U.S. patent application number 13/196077 was filed with the patent office on 2012-02-16 for microscope and ghosting elimination method.
This patent application is currently assigned to SONY CORPORATION. Invention is credited to Norihiro Tanabe, Takashi Yamamoto.
Application Number | 20120038978 13/196077 |
Document ID | / |
Family ID | 44763792 |
Filed Date | 2012-02-16 |
United States Patent
Application |
20120038978 |
Kind Code |
A1 |
Tanabe; Norihiro ; et
al. |
February 16, 2012 |
MICROSCOPE AND GHOSTING ELIMINATION METHOD
Abstract
A microscope includes a first imaging optical system that images
sample transmitted light transmitted through a sample provided on a
stage, and a second imaging optical system that images a part of
the sample transmitted light branched from the first imaging
optical system. Here, the second imaging optical system includes a
light beam branching element that branches the part of the sample
transmitted light from the first imaging optical system, and has a
thickness of a predetermined threshold or more, an imaging element
that images a phase difference image of the branched sample
transmitted light, one or a plurality of optical elements that
images an image of the phase difference image of the branched
sample transmitted light on the imaging element, and a filter that
shields a part of the branched sample transmitted light imaged on
the imaging element.
Inventors: |
Tanabe; Norihiro; (Tokyo,
JP) ; Yamamoto; Takashi; (Tokyo, JP) |
Assignee: |
SONY CORPORATION
Tokyo
JP
|
Family ID: |
44763792 |
Appl. No.: |
13/196077 |
Filed: |
August 2, 2011 |
Current U.S.
Class: |
359/372 |
Current CPC
Class: |
G02B 21/245 20130101;
G02B 21/247 20130101; G02B 27/0018 20130101; G02B 21/18
20130101 |
Class at
Publication: |
359/372 |
International
Class: |
G02B 21/06 20060101
G02B021/06 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 16, 2010 |
JP |
2010-181760 |
Claims
1. A microscope, comprising: a first imaging optical system that
images sample transmitted light transmitted through a sample
provided on a stage; and a second imaging optical system that
images a part of the sample transmitted light branched from the
first imaging optical system, wherein the second imaging optical
system includes a light beam branching element that branches the
part of the sample transmitted light from the first imaging optical
system, and has a thickness of a predetermined threshold or more,
an imaging element that images a phase difference image of the
branched sample transmitted light, one or a plurality of optical
elements that images an image of the phase difference image of the
branched sample transmitted light on the imaging element, and a
filter that shields a part of the branched sample transmitted light
imaged on the imaging element.
2. The microscope according to claim 1, wherein the sample
transmitted light reflected by the light beam branching element is
imaged in the first imaging optical system, and the phase
difference image of the sample transmitted light transmitted
through the light beam branching element is imaged in the second
imaging optical system.
3. The microscope according to claim 1, wherein the sample
transmitted light transmitted through the light beam branching
element is imaged in the first imaging optical system, and the
phase difference image of the sample transmitted light reflected by
the light beam branching element is imaged in the second imaging
optical system.
4. The microscope according to claim 2, wherein the filter is a
diaphragm in which a through hole set for allowing a luminous flux
set which becomes the phase difference image to pass therethrough
is provided, and the thickness of the light beam branching element
has a larger value than a feature value calculated based on a
diameter of the through hole, a center distance between the through
holes of the through hole set, and a luminous flux diameter at a
position of the filter of the sample transmitted light.
5. The microscope according to claim 4, wherein the thickness of
the light beam branching element has a larger value than a feature
value calculated based on the following Inequality 1, which is
represented as t > k .times. ( .phi. a + .phi. b + d ) 2 Math .
1 ##EQU00004## where t denotes a thickness of the light beam
branching element, k denotes a specific constant in an optical
system, .phi.a denotes a luminous flux diameter at a filter
position of the sample transmitted light, .phi.b denotes a diameter
of the through hole, and d denotes a center distance of through
holes of the through hole set.
6. A ghosting elimination method, comprising: branching, by a light
beam branching element having a thickness of a predetermined
threshold or more, a part of sample transmitted light transmitted
through a sample provided on a stage; and shielding, by an imaging
element for imaging a phase difference image of the branched sample
transmitted light and a filter provided between the imaging element
and the light beam branching element, ghosting light caused by a
corresponding light beam branching element from the part of the
sample transmitted light branched by the light beam branching
element.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] The present application claims priority to Japanese Priority
Patent Application JP 2010-181760 filed in the Japan Patent Office
on Aug. 16, 2010, the entire contents of which are hereby
incorporated by reference.
BACKGROUND
[0002] The present application relates to a microscope and a
ghosting elimination method.
[0003] In the related art, a motor-driven microscope in which a
condenser lens, a visual field diaphragm, an aperture diaphragm,
the optical axis direction driving mechanism for the objective lens
of a sample stage, a filter, a dimming power supply with respect to
a light source, and the like are automatically adjusted in
accordance with the switching of the objective lens has been
disclosed (For example, see Japanese Unexamined Patent Application
Publication No. 11-133311).
SUMMARY
[0004] However, in order to achieve an autofocus function with
respect to the microscope described in Japanese Unexamined Patent
Application Publication No. 11-133311, attaching an autofocus
device using a phase difference optical system that obtains a
defocus position to be observed to the microscope has been
considered. In such a case, a light beam branching element is
provided on the optical axis of an imaging optical system for
imaging, on an imaging element, light transmitted through a sample,
so that a part of the light transmitted through the sample is
guided to the phase difference optical system.
[0005] As a result of intensive studies made by the inventors, with
respect to the autofocus device using the phase difference optical
system, it was found that ghosting caused by the light beam
branching element affects an image that is imaged by the imaging
optical system and the phase difference optical system.
[0006] The present application is to solve the above problem, and
it is desirable to provide a microscope having an autofocus
function using a phase difference optical system, and provide a
ghosting elimination method in which ghosting caused by a light
beam branching element is eliminated with respect to the
microscope.
[0007] According to an embodiment, there is provided a microscope,
including: a first imaging optical system that images sample
transmitted light transmitted through a sample provided on a stage;
and a second imaging optical system that images a part of the
sample transmitted light branched from the first imaging optical
system. Here, the second imaging optical system may include a light
beam branching element that branches the part of the sample
transmitted light from the first imaging optical system, and has a
thickness of a predetermined threshold or more, an imaging element
that images a phase difference image of the branched sample
transmitted light, one or a plurality of optical elements that
images an image of the phase difference image of the branched
sample transmitted light on the imaging element, and a filter that
shields a part of the branched sample transmitted light focused on
the imaging element.
[0008] The sample transmitted light reflected by the light beam
branching element may be imaged in the first imaging optical
system, and the phase difference image of the sample transmitted
light transmitted through the light beam branching element may be
imaged in the second imaging optical system.
[0009] The sample transmitted light transmitted through the light
beam branching element may be imaged in the first imaging optical
system, and the phase difference image of the sample transmitted
light reflected by the light beam branching element may be imaged
in the second imaging optical system.
