JPH0668019U - Differential interference microscope - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention is capable of easily moving a light branching member to a predetermined position on the optical axis by a simple operation, simplifies the structure of the device, and lowers the cost. The purpose is to simplify the operation. [Structure] The illumination light is divided into two and guided to the object side,
In a differential interference microscope that includes a light branching member made of a uniaxial crystal that combines two split light beams from an object to be examined, and performs differential interference observation with the light beams combined by the light branching member, A branching member holding means (15) for holding the light branching member at a plurality of positions in the axial direction so as to be switchably movable and for holding the light branching member in a direction perpendicular to the optical axis is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a differential interference microscope for observing minute irregularities on the surface of an object by the interference color or contrast of light and dark.

[0002]

[Prior art]

 Conventionally, in the field of microscope observation, a differential interference observation method capable of confirming minute irregularities on the surface of a test object has been known.

According to this differential interference observation method, linearly polarized illumination light that has passed through a polarizer is separated into two light beams by a combination prism made of a uniaxial birefringent substance, and the two light beams are irradiated to the test object. This is a method of observing the optical path difference due to minute unevenness of the test object as an interference color of light by combining the observation lights with the same prism and then making them interfere with the analyzer. In differential interference observation with epi-illumination, one combination prism is used to split the illumination light into two beams and combine the observation light.

In the Nomarski-type differential interference method, which is the most common differential interference observation method, two rays passing through a Nomarski prism have an angle, and the rays intersect at a certain point. This intersection is called the localized surface. Moreover, in the epi-illumination Nomarski differential interference method, since the observation light must be combined by the prism that separates the illumination light as described above, the localization surface of the Nomarski prism is made to coincide with the back focal plane of the objective lens. At this time, if the two are misaligned, the interference color becomes uneven, and good observation cannot be performed.

In addition, in a microscope observation, since the rear focal length of the objective lens generally varies depending on the magnification, it is necessary to adjust the localization surface of the Nomarski prism to the rear focal surface of the objective lens every time the objective lens is converted. is there.

For this reason, a structure as disclosed in Japanese Utility Model Laid-Open No. 4-59815 is considered. FIG. 8 is a sectional view showing a drive mechanism of the Nomarski prism of such a microscope. This drive mechanism is housed in a box 103 provided under a revolver 102 to which a plurality of objective lenses 101 are attached. The box 103 has a nut 104 fixed to the lower center thereof, a male screw 105a formed on the lower portion so as to be screwed with the nut 104, and a gear 105b fixed on the upper portion of the holding shaft. 105 is rotatably supported on the upper part of the box. Further, an adjusting knob 106 having a gear 106a at the lower part is rotatably supported on the upper part of the box 103, and a gear 106a is meshed with a gear 105b of a holding shaft 105.

Further, a turret board 107 is rotatably provided around the holding shaft 105 as a central axis, and a miniature bear ring 108 is interposed between the turret board 107 and the holding shaft 105. The turret plate 107 has a Nomarski prism 109 on the optical axis L.

That is, in this drive mechanism, the rotation of the adjustment knob 106 causes the rotational force of the gear 106a to be transmitted via the gear 105b to rotate the holding shaft 105, and the male screw 105a at the lower end of the holding shaft 105 turns into a nut. By being screwed into 104, the turret board 107 itself is configured to move up and down as the holding shaft 105 rotates.

Therefore, in this microscope, the Nomarski prism 109 can be moved in the optical axis direction by the drive mechanism described above, and the Nomarski prism position is adjusted when the objective lens is converted.

On the other hand, it is also considered to use a Nomarski prism designed such that the localization position is adjusted for each objective lens as shown in Japanese Utility Model Publication No. 51-51242 and Japanese Utility Model Publication No. 4-107212.

[0011]

However, in the differential interference microscope as disclosed in Japanese Utility Model Laid-Open No. 4-59815, when the Nomarski prism position is adjusted, the operator looks at the image for each conversion of the objective lens 101. Since the position of the Nomarski prism on the optical axis must be finely adjusted while rotating the adjustment knob 106 so as to eliminate the interference unevenness, there is a problem that a troublesome fine adjustment operation is performed for each observation magnification of the sample.

In addition, as described above, the microscope in which fine adjustment is performed for each objective lens 101 has a complicated mechanism, and the rotation operation of the adjustment knob 106 causes the Nomarski prism 9 to rotate through the gears 106a and 105b. Since it is moved up and down, there is a problem that operability is extremely low.

