systems can be simultaneously manufactured on a wafer, and can be
more easily adjusted and assembled than for a conventional optical
pickup. Also, since the structure is simple and the most parts are
integrated, the size of the optical pickup can be reduced.
[0119] A method of manufacturing the integrated optical system
according to the present invention will now be explained.
[0120] First, the optical bench 10 can be manufactured as follows.
After the main photodetector 17 and the monitor photodetector 19
are directly formed on the optical bench wafer, the internal wires
21 and the pads 23 are formed through a thin film process. To mount
the light source 15, i.e., the semiconductor laser, on the optical
bench 10, the sub mount 13 to which the light source 15 is bonded
is manufactured, and the sub mount 13 is bonded to the bottom
surface 11 of the optical bench 10 on which the main photodetector
17 and the monitor photodetector 19 are disposed. The wires 21 are
connected by wire bonding, if necessary. Alternatively, the main
photodetector 17 and the monitor photodetector 19 may be separately
manufactured and then bonded to the bottom surface 11 of the
optical bench 10, and the light source 15 may be directly formed on
the optical bench 10 through a semiconductor process.
[0121] The optical path forming unit 30 comprising the first and
second mirrors 31 and 35 is manufactured through a wafer process,
that is, the first and second mirrors 31 and 35 are in array formed
on the wafer by etching the optical path forming unit wafer or
molding polymer or glass.
[0122] After the optical bench wafer on which the optical bench 10
is formed and the optical path forming unit wafer on which the
optical path forming unit 30 including the first and second mirrors
31 and 35 is formed are manufactured, the optical path forming unit
wafer and the optical bench wafer are aligned, bonded, and diced to
obtain an optical bench and optical path forming unit assembly.
[0123] By coupling the optical path separating member 50 and the
lens unit 70 to each optical bench and optical path forming unit
assembly die, the integrated optical system used as the optical
pickup or the optical module can be manufactured.
[0124] In the exemplary embodiment, the lens unit 70 and the
optical path separating member 50 are coupled to the optical bench
10 by centering the lens unit 70 (e.g., the objective lens) and
adjusting the optical path separating member 50 and the lens unit
70 so that light can be properly received by the main photodetector
17. When the lens unit 70 and the optical path separating member 50
are coupled to the optical bench 10 through this adjustment
process, the integrated optical system according to the present
invention is obtained.
[0125] Alternatively, to manufacture the integrated optical system,
the optical bench wafer on which the optical bench 10 is formed is
prepared, and mirrors which are manufactured through a wafer
process or are separately manufactured are attached at appropriate
positions to the optical bench 10 on the optical bench wafer to
form a structure in which the first and second mirrors 31 and 35 of
the optical path forming unit 30 are attached to the optical bench
10. Subsequently, the optical bench wafer to which the optical path
forming unit 30 is attached is diced to obtain an optical bench and
optical path forming unit assembly.
[0126] In the exemplary embodiment, the mirrors 31 and 35
constituting the optical path forming unit 30 may be processed in
an array from on the optical path forming unit wafer through a
wafer process. The optical path forming unit wafer is diced into
mirrors, the mirrors are separated and then attached at appropriate
positions to the optical bench wafer, and the optical bench wafer
is diced, to obtain the optical bench and optical path forming unit
assembly. Alternatively, the optical bench wafer may be first
diced, and the mirrors may be attached at appropriate positions to
each of the optical benches to obtain an optical bench and optical
path forming unit assembly.
[0127] In the exemplary embodiment, the objective lens of the lens
unit 70 may be first fixed to the optical bench 10 and then the
first and second mirrors 31 and 35 of the optical path forming unit
30 may be attached to the optical bench 10. In this case, after the
objective lens is fixed, the position of the first mirror 31 is
determined according to the position of the objective lens. Next,
the optical path separating member 50 is adjusted so that the main
photodetector 17 can properly receive light and the optical path
separating member 50 can be inserted into the optical bench 10 to
obtain the integrated optical system according to the present
invention.
[0128] Alternatively, the objective lens and the optical path
separating member 50 may be first fixed to the optical bench 10 and
then the first mirror 31 and the second mirror 35 may be attached
to the optical bench 10. In this case, after the objective lens is
fixed, the position of the first mirror 31 is determined according
to the position of the objective lens and the position of the
second mirror 35 is determined so that light can be properly
received by the main photodetector 17.
[0129] While methods of manufacturing the integrated optical system
according to the present invention have been explained in detail,
the present invention is not limited thereto, and various
modifications falling within the spirit and scope of the appended
claims can be made.
[0130] Examples of various arrangements of the monitor
photodetector 19 in the integrated optical system according to the
present invention will now be explained. The monitor photodetector
19 is disposed in front of the light source as described above.