[0010] The filter may be a diaphragm in which a through hole set
for allowing a luminous flux set which becomes the phase difference
image to pass therethrough is provided, and the thickness of the
light beam branching element may have a larger value than a feature
value calculated based on a diameter of the through hole, a center
distance between the through holes of the through hole set, and a
luminous flux diameter at the position of the filter of the sample
transmitted light.
[0011] The thickness of the light beam branching element may have a
larger value than a feature value calculated based on the following
Inequality 1, which is represented as
t > k .times. ( .phi. a + .phi. b + d ) 2 [ Inequality 1 ]
##EQU00001##
[0012] where t denotes the thickness of the light beam branching
element, k denotes a specific constant in an optical system, .phi.a
denotes a luminous flux diameter at a filter position of the sample
transmitted light, .phi.b denotes the diameter of the through hole,
and d denotes the distance between centers of the through holes of
the through hole set.
[0013] According to another embodiment, there is provided a
ghosting elimination method, including: branching, by a light beam
branching element having a thickness of a predetermined threshold
or more, a part of sample transmitted light transmitted through a
sample provided on a stage; and shielding, by an imaging element
for imaging a phase difference image of the branched sample
transmitted light and a filter provided between the imaging element
and the light beam branching element, ghosting light caused by a
corresponding light beam branching element from the part of the
sample transmitted light branched by the light beam branching
element.
[0014] As described above, it is possible to eliminate ghosting
caused by a light beam branching element with respect to a
microscope having an autofocus function using a phase difference
optical system.
[0015] Additional features and advantages are described herein, and
will be apparent from the following Detailed Description and the
figures.
BRIEF DESCRIPTION OF THE FIGURES
[0016] FIG. 1 is a diagram showing a configuration of a microscope
according to a first embodiment;
[0017] FIG. 2 is a block diagram showing a configuration of an
integration control unit according to a first embodiment;
[0018] FIG. 3 is a diagram showing a light beam branching
element;
[0019] FIG. 4 is a diagram showing an example of a defocus quantity
detection unit according to a first embodiment;
[0020] FIG. 5 is a graph showing a relationship between a surface
transmittance of a light beam branching element and an SN ratio of
ghosting;
[0021] FIG. 6 is a graph showing a relationship between a thickness
of a light beam branching element and an amount of deflection;
[0022] FIG. 7 is a diagram showing an example of a two eye lens
filter according to a first embodiment;
[0023] FIG. 8 is a graph showing a relationship between a wavefront
aberration and a thickness of an optical branching element; and
[0024] FIG. 9 is a schematic diagram showing an example of a
defocus quantity detection unit according to a second
embodiment.
DETAILED DESCRIPTION
[0025] Embodiments of the present application will be described
below in detail with reference to the drawings.
[0026] Further, the description will be made in the following
order:
[0027] (1) First Embodiment
[0028] (1-1) Configuration of microscope
[0029] (1-2) Light beam branching element
[0030] (1-3) configuration of defocus quantity detection unit
[0031] (2) Second Embodiment
First Embodiment
[0032] <Configuration of Microscope>
[0033] A configuration of a microscope 1 according to a first
embodiment will be described with reference to FIG. 1. FIG. 1 is a
diagram showing a configuration of a microscope 1 according to the
present embodiment.
[0034] [Entire Configuration]
[0035] As shown in FIG. 1, the microscope 1 according to the
present embodiment includes a thumbnail image imaging unit 10 for
imaging an image (hereinafter, referred to as "thumbnail image") of
the entire preparation PRT in which a biological sample SPL is
embedded, and a magnified image imaging unit 20 for imaging an
image (hereinafter, referred to as "magnified image") in which the
biological sample SPL is magnified at a predetermined magnification
ratio. In addition, in the magnified image imaging unit 20, a
defocus quantity detection unit 30 for detecting a defocus quantity
of an illumination visual field diaphragm existing within the
magnified image imaging unit 20 is provided.
[0036] The preparation PRT is obtained by fixing, on a slide glass,
the biological sample SPL including tissue sections such as
connective tissue such as blood, epithelial tissue, or both of
these organizations, or smear cells using a predetermined fixing
means. The tissue sections or the smear cells are subjected to
various types of staining, as necessary. This staining includes
general staining represented by HE (Hematoxylin and Eosin)
staining, Giemsa staining, and Papanicolaou staining, and
fluorescent staining such as FISH (Fluorescence In-Situ
Hybridization), an enzyme antibody method, or the like.
[0037] In addition, a label in which supplementary information (for
example, name of the person who collects sample, collection date,
and type of staining, and the like) for specifying a corresponding
biological sample SPL is described is attached to the preparation
PRT.
[0038] In the microscope 1 according to the present embodiment, a
stage 40 in which the above described preparation PRT is placed,
and a stage driving mechanism 41 for moving the stage 40 in a
variety of directions are provided. By the stage driving mechanism
41, the stage 40 is freely moved in a direction (Z-axis direction)
perpendicular to a direction (X-axis and Y-axis direction) parallel
to a stage surface.
[0039] In addition, in the magnified image imaging unit 20, a
condenser lens driving mechanism 42 as an example of a focus
adjustment unit for an illumination visual field diaphragm is
provided.
[0040] <Thumbnail Image Imaging Unit>
[0041] As shown in FIG. 1, the thumbnail image imaging unit 10
mainly includes a light source 11, an objective lens 12, and an
imaging element 13.
[0042] The light source 11 is provided on a surface opposite to a
surface on which the preparation of the stage 40 is disposed. The
light source 11 may perform irradiation by switching light
(hereinafter, referred to as bright visual field illumination
light, or simply referred to illumination light) for illuminating
the biological sample SPL having been subjected to the general
staining, and light (hereinafter, referred to as dark visual field
illumination light) for illuminating the biological sample SPL
having been subjected to special staining. In addition, the light
source 11 may perform irradiation with respect to only one of the
bright visual field illumination light and the dark visual field
illumination light. In this case, as the light source 11, two types
of light sources such as a light source for irradiating the bright
visual field illumination light and a light source for irradiating
the dark visual field illumination light are provided.
[0043] In addition, in the thumbnail image imaging unit 10, a label
light source (not shown) that irradiates light for imaging the
supplementary information described on the label attached to the
preparation PRT may not be separately provided.
[0044] The objective lens 12 with a predetermined magnification is
arranged on the preparation disposition surface side of the stage
40 using, as the optical axis SRA, a normal line of a reference
position of the thumbnail image imaging unit 10 in the preparation
disposition surface. Transmitted light transmitted through the
preparation PRT arranged on the stage 40 is condensed by the
objective lens 12, and is imaged on the imaging element 13 provided
behind (that is, advancing direction of the illumination light) the
objective lens 12.
[0045] On the imaging element 13, light (in other words,
transmitted light transmitted through the entire preparation PRT)
of an imaging range including the entire preparation PRT placed in
the preparation disposition surface of the stage 40 is imaged. An
image imaged on the imaging element 13 is a thumbnail image being a
microscope image obtained by imaging the entire preparation
PRT.
