JP5572561B2 - Lens module, magnification observation apparatus using the lens module, and magnification observation method - Google Patents

Description

  The present invention relates to a lens module capable of performing differential interference observation even when the magnification of an optical system is low, a magnification observation apparatus using the lens module, and a magnification observation method.

  When observing an object using reflective coaxial epi-illumination (hereinafter referred to as normal observation), light from the light source is partially reflected by the objective lens, and unnecessary light (flare) that does not contain information about the object is generated. . In order to suppress flare as much as possible, a polarizer (polarizer) is provided in the illumination optical system, a depolarizer (quarter wave plate) is provided at the tip of the objective lens, and a polarization axis in the observation optical system is the polarization axis of the polarizer. An objective lens in which analyzers (analyzers) are arranged so as to have a crossed Nicol positional relationship has been developed (see Patent Document 1). In the objective lens disclosed in Patent Document 1, flare can be effectively suppressed.

  In addition, when performing so-called “differential interference observation” on an object, the amount of received light detected by the light receiver does not use a depolarizer (¼ wavelength plate), but is a birefringent optical member for differential interference (hereinafter, differential interference). DIC prism) is disposed on the optical path (see Patent Document 2). The reason why the depolarizer is not used in the zoom microscope disclosed in Patent Document 2 is that the differential interference observation often observes a mirror-like object, and the S / N ratio is high, so that flare is not noticeable. . In addition, since an objective lens with a relatively high magnification (for example, several tens of times or more) is used to detect minute defects in the object, light from the light source is reflected by the objective lens due to the characteristics of the lens design. This is because flare is less conspicuous as a result of a decrease in the amount of light incident on.

JP-A-2005-164652 JP 2006-154230 A

  Here, when the presence of minute defects is confirmed (screened) at a glance by overlooking the entire object during differential interference observation, it is necessary to use a low-magnification objective lens during differential interference observation. Further, in order to perform normal observation so that a non-specular object can also be observed, it is necessary to make the differential interference DIC prism (and the polarizer) detachable from the differential interference observation microscope. Differential interference observation can be performed when the differential interference DIC prism is attached, and normal observation can be performed when the differential interference DIC prism is removed.

  However, when a low-magnification objective lens is used, flare is noticeable when performing normal observation. In order to solve this problem, a depolarizer may be arranged at the tip of the objective lens as described above. However, when differential interference observation is performed, the brightness in a flat portion where there is no defect in the object is maximized. Thus, there is a problem that it is difficult to visually recognize a minute defect.

  The present invention has been made in view of the above circumstances, and can perform both differential interference observation and normal observation, and in the case of performing differential interference observation, a lens module capable of more reliably detecting minute defects. An object of the present invention is to provide a magnification observation apparatus and a magnification observation method using the lens module.

In order to achieve the above object, a lens module according to the present invention includes a polarizer that polarizes light from a light source, and a light receiving axis of a camera that can reflect and connect a part of the light that has passed through the polarizer. A light transmitting member that guides the object along the direction and passes a part of the reflected light from the object, and two polarization axes that are orthogonal to each other and have no phase difference between the light reflected by the light transmitting member A birefringent optical member that can be separated into directional light and can be attached and detached, an objective lens that collects the light that has passed through the birefringent optical member and irradiates the object, and the light that has passed through the objective lens A polarization conversion member that converts a polarization state; and an analyzer that polarizes a part of the reflected light from the object that has passed through the light transmission member, and the polarization axis direction of the polarizer and the analyzer has a polarization axis direction. Yes disposed so as to be flat line to each other, the birefringent optical member, To the polarization axis direction of Kihen photons, Yes arranged the such that the two directions of the polarization axes is 4 5 times none, the polarization conversion member has a fast axis or slow axis, of any axis is characterized in that is arranged such that the polarization axis direction and 4 5 ° of the polarizer.

In the present invention, when performing differential interference observation, a polarizer and an analyzer, the polarization axis is disposed such that the flat line with each other, a birefringent optical element, e.g. DIC prism, perpendicular to each other, the phase difference two polarization axis no, Yes arranged so either the 4 5 ° relative to the polarization axis of the polarizer, the polarization conversion member, fast axis or slow axis and polarization axis of the polarizer 4 It arrange | positions in what is called parallel Nicol so that it may become 5 degree | times. By configuring the optical system in this way, the light reflected by the flat part of the object cancels each other when passing through the analyzer, so that the original purpose of differential interference observation such as recognition of minute defects is achieved. It becomes easy to do. In other words, when differential interference observation is performed even though a low-magnification objective lens and a polarization conversion member are mounted on the lens module in the same manner as in normal observation, the flat portion without defects becomes dark and defective. Since an observation image in which a certain uneven portion becomes bright can be acquired, a minute defect can be detected more reliably.

In the lens module according to another aspect of the invention, the analyzer is fixed (to the lens module), and the two polarization axis directions of the birefringent optical member are orthogonal to each other. 4 5 ° between a first opening capable of inserting the birefringent optical member so that, the polarization axis direction of the polarizer and the polarization axis direction of the analyzer to each other with respect to the polarization axis direction of the Rights Komata is characterized by having a second opening capable of inserting the polarizer such that vertically into the.