[0131] FIGS. 9 through 11 respectively illustrate examples in which
the monitor photodetector 19 is disposed on the bottom surface 11
of the optical bench 10 and parallel to the light source 15, the
monitor photodetector 19 is slanted toward the light source 15, and
the monitor photodetector 19 is disposed on a portion protruding
from the bottom surface 11 of the optical bench 10 and parallel to
the light source 15. FIGS. 9 through 11 illustrate examples in
which the width of the effective light receiving area of the
monitor photodetector 19 is 0.7 mm. Referring to FIGS. 9 through
11, LD denotes a light emitting point of the light source 15, MPD
denotes the monitor photodetector 19, effective beam area denotes
the portion of the beam used for information recording and/or
reproduction, and beam area incident on MPD denotes the portion of
the beam incident on the effective light receiving area of the
monitor photodetector 19.
[0132] Table 1 shows the ratios of the intensity of light received
by the monitor photodetector 19 to the total light emitted from the
light source 15 respectively when the monitor photodetector 19 is
positioned relatively to the light source 19 as shown in FIGS. 9
through 11 and the effective light receiving area of the monitor
photodetector 19 is 0.7 mm and 0.5 mm.
TABLE-US-00001 TABLE 1 Ratio of amount of light (energy) received
by MPD MPD effective MPD effective light receiving light receiving
Position of MPD area .PHI. = 0.7 mm area .PHI. = 0.5 mm Disposed on
bottom 6.9% 4.75% surface and parallel to LD Slanted toward LD
23.1% 22.58% Disposed on portion 17.96% 13.58% protruding from
bottom surface of optical bench and parallel to LD
[0133] Referring to Table 1, when the width of the effective light
receiving area of the monitor photodetector 19 is 0.7 mm, the ratio
of the amount of light received by the monitor photodetector 19 is
6.9%, 23.1% and 17.96% respectively in FIGS. 9, 10, and 11. When
the width of the effective light receiving area of the monitor
photodetector 19 is 0.5 mm, the ratio of the intensity of light
received by the monitor photodetector 19 is 4.75%, 22.58% and
13.58% respectively in FIGS. 9, 10, and 11.
[0134] It is known that when the amount of light received by the
monitor photodetector 19 ranges from 5% to 10% of the total light
emitted from the light source 15, the total amount of light emitted
from the light source 15 can be monitored.
[0135] Considering this, when the monitor photodetector 19 is
disposed on the bottom surface 11 of the optical bench 10, which is
spaced 2.085 mm from the light source 15 so that the width of the
effective light receiving area is 0.7 mm, the ratio of light
received by the monitor photodetector 19 is 6.9%. Accordingly,
light of sufficient amount for monitoring can be received.
[0136] Referring to FIG. 9, when the monitor photodetector 19 is
disposed on the bottom surface 11 of the optical bench 10, if the
monitor photodetector 19 is distanced farther from the light source
15, the width of the effective light receiving area may be less
than 0.7 mm. Further, if the monitor photodetector 19 is brought
closer to the light source 15, the width of the effective light
receiving area may be greater than 0.7 mm.
[0137] FIG. 9 illustrates a specific design example. Accordingly,
the distance between the monitor photodetector 19 and the light
source 15, and the effective light receiving area are not limited
to the example illustrated in FIG. 9, and various modifications can
be made within a range where light of sufficient amount for
monitoring can be received.
[0138] Referring to FIG. 10, when the monitor photodetector 19 is
disposed at a point spaced 1.099 mm from the light source 15 and
slanted at 15 degrees toward the light source 15 so that the width
of the effective light receiving area is 0.7 mm, the ratio of light
received by the monitor photodetector 19 is 23.1%. Under the same
conditions, when the width of the effective light receiving area of
the monitor photodetector 19 is 0.5 mm, the ratio of light received
by the monitor photodetector 19 is 22.58%.
[0139] When the monitor photodetector 19 is slanted toward the
light source 15 as shown in FIG. 10, even if the amount of light
received by the monitor photodetector 19 is reduced, monitoring can
be conducted. Accordingly, the monitor photodetector 19 may be
slanted at an angle less than 15 degrees or the monitor
photodetector 19 may be positioned closer to the light source
15.
[0140] FIG. 10 illustrates a specific design example. Accordingly,
the distance between the monitor photodetector 19 and the light
source 15, the effective light receiving area, and the slanting
angle of the monitor photodetector 19 are not limited to the
example illustrated in FIG. 10, and various modifications can be
made within a range where light of sufficient amount for monitoring
can be received.
[0141] When the monitor photodetector 19 is disposed on a portion
protruding 0.218 mm from the bottom surface 11 of the optical bench
10 and spaced 0.5 mm from the light source 15 so that the width of
the effective light receiving area can be 0.7 mm as shown in FIG.