On the other hand, in the method of using the Nomarski prism designed corresponding to each objective lens, the trouble of fine adjustment is eliminated, but since the Nomarski prism is provided for each objective lens used, many It is expensive when using an objective lens.

In order to solve these problems, it is necessary to make the back focal planes of the objective lenses, which differ according to the magnification, match between the objective lenses of each magnification. As a result, one Nomarski prism can be used without adjustment even if the objective lens is converted and the magnification is changed. However, in the long working distance objective lens, since the lens group is located rearward of the general objective lens, there is a problem that the rear focal plane is rearward due to the design.

Therefore, the rear focal planes of the same type of objective lenses can match at different magnifications, but the rear focal planes of the general objective lens and the long working objective lens cannot match.

Therefore, when a general objective lens and a long working objective lens are used in combination, one Nomarski prism can be used without adjustment for magnification conversion between objective lenses of the same type, but from a general objective lens to a long working distance objective lens. When converting to or vice versa, it is necessary to adjust the localization surface of the Nomarski prism.

The present invention has been made in consideration of the above situation, and the light branching member can be easily moved to a predetermined position on the optical axis by a simple operation, and the structure of the device is simplified and the cost is reduced. It is an object of the present invention to provide a differential interference microscope that can be operated and can be simplified in operation.

[0018]

[Means for Solving the Problems]

 In order to achieve the above object, in the differential interference microscope of the present invention, the light splitting member made of a uniaxial crystal that splits the illumination light into two and guides it to the test object side, and combines the two split light beams from the test object. In the differential interference microscope, the branching member holding means for holding the branching member so as to be switchably movable to a plurality of positions in the optical axis direction is provided. is there. Here, in particular, the branching member holding means holds the light branching member so as to be movable in the direction perpendicular to the optical axis.

[0019]

[Action]

 Therefore, in the differential interference contrast microscope of the present invention, the light branching member holding means holds the light branching member switchably at a plurality of positions in the optical axis direction, and the light branching member with respect to the optical axis. Holds vertically movable.

With this, the light branching member can be easily moved to a predetermined position on the optical axis by a simple operation, so that the configuration of the device can be simplified and the cost can be reduced, and the operation can be simplified. Can be achieved.

[0021]

【Example】

 A Nomarski differential interference microscope according to an embodiment of the present invention will be described below. Before explaining the details of the embodiment, the basic optical system of the Nomarski type epi-illumination differential interference microscope will be described with reference to FIG. In this Nomarski-type epi-illumination differential interference microscope, the illumination light generated by the light source 1 is linearly polarized by the polarizer 2 provided on the optical axis, and the linearly polarized light ray is directed on the observation optical axis of the microscope. It is reflected by the half mirror 3 arranged and enters the Nomarski prism 4.

The Nomarski prism 4 is a light splitting member formed of two wedge-shaped uniaxial crystals, and splits the light beam linearly polarized by the polarizer 2 into two light beams and outputs them with respective angles. At the same time, the two light rays are made to intersect at the localization surface 5 and then made incident on the objective lens 6, respectively.

Here, since the Nomarski prism 4 is arranged so that the localization surface 5 coincides with the rear focal plane 7 of the objective lens, the two rays incident on the objective lens 6 are slightly laterally displaced and are parallel to each other. The sample 8 is irradiated with light rays.

The two light rays reflected by the sample 8 pass through the objective lens 6 again, intersect at the rear focal plane 7, and enter the Nomarski prism 4, respectively. In the Nomarski prism 4, two light rays are combined and emitted, contrary to the above, and the combined light rays are transmitted through the half mirror 3 and are incident on the analyzer 9 arranged at the subsequent stage of the half mirror 3. The analyzer 9 acts to interfere the two rays combined by the Nomarski prism 4.

Here, if the surface of the sample 8 has minute unevenness, a slight optical path difference occurs between the two light rays, so that when these two light rays are interfered by the analyzer 9, a contrast of the interference color is generated. Occurs. If the Nomarski prism 4 is displaced in the optical axis direction, the localization surface 5 and the rear focal plane 7 of the objective lens 6 do not coincide with each other, and the contrast of the interference color is uneven, resulting in a good differential interference image. Can't get

When the differential interference image is good but the interference color is desired to be changed, the interference color can be arbitrarily changed by shifting the Nomarski prism 4 in the direction perpendicular to the optical axis. Next, details of the differential interference microscope using such an optical system will be described.