In another aspect of the present invention, leave secure the analyzer, the polarization axis direction with each other on a flat Komata polarization axis direction analyzer polarizer Chapter capable of inserting a polarizer so vertically into 2 Therefore, the polarization axis direction of the polarizer can be easily changed according to whether differential interference observation is performed or normal observation is performed. Further, the birefringent optical element, two polarization axes directions perpendicular to each other, a first opening capable of inserting the birefringent optical member so as to be 4 5 degrees relative to the polarization axis of the analyzer Therefore, the birefringent optical member can be easily attached and detached according to whether differential interference observation is performed or normal observation is performed. In particular, remove the birefringent optical member from the first opening, a polarizer is inserted into the second opening, the polarization axis and the analyzer is arranged such that the Cartesian to each other when performing normal observation Thus, flare light reflected by the objective lens can be greatly suppressed. In this way, when performing normal observation, flare can be effectively suppressed, and when performing differential interference observation, micro defects can be detected more reliably, so a lens with high usability or versatility. Modules can be provided.

  A lens module according to another invention is characterized in that, in the above invention, the polarizer inserted into the second opening can change an angle of a polarization axis.

  In another invention, the polarizer inserted into the second opening can change the angle of the polarization axis, so that the polarization axis can be finely adjusted. Can be minimized, and contrast can be adjusted when differential interference observation is performed.

  In the lens module according to another aspect of the present invention, the polarization conversion member is disposed between the objective lens and an object.

  In another aspect of the invention, when the objective lens is composed of a plurality of lenses, the polarization conversion member is closer to the object side than each lens constituting the objective lens. Therefore, flare can be effectively suppressed.

  Next, in order to achieve the above object, a magnifying observation apparatus according to the present invention includes a lens module according to the present invention, a rotating support column that is mounted so that the lens module can be moved up and down, and the rotating support column. A rotation mechanism that supports rotation about a horizontal rotation axis, a fixed column on which the rotation mechanism is provided, a base on which the fixed column is erected, It is provided in a fixed support | pillar or the said base, and is provided with the mounting part which mounts a target object.

  In the present invention, since the lens module can be rotated in accordance with the rotation of the mounted rotation support column, the angle at which the object placed on the placement unit is imaged is changed to a desired angle. This makes it possible to detect minute defects from an angle that is easier to see. In particular, when the rotation support is tilted to the left and right during normal observation, the object displayed on the display unit is also tilted to the left and right. By rotating the cameras connected in this state by 90 degrees, the object displayed on the display unit can be tilted back and forth.

Next, in order to achieve the above object, the magnification observation method according to the present invention is capable of reflecting and connecting a polarizer that polarizes light from a light source and a part of the light that has passed through the polarizer. The light transmitting member that guides to the object along the light receiving axis direction of the camera and passes part of the reflected light from the object and the light reflected by the light transmitting member are orthogonal to each other and have no phase difference A birefringent optical member that can be separated into two light beams in the direction of the polarization axis and can be attached and detached, an objective lens that collects the light that has passed through the birefringent optical member and irradiates the object, and the objective lens Magnification observation method for magnifying observation using a lens module having a polarization conversion member that converts a polarization state of light that has passed through, and an analyzer that polarizes part of the reflected light from the object that has passed through the light transmission member Wherein the polarizer and the analyzer are in a polarization axis direction. It is possible to switch whether a or vertical a flat line to each other, said birefringent optical element, the relative polarization axis direction of the polarizer, the two polarization axes directions 4 5 degrees either and arranged such that, the polarizer and the analyzer, when the polarization axis direction is disposed such that the flat line with each other, the polarization conversion member having a fast axis or slow axis, one of axes characterized in that it placed so that the polarization axis direction and 4 5 ° of the polarizer.

In the present invention, when performing differential interference observation, a polarizer and an analyzer, the polarization axis is disposed such that the flat line with each other, a birefringent optical element, e.g. DIC prism, perpendicular to each other, the phase difference two polarization axis no, Yes arranged so either the 4 5 ° relative to the polarization axis of the polarizer, the polarization conversion member, fast axis or slow axis and polarization axis of the polarizer 4 Arrange them to be 5 degrees. By configuring the optical system in this way, the light reflected by the flat part of the object cancels each other when passing through the analyzer, so that the original purpose of differential interference observation such as recognition of minute defects is achieved. It becomes easy to do. In other words, when differential interference observation is performed even though a low-magnification objective lens and a polarization conversion member are mounted on the lens module in the same manner as in normal observation, the flat portion without defects becomes dark and defective. Since an observation image in which a certain uneven portion becomes bright can be acquired, a minute defect can be detected more reliably.