[0046] <Magnified Image Imaging Unit>
[0047] As shown in FIG. 1, the magnified image imaging unit 20
mainly includes a light source 21, a condenser lens 22, an
objective lens 23, and an imaging element 24. In addition, an
illumination visual field diaphragm (not shown) is provided in the
magnified image imaging unit 20.
[0048] The light source 21 irradiates bright visual field
illumination light, and is provided on a surface opposite to a
surface on which the preparation of the stage 40 is disposed. In
addition, a light source (not shown) that irradiates dark visual
field illumination light is provided in different position (for
example, preparation disposition surface side) from that of the
light source 21.
[0049] The condenser lens 22 is a lens that condenses the bright
visual field illumination light irradiated from the light source 21
or the dark visual field illumination light irradiated from a light
source for dark visual field illumination, and guides the condensed
light to the preparation PRT on the stage 40. The condenser lens 22
is arranged between the light source 21 and the stage 40 using, as
the optical axis ERA, a normal line of a reference position of the
magnified image imaging unit 20 in the preparation disposition
surface. In addition, the condenser lens driving mechanism 42 may
drive the condenser lens 22 in a direction of the optical axis ERA.
The condenser lens 22 may change the position on the optical axis
ERA by the condenser lens driving mechanism 42.
[0050] The objective lens 23 of the predetermined magnification is
arranged in the preparation disposition surface side of the stage
40 using, as the optical axis ERA, the normal line of the reference
position of the magnified image imaging unit 20 in the preparation
disposition surface. In the magnified image imaging unit 20, the
biological sample SPL is magnified at a variety of magnification
ratios by appropriately changing the objective lens 23, and the
magnified sample is imaged. The transmitted light transmitted
through the preparation PRT arranged on the stage 40 is condensed
by the objective lens 23, and is imaged on the imaging element 24
provided behind (that is, advancing direction of illumination
light) the objective lens 23.
[0051] In addition, on the optical axis ERA between the objective
lens 23 as an example of a first imaging optical system, and the
imaging element 24, a light beam branching element 31 is provided,
and a part of the transmitted light transmitted through the
objective lens 23 is guided to a defocus quantity detection unit
30, which will be described later.
[0052] In the imaging element 24, an image of an imaging range
having a predetermined width and height is imaged on the
preparation disposition surface of the stage 40 depending on a
pixel size of the imaging element 24 and a magnification ratio of
the objective lens 23. In addition, since a part of the biological
sample SPL is magnified by the objective lens 23, the above
described imaging range is a satisfactorily narrow range, compared
with the imaging range of the imaging element 13.
[0053] Here, as shown in FIG. 1, the thumbnail image imaging unit
10 and the magnified image imaging unit 20 are arranged in such a
manner that the optical axes SRA and ERA of the normal line of the
reference position of each of the thumbnail image imaging unit 10
and the magnified image imaging unit 20 are separated from each
other by a distance D in a Y-axis direction. The distance D is set
to a short distance for miniaturization while a lens barrel (not
shown) holding the objective lens 23 of the magnified image imaging
unit 20 does not appear in the imaging range of the imaging element
13.
[0054] <Defocus Quantity Detection Unit>
[0055] The defocus quantity detection unit 30 as an example of a
second imaging optical system mainly includes a light beam
branching element 31, a condenser lens 32, a two eye lens filter
33, a two eye lens 34, and an imaging element 35, as shown in FIG.
1.
[0056] As described above, the light beam branching element 31 is
provided on the optical axis ERA between the objective lens 23 of
the magnified image imaging unit 20 and the imaging element 24, so
that a part of sample transmitted light (light transmitted through
the sample) transmitted through the objective lens 23 is reflected.
In other words, by the light beam branching element 31, the sample
transmitted light transmitted through the objective lens 23 is
branched to transmitted light advancing toward the imaging element
24 and reflected light advancing toward the condenser lens 32
within the defocus quantity detection unit 30, which will be
described later.
[0057] According to the present embodiment, in an advancing
direction side of the reflected light branched by the light beam
branching element 31, the condenser lens 32 is provided. The
condenser lens 32 condenses the reflected light branched by the
light beam branching element 31, and guides the condensed light to
the two eye lens 34 provided behind (advancing direction side of
reflected light) the condenser lens 32.
[0058] The two eye lens filter 33 is a filter that is provided
between the condenser lens 32 and the two eye lens 34, which will
be described later, and shields a part of the reflected light
(reflected light of sample transmitted light) imaged on the imaging
element 35 provided within the defocus quantity detection unit 30.
The reflected light transmitted through the two eye filter 33 is
guided to the two eye lens 34 provided behind the two eye lens
filter 33.
[0059] The two eye lens 34 splits a luminous flux introduced by the
condenser lens 32 into two luminous fluxes. The split luminous flux
forms a set of object images on a imaging surface of the imaging
element 35 provided behind (advancing direction side of reflected
light) the two eye lens 34.
[0060] On the imaging element 35, each of light transmitted through
the two eye lens 34 is imaged. As a result, on an imaging surface
of the imaging element 35, the set of object images is formed.
Since luminous fluxes of a variety of directions emitted from the
condenser lens 32 are made incident on the two eye lens 34, a phase
difference exists between the formed set of object images.
Hereinafter, the set of object images is referred to as a phase
difference image. The defocus quantity detection unit 30 according
to the present embodiment detects a defocus quantity of an
illumination visual field diaphragm existing within the magnified
image imaging unit 20, using the phase difference.
[0061] Further, in the described above, a configuration in which
the condenser lens as a phase difference AF optical system within
the defocus quantity detection unit 30, the two eye lens filter,
the two eye lens, and the imaging element are provided is shown,
however, the configuration is not limited to the example. Another
optical system may be used as long as the other optical system can
realize the same function as that of the phase difference AF
optical system, such as using a field lens and a separator lens
instead of the condenser lens and the two eye lens.
[0062] In addition, the imaging elements which are provided on the
thumbnail image imaging unit 10, the magnified image imaging unit
20 and the defocus quantity detection unit 30 respectively, may be
an one dimensional imaging element or a two dimensional
element.
[0063] Further, the defocus quantity detection unit 30 will be
described in detail below again.
[0064] <Control Unit>
[0065] As shown in FIG. 1, a control unit for controlling various
positions of the microscope is connected to the microscope 1
according to the present embodiment. Specifically, an illumination
control unit 51 for controlling a variety of light sources of the
microscope 1 which includes a light source 11 and a light source 21
is connected to the microscope 1 according to the present
embodiment, and a stage driving control unit 52 for controlling the
stage driving mechanism 41 is connected to the stage driving
mechanism 41. In addition, a condenser lens driving control unit 53
for performing position control of the condenser lens 22 is
connected to the condenser lens 22. Further, a phase difference
image imaging control unit 54 is connected to the imaging element
35 for imaging the phase difference image, and a thumbnail image
imaging control unit 55 is connected to the imaging element 13 for
imaging a thumbnail image. In addition, a magnified image imaging
control unit 56 is connected to the imaging element 24 for imaging
a magnified image of the biological sample SPL. These control units
are connected with respect to a position for performing control via
a variety of data communication channels.