FIG. 7 is an external view showing the configuration of the differential interference microscope according to the first embodiment of the present invention. In this differential interference microscope, a lamp house 10 incorporating a light source 1 is provided on the upper part of the microscope, and one end of an epi-illumination light projection tube 11 is connected to the lamp house 10. A polarizer slider 12 having a polarizer 2 and an analyzer slider 13 having an analyzer 9 are inserted into the epi-illumination light projection tube 11 so as to form the above-mentioned optical system, and a half mirror 3 (not shown) is built in. There is.

The revolver unit 14 is arranged below the epi-illumination light projection tube 11, and the Nomarski unit 15 as a branch member holding means having the Nomarski prism 4 is inserted perpendicularly to the optical axis. To be done. Further, the revolver unit 14 has a revolver body 16 rotatably provided below the Nomarski unit 14, and the plurality of objective lenses 6 are attached to the revolver body 16. Therefore, the revolver unit 14 can replace each objective lens 6 on the optical axis by rotating the revolver body 16. Here, the Nomarski unit 15 inserted into this differential interference microscope perpendicularly to the optical axis will be described in detail with reference to FIGS. 1 to 3.

1 to 3 are plan views or side views showing the configuration of the Nomarski unit 15. The Nomarski unit 15 has a unit main body 17 formed in a rectangular shape, a light beam transmission hole formed in a rectangular shape in the center of the unit main body 17, and formed in a frame shape so as not to block the transmission hole. The cam slider 18 is held slidably in the longitudinal direction of the unit body 17. The unit body 17 is inserted into the microscope along its longitudinal direction (hereinafter referred to as the slide direction). When locking the unit main body 17 on the optical axis of the microscope, a click (not shown) is provided on the microscope side, and the unit main body 17 inserted along the slide direction has a click groove 35a for inserting and removing the optical axis. 35b is cut.

The cam slider 18 has a cam 19 having a cam surface on its upper surface and horizontal portions 20 and 21 having horizontal surfaces on the upper and lower sides of the cam 19, respectively, and a lever 22 at the front end in the sliding direction. The one end portion 22a is connected, and the other end of the lever 22 is slidably brought into contact with the inner surface of the unit body 17 by advancing and retracting from the outside of the unit body 17.

Further, the cam slider 18 has a prism frame 23 between the cam 19 and the horizontal portions 20 and 21 and the inner surface of the unit main body 17, and is moved forward and backward in the sliding direction. The prism frame 23 is moved in the optical axis direction.

The prism frame 23 is provided with a cam 24 having a cam surface on the lower surface and a horizontal portion 25 having a horizontal surface on both sides thereof so as to contact the cam 19 and the horizontal portions 20 and 21 of the cam slider 18. The horizontal portion 25 is designed so that its length is shorter than the horizontal portion 21 of the cam slider 18.

Further, the prism frame 23 is provided with a frame-shaped prism holding portion 26 on the flat surface portion on the back side in the sliding direction so as not to close the transmission hole, and the Nomarski prism 4 is mounted on the prism holding portion 26. Is held. The prism holding portion 26 is provided with a substantially elliptical hole 26a for transmitting light on the lower surface of the prism. Further, the unit body 17 is also provided with a hole 17a for transmitting light.

Further, in the prism frame 23, a fitting portion 27 is formed adjacent to the prism holding portion 26, and the block 28 having a groove 28a in the optical axis direction is fitted into the groove 28a. By holding. Further, the prism frame 23 has a block 29 at the end portion on the front side in the sliding direction. In the blocks 28 and 29, guide grooves having a threaded portion are formed in the sliding direction of the prism frame 23.

The color adjustment shaft 30 has a knob 31 at one end, and screw portions 32 and 33 are formed at the other end and in the middle thereof, and the screw portion 32 at the other end penetrates the unit main body 17 from the front side in the sliding direction. It is provided to do. Further, in the color adjusting shaft 30, the threaded portion 32 at the other end is engaged with the guide groove of the block 28, and the threaded portion 33 in the middle is engaged with the guide groove of the block 29.

Rings 34 are attached to both ends of a threaded portion 33 formed in the middle of the color adjusting shaft 30 so as to extend along the outer periphery of the color adjusting shaft 30. The ring 34 collides with the block 29 which is moved by the rotation of the color adjusting shaft 30, and limits the moving range of the block 29.