According to the present invention, when performing differential interference observation, a polarizer and an analyzer, the polarization axis is disposed such that the flat line with each other, a birefringent optical element, e.g. DIC prism, perpendicular to each other, position two polarization axis without retardation is, Yes arranged so either the 4 5 ° relative to the polarization axis of the polarizer, the polarization conversion member, fast axis or slow axis the polarization axis of the polarizer And 45 degrees. By configuring the optical system in this way, the light reflected by the flat part of the object cancels each other when passing through the analyzer, so that the original purpose of differential interference observation such as recognition of minute defects is achieved. It becomes easy to do. In other words, when differential interference observation is performed even though a low-magnification objective lens and a polarization conversion member are mounted on the lens module in the same manner as in normal observation, the flat portion without defects becomes dark and defective. Since an observation image in which a certain uneven portion becomes bright can be acquired, a minute defect can be detected more reliably.

It is a schematic diagram which shows the structure of the magnification observation apparatus using the lens module which concerns on embodiment of this invention. It is a functional block diagram of a controller concerning an embodiment of the invention. It is a front view which shows the structure of the lens module which concerns on embodiment of this invention. It is an enlarged front view which shows the polarizer vicinity of the lens module which concerns on embodiment of this invention. It is a schematic diagram which shows the structure of the optical system of the lens module which concerns on embodiment of this invention. It is a schematic diagram which shows the polarization state in the lens module which concerns on embodiment of this invention in the case of performing differential interference observation. It is a schematic diagram which shows the polarization state in the lens module which concerns on embodiment of this invention three-dimensionally. It is a schematic diagram which shows the state which looked at the inclination of the polarization axis in the lens module which concerns on embodiment of this invention from the optical axis direction of the light source. It is a schematic diagram which shows the structure of the optical system of the lens module in the case of performing normal observation by suppressing flare. It is a comparison figure which shows the image which changed the conditions and imaged the surface of the target object. It is a comparison figure which shows the image which changed the conditions and imaged the surface of the target object which has a level | step difference gauge. It is an illustration figure which shows the difference in the image imaged by normal observation and differential interference observation according to the angle which inclines the high-speed axis | shaft of (lambda) / 4 wavelength plate. It is a graph explaining the brightness | luminance change according to the inclination angle of the high-speed axis | shaft of (lambda) / 4 wavelength plate with respect to the polarization axis of a polarizer in the lens module which concerns on embodiment of this invention. It is a perspective view which shows the structure of the lens stand of the magnification observation apparatus using the lens module which concerns on embodiment of this invention. It is a schematic diagram which shows a mode that the rotation support | pillar of a lens stand inclines to a desired angle. It is an illustration figure at the time of inclining and imaging the rotation support | pillar of a lens stand.

  Hereinafter, a lens module according to an embodiment of the present invention will be described with reference to the drawings. Throughout the drawings to be referred, elements having the same or similar configuration or function are denoted by the same or similar reference numerals, and detailed description thereof is omitted.

  FIG. 1 is a schematic diagram showing a configuration of a magnification observation apparatus using a lens module 1 according to an embodiment of the present invention. As shown in FIG. 1, the lens module 1 is fixed to a lens stand 62 and is provided so as to stand upright with respect to a stage (mounting portion) 61 on which an object (not shown) is placed. The camera 5 is connected to the controller 63 via the camera cable 51, and the coaxial epi-illumination unit 2 is connected to the controller 63 via the light cable 60.

  The controller 63 has a control unit composed of a microcomputer, a CPU, and the like, and controls the operation of each connected hardware. Necessary data is input by the user via the keyboard 65, mouse 66, etc. while visually recognizing on the display unit (monitor unit) 64.

  FIG. 2 is a functional block diagram of the controller 63 according to the embodiment of the present invention. The input receiving unit 71 receives input of necessary data via the keyboard 65 and the mouse 66. Further, image data captured by the camera 5 is subjected to arithmetic processing by the camera signal processing unit 72, and after necessary image processing is performed by the image processing unit 73, it is displayed on the display unit 64 by the display image creation unit 74. Create a display image for.

  Moreover, the illumination control part 75 adjusts the illumination intensity of the light source 3 based on the data which received the input. The mechanism control unit 76 sends an instruction signal to a stage motor or the like that controls the operation of the stage 61 based on the data that has received the input.

  FIG. 3 is a front view showing the configuration of the lens module 1 according to the embodiment of the present invention. In the lens module 1, the analyzer 9 is fixed inside the lens module 1. Even when the camera 5 is rotated about the lens optical axis, the polarization axis of the analyzer 9 does not rotate, and the relative relationship between the polarization axis of the analyzer 9 and the polarization axis of the polarizer 21 is maintained in a fixed relationship. It is to do.

  The lens module 1 according to the embodiment of the present invention includes a slot (second opening) so that the polarizer 21 can be attached to and detached from the coaxial epi-illumination unit 2. FIG. 4 is an enlarged front view showing the vicinity of the polarizer 21 of the lens module 1 according to the embodiment of the present invention. As shown in FIG. 4, by providing a slot (second opening) 121 in which the polarizer 21 can be attached and detached, when switching between differential interference observation and normal observation, the polarizers 21 having different polarization axis directions can be provided. It can be attached and detached in a direction perpendicular to the paper surface. By switching to a polarizer 21 having a polarization axis in an appropriate direction, it is possible to easily switch between differential interference observation and normal observation. In other words, the polarizer 21 is configured to be insertable from the direction substantially orthogonal to the longitudinal direction of the lens module 1 toward the second opening 121, and the analyzer 9 and the λ / 4 wavelength plate 7 include the lens module. In the state fixed to 1, the polarizer 21 is inserted and attached from the direction substantially orthogonal to the longitudinal direction of the lens module 1 toward the second opening 121, and the parallel Nicol state described later (see FIG. 10). Can be realized. Accordingly, the user can detect a micro defect more reliably when performing differential interference observation by performing a simple operation of attaching the polarizer 21 to the second opening 121 in the lens module 1. Module 1 can be configured.

