JP3455194B2 - Phase contrast microscope - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase contrast microscope for observing a phase distribution of a sample by utilizing light interference.

[0002]

2. Description of the Related Art There is a phase contrast microscope as a microscope for observing the phase distribution of a sample by utilizing the interference of light. FIG. 18 shows a block diagram of a conventional phase contrast microscope. The light emitted from the light source 1 is emitted from the ring-shaped opening 11 which is partly composed of a ring-shaped opening, and this light is condensed by the condenser lens 12 to form the sample 5 on the slide glass 4.
Is irradiated. Here, this light is divided into transmitted light and diffracted light, and the transmitted light is a phase film 1 having a retardation of λ / 4.
3 and the transparent film 14 on which the phase film 13 is attached is transmitted. Also, the diffracted light will pass through the entire transparent substrate 14. Then, the transmitted light and the diffracted light are transferred to the CCD 9
Interfere on. The interference image obtained here represents a Fourier transform image of the sample 5. Therefore, with this phase contrast microscope, the image can be observed even with a transparent sample.

[0003]

By the way, in the phase contrast microscope, some contrivances have been made in order to generate the most visible bright and dark image. For example, if the phase film 13 is λ /
By setting so as to have a phase difference of 4, an image with the best contrast is generated. However, since the contrast is determined by the thickness of the phase film 13, the user cannot change the contrast once determined. Therefore, even if the user or the like wants to adjust the contrast of the interference image at the time of observation or inspection, there is a drawback that it cannot be changed.

In view of the above problems, it is an object of the present invention to provide a phase contrast microscope in which the contrast can be set easily and smoothly and can be adjusted appropriately.

[0005]

SUMMARY OF THE INVENTION A phase contrast microscope according to the present invention comprises a light source for illuminating a sample, and an interference image generation for guiding a transmitted light and a diffracted light emitted from the sample onto an observation surface to obtain an interference image. In a phase contrast microscope having a means and a detecting means for detecting the interference image, a polarization state changing means arranged between the light source and the detecting means for changing a polarization state of light, and a polarization state conjugating means. Position of the opening and the opening
First polarization extractor with mouth projected and other second polarization
It consists of an extraction part and is placed at a position conjugate with the opening.
The first polarization extraction unit extracts a specific polarization component from the transmitted light, and the second polarization extraction unit extracts from the diffracted light a polarization component that intersects the polarization direction extracted by the first polarization extraction unit. Complex polarization
And a light plate .

Further, the phase contrast microscope according to the present invention has a light source for illuminating the sample, and an interference image generating means for guiding the transmitted light and the diffracted light emitted from the sample onto the observation surface to obtain an interference image. In the phase contrast microscope, the light source has a wavelength variable function for changing the wavelength of the emitted light, or is provided with a wavelength variable means separately from the light source.

[0007]

According to the phase contrast microscope of the present invention, the phase difference or wavelength of polarized light can be changed by operating the polarization state varying means or the wavelength varying means, and the contrast can be easily set and adjusted. it can.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 2 show a first embodiment of the present invention. FIG. 1 is a configuration diagram of a phase contrast microscope, and FIG. 2 is a diagram showing polarization states of polarized light. 3 to 10 show an example of the configuration of the light source system used in the first embodiment. In the phase contrast microscope shown in FIG. 1, the light source system 16 is capable of changing the polarization state of the emitted light. These polarization states can be considered by being decomposed into two linearly polarized waves whose vibrating directions are perpendicular to each other. These two linear polarizations are x polarization and y, respectively.
If we call it polarization, the change of polarization state is x polarization and y
It can be considered that it is obtained by the change of the phase difference of the polarization. For example, as shown in FIG. 2, the polarization state can be changed to linearly polarized light, circularly polarized light, or elliptically polarized light by changing the phase difference by 90 °. The light source system 16 can control such a change in the polarization state continuously or discretely.

An example of the structure of such a light source system 16 will be described with reference to FIG. In the figure, the light source system 16 includes a light source 17 that emits coherent light and a polarization variable element 18. The polarization variable element 18 is provided with a rotation-controllable half-wave plate 19 on which coherent light from a light source is incident, and a quarter-wave plate 20 fixed behind the half-wave plate 19. . The half-wave plate 19 is held by a holder 21, and the holder 21 is connected to a gear 22. The gear 22 is connected to a motor 24 via a meshing small gear 23, and the rotation of the half-wave plate 19 is controlled by the motor 24 driven and controlled by the rotation control circuit 25. The rotation angle of the half-wave plate 19 is detected by an angle sensor 26 connected to the motor shaft.