[0066] In addition, in the microscope 1 according to the present
embodiment, a control unit (hereinafter, referred to as integrated
control unit 50) for controlling the entire microscope is
separately provided, and connected to the above described control
units via the variety of data communication channels.
[0067] The above described control unit is realized by CPU (Central
Processing Unit), GPU (Graphics Processing Unit), ROM (Read Only
Memory), RAM (Random Access Memory), a storage device, a
communication device, an arithmetic circuit, and the like.
[0068] Hereinafter, function of the above described control unit
will be briefly described.
[0069] <Illumination Control Unit>
[0070] An illumination control unit 51 is a processing unit for
controlling a variety of light sources of the microscope 1
according to the present embodiment. The illumination control unit
51 performs irradiation control of a corresponding light source
based on information indicating an acquired illumination method
when information indicating an illumination method of the
biological sample SPL is output from the integrated control unit
50.
[0071] For example, a case in which the illumination control unit
51 controls the light source 11 provided in the thumbnail image
imaging unit 10 will be herein noted. In such a case, with
reference to information indicating the illumination method, the
illumination control unit 51 determines which one of a mode
(hereinafter, referred to as bright visual field mode) which is
necessary for acquiring a bright visual field image, and a mode
(hereinafter, referred to as dark visual field mode) which is
necessary for acquiring a dark visual field image is performed.
Thereafter, the illumination control unit 51 sets parameters
depending on each mode with respect to the light source 11, and
irradiates illumination light applied to each mode from the light
source 11. Thus, the illumination light irradiated from the light
source 11 is irradiated to the entire biological sample SPL via an
opening of the stage 40. Further, as examples of the parameters set
by the illumination control unit 51, intensity of the illumination
light, selection in type of the light source, and the like may be
given.
[0072] In addition, a case in which the illumination control unit
51 controls the light source 21 provided in the magnified image
imaging unit 20 will be herein noted. In such a case, with
reference to information indicating the illumination method, the
illumination control unit 51 determines which one of the bright
visual field mode and the dark visual field mode is performed.
Thereafter, the illumination control unit 51 sets parameters
depending on each mode with respect to the light source 21, and
irradiates illumination light applied to each mode from the light
source 21. Thus, the illumination light irradiated from the light
source 21 is irradiated to the entire biological sample SPL via the
opening of the stage 40. Further, as examples of the parameters set
by the illumination control unit 51, intensity of the illumination
light, selection in the type of the light source, and the like may
be given.
[0073] Further, as irradiation light in the bright visual field
mode, visible light may be used. In addition, as irradiation light
in the dark visual field mode, light including a wavelength which
can excite a fluorescent marker used in the special staining may be
used. In addition, in the dark visual field mode, a background
portion with respect to the fluorescent marker is cut out.
[0074] <Stage Driving Control Unit>
[0075] The stage driving control unit 52 is a processing unit that
controls the stage driving mechanism 41 for driving the stage
provided in the microscope 1 according to the present embodiment.
The stage driving control unit 52 controls the stage driving
mechanism 41 based on information indicating an acquired imaging
method when information indicating an imaging method of the
biological sample SPL is output from the integrated control unit
50.
[0076] For example, a case in which a thumbnail image is imaged by
the microscope 1 according to the present embodiment will be noted
herein. When information indicating that the thumbnail image of the
biological sample SPL is imaged is output from the integrated
control unit 50, the stage driving control unit 52 moves the stage
40 in a stage surface direction (X-Y axis direction) so that the
entire preparation PRT is within the imaging range of the imaging
element 13. In addition, the stage driving control unit 52 moves
the stage 40 in a Z-axis direction so that focal point of the
objective lens 12 matches the entire preparation PRT.
[0077] In addition, a case in which a magnified image is imaged by
the microscope 1 according to the present embodiment will be herein
noted. When information indicating that the magnified image of the
biological sample SPL is imaged is output from the integrated
control unit 50, the stage driving control unit 52 drives and
controls the stage driving mechanism 41, and moves the stage 40 in
the stage surface direction so that the biological sample SPL is
positioned between the light source 11 and the objective lens 12
and between the condenser lens 22 and the objective lens 23.
[0078] In addition, the stage driving control unit 52 moves the
stage 40 in the stage surface direction (X-Y axis direction) so
that a predetermined portion of the biological sample is positioned
in the imaging range imaged by the imaging element 24.
[0079] Further, the stage driving control unit 52 moves the stage
40 in a direction (Z-axis direction, and depth direction of tissue
sections) perpendicular to the stage surface so that the position
of the biological sample SPL positioned within a predetermined
shooting range matches the focal point of the objective lens 23 by
driving and controlling the stage driving mechanism 41.
[0080] <Condenser Lens Driving Control Unit>
[0081] The condenser lens driving control unit 53 is a processing
unit that controls the condenser lens driving mechanism 42 for
driving the condenser lens 22 provided in the magnified image
imaging unit 20 of the microscope 1 according to the present
embodiment. When information relating to the defocus quantity of
the illumination visual field diaphragm is output from the
integrated control unit 50, the condenser lens driving control unit
53 controls the condenser lens driving mechanism 42 based on
acquired information relating to the defocus quantity.
[0082] As described below, when the illumination visual field
diaphragm provided within the magnified image imaging unit 20 is
not properly imaged, a generated contrast of the magnified image is
degraded. In order to prevent the degradation of the contrast, in
integrated control unit 50 which will be described later, a
specification processing is performed with respect to the defocus
quantity of the illumination visual field diaphragm based on a
phase difference image generated by the defocus quantity detection
unit 30, in the microscope 1 according to the present embodiment.
The integrated control unit 50 outputs information indicating the
specified defocus quantity of the illumination visual field
diaphragm to the condenser lens driving control unit 53, and
changes the position of the condenser lens 22 so that the
illumination visual field diaphragm is imaged.
[0083] So that the illumination visual field diaphragm is imaged by
performing driving control of the condenser lens driving mechanism
42, the condenser lens driving control unit 53 corrects the
position (position on the optical axis ERA) of the condenser lens
22.
[0084] <Phase Difference Image Imaging Control Unit>
[0085] The phase difference image imaging control unit 54 is a
processing unit that controls the imaging element 35 provided in
the defocus quantity detection unit 30. The phase difference image
imaging control unit 54 sets parameters according to the bright
visual field mode or the dark visual field mode in the imaging
element 35. In addition, when acquiring output signals, which are
output from the imaging element 35, equivalent to an image imaged
on the imaging surface of the imaging element 35, the phase
difference image imaging control unit 54 uses the acquired output
signals as output signals equivalent to the phase difference image.
When acquiring the output signals equivalent to the phase
difference image, the phase difference image imaging control unit
54 outputs data equivalent to the acquired signals to the
integrated control unit 50. Further, as examples of the parameters
set by the phase difference image imaging control unit 54, a start
timing and a termination timing of exposure (in other words,
exposure time), and the like may be given.