  The polarizer 21 includes a polarizing filter, a rectangular parallelepiped case that stores the polarizing filter, and a rotation adjusting mechanism that adjusts the rotation angle of the polarization axis of the polarizing filter. Further, in the lens module 1 according to the present embodiment, the rotation adjustment mechanism has a dial unit 211 operated by the user, and a scale indicating the rotation angle of the polarization axis of the polarization filter is provided on one surface of the dial unit 211. Is provided. That is, the user can adjust the rotation angle of the polarization axis of the polarization filter of the polarizer 21 to an optimum angle by operating the dial unit 211 while visually checking the scale.

  The differential interference DIC prism 15 is preferably removable. This is because it is possible to easily switch between differential interference observation and normal observation. Therefore, the lens module 1 also includes an opening (first opening) from which the differential interference DIC prism 15 can be attached and detached.

  FIG. 5 is a schematic diagram showing the configuration of the optical system of the lens module 1 according to the embodiment of the present invention. As shown in FIG. 5, in the lens module 1 according to the embodiment of the present invention, the polarizer 21 is disposed as a polarizer in the coaxial incident illumination unit 2, and the illumination light emitted from the light source 3 is linearly polarized light. In FIG. 5, the linearly polarized light in the direction of the arrow near the polarizer 21 is parallel to the polarization axis direction of the analyzer 9.

  The illumination light that has become linearly polarized light is guided to a differential interference DIC prism (birefringent optical member) 15 by a half mirror (light transmitting member) 8. The λ / 4 wavelength plate 7 is disposed between the objective lens 4 and the object 6 so that the high-speed axis is approximately 45 degrees with the polarization axis direction of the polarizer 21. The differential interference DIC prism 15 is arranged so as to emit two orthogonal linearly polarized lights that form an angle of about 45 degrees with respect to the polarization axis direction of the polarizer 21. Thus, the two linearly polarized light that passes through the differential interference DIC prism 15 and reaches the λ / 4 wavelength plate (polarization conversion member) 7 is not approximately 45 degrees with respect to the high-speed axis of the λ / 4 wavelength plate 7. , Approximately parallel or approximately vertical.

  The λ / 4 wavelength plate 7 passes these linearly polarized light as linearly polarized light and the polarization axis and the like as it is. However, the phase of the other is shifted by λ / 4 with respect to one. When the light is reflected from the surface of the object 6 and passes through the λ / 4 wavelength plate 7 again, both the state of linear polarization and the polarization axis are maintained, but the phase between the two is further shifted by λ / 4, and λ / A phase difference of 2 occurs. Two orthogonal linearly polarized lights having no change other than the phase difference are again combined into one light by the differential interference DIC prism 15 and pass through an analyzer (analyzer) 9. In the present embodiment, the λ / 4 wavelength plate 7 is fixed to the lens module 1, but may be configured to be removable by the user. In the case of detachable configuration, in FIG. 3, the λ / 4 wavelength plate unit 7 a is attached to the tip of the lens module 1 so that the λ / 4 wavelength plate 7 is fixed and the objective lens 4 is covered. When the λ / 4 wavelength plate unit 7 a is rotated counterclockwise, the λ / 4 wavelength plate 7 is also rotated and removed from the lens module 1. In the present embodiment, the λ / 4 wavelength plate unit 7a is rotated clockwise, and the λ / 4 wavelength plate unit 7a is fully tightened. The polarization axis is approximately 45 degrees. In other words, the manufacturer's shipping person or user rotates the λ / 4 wavelength plate unit 7a clockwise as much as possible, and fixes the λ / 4 wavelength plate unit 7a to the lens module 1, thereby the λ / 4 wavelength plate. It is possible to easily create a state in which the high-speed axis or the low-speed axis 7 and the polarization axis of the polarizer 21 are approximately 45 degrees.

  At this time, since the phase difference is λ / 2, both linearly polarized light cancel each other when passing through the analyzer 9 where the polarization axis of the polarizer 21 and the polarization axis are substantially parallel. That is, differential interference observation can be performed by setting the polarizer 21 and the analyzer 9 to a parallel Nicol positional relationship in which the polarization axes are substantially parallel to each other rather than a crossed Nicol positional relationship.

  FIG. 6 is a schematic diagram showing a polarization state in the lens module 1 according to the embodiment of the present invention when differential interference observation is performed. A, B, E, and F in FIG. 6 indicate polarization states at positions A, B, E, and F in FIG. 5, respectively.