11, the ratio of light received by the monitor photodetector 19 is
17.96%. Under the same conditions, when the width of the effective
light receiving area of the monitor photodetector 19 is 0.5 mm, the
ratio of light received by the monitor photodetector 19 is
13.58%.
[0142] When the monitor photodetector 19 is disposed at the portion
protruding from the bottom surface 11 of the optical bench 10 as
shown in FIG. 11, even if the amount of light received by the
monitor photodetector 19 is reduced, monitoring can be conducted.
Accordingly, the protrusion of the monitor photodetector 19 may be
less than 0.218 mm as indicated in FIG. 11, or the monitor
photodetector 19 may be closer to the light source 15.
[0143] FIG. 11 illustrates a specific design example. The distance
between the monitor photodetector 19 and the light source 15, the
distance between the monitor photodetector 19 and the bottom
surface 11 of the optical bench 10, and the effective light
receiving area are not limited to the example illustrated in FIG.
11, and various modifications can be made within a range where
light of sufficient amount for monitoring can be received.
[0144] It can be seen from Table 1 that the monitor photodetector
19 may be disposed on the bottom surface 11 of the optical bench 10
in front of the light source 15, and in this case, the structure to
dispose the monitor photodetector 19 can be simple.
[0145] Also, the monitor photodetector 19 may be slanted toward the
light source 15, or disposed on the portion protruding from the
bottom surface 11 of the optical bench 10.
[0146] FIG. 12 is a schematic view of an information recording
and/or reproducing apparatus employing the integrated optical
system according to the present invention.
[0147] Referring to FIG. 12, the information recording and/or
reproducing apparatus comprises a rotating unit including a spindle
motor 455 rotating an information storage medium 1 (e.g., an
optical disc), an optical pickup 400 installed to be movable in a
radial direction of the information storage medium 1 and
reproducing information recorded on the information storage medium
1 and/or recording information, a driving unit 457 driving the
rotating unit and the optical pickup 400, and a control unit 470
controlling the driving unit 457 to control focusing and tracking
servos of the optical pickup 450. The apparatus further includes a
turntable 452, and a clamp 453 chucking the information storage
medium 1.
[0148] The optical pickup 400 includes the integrated optical
system according to an exemplary embodiment of the present
invention. That is, the optical pickup 400 may be the integrated
optical system according to the present invention when the
integrated optical system is formed to function as an optical
pickup as shown in FIG. 7.
[0149] Alternatively, the optical pickup 400 may comprise the
integrated optical system according to the present invention when
the integrated optical system is formed to function as an optical
module as shown in FIG. 8.
[0150] Light reflected by the information storage medium 1 is
detected by the main photodetector 17 mounted on the optical pickup
400 and converted into an electrical signal through photoelectric
conversion. The electrical signal is input to the control unit 459
via the driving unit 457. The driving unit 457 controls the rate of
rotation of the spindle motor 455, amplifies the input signal and
drives the optical pickup 400. The control unit 459 transmits a
focusing servo command and a tracking servo command, both of which
are adjusted based on the signal input from the driving unit 457,
to the driving unit 457 again to implement a focusing and tracking
servo operation of the optical pickup 400. Further, the control
unit 459 uses the light amount signal detected by the monitor
photodetector 19 and controls the light output from the light
source 15 so that light of proper amount can be emitted from the
light source 15.
[0151] When an optical pickup according to any one of embodiments
of the present invention is used, a small, slim information
recording and/or reproducing apparatus can be realized.
[0152] Accordingly, the information recording and/or reproducing
apparatus employing the optical pickup according to the present
invention can be applied to a portable terminal, such as a personal
digital assistant (PDA), a mobile phone, a digital camera, a
portable disc player or a camcorder.
[0153] While the integrated optical system, the method thereof, and
the information recording and/or reproducing apparatus using the
integrated optical system as the optical module or the optical
pickup have been described with reference to the appended drawings,
the present invention is not limited thereto, and various
modifications can be conducted within the technical scope of the
claims.
[0154] Since the integrated optical system according to the present
invention can satisfy requirements for small, slim devices, and can
be integrated using a MEMS process, a plurality of integrated
optical systems can be simultaneously manufactured on a wafer and
can be more easily adjusted and assembled than conventional optical
pickups. Additionally, since the structure is simple and most of
the parts can be integrated, the size of the optical pickup can be
reduced.
[0155] Furthermore, when the lens unit is structured such that a
lens functioning as a collimating lens is formed on one surface of
the lens holder and a refractive lens functioning as an objective
lens can be selectively inserted into the lens holder, the
integrated optical system according to the present invention can be
easily converted for use as an optical module and an integrated
optical pickup according to the formation of the diffractive lens
and the existence of the refractive lens.
[0156] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those of ordinary skill in the art that various
changes in form and details may be made therein without departing
from the spirit and scope of the present invention as defined by
the following claims.
* * * * *