With respect to such a unit body 17, one end portion 35 a of the leaf spring 35 is fixed to the unit body 17, and the other end portion 35 b of the leaf spring 35 is in contact with the prism frame 23. Therefore, by the leaf spring 35 urging the prism frame 23 toward the cam 19, the prism frame 23 is configured to move without rattling with respect to the cam 19. Next, the operation of the differential interference microscope configured as described above will be described. Now, it is assumed that the objective lens 6 is converted by the rotation of the revolver body 16 by the operator.

Here, when the lever 22 of the Nomarski unit 15 is pulled out by the operator, the cam slider 18 connected to the lever 22 slides inside the unit body 17, and the prism frame 23 follows the cam 19 and slides. Go up along the optical axis. Conversely, when the lever 22 is pushed in, the prism frame 23 lowers in the optical axis direction.

Therefore, the position of the Nomarski prism 4 can be moved in the optical axis direction by pushing and pulling the lever 22 to switch the position in two steps, and the localized surface 5 on the optical axis can be switched and moved with one touch.

When the operator further turns the knob 31 of the color adjusting shaft 30, the block 28 screwed into the screw 32 at the tip of the shaft moves in the direction of the color adjusting shaft 30 with the screw as a lead. Accordingly, the prism frame 23 fitted in the block 28 slides on the horizontal portion 20 or 21 of the cam slider 18. Even when the prism frame 23 is at the lower position on the optical axis, since the horizontal portion 25 of the prism frame 23 is designed to be shorter than the horizontal portion 21 of the cam slider 18, the prism frame 23 moves in the horizontal direction. However, since the horizontal portion 25 of the prism frame 23 only moves horizontally on the horizontal portion 21 of the cam slider 18, the position of the prism frame 23 on the optical axis does not change.

Further, in response to this horizontal movement, the block 29 engaged with the screw portion 33 in the middle of the color adjusting shaft 30 moves in the axial direction. The ring 34 provided on the color adjusting shaft 30 limits the moving range of the block 29, so that the rotation of the color adjusting shaft 30 is restricted. Thus, the sliding range of the prism frame 23 is regulated. Therefore, by rotating the knob 31, the Nomarski prism 4 can be moved in the direction perpendicular to the optical axis regardless of the position of the Nomarski prism 4 on the optical axis, and the interference color of the sample 8 can be changed arbitrarily. Can be transformed.

Further, the hole 17a is locked on the optical axis of the microscope by the optical axis inserting / removing click groove 35a. The hole 17a is also locked by the optical axis inserting / removing click groove 35a even at a position off the optical axis of the microscope. The unit body 17 can be attached to and detached from the microscope body.

As described above, in the first embodiment, the cam slider 18 moves back and forth in response to the forward / backward movement of the lever 22, and the cam portion 19 of the cam slider 18 pushes the prism frame 23 to a predetermined position on the optical axis. By raising or lowering, it is possible to complete the switching of the Nomarski prism 4 fixed to the prism frame 23 to a predetermined position in a short time as compared with the case of rotating the adjustment knob.

Further, in the first embodiment, by rotating the knob 31 of the color adjusting shaft 30, the screw portion 32 at the tip of the shaft rotates and the block 28 engaged with the screw portion 32 is rotated. Since the prism frame 23 engaged with the block 28 is moved back and forth in the sliding direction of the Nomarski unit 15 via the, the Nomarski prism 4 fixed to the prism frame 23 is moved vertically to the optical axis. It is possible to change the interference color of the sample 8.

Therefore, in the first embodiment, since only one Nomarski unit having one Nomarski prism can deal with all objective lenses including the long working distance objective lens, the operation is inexpensive and simple. Differential interference observation can be performed with. Next, a second embodiment of the present invention will be described with reference to FIGS.

Since the second embodiment is an example in which the Nomarski unit 15 of the apparatus shown in FIG. 7 is realized by another configuration, the same parts as those in FIG. 7 are designated by the same reference numerals and their detailed description will be given. Is omitted and only different parts will be described here.

FIG. 4 and FIG. 5 are plan views or side views showing the second embodiment of the Nomarski unit 15. In the Nomarski unit 15, a unit main body 41 is formed in a rectangular shape, a light transmission hole is formed in a rectangular shape in a central portion of the main body 41, and a slide base 42 is arranged in a longitudinal direction (sliding direction) of the main body 41. Is held slidably. Further, the unit main body 41 has through holes 41a and 41b on the end face on the front side in the sliding direction.