  At position A, the light is linearly polarized after passing through the polarizer 21. The direction of linearly polarized light is parallel to the polarization axis of the analyzer 9. At the position B, the DIC prism 15 for differential interference separates the light into two orthogonal linearly polarized lights whose polarization axes are rotated by about 45 degrees with respect to the incident linearly polarized light. The two separated linearly polarized lights are emitted with a slight deviation with respect to the optical axis, and the intersection point thereof coincides with the focal position of the objective lens 4 opposite to the side facing the object 6. .

  At the position E, the differential interference DIC prism 15 combines again with one light beam, but the polarization axes remain orthogonal to each other. At position F, when the two linearly polarized lights have exactly the same optical path length by passing through the analyzer 9, the two lights are polarized in the same direction in which the peaks and valleys are just opposite, and thus cancel each other.

  In order to clarify the relationship between the peaks and valleys of light, the polarization state will be illustrated and described three-dimensionally. FIG. 7 is a schematic diagram three-dimensionally showing the polarization state in the lens module 1 according to the embodiment of the present invention, and FIG. 8 shows the inclination of the polarization axis in the lens module 1 according to the embodiment of the present invention. It is a schematic diagram which shows the state seen from the optical axis direction of the light source 3. FIG. In FIGS. 7 and 8, in order to clarify the polarization state, the optical axis shift caused by separating the light into two lights is not mentioned. The depth direction of the three-dimensional graph in FIG. 7 indicates the time axis t, and the X-axis direction and the Y-axis direction indicate the light amplitude direction (direction orthogonal to the traveling direction).

  FIGS. 7A and 8A show the polarization state immediately after the illumination light emitted from the light source 3 passes through the polarizer 21. FIG. As can be seen from FIGS. 7 (a) and 8 (a), when passing through the polarizer 21, only light having the same direction as the polarization axis of the polarizer 21 passes, so that it is inclined by 45 degrees when viewed from the traveling direction. Light that oscillates.

  FIGS. 7B and 8B show the polarization state immediately after passing through the differential interference DIC prism 15. As can be seen from FIG. 7B and FIG. 8B, when passing through the differential interference DIC prism 15, the light is separated into components of the polarization interference (crystal axis) direction of the differential interference DIC prism 15. Specifically, when viewed from the traveling direction, the light is separated into light that vibrates in the X-axis direction and light that vibrates in the Y-axis direction.

  For example, at the time when the light wave is a mountain, that is, at time t1 indicating the position where the amplitude is maximum, the light wave oscillating in the X-axis direction is minimum (maximum peak in the negative direction of the X-axis). The wave of light oscillating in the Y-axis direction is maximum (maximum peak in the positive direction of the Y-axis). Therefore, as shown in FIG. 8B, at time t1, the wave of light oscillating in the X-axis direction becomes a mountain in the negative direction of the X-axis, and the wave of light oscillating in the Y-axis direction is positive on the Y-axis. It becomes a mountain in the direction of.

  FIGS. 7C and 8C show the polarization state after passing through the λ / 4 wavelength plate 7 once and passing again. As can be seen from FIGS. 7C and 8C, when the light passes through the λ / 4 wavelength plate 7 twice, the phase of the light wave oscillating in the X-axis direction is delayed by 90 degrees and in the Y-axis direction. The phase of the oscillating light wave advances by 90 degrees. Note that the direction of the separated light remains the X-axis direction (low-speed axis direction of the λ / 4 wavelength plate 7) and the Y-axis direction (high-speed axis direction of the λ / 4 wavelength plate 7).

  For example, at the time when the wave of light is a mountain, that is, at time t2 indicating the position where the amplitude is maximum, the wave of light oscillating in the X-axis direction is maximum (maximum peak in the positive direction of the X-axis). The wave of light oscillating in the Y-axis direction is maximum (maximum peak in the positive direction of the Y-axis). Therefore, as shown in FIG. 8C, at time t2, the wave of light oscillating in the X-axis direction becomes a mountain in the positive direction of the X-axis, and the wave of light oscillating in the Y-axis direction is positive in the Y-axis direction. It becomes a mountain in the direction of.

  FIGS. 7D and 8D show the polarization state after passing through the analyzer 9 when the polarizer 21 and the analyzer 9 are arranged in a crossed Nicols positional relationship. As can be seen from FIGS. 7 (d) and 8 (d), the two lights are combined and strengthened to become polarized light in the direction of the polarization axis of the analyzer 9.

  For example, at the time when the wave of light is a mountain, that is, at time t2 indicating the position where the amplitude is maximum, the object 6 is synthesized as light that vibrates in a direction inclined 45 degrees from both the X-axis direction and the Y-axis direction. In the case of being flat, the phase difference between the two lights to be combined is 0 (zero), so that the light waves are strengthened by overlapping the peaks and valleys, and the camera 5 captures a bright image.

  On the other hand, FIGS. 7E and 8E show the polarization state after passing through the analyzer 9 when the polarizer 21 and the analyzer 9 are arranged in a parallel Nicol positional relationship. As can be seen from FIGS. 7 (e) and 8 (e), the two lights are combined and weakened to become weakly polarized light in the direction of the polarization axis of the analyzer 9.