In the phase contrast microscope of FIG. 1, the polarization state of the light emitted from the light source system 16 is controlled by the polarization control device 28 electrically connected to (the rotation control circuit 25 of) the light source system 16. It can be changed.

A ring opening 11 and a condenser lens 12 are provided at the rear of the light source system 16 as in the conventional example shown in FIG. It is divided into light and light. A circular composite polarizing plate 68, which is composed of two polarizing plates 66 and 67 whose polarization axes are different from each other in a direction orthogonal to each other, is disposed behind the polarizing plate 66. The plate 67 is formed in a ring and a circular shape occupying the front and rear regions thereof (see FIG. 11A). In the composite polarizing plate 68, the polarization axis of the doughnut-shaped polarizing plate 66 is the x axis, and the polarization axis of the other polarizing plate 67 is the y axis orthogonal to the x axis.
The transmitted light of the sample 5 enters the donut type polarizing plate 66, and the diffracted light enters the other polarizing plate 67. Therefore, only the x-polarized light transmitted through the sample 5 is the polarizing plate 6.
6, the diffracted light passes through the polarizing plate 67 only in the y-polarized light. The polarizing plate 8 is arranged between the composite polarizing plate 68 and the CCD 9, and the polarizing plate 8 has a polarization axis inclined by 45 ° with respect to the x axis and the y axis of the composite polarizing plate 68. (See FIG. 11B). Therefore, the transmitted light and the diffracted light interfere at the CCD 9. The polarizing plate 8 is arranged such that its polarization axis forms a predetermined angle with respect to the x polarization and the y polarization. The predetermined angle represents the polarization axis direction in which the contrast of the interference image obtained by the CCD 9 is high, and when the x polarization and the y polarization have the same light intensity, the angle is as shown in FIG.
It is about 45 ° as shown in (B). And CC
The interference image captured in D9 is captured in the frame memory 29, and is calculated in the computer 30 connected to the frame memory 29 and the polarization controller 28 based on the interference image input from the frame memory 29 to obtain the sample 5 Information on the phase distribution of is obtained.

This embodiment is constructed as described above,
Next, the operation will be described. In the light source system 16, the coherent light emitted from the light source 17
Although the light passes through the 1/2 wavelength plate 19 (see FIG. 3), the vibration direction of the light at that time changes according to the azimuth direction of the 1/2 wavelength plate 19 whose rotation is controlled. Then, when it enters the quarter-wave plate 20, it becomes a linearly polarized wave or a circularly polarized wave depending on the vibration direction. It can be considered that this is because the phase difference between the x polarized wave and the y polarized wave that vibrate at right angles to each other as described above. Here, the rotation speed of the half-wave plate 19 is θ
Then, the phase difference between the x-polarized light and the y-polarized light emitted from the quarter-wave plate 20 changes by 4θ. Therefore, while the angle sensor 26 detects the angle of the half-wave plate 19, the computer 30 rotates the half-wave plate 19 to a predetermined angle through the rotation control circuit 25.

In this way, a part of the light emitted from the light source system 16 in the required polarization state enters the sample 5 through the ring opening 11 and the condenser lens 12 as in the conventional example. It is divided into transmitted light and diffracted light. The transmitted light of the sample 5 enters the donut type polarizing plate 66, and only the x-polarized light passes through the polarizing plate 66. In addition, the diffracted light of the sample 5 enters the other polarizing plate 67, and only the y-polarized light is polarized by the polarizing plate 6.
Through 7. Then, the two polarized waves pass through the polarizing plate 8 arranged at a predetermined angle so that the contrast of the interference image is high with respect to the x-polarized light and the y-polarized light.
Interfere on 9. The interference image picked up by this CCD 9
The user can observe it on a monitor or the like. next,
When the polarization state of the light emitted from the light source system 16 is changed by the polarization control device 28, the phase difference between the x polarization and the y polarization changes, and the brightness or darkness of the image of the sample 5 being observed changes. Therefore, the user can adjust the image so that it has the best contrast.