The slide base 42 is formed in a hollow shape, and a prism base 43 having a thickness half that of the main slide base 42 is movably held on the inner surface on the back side in the sliding direction. Further, the slide base 42 is provided with a switching support rod 44 on the inner surface on the front side in the sliding direction in a direction perpendicular to the optical axis direction and the sliding direction, and a female screw portion 45 is formed at the end portion on the front side in the sliding direction. Has been done. A color adjusting shaft 46 is screwed into the female screw portion 45.

The color adjusting shaft 46 has a knob 46 a at one end and a male screw portion 46 b at the other end, and is provided so as to penetrate the through hole 41 a of the unit main body 41 in the sliding direction. . Further, the color adjusting shaft 46 has its male screw portion 46 b screwed onto the female screw portion 45 of the slide base 42. Therefore, the color adjustment shaft 46 slides the slide base 42 so as to be able to move forward and backward in the sliding direction by the rotation operation of the knob 46a. Rings 47 are attached to both ends of the male screw portion 46 b of the color adjusting shaft 46, and the operation is restricted by the rings 47 so as not to come off the slide base 42.

The prism base 43 has a transmission hole 43a for passing a light beam in the center, and the Nomarski prism 4 is fixed by an adhesive or the like so as to cover the transmission hole 43a. The prism base 43 is provided with a substantially elliptical hole 43a for transmitting light on the lower surface of the prism. Further, the unit body 41 is similarly provided with a hole 41c for transmitting light.

Further, the prism base 43 is provided with projections 43b and 43c on both sides thereof perpendicularly to the optical axis direction and the sliding direction, and the switching rod 48 is engaged with these projections 43b and 43c. .

The switching rod 48 is provided inside the unit body 41, has one end branched into two and has elongated holes 48 a and 48 b respectively, and the other end projects to the outside of the unit body 41. Further, in the switching rod 48, the protrusions 43b and 43c of the prism base 43 are loosely inserted into the corresponding long holes 48a and 48b, respectively, and the middle portion of the switching rod 48 is the switching support of the slide base 42 described above. It is pivotally supported by the rod 44. Therefore, the switching rod 48 moves the prism base 43 in the optical axis direction in response to an up / down operation from the outside.

Further, in the unit main body 41, the main body protrusion 49 is provided on the inner surface on the front side in the sliding direction from the prism base 43, and the spring 50 is interposed between the main body protrusion 49 and the prism base 43. The repulsive force of the spring 50 pushes the prism base 43 against the inner part of the unit body 41 in the sliding direction.

A groove 51 is formed in the center of the rear portion of the unit main body 41 in the sliding direction, and a ball click 52 is provided in the groove 51. The ball click 52 pushes the prism base 43 back to the center portion. By not positioning the prism base 43, the prism base 43 is stabilized at the upper position or the lower position in the optical axis direction. Next, the operation of the differential interference microscope configured as described above will be described. Now, it is assumed that the objective lens 6 is converted by the rotation of the revolver body 16 by the operator.

Here, when the operator operates the switching rod 48 outside the unit main body 41 upward, since the switching rod 48 is axially supported by the switching support rod 44 midway, the long hole 48 a at the tip of the switching rod 48 is provided. , 48b move the prism base 43 downward along the optical axis via the protrusions 43b and 43c. At this time, the prism base 43 is sandwiched by the spring 50 and the ball click 51, so that the prism base 43 is stably positioned at the lower position on the optical axis.

When the operator operates the switching rod 48 outside the unit main body 41 downward, the elongated holes 48a and 48b at the tip of the switching rod 48 move the prism base 43 through the projections 43b and 43c as described above. By moving the prism base 43 upward in the optical axis, the prism base 43 is stably positioned at the upper position in the optical axis.

Therefore, the Nomarski prism 4 fixedly mounted on the prism base 43 is arranged on the localization surface 5 that coincides with the rear focal plane 7 of the converted objective lens 6.

When changing the interference color of the sample 8, the operator rotates the knob 46 a of the color adjusting shaft 46 so that the rotational force of the color adjusting shaft 46 is changed from the male screw portion 46 b to the slide base 43. It is transmitted to the female screw part 45 of FIG.