[0086] <Thumbnail Image Imaging Control Unit>
[0087] The thumbnail image imaging control unit 55 is a processing
unit that controls the imaging element 13 provided in the thumbnail
image imaging unit 10. The thumbnail image imaging control unit 55
sets parameters according to the bright visual field mode or the
dark visual field mode in the imaging element 13. In addition, when
acquiring output signals corresponding to an image imaged on the
imaging surface of the imaging element 13 which is output from the
imaging element 13, the thumbnail image imaging control unit 55
uses the acquired output signals as output signals corresponding to
the thumbnail image. When acquiring the output signals
corresponding to the thumbnail image, the thumbnail image imaging
control unit 55 outputs data corresponding to the acquired signals
to the integrated control unit 50. Further, as examples of the
parameters set by the thumbnail image imaging control unit 55, a
start timing and a termination timing of exposure (in other words,
exposure time), and the like may be given.
[0088] <Magnified Image Imaging Control Unit>
[0089] The magnified image imaging control unit 56 is a processing
unit that controls the imaging element 24 provided in the magnified
image imaging unit 20. The magnified image imaging control unit 56
sets parameters according to the bright visual field mode or the
dark visual field mode in the imaging element 24. In addition, when
acquiring output signals corresponding to an image imaged on the
imaging surface of the imaging element 24 which is output from the
imaging element 24, the magnified image imaging control unit 56
uses the acquired output signals as output signals corresponding to
a magnified image. When acquiring the output signals corresponding
to the magnified image, the magnified image imaging control unit 56
outputs data corresponding to the acquired signals to the
integrated control unit 50. Further, as examples of the parameters
set by the magnified image imaging control unit 56, a start timing
and a termination timing of exposure (in other words, exposure
time), and the like may be given.
[0090] The storage unit 57 is an example of a storage device
included in the microscope 1 according to the present embodiment.
In the storage unit 57, various setting information for controlling
the microscope 1 according to the present embodiment, various
databases, or a look-up table, or the like is stored. In addition,
in the storage unit 57, a variety of historical information such as
an imaging history of the sample in the microscope 1 may be
recorded. Further, in the storage unit 57, various parameters have
to be saved when performing certain processing by the microscope 1
(particularly, integrated control unit 50) according to the present
embodiment, a progress of the process, various databases or
programs, and the like are appropriately recorded.
[0091] In the storage unit 57, it is possible for the respective
processing units included in the microscope 1 to freely perform
reading and writing.
[0092] <Integrated Control Unit>
[0093] The integrated control unit 50 is a processing unit that
controls the entire microscope including the above described
various control units.
[0094] The integrated control unit 50 acquires data relating to the
phase difference image imaged by the microscope 1, and calculates a
defocus quantity of the illumination visual field diaphragm and the
amount of change in the thickness of a slide glass, based on the
phase difference image data. The integrated control unit 50
executes imaging of the optical system present within the magnified
image imaging unit 20 of the microscope 1 using the defocus
quantity and the amount of change in the thickness of the slide
glass, so that it is possible to further improve imaging precision
of the obtained magnified image.
[0095] In addition, the integrated control unit 50 acquires, from
the microscope 1, microscope image data relating to the thumbnail
image and the magnified image which are imaged by the microscope 1,
and develops this data, or executes a predetermined digital
processing. Thereafter, the integrated control unit 50 uploads the
microscope image data obtained from the thumbnail image and the
magnified image to an image management server via a network such as
the Internet, a dedicated line, and the like. Thus, the microscope
image of the sample imaged by the microscope 1 is able to be
browsed by a client device connected to the network.
[0096] Hereinafter, with reference to FIG. 2, a configuration of
the integrated control unit 50 according to the present embodiment
will be described in detail. FIG. 2 is a block diagram showing a
configuration of the integrated control unit 50 according to the
present embodiment.
[0097] As shown in FIG. 2, the integrated control unit 50 according
to the present embodiment mainly includes an integrated driving
control unit 501, an image acquisition unit 503, an image
processing unit 505, a feature value calculation unit 507, a
microscope image output unit 509, and a communication control unit
511.
[0098] The integrated driving control unit 501 is realized by, for
example, CPU, ROM, RAM, or the like. The integrated driving control
unit 501 is a driving control unit that integrally controls the
control unit (the illumination control unit 51, the stage driving
control unit 52, the condenser lens driving control unit 53, and
the phase difference image imaging control unit 54, the thumbnail
image imaging control unit 55, and the magnified image imaging
control unit 56) for controlling each part of the microscope 1. The
integrated driving control unit 501 sets a variety of information
(for example, various setting parameters, and the like) with
respect to each part of the microscope 1, or acquires a variety of
information from each part of the microscope 1. The integrated
driving control unit 501 may output the variety of information
acquired from each part of the microscope 1 to the feature value
calculation unit 507, which will be described later.
[0099] The image acquisition unit 503 is realized by, for example,
CPU, ROM, RAM, a communication device, or the like. The image
acquisition unit 503 acquires data corresponding to the thumbnail
image imaged by the thumbnail image imaging unit 10, data
corresponding to the magnified image imaged by the magnified image
imaging unit 20, and data corresponding to the phase difference
image imaged by the defocus quantity detection unit 30 through each
imaging control unit.
[0100] When acquiring the image data through each imaging control
unit, the image acquisition unit 503 outputs the acquired image
data to the image control unit 225, which will be described
later.
[0101] Further, the image acquisition unit 503 may associate the
acquired image data (the microscope image data) with information
concerning an acquisition date, and the like, and store the
associated information in the storage unit 57, and the like.
[0102] The image processing unit 505 is realized by, for example,
CPU, GPU, ROM, RAM, and the like. The image processing unit 505
executes a predetermined image process on the microscope image
output from the image acquisition unit 503.
[0103] Specifically, when acquiring the phase difference image
data, the thumbnail image data, and the magnified image data (more
specifically, RAW data of these images) which are output from the
image acquisition unit 503, the image processing unit 505 performs
a developing process of the RAW data. In addition, the image
processing unit 505 executes a process (stitching process) in which
a plurality of images constituting these images is connected
together, while performing the developing process of the image
data.
[0104] In addition, the image processing unit 505 is able to
execute a conversion process (transcoding) of acquired digital
image data, if necessary. As the conversion process of the digital
image, a process in which the digital image is compressed to
generate a JPEG image, or a process in which the data compressed
into the JPEG image is converted into a compressed image of a
different type (for example, GIF format, and the like) may be
given. In addition, in the conversion process of the digital image,
a re-compressing process in which the compressed image data is
decompressed once, and then is subjected to a process such as edge
enhancement, and the like, or a process of changing the compression
ratio of the compressed image may be included.
[0105] When the above described image process is executed with
respect to the phase difference image data, the image processing
unit 505 outputs the phase difference image data obtained after
executing the image process to the feature value calculation unit
507, which will be described later. In addition, when the above
described image process is executed with respect to the thumbnail
image data and the magnified image data, the image processing unit
505 outputs the microscope image obtained from these images and
various metadata representing the microscope image to the
microscope image output unit 509, which will be described
later.