  For example, at the time when the wave of light is a mountain, that is, at time t2 indicating the position where the amplitude is maximum, the object 6 is synthesized as light that vibrates in a direction inclined 45 degrees from both the X-axis direction and the Y-axis direction. In the case of being flat, the phase difference between the two lights to be synthesized is 180 degrees, so that they cancel each other out at the peaks and troughs of the light waves. Therefore, the light intensity reaching the camera 5 is almost 0 (zero), and is captured as a dark image.

  When performing normal observation, the differential interference DIC prism 15 is not originally required. FIG. 9 is a schematic diagram showing the configuration of the optical system of the lens module when performing normal observation while suppressing flare. As shown in FIG. 9, the polarizer 21 is arranged as a polarizer in the coaxial incident illumination unit 2, and the illumination light emitted from the light source 3 becomes linearly polarized light (referred to as S-polarized light). In FIG. 9, the light is linearly polarized in a direction perpendicular to the paper surface.

  The illumination light that has become linearly polarized light is guided to the objective lens 4 by a half mirror (light transmitting member) 8. A part of the S-polarized light is reflected by the objective lens 4 and proceeds in the direction of the camera 5 having the light receiving element as it is. In other words, this light is unnecessary light 10 that causes flare. The rest passes through the objective lens 4 and is reflected by the object 6, and the reflected light 11 passes again through the objective lens 4 and travels toward the camera 5 having the light receiving element.

  A λ / 4 wavelength plate (polarization conversion member) 7 is disposed between the objective lens 4 and the object 6 with respect to the direction of S-polarized light so that the high-speed axis forms an angle of approximately 45 degrees with the polarization axis direction of the polarizer. , The S-polarized light that has passed through the λ / 4 wavelength plate 7 becomes circularly polarized light. When circularly polarized light is reflected by the object 6, the polarization state is maintained when the surface of the object 6 has a mirror shape or a shape similar thereto, but the direction of rotation with respect to the traveling direction of the circularly polarized light is reversed.

  When the circularly polarized light passes through the λ / 4 wavelength plate 7 disposed between the objective lens 4 and the object 6 again, it becomes linearly polarized light whose polarization axis direction is orthogonal to that at the time of incidence (referred to as P-polarized light). In FIG. 9, the light is linearly polarized in the direction parallel to the paper surface, that is, in the direction of the arrow. The unnecessary light 10 reflected by the objective lens 4 and traveling in the direction of the camera 5 having the light receiving element is S-polarized light, and the reflected light 11 from the object 6 is P-polarized light, so that both can be easily distinguished. .

  When the analyzer 9 is arranged between the objective lens 4 and the camera 5 as an analyzer so that the polarizer 21 of the coaxial incident illumination unit 2 and the crossed Nicols whose polarization axes are orthogonal to each other, the analyzer 9 only emits P-polarized light. Let it pass. By disposing the analyzer 9, almost all unnecessary light (S-polarized light) 10 reflected by the objective lens 4 is blocked, and almost all reflected light (P-polarized light) 11 from the object 6 passes. By doing in this way, the influence by the flare resulting from coaxial epi-illumination can be suppressed.

  Moreover, when the surface of the target object 6 is not a mirror surface, the polarization state of illumination light is not maintained, but becomes random polarization (similar to not being polarized). Even after the random polarized light passes through the λ / 4 wave plate 7 again, it is also random polarized light. When the random polarized light from the object 6 reaches the analyzer 9, half of the light is blocked, but the other half passes. Since unnecessary light (S-polarized light) 10 reflected by the objective lens 4 is blocked by at least 99% by the analyzer 9, S / N even when the reflected light 11 from the object 6 is halved by the analyzer 9. The ratio can be kept high enough. Therefore, even if the surface of the object 6 is not mirror-like, the influence of flare can be suppressed.

  FIG. 10 is a comparative view showing an image obtained by imaging the surface of the object 6 under different conditions. In FIG. 10A, the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a crossed Nicols positional relationship, and in the direction of S polarization, that is, the polarization axis direction of the polarizer 21. On the other hand, it is an image taken when the high-speed axis of the λ / 4 wavelength plate 7 is arranged at an angle of 45 degrees. A fine portion of the surface of the object 6 can be imaged.

  On the other hand, in FIG. 10B, the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a crossed Nicol positional relationship, and the direction of S-polarized light, that is, the polarizer 21 is arranged. This is an image picked up when the high-speed axis of the λ / 4 wavelength plate 7 is arranged at an angle of 90 degrees with respect to the polarization axis. Since flare and reflected light 11 from the object 6 are blocked, nothing is imaged.

  FIG. 10C shows the polarization axis of the polarizer 21 so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a parallel Nicol positional relationship, and the direction of S polarization, that is, the polarization axis of the polarizer 21. Is an image taken when the high-speed axis of the λ / 4 wavelength plate 7 is arranged at an angle of 45 degrees. Only the reflected light 11 from the object 6 is blocked, and only the flare is imaged.

  Further, FIG. 10D shows that the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a parallel Nicol positional relationship, and the direction of S polarization, that is, the polarization axis of the polarizer 21. Is an image captured when the high-speed axis of the λ / 4 wavelength plate 7 is arranged at an angle of 90 degrees. Since the flare is superimposed on the reflected light 11 from the object 6, the surface of the object 6 cannot be clearly imaged.