Further, in the present invention, the phase difference between the two light beams that interfere can be changed with high accuracy, so that the fringe scanning method used in an interferometer device or the like can be incorporated in observation by an interference microscope. Using this fringe scanning method, sample 5
It is possible to quantitatively know the phase distribution of. For example, a technique called phase shift is used in the lithography of semiconductor memory, but the phase distribution of the phase film used here has a great influence on the accuracy of the pattern. According to the present invention, it becomes possible to quantitatively measure the phase distribution of this phase film.

Next, the specific measuring method will be described.
First, under the condition that the polarization state of the light emitted from the light source system 16 is set to a specific phase difference between the x polarization and the y polarization, the image obtained by the CCD 9 is loaded into the frame memory 29, and Let the image be the first interference image. Then the x polarization and y
The polarization controller 28 controls the light source system 1 so that the phase difference between the polarized waves changes by 90 ° as compared with the case of the first interference image.
The polarization state of the light emitted from 6 is changed. As a result, the contrast of the interference image obtained by the CCD 9 changes. This image is captured by the frame memory 29 and is used as the second interference image. In this way, the phase difference between the x polarization and the y polarization is changed by 90 ° so that the third and fourth interference images are captured.

Next, the phase distribution of the sample 5 is calculated from these four interference images by using the algorithm of the fringe scanning method. C
The interference intensity distribution In (x, y) of four patterns is represented by the following equation, with the light receiving plane of the CD 9 as the xy coordinate plane. I1 (x, y, d) = A (x, y) + B (x, y) cos [(2π / λ) ω (x, y)] I2 (x, y, d) = A (x, y) -B (x, y) sin [(2π / λ) ω (x, y)] I3 (x, y, d) = A (x, y) -B (x, y) cos [(2π / λ) ω (x, y)] I4 (x, y, d) = A (x, y) + B (x, y) sin [(2π / λ) ω (x, y)] (1) where A ( x, y) is the average light intensity, B (x, y) is the interference intensity,
λ is the wavelength, and ω (x, y) is the phase difference of the interference light. In the case of the differential interference microscope, the phase distribution of the sample 5 is differentiated.

Based on these images, the computer 30
Therefore, if ω (x, y) = (λ / 2π) tan-1 [(I4−I2) / (I1−I3)] (2) is calculated for each pixel of the CCD 9, only the information of the phase distribution ω will be obtained. Can be obtained. Next, the phase distribution of the sample 5 can be obtained by integrating ω with the separation width of the x polarization and the y polarization. In this example, the case of using the images of four patterns is shown, but the present invention is not limited to this, and the information of the phase distribution can be obtained by using the images of at least three patterns.

As described above, according to the present embodiment, in the phase contrast microscope, the contrast can be set by the polarization variable element 18 without affecting the image formation relationship. Further, since the light source system 16 has the polarization control means, if the light source system 16 is provided with a detaching function,
It can also be applied to various phase contrast microscopes.
Further, by connecting the frame memory 29 and the computer 30, the phase distribution of the sample can be quantitatively measured. In the case of measuring the phase distribution, a plurality of interference images of different brightness are captured in the memory frame 29, and the computer 30 performs the calculation of the above formula (2). In the case of a phase contrast microscope, the result obtained here is a Fourier transform of the phase distribution of the sample 5. Therefore, the phase distribution of the sample 5 can be quantitatively obtained by performing the inverse Fourier transform.

Next, another configuration example of the light source system 16 will be described with reference to FIGS. In the light source system 16 shown in FIG. 4, a Faraday element 32 is arranged in place of the half-wave plate 19 and the like, and the oscillation direction of the linearly polarized light incident from the light source 17 is changed by its optical activity. Further, the magnetic field generator 33 arranged around the Faraday element 32 is connected to the magnetic field control circuit 34, and by adjusting the strength of the magnetic field generated by the magnetic field generator 33 in the magnetic field control circuit 34, the polarization of The direction of vibration can be controlled.

The light source system 16 shown in FIG. 5 has a pair of optical rotatory liquid crystals instead of the half-wave plate 19 and the like. The liquid crystal 36 located on the side of the light source 17 is capable of changing the vibration direction of the polarized wave by 90 °.
The liquid crystal 37 located on the 0 side can change the vibration direction by 45 °. These liquid crystals 36 and 37 are controlled to turn on and off the energization of the transparent electrodes 38 provided on both sides thereof so that the vibration direction of the incident linearly polarized light is 0 °, 4 °.
It can be changed to 5 °, 90 ° and 135 °.