[0106] The feature value calculation unit 507 is realized by, for
example, CPU, GPU, ROM, RAM, or the like. The feature value
calculation unit 507 acquires data concerning the phase difference
image imaged by the microscope 1, and calculates a defocus quantity
of the sample placed in the stage of the microscope 1 based on the
phase difference image data. In addition, the feature value
calculation unit 507 is able to calculate the defocus quantity of
the illumination visual field diaphragm, and the amount of change
in the thickness of the slide glass based on the phase difference
image data. The integrated control unit 50 executes imaging of the
optical system present within the magnified image imaging unit 20
of the microscope 1 using the defocus quantity and the amount of
change in the thickness of the slide glass, so that it is possible
to further improve imaging precision of the obtained magnified
image.
[0107] Various feature values described above that are calculated
by the feature value calculation unit 507 are output to the
integrated driving control unit 501.
[0108] The microscope image output unit 509 is realized by, for
example, CPU, ROM, RAM, or the like. The microscope image output
unit 509 outputs, to the image management server through the
communication control unit 511 which will be described later, a
variety of information such as the microscope image output from the
image processing unit 505, metadata associated with the microscope
image, and the like. Thus, the microscope image (digital microscope
image) of the sample imaged by the microscope 1 is managed by the
image management server.
[0109] The communication control unit 511 is realized by, for
example, CPU, ROM, RAM, a communication device, or the like. The
communication control unit 511 performs control of the
communication performed through a network such as the Internet, a
dedicated line, and the like between the integrated control unit 50
and the image management server provided externally to microscope
1.
[0110] As above, an example of the functions of the integrated
control unit 50 according to the present embodiment has been shown.
The above described components may be configured using members or
circuits for general purpose, or configured by hardware specialized
for the function of each of the components. In addition, the
functions of each of the components are entirely performed by CPU,
and the like. Accordingly, depending on levels of technologies when
the present embodiment is executed, it is possible to appropriately
change the configuration to be used.
[0111] Further, it is possible to prepare a computer program for
realizing each function of the integrated control unit according to
the present embodiment or of other control units, and to implement
the prepared computer program in a personal computer, and the like.
In addition, it is possible to provide a computer-readable
recording medium in which the above described computer program is
stored. The recording medium is, for example, a magnetic disk, an
optical disc, a magneto-optical disc, a flash memory, and the like.
In addition, the computer program may be delivered over, for
example, the network without using the recording medium.
[0112] As above, the entire configuration of the microscope 1
according to the present embodiment has been described in detail
with reference to FIGS. 1 to 2.
[0113] <Light Beam Branching Element>
[0114] Next, before describing the defocus quantity detection unit
30 according to the present embodiment in detail, studies for the
light beam branching element conducted by the present inventors
will be described in detail with reference to FIG. 3. FIG. 3 is a
diagram showing the light beam branching element.
[0115] As shown in FIG. 3, light made incident on the light beam
branching element is branched to reflected light R1 reflected from
a front surface of the light beam branching element, and
transmitted light T1T2 transmitted through the front surface and
the rear surface of the light beam branching element. However, the
light made incident on the light beam branching element is
multiplex-reflected within the light beam branching element to
thereby become reflected light called ghosting light or transmitted
light, other than the reflected light R1 and the transmitted light
T1T2.
[0116] For example, the light made incident on the light beam
branching element is reflected from the rear surface of the light
beam branching element, and further escaped from the front surface
of the light beam branching element (light beam shown in T1R2T1 of
FIG. 3) to thereby become ghosting light of the reflected light R1.
Similarly, the light made incident on the light beam branching
element is reflected from the rear surface and the front surface of
the light beam branching element, and escaped from the rear surface
of the light beam branching element (light beam shown in T1R2R1T2
of FIG. 3) to thereby become ghosting light of the transmitted
light T1T2. The reflected light or the transmitted light and the
ghosting light corresponding to this light are separated from each
other by an interval .DELTA. as shown in FIG. 3, and image blurring
or the like is caused by the ghosting light.
[0117] The separation distance .DELTA. between the transmitted
light or the reflected light and the ghosting light is changed
depending on a thickness t of the light beam branching element, and
when a reflective index n of the light beam branching element is
uniform, .DELTA. is reduced along with a reduction in the thickness
t. Due to this, in the related art, it is possible to match the
ghosting light with the transmitted light or the reflected light as
much as possible by reducing the thickness t.
[0118] In addition, as described above, since the ghosting light is
generated by reflection within the light beam branching element,
the light beam branching element is subjected to an AR coating, and
the like in the related art, and thereby generation of the ghosting
light in the transmitted side or the reflected side is
suppressed.
[0119] Here, as is apparent from FIG. 1, in the microscope 1
according to the present embodiment, both the transmitted light and
the reflected light of the light beam branching element are used in
various processes performed within the microscope 1, so that it is
necessary that generation of the ghosting light in both the
transmitted side and the reflected side is suppressed.
[0120] However, even though the coating is executed on the light
beam branching element, it is difficult for the generation of the
ghosting light in both the transmitted side and the reflected side
to be suppressed. In addition, studies for using a pellicle mirror
as the light beam branching element have been conducted by the
present inventors, however, it was found that there are problems
such as temperature characteristics, disturbance of wave front due
to deflection of the mirror itself, and the like.
[0121] Therefore, the present inventors have conducted extensive
studies for a method of capable of removing ghosting due to the
light beam branching element using luminous fluxes of both of the
transmitted side and the reflected side in the microscope including
a phase difference autofocus optical system. As a result, as
described below, the microscope 1 according to the present
embodiment is obtained.
[0122] <Configuration of Defocus Quantity Detection Unit>
[0123] Hereinafter, a phase difference autofocus (AF) optical
system (hereinafter, simply referred to as phase difference optical
system) included in the defocus quantity detection unit 30
according to the present embodiment will be described in detail
with reference to FIGS. 4 to 7.
[0124] As shown in FIG. 4, the phase difference optical system
included in the defocus quantity detection unit 30 according to the
present embodiment includes a light beam branching element 31 for
branching a part of light (sample transmitted light) transmitted
through a sample SPL, a condenser lens 32 for condensing the sample
transmitted light branched by the light beam branching element 31,
a two eye lens filter 33, a two eye lens 34, and an imaging element
35.
[0125] Here, the light beam branching element 31 according to the
present embodiment is provided within an imaging optical system
that includes the condenser lens 23 for condensing the light
(sample transmitted light) transmitted through the sample SPL, and
the imaging element 24 on which the sample transmitted light
condensed by the condenser lens 23 is imaged. In addition, since
the light beam branching element 31 according to the present
embodiment eliminates the above described ghosting light, the light
beam branching element 31 has a thickness more than a predetermined
threshold value.