  Therefore, the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a crossed Nicols position, and the λ / 4 wavelength with respect to the direction of S polarization, that is, the polarization axis of the polarizer 21. It is necessary to arrange and image so that the high-speed axis of the plate 7 forms an angle of 45 degrees.

  On the other hand, when the DIC prism 15 for differential interference is arranged to perform differential interference observation, the polarization axis of the polarizer 21 is set so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a crossed Nicols positional relationship. FIG. 8 (d) also shows the arrangement of the S-polarized light, that is, the image where the high-speed axis of the λ / 4 wave plate 7 forms an angle of 45 degrees with respect to the polarization axis of the polarizer 21. As described above, when the object 6 is flat, the phase difference between the two lights to be combined is 0 (zero), so that the peaks and valleys of the light waves overlap and strengthen each other. Is imaged. Although the background is bright and fine uneven portions are imaged dark, the contrast is not so high on the captured image. Therefore, it becomes difficult to use for differential interference.

  Therefore, as shown in FIG. 8E, the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 have a parallel Nicol positional relationship as in the present embodiment. As described above, when the object 6 is flat, the phase difference between the two lights to be combined is 180 degrees, so that the peaks and troughs of the light waves cancel each other. Since the background is dark and fine uneven portions are imaged brightly, an image with high contrast is easily acquired even on the captured image. Therefore, it can be detected without missing a phase shift due to a slight step, and can be used for differential interference.

  FIG. 11 is a comparative view showing an image obtained by imaging the surface of the object 6 having a step gauge (a member having a step shape with a predetermined pattern on the surface) under different conditions. In FIG. 11A, the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a crossed Nicols positional relationship, and the direction of S polarization, that is, the polarization axis of the polarizer 21 is arranged. This is an image taken when the high-speed axis of the λ / 4 wavelength plate 7 is arranged at an angle of 45 degrees. The background (flat part) is bright because it is strengthened by light interference. The phase of the edge portion of the step is out of phase and the image is taken darker than the surroundings, but the contrast with the brightness of the background is low, and the image is difficult to distinguish between the edge portion of the step and the other portions.

  On the other hand, in FIG. 11B, the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a crossed Nicols positional relationship, and the direction of the S-polarized light, that is, the polarizer 21. This is an image picked up when the high-speed axis of the λ / 4 wavelength plate 7 is arranged at an angle of 90 degrees with respect to the polarization axis. Since the light combining by the differential interference DIC prism 15 is not performed well, there is no interference of light, and a double image is formed and the step portion is not clear.

  FIG. 11C shows the polarization axis of the polarizer 21 so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a parallel Nicol positional relationship, and the direction of S polarization, that is, the polarization axis of the polarizer 21. Is an image taken when the high-speed axis of the λ / 4 wavelength plate 7 is arranged at an angle of 45 degrees. Light interference occurs, and the background (flat part) is weakened by the interference and is dark. At the edge of the step, the phase shifts and the condition for weakening is weakened, so it looks bright. Bright and fine information in a dark background has a high contrast and is easy to recognize as an image captured by a camera (or eyes). Therefore, the image can clearly distinguish the edge portion of the step from the other portion.

  Further, FIG. 11D shows that the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a parallel Nicol positional relationship, and the direction of S polarization, that is, the polarization axis of the polarizer 21. Is an image captured when the high-speed axis of the λ / 4 wavelength plate 7 is arranged at an angle of 90 degrees. Similarly to FIG. 11B, since the light is not successfully combined by the differential interference DIC prism 15, no light interference occurs, and the double image is formed and the step portion is not clear.

  Accordingly, the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a parallel Nicol positional relationship, and the λ / 4 wavelength with respect to the direction of S polarization, that is, the polarization axis of the polarizer 21. By arranging and imaging so that the high-speed axis of the plate 7 forms an angle of 45 degrees, even a slight step can be reliably detected.

  The high-speed axis of the λ / 4 wavelength plate 7 is inclined by approximately 45 degrees with respect to the polarization axis direction of the polarizer 21, but the angle of inclination is preferably around 45 degrees. This is because, when the angle changes and the degree of interference of light fluctuates, there is a large difference in the results in differential interference observation.

  FIG. 12 is an exemplary diagram illustrating a difference between images captured in normal observation and differential interference observation according to an angle at which the high-speed axis of the λ / 4 wavelength plate 7 is tilted. In FIG. 12A, the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 have a crossed Nicols positional relationship, and the direction of S polarization, that is, the polarization axis of the polarizer 21 is shown. This is an image obtained by imaging the surface of the object 6 when the λ / 4 wavelength plate 7 is arranged so that the high-speed axis forms an angle of 45 degrees. The flare is properly blocked, and a fine portion of the surface of the object 6 can be imaged.