Next, the light source system 16 shown in FIG. 6 uses the Babinet-Soleil plate 39 as the polarization variable element 18, and moves the wedge-shaped crystal of the Babinet-Soleil plate 39 perpendicularly to the optical axis. Thus, x polarization and y
The phase difference of polarization can be changed directly. In FIG. 6, the position of one wedge-shaped crystal 39a is moved by the piezo element 40, and the piezo element 40 is connected to the voltage control circuit 41 and driven by this circuit 41. There is.

The light source system 16 shown in FIG. 7 has a crystal 43 such as KDP having an electro-optical effect as the polarization variable element 18.
Is used to change the phase difference by changing the birefringence. The crystal 43 is sandwiched by a pair of electrodes 44, and the voltage control circuit 41 controls the electric field strength applied to the crystal 43. In addition, the light source system 16 shown in FIG. 8 uses the nematic liquid crystal 4 as the polarization variable element 18.
5 is used. By changing the intensity of the electric field applied to the liquid crystal 45, the light distribution direction of the liquid crystal is changed to change the birefringence.

In the polarization variable element 18 of the light source system 16 shown in FIG. 9, a polarization beam splitter 46 is arranged on the optical axis, and a ¼ wavelength plate 47 and a quarter wavelength plate 47 are provided on both sides of the polarization beam splitter 46 with the optical axis interposed therebetween. A mirror 48, a quarter-wave plate 47, a mirror 48 and a piezo element 40 are arranged respectively. Therefore, of the light emitted from the light source 17, P
The wave passes through the polarizing beam splitter 46, but the S wave is reflected. Then, the S wave passes through the quarter-wave plate 47, is reflected by the mirror 48, passes through the quarter-wave plate 47 again, and is converted into the P-wave. Therefore, the reflected light passes through the polarization beam splitter 46, similarly passes through the quarter-wave plate 47, is reflected by the mirror 48, passes through the quarter-wave plate 47 again, and becomes an S wave. It is reflected by the splitter 46 and emitted. One mirror 4
A piezo element 40 is fixedly adhered to the back surface of 8, and the mirror 48 can be moved in the optical axis direction by the voltage control circuit 41. Thereby, the phase difference between the P wave and the S wave can be changed.

The light source system 16 shown in FIG. 10 uses a Zeeman laser 50 as a light source to change the phase difference. The Zeeman laser 50 emits linearly polarized light having different frequencies and oscillating at right angles to each other. That is, this polarized light is emitted as x-polarized light and y-polarized light whose phase difference changes with time, and the Zeeman laser 50
A timing pulse is generated from the oscillator built in the and the image is captured based on this pulse. According to the above-described configuration examples, the present embodiment has an advantage that it is less susceptible to the influence of disturbance such as temperature change and vibration because the optical element that changes the phase difference is installed on the common optical path of the two light beams that interfere with each other. .

In this embodiment, the polarization axes of the two polarizing plates 66 and 67 constituting the composite polarizing plate 68 are shown as being orthogonal to each other, but they are not necessarily orthogonal to each other depending on how the polarization state is changed. You don't have to. Further, depending on the value of the intensity difference between the transmitted light and the diffracted light, the rear polarizing plate 8 need not be 45 °. The light source system 16 is shown in FIGS.
The configuration shown in 0 can be used. Of these light source systems 16, the polarization variable element 18 is the light source 1
7 may be separated and inserted into any position of the optical path from the light source 17 to the polarizing plate 8. Alternatively, as the polarization variable element 18, the polarizing plate 8 may be rotatable and the quarter wavelength plate 20 may be inserted and disposed between the polarizing plate 8 and the composite polarizing plate 68.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 12 is a block diagram of the phase contrast microscope which is the second embodiment of the present invention. In this embodiment,
Instead of the light source system 16, a variable wavelength light source 54 that can change the wavelength of emitted polarized light, and the light source 54
The optical path length difference generation unit 5 having different optical path lengths for the polarized light emitted from the
And 5 are provided. These polarized waves orthogonal to each other are defined as x polarized wave and y polarized wave. Further, the variable wavelength light source 54 is connected to a wavelength control device 56, and the wavelength of the polarized light from the variable wavelength light source 54 can be changed by the wavelength control device 56.