[0126] As described above, a separation distance .DELTA. between
the transmitted light or the reflected light and the ghosting light
is proportional to the thickness t of the light beam branching
element. Thus, in order to separate the ghosting light from the
transmitted light and the reflected light used in the microscope 1
as much as possible, a thickness of the light beam branching
element 31 is to be thicker than that of the light beam branching
element in the related art. The light beam branching element 31 has
a thickness more than a predetermined threshold value, so that the
ghosting light generated in the light beam branching element 31 is
separated significantly from the sample transmitted light (surface
reflected light) reflected by the light beam branching element 31.
As a result, it is possible to shield the ghosting light separated
significantly from the surface reflected light by the two eye lens
filter 33, which will be described later, so that it is possible to
prevent the ghosting light from being imaged on the imaging element
35.
[0127] Here, by increasing the thickness of the light beam
branching element 31, an amount of deflection of the light beam
branching element is changed. FIG. 5 is a graph showing a result in
which a flat plate using BK7 as a glass material is fixed in such a
manner that free ends of the flat plate are fixed, and the amount
of deflection of the glass material is measured. As is apparent
from FIG. 5, it is found that the amount of deflection generated in
the glass material is rapidly increased along with a reduction in
the thickness of the glass material. In addition, in FIG. 5, the
case of using the BK7 as the glass material is shown, however, a
behavior such that the amount of deflection is increased along with
the reduction in the thickness is common even using other glass
materials.
[0128] In the case of manufacturing the light beam branching
element using the glass material, the reflected surface of the
light beam branching element functions as a curvature reflection
mirror different from an original plane reflection mirror due to
the deflection of the light beam branching element. Therefore, such
as the light beam branching element 31 according to the present
embodiment, the thickness of the light beam branching element is
increased reversely to the related art, so that it is possible to
achieve separation of the ghosting light, and to prevent the
deflection of the light beam branching element. Here, to prevent
effect due to the above described deflection, in the light beam
branching element 31 according to the present embodiment, a plate
thickness of the light beam branching element 31 is preferably
increased so that the deflection is negligible.
[0129] Further, the glass material used when manufacturing the
light beam branching element is preferably selected in
consideration of temperature characteristics of the glass material,
and the like. For example, since change in the plate thickness of
the light beam branching element due to thermal expansion is
proportional to a thermal expansion coefficient of the glass
material, synthetic quartz having the thermal expansion coefficient
of about 8% is used in comparison with the thermal expansion
coefficient of the BK7, and the like, so that it is possible to
suppress effects relating to the thermal expansion, and to further
suppress effects caused by the change in the thickness.
[0130] In addition, as described above, the light beam branched by
the light beam branching element 31 is used to acquire focus
information (defocus information) by the defocus quantity detection
unit 30 (phase difference optical system). Thus, so that even a
defocused light beam is able to be detected, the light beam
branching element 31 preferably has a plane size which does not
have light beam vignetting in a desired defocus range.
[0131] As described above, in the microscope 1 according to the
present embodiment, the ghosting light is shielded by the two eye
lens filter provided within the phase difference optical system, so
that it is preferable that a desired amount of light is guided to
the phase difference optical system, and then effects of the
ghosting light generated in the imaging element 24 of the imaging
optical system (magnified image imaging unit 20) are made small to
a minimum.
[0132] For example, in a case in which the imaging element 24
provided in the imaging optical system is an imaging element with
12 bit gradation, it is preferable that the ratio SNR of the
imaging element 24 to an amount of the ghosting light is at least
20 log(2.sup.12/1)=72.24 dB.
[0133] In addition, it is assumed that the front surface
reflectance and transmittance of the light beam branching element
are R1 and T1, respectively, and the rear surface reflectance and
transmittance are R2 and T2. In this case, the ratio of the
reflected side to the amount of the ghosting light is represented
as 20 log(R1/(T1R2T1)), and the ratio of the transmitted side to
the amount of the ghosting light is represented as 20
log(1/(R1R2)).
[0134] Thus, for example, an AR (Anti-Reflective) coating is
performed on a rear surface, and the amount of the ghosting light
in a case in which T2=0.98 and R2=0.02 is calculated to be shown in
FIG. 6. In FIG. 6, so that effect of the ghosting light is
approximately the noise level of the imaging element 24 in the
imaging element 24, it is preferable to satisfy T1>0.988 and
R1<0.012 when the imaging element 24 is provided on the
transmitted light side of the light beam branching element 31 as
shown in FIG. 4.
[0135] In addition, according to a second embodiment, which will be
described later, when the imaging element 24 is provided on the
reflected light side of the light beam branching element 31, it is
preferable to satisfy T1<0.11 and R1>0.89.
[0136] Further, as for the coating performed on the light beam
branching element 31, it is preferable to satisfy the above
described conditions over the whole range of wavelengths used in
the microscope 1, that is, a visible region. In addition, in a case
in which even an ultraviolet (UV) wavelength region and an infrared
(IR) wavelength range are used in the microscope 1, it is
preferable that performance of the coating even in these wavelength
regions satisfies the above described conditions.
[0137] In addition, as for the coating performed on the light beam
branching element 31, it is preferable to satisfy the above
described conditions over the whole angle of light beam which is
made incident. For example, such as the microscope 1 according to
the present embodiment shown in FIG. 4, when the light beam
branching element 31 is installed to be inclined to the main light
beam by 45.degree., it is preferable to satisfy the above described
conditions in a range including an off-axis light beam with angle
45.degree. as the center.
[0138] Further, using the front surface reflected light in the
light beam branching element 31, effects due to a variety of plate
thicknesses are able to be negligible. Thus, it is preferable that
the front surface reflected light is guided to the imaging element
24 installed on the reflected light side or the phase difference
optical system.
[0139] Next, the thickness of the light beam branching element 31
will be further described in consideration of a relationship
between the thickness of the light beam branching element 31 and
the two eye lens filter 33 with reference to FIG. 7. FIG. 7 is a
diagram showing an example of the two eye lens filter 33 according
to the present embodiment.
[0140] As shown in FIG. 7, the two eye lens filter 33 according to
the present embodiment is a diaphragm in which a set of through
holes through which a luminous flux (luminous flux A in FIG. 7)
being the phase difference image passes is provided. In the phase
difference optical system according to the present embodiment, a
luminous flux (luminous flux B in FIG. 7) corresponding to the
ghosting light is separated from the luminous flux (luminous flux
A) being the phase difference image by increasing the thickness t
of the light beam branching element 31. When the luminous flux
corresponding to the ghosting light does not pass through the
through hole by separating the luminous flux corresponding to the
ghosting light from the luminous flux being the phase difference
image, it is possible to prevent the ghosting light from being
imaged on the imaging element 35.