As a result, the prism base 43 held by the slide base 42 moves, and the Nomarski prism 4 fixedly mounted on the prism base 43 moves in the direction perpendicular to the optical axis to change the interference color. Can be made.

As described above, in the second embodiment, the one-touch operation of simply switching the switching rod 48 up and down allows the normal ski prism 4 to be illuminated in an extremely short time as compared with the case of rotating the adjustment knob. It is possible to switch and move to a predetermined upper position or lower position on the shaft. Therefore, fine adjustment of the Nomarski prism 4 in the direction of the optical axis is unnecessary, and the operability of the microscope can be significantly improved.

Further, in the second embodiment, by rotating the knob 46 a of the color adjusting shaft 46, the male screw portion 46 b of the color adjusting shaft 46 rotates, and the slide base 43 holding the prism base 43. Through the female screw portion 45 in the sliding direction. Thus, the Nomarski prism 4 fixed to the prism base 43 can be moved vertically with respect to the optical axis to change the interference color of the sample 8.

Therefore, in the second embodiment, only one Nomarski prism 4 is used, and the driving force of the switching rod 48 and the color adjusting shaft 46 is directly transmitted to the Nomarski prism 4. Since it is realized by a simple mechanism, it can be constructed at low cost.

In the first embodiment, the case where there are two moving positions in the optical axis direction corresponding to the two rear focal planes has been described, but the present invention is not limited to this, and the design of the objective lens is not limited to this. Even if the cam slider 18 is lengthened so as to correspond to the rear focal plane at three or more places and the cam has three or more stages, the same effect can be obtained by implementing the present invention in the same manner.

Further, in the second embodiment described above, the case where the prism base 43 is fixed to the upper position or the lower position by the ball click 52 pushing the prism base 43 back is explained, but the present invention is not limited to this. Instead, a groove is formed at a predetermined position of the prism base 43 that comes into contact with the ball click 52, and the ball click 52 is fitted in the groove to increase the fixing position of the prism base 43, or the thick slide base 43 is provided with the ball click Even if the fixing position of the prism base 43 is increased by providing a plurality of 52 in the optical axis direction, the same effects can be obtained by implementing the present invention in the same manner. In addition, the present invention can be modified in various ways without departing from the scope of the invention.

[0065]

[Effect of device]

 As described above, according to the present invention, the branching member holding means holds the light branching member so as to be switchably movable at a plurality of predetermined positions in the optical axis direction, and the light branching member with respect to the optical axis. Since it is held so as to be movable in the vertical direction, the light branching member can be easily moved to a predetermined position on the optical axis by a simple operation, and the structure of the device can be simplified and the cost can be reduced. At the same time, the operation can be simplified.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration of a Nomarski unit according to a first embodiment of the present invention.

FIG. 2 is a side view showing the configuration of a Nomarski unit in the same embodiment.

FIG. 3 is a side view showing the configuration of a Nomarski unit in the embodiment.

FIG. 4 is a plan view showing the configuration of a Nomarski unit in the second embodiment.

FIG. 5 is a side view showing the configuration of the Nomarski unit in the embodiment.

FIG. 6 is a diagram showing a configuration of an optical system in first and second examples.

FIG. 7 is an external view of a microscope in the same example.

FIG. 8 is a cross-sectional view showing a conventional Nomarski prism drive mechanism.

[Explanation of symbols]

4 ... Nomarski prism, 15 ... Nomarski unit, 17 ... Unit body, 18 ... Cam slider, 19,
24 ... Cam, 20, 21, 25 ... Horizontal part, 22 ... Lever, 23 ... Prism frame, 26 ... Prism holding part, 27 ...
Fitting portion, 28, 29 ... Block, 28a ... Groove, 30 ... Color adjusting shaft, 31 ... Knob, 32, 33 ... Screw portion, 34 ... Ring, 35 ... Leaf spring.

Claims (2)

[Scope of utility model registration request] 1. A light splitting member made of a uniaxial crystal that splits illumination light into two and guides it to the object side and couples the split light flux from the object to be examined, and the light splitting member couples the light. A differential interference microscope for performing differential interference observation with a light beam, comprising a branch member holding means for holding the light branch member at a plurality of positions in the optical axis direction so as to be switchably movable. 2. The differential interference microscope according to claim 1, wherein the branching member holding means holds the light branching member movably in a direction perpendicular to the optical axis.