  FIG. 12B shows the arrangement of the polarization axis of the polarizer 21 such that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a crossed Nicols positional relationship, and a λ / 4 wavelength plate with respect to the polarization axis of the polarizer 21. 7 is an image obtained by imaging the surface of the object 6 by normal observation when the high-speed axis 7 is arranged at an angle of approximately 55 degrees. If the high-speed axis of the λ / 4 wavelength plate 7 is tilted by about 10 degrees larger than 45 degrees, a large difference in the image cannot be recognized as compared with the case of tilting 45 degrees.

  Therefore, it can be seen that in normal observation, even if the angle of the high-speed axis of the λ / 4 wave plate 7 with respect to the polarization axis of the polarizer 21 is slightly deviated from around 45 degrees, there is no significant effect.

  FIG. 12C shows the polarization axis of the polarizer 21 so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a parallel Nicol positional relationship, and a λ / 4 wavelength plate with respect to the polarization axis of the polarizer 21. 7 is an image obtained by imaging the surface of an object 6 having a step gauge by differential interference observation when the high-speed axis 7 is arranged at an angle of 45 degrees. Similarly to FIG. 11C, light interference occurs, the degree of interference due to the phase shift fluctuates at the edge portion of the step, and the edge portion of the step and the other portion can be clearly distinguished.

  On the other hand, in FIG. 12D, the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a parallel Nicol positional relationship, and λ / 4 with respect to the polarization axis of the polarizer 21. It is the image which imaged the surface of the target object 6 which has a level | step difference gauge, when arrange | positioning so that the high-speed axis | shaft of the wave plate 7 may make an angle of about 55 degree | times. Unlike FIG. 11 (c), the slight interference between the λ / 4 wavelength plate 7 causes the light interference degree to fluctuate greatly, and the distinction between the edge portion of the step and the other portion is reduced in contrast. It is difficult to see.

  Therefore, it can be seen that, when differential interference observation is performed, the deviation of the angle of the high-speed axis of the λ / 4 wavelength plate 7 with respect to the polarization axis of the polarizer 21 has a great influence.

  FIG. 13 is a graph for explaining a change in luminance according to the inclination angle of the high-speed axis of the λ / 4 wavelength plate 7 with respect to the polarization axis of the polarizer 21 in the lens module 1 according to the embodiment of the present invention. FIG. 13A shows a case where the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a crossed Nicols positional relationship, and FIG. 13B shows the polarization of the polarizer 21. The case where the polarization axis of the polarizer 21 is arranged so that the axis and the polarization axis of the analyzer 9 are in a parallel Nicol positional relationship is shown.

  When the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a crossed Nicols positional relationship, the high-speed axis of the λ / 4 wavelength plate 7 is substantially the same as the polarization axis of the polarizer 21. When arranged at an angle of 45 degrees, the luminance 132 of reflected light from the object 6 has a maximum value X1, and the luminance 131 of flare light has a minimum value X3. When the high-speed axis of the λ / 4 wave plate 7 is changed to make an angle of about 55 degrees with respect to the polarization axis of the polarizer 21, the brightness 132 of the reflected light from the object 6 decreases to X2, and flare light However, since the decrease in the brightness 132 of the reflected light from the object 6 and the increase in the brightness 131 of the flare light are small, there is a large change in the image captured by the camera 5. It does not occur (see FIGS. 12A and 12B). Therefore, it is difficult to set the λ / 4 wavelength plate 7 to an optimum angle only from the captured image.

  On the other hand, when the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a parallel Nicol positional relationship, the λ / 4 wavelength plate 7 of the polarizer 21 with respect to the polarization axis of the polarizer 21 is arranged. When the high-speed axis is arranged at an angle of about 45 degrees, the luminance 133 of the differential interference image of the flat portion of the target object 6 captured by the camera 5 is the minimum value Y1. When the high-speed axis of the λ / 4 wave plate 7 is changed to make an angle of approximately 55 degrees with respect to the polarization axis of the polarizer 21, the luminance 133 of the interference image increases at a stretch to Y2, and the captured image suddenly increases. (See FIGS. 12C and 12D). Therefore, for example, when the lens module 1 is manufactured or maintained, it is easy to set the λ / 4 wavelength plate 7 to an optimum angle while viewing the captured image.

  FIG. 14 is a perspective view showing the configuration of the lens stand 62 of the magnification observation apparatus using the lens module 1 according to the embodiment of the present invention. FIG. 14 illustrates the lens module 1 to which the camera 5 is already connected. In FIG. 14, the coaxial epi-illumination unit 2 of the lens module 1 is not shown, and the external appearance of the lens module 1 is conceptually shown unlike FIGS. The lens stand 62 has a rotating support column 81 attached so that the lens module 1 can be moved up and down, and a rotating mechanism that supports the rotating support column 81 so as to be able to rotate around a horizontal rotation axis. 82, a fixed support 83 on which the rotation mechanism 82 is provided above, a base 84 on which the fixed support 83 is erected, and the fixed support 83 or the base 84, on which the object 6 is placed. The stage 61 to be provided.

  The stage 61 is, for example, an XY-θ (rotation) stage, and is fixed to the fixed support 83 with a set screw or the like, for example. The rotation mechanism 82 enables the rotation column 81 to rotate about a horizontal rotation axis. Thereby, the angle which images the target object 6 mounted on the stage 61 