Here, referring to FIG. 13, the optical path length difference generator 55 is shown.
An example of the configuration will be described. In FIG. 13, a polarization beam splitter 57 is arranged on the optical axis, and a quarter wavelength plate 58 and a mirror 59 are arranged on both sides of the polarization beam splitter 57 with the optical axis interposed therebetween. Therefore, of the light emitted from the variable wavelength light source 54, the P wave passes through the polarization beam splitter 57, but the S wave is reflected. And
The S wave passes through the quarter-wave plate 58, is reflected by the mirror 59, passes through the quarter-wave plate 58 again, and is converted into the P-wave. Therefore, the light passes through the polarization beam splitter 57, similarly passes through the quarter wavelength plate 58, is reflected by the mirror 59, passes through the quarter wavelength plate 58 again, and becomes an S wave. It will be reflected and emitted. In this way, the optical path length difference generation unit 55 causes an optical path length difference of two round trips of the polarization beam splitter 57 between the P wave and the S wave. The P wave and S wave are used as the x polarization and the y polarization. Then, the optical path length difference generation unit 55
In the polarized light propagated through, the phase of the x polarization and the phase of the y polarization are changed.

In this embodiment, when the wavelength of the polarized light emitted from the variable wavelength light source 54 is changed by the wavelength control device 56, the phase difference generated in the optical path length difference generator 55 also changes. The change amount Δθ of the phase difference is represented by Δθ = 2πΔλ · d / λ2 (3). Here, Δλ is the wavelength shift amount, and d is the optical path length difference. Therefore, in order to set the change amount Δθ of the phase difference to 2π, the wavelength may be changed by the wavelength shift amount Δλ of the following equation. Δλ = λ2 / d (4) Therefore, by changing the wavelength linearly or stepwise so that the phase difference between the x-polarized wave and the y-polarized wave changes by 90 °, it is possible to obtain an interference image with different light and dark. it can. The processing method in the case of measuring the phase distribution is the same as that of the above-mentioned embodiment.

As can be understood from the equation (4), the larger the optical path length difference d generated by the optical path length difference generating section 55, the greater the brightness can be changed with a small wavelength shift amount Δλ. If the wavelength shift amount Δλ is large, the error and the phase change amount Δθ become non-linear due to the influence of chromatic dispersion, and a large error occurs in the phase distribution measurement. Optical path length difference generation unit 55
Is used to solve this problem, and when such a problem does not occur, the optical path length difference generation unit 55 may be removed. As the variable wavelength light source 54, a semiconductor laser, a dye laser, or an F center laser can be used. Alternatively, a method of combining a white light source and a variable wavelength filter may be adopted. Especially semiconductor lasers
The wavelength can be easily changed by increasing or decreasing the injection current.

As described above, this embodiment has the advantage that it does not generate vibrations due to the driving of the movable part because it has no mechanically movable part, and is stable and excellent. Although the light source is the variable wavelength light source 54 and the light source has a variable wavelength function in the above-described embodiment, instead of this, the light source is a white light source and a variable wavelength means such as a filter is arranged in front of it. It may be arranged to change the wavelength.

Next, another configuration example of the optical path length difference generating section 55 will be described with reference to FIGS. 14 to 16. The optical path length difference generation unit 55 shown in FIG. 14 uses a birefringent element 61. When the azimuth axes of the birefringent element 61 are the x-axis and the y-axis, the straight line emitted from the variable wavelength light source 54 is used. When the polarized wave is incident with the vibration direction inclined by 45 °, the optical path length difference can be set between the x polarized wave and the y polarized wave by propagating through the birefringent element 61. As the birefringent element 61, quartz, calcite, or rutile can be used. The optical path length difference generation unit 55 shown in FIG. 15 has two polarization prisms 62 and 63.
It consists of The crystal axes of the polarizing prisms 62 and 63 are inclined by 45 ° in directions opposite to each other with respect to the optical axis as indicated by arrows in the figure, and the crystal axes of the prisms are different by 90 °. Therefore, the polarization component perpendicular to the paper surface becomes ordinary light, and the parallel polarization component becomes extraordinary light, and one optical axis of the first polarization prism 62 is laterally displaced. And
The optical axis of the second polarizing prism 63 again coincides with the other optical axis. The two polarization prisms 62 and 63 provide an optical path length difference between the ordinary light and the extraordinary light.

Another optical path length difference generator 55 shown in FIG.
The polarization-maintaining optical fiber 64 is used. The polarization-maintaining optical fiber 64 generally has birefringence and may be considered to be equivalent to the configuration example of FIG. However, in the present configuration example, the polarization-maintaining optical fiber 6
Since 4 also functions as a light transmitting means, it is effective when it is desired to set the distance between the light source 54 and the sample 5 at a large distance.