[0141] Here, as shown in FIG. 7, a luminous flux diameter of each
of the luminous flux A and the luminous flux B in a position where
the two eye lens filter 33 is provided is represented as .phi.a, a
diameter (that is, diameter of the diaphragm) of the through hole
provided in the two eye lens filter 33 is represented as .phi.b,
and a center distance between the through holes is represented as
d. When the optical system is adjusted in such a manner that a
center of the luminous flux A is a center of the two eye lens
filter 33, a separation distance x between the luminous flux A and
the luminous flux B may satisfy a relationship shown in the
following inequality 101 so that the luminous flux corresponding to
the ghosting light does not pass through the through hole. In
addition, a threshold value of the distance x calculated based on
the following inequality 101 may be corrected to a larger value in
consideration of defocus characteristics, and the like of the
optical system.
x > ( .phi. a + .phi. b + d ) 2 [ Inequality 101 ]
##EQU00002##
[0142] In addition, as described above, the separation distance x
is compared with the thickness t of the light beam branching
element 31, a proportional constant thereof is a unique one in the
optical system. Accordingly, the thickness t of the light beam
branching element 31 may be determined so as to satisfy a
relationship shown in the following inequality 102. Here, in the
following inequality 102, a coefficient k is an inverse number of
the unique proportional constant in the optical system between the
separation distance x and the thickness t of the light beam
branching element 31.
t > k .times. ( .phi. a + .phi. b + d ) 2 [ Inequality 102 ]
##EQU00003##
[0143] As described above, in the defocus quantity detection unit
30 according to the present embodiment, the thickness t of the
light beam branching element 31 is at least a predetermined
threshold value, so that the ghosting light generated by the light
beam branching element 31 may be sufficiently separated from the
reflected light used in the process in the microscope 1. The
separated ghosting light as described above is shielded by the two
eye lens filter provided within the phase difference optical
system, so that the separated ghosting light is not imaged on the
imaging element 35 within the optical system. Thus, in the
microscope 1 according to the present embodiment, it is possible to
eliminate the ghosting light generated by the light beam branching
element 31.
[0144] In addition, in the imaging element 24 provided on the
transmitted side of the light beam branching element 31, it is
possible to suppress effects due to the ghosting light to be not
higher than the noise level of the imaging element 24 by adjusting
the coating, and the like performed on the light beam branching
element 31. Thus, even in the imaging element provided on the
transmitted side of the light beam branching element 31, it is
possible to eliminate the effects due to the ghosting light.
Second Embodiment
[0145] The microscope 1 according to the first embodiment installs
the phase difference optical system on the reflected light side of
the light beam branching element 31, and installs the imaging
element 24 of the magnified image imaging unit 20 on the
transmitted light side of the light beam branching element 31. In
the microscope 1 according to a second embodiment, which will be
described below, the phase difference optical system is installed
on the transmitted light side of the light beam branching element
31, and the imaging element 24 of the magnified image imaging unit
20 is installed on the reflected light side of the light beam
branching element 31.
[0146] In the microscope 1 according to the present embodiment,
both the transmitted light and the reflected light branched by the
light beam branching element 31 are used in the process in the
microscope 1. The front surface reflected light is used with
respect to the reflected light reflected from the light beam
branching element 31, so that it is possible to suppress effects
due to the plate thickness of the light beam branching element 31,
however, the transmitted light transmitted through the light beam
branching element 31 is influenced by the effects due to the plate
thickness of the light beam branching element 31.
[0147] In addition, in order to branch the light beam transmitted
through the sample, the light beam branching element 31 is
installed to have an inclination with respect to the normal
direction of the incident light beam, as shown in FIG. 1. Due to
this, an amount of deviation of the light beam due to the image
height is changed, so that there are possibilities that distortion,
a chromatic aberration of magnification, a wavefront aberration,
and the like are changed.
[0148] For example, it is assumed that the light beam transmitted
through the condenser lens 23 is branched by the light beam
branching element 31, and the branched light beam is detected in
the imaging element 24 of the magnified image imaging unit 20 or
the defocus quantity detection unit 30 (phase difference optical
system). In this case, in the phase difference optical system, the
light beam is detected in the two eye lens 34, and the light beam
is injured in the diaphragm (two eye lens filter), so that a
numerical aperture of an incident side (NA) becomes smaller than
that in a case where the light beam is detected in the imaging
element 24.
[0149] FIG. 8 is a graph showing a relationship between a size of a
wavefront aberration (WFE) in light propagated in the imaging
system (magnified image imaging unit 20) and light propagated in
the imaging system and the phase difference optical system, and the
plate thickness of the light beam branching element 31. As shown in
FIG. 8, since the numerical aperture of the incident side becomes
smaller, it is found that effects of the wavefront aberration due
to the plate thickness is reduced in the phase difference optical
system.
[0150] Thus, as shown in FIG. 9, in the microscope 1 according to
the present embodiment, the defocus quantity detection unit 30
(phase difference optical system) is installed on the transmitted
light side of the light beam branching element 31, and the
magnified image imaging unit 20 (that is, the imaging optical
system) is installed on the reflected light side of the light beam
branching element 31.
[0151] Since the imaging element 24 included in the magnified image
imaging unit 20 is an imaging element used for precisely imaging
the magnified image of the sample, the imaging element 24 is
sensitive to the effects of aberration. Accordingly, the optical
system of the magnified image imaging unit 20 is provided on the
reflected light side of the light beam branching element 31, and
only the front surface reflected light of the light beam branching
element 31 is used, so that it is possible to eliminate the effects
of aberration caused by the thickness of the light beam branching
element. Further, when the magnified image imaging unit 20 is
provided, it is preferable to reflect the sample transmitted light
from the stage side of the light beam branching element 31.
[0152] In addition, there are possibilities that the transmitted
light side of the light beam branching element 31 is influenced by
the effects of aberration such as the distortion, the chromatic
aberration of magnification, the wavefront aberration, and the
like, however, the phase difference optical system is provided on
the transmitted light side of the light beam branching element 31
to thereby reduce the effects due to aberration, as shown in FIG.
8.
[0153] Further, the light beam branching element 31 according to
the present embodiment that is the same as that according to the
first embodiment may be used, except that the front surface
transmittance T1<0.11, and the front surface reflectance
R1>0.89 are satisfied. The above described light beam branching
element 31 is adopted, so that it is possible to eliminate the
ghosting light, which is propagated in the phase difference optical
system, using the two eye lens filter 33, and to suppress an
intensity of the ghosting light imaged to the imaging element 24 so
as not to affect the process of the imaging element 24.
[0154] In addition, the condenser lens 32, the two eye lens filter
33, the two eye lens 34, and the imaging element 35 according to
the present embodiment, which are the same as those according to
the first embodiment, may be used. Thus, the repeated description
thereof will be herein omitted.
[0155] As described above, in the microscope 1 according to the
present embodiment, the phase difference optical system is
installed on the transmitted light side of the light beam branching
element 31, and the imaging element 24 of the magnified image
imaging unit 20 is installed on the reflected light side of the
light beam branching element 31, so that it is possible to
eliminate the ghosting caused by the light beam branching element,
and to eliminate effects of various aberrations in the imaging
element 24. As a result, it is possible to further improve accuracy
of the microscope image imaged in the imaging element 24.
[0156] It should be understood that various changes and
modifications to the presently preferred embodiments described
herein will be apparent to those skilled in the art. Such changes
and modifications can be made without departing from the spirit and
scope and without diminishing its intended advantages. It is
therefore intended that such changes and modifications be covered
by the appended claims.
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