In the phase contrast microscope of the present embodiment having such a configuration, the polarized light emitted from the variable wavelength light source 54 is transmitted through the optical path length difference generating section 55 and is separated into transmitted light and diffracted light by the sample 5. Then, when it passes through the composite polarizing plate 68, it becomes x-polarized light and y-polarized light, and interferes on the CCD 9 by the polarizing plate 8. In the present embodiment, the optical path length difference generation unit 55 provides an optical path length difference between the x polarization and the y polarization, and when the wavelength of the light emitted from the tunable light source 54 is changed, the x polarization and the y polarization are changed. The phase difference with the wave changes, and the brightness changes. Further, in the present embodiment, the optical path length difference generation unit 55 may be inserted and arranged at any position on the optical path from the light source 54 to the polarizing plate 8.

The optical path length difference generator 55 is for increasing the optical path length difference between the x polarization and the y polarization. Therefore, the optical path length difference between the x polarization and the y polarization may be set by sufficiently increasing the thickness of the phase film 69 used in the conventional phase contrast microscope. It shows in FIG. Of course, in this case, the optical path length difference generation unit 55
Is not necessary.

[0035]

As described above, according to the phase contrast microscope of the present invention, contrast setting and adjustment can be performed easily and smoothly without affecting the image formation relationship.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a phase contrast microscope that is a first embodiment of the present invention.

FIG. 2 is a diagram showing polarization states when the phase difference between the x polarization and the y polarization differs by 90 °.

FIG. 3 is a diagram showing an example of a configuration of a light source system according to a first embodiment.

FIG. 4 is a diagram showing a configuration of another light source system.

FIG. 5 is a diagram showing a configuration of another light source system.

FIG. 6 is a diagram showing a configuration of another light source system.

FIG. 7 is a diagram showing a configuration of another light source system.

FIG. 8 is a diagram showing a configuration of another light source system.

FIG. 9 is a diagram showing a configuration of another light source system.

FIG. 10 is a diagram showing a configuration of another light source system.

FIG. 11A is a plan view showing a structure of a composite polarizing plate,
(B) is a plan view of a polarizing plate.

FIG. 12 is a configuration diagram of a phase contrast microscope that is a second embodiment of the present invention.

FIG. 13 is a diagram showing a configuration example of a wavelength variable light source and an optical path length difference generation unit of a second embodiment.

FIG. 14 is a diagram showing a configuration of a variable wavelength light source and another optical path length difference generation unit.

FIG. 15 is a diagram showing a configuration of a variable wavelength light source and another optical path length difference generation unit.

FIG. 16 is a diagram showing a configuration of a variable wavelength light source and another optical path length difference generation unit.

FIG. 17 is a configuration diagram of a phase contrast microscope that is a third embodiment of the present invention.

FIG. 18 is a configuration diagram of a conventional phase contrast microscope.

[Explanation of symbols]

5 ... Sample, 8 ... Polarizer, 9 ... CCD, 17 ... Light source, 18 ... Polarization variable element, 20 ... Quarter wave plate, 2
8 ... Polarization control device, 54 ... Tunable wavelength light source, 55 ...
Optical path length difference generator, 68 ... Composite polarizing plate, 69 ... Phase film.

Claims (2)

(57) [Claims] 1. A light source for irradiating a sample, an interference image generating means for guiding transmitted light and diffracted light emitted from the sample onto an observation surface so as to obtain an interference image, and the interference image is detected. In the phase contrast microscope having a detecting means for performing the polarization state changing means arranged between the light source and the detecting means for changing the polarization state of the light,
The openings that are placed in useful positions and the openings are projected
The first polarization extraction part and the other second polarization extraction part.
And is arranged at a position conjugate with the opening.
The polarization excised section was excised specific polarization component from the transmitted light
Double polarization excised portion of the second is to remove the polarization component crossing the polarizing direction of the polarization extraction portion of the first is removed from the diffracted light
A phase contrast microscope comprising: a polarizing plate . 2. A phase contrast microscope having a light source for irradiating a sample, and an interference image generating means for guiding transmitted light and diffracted light emitted from the sample onto an observation plane so as to obtain an interference image. The phase difference microscope, wherein the light source has a wavelength variable function of changing the wavelength of emitted light, or a wavelength variable means is provided separately from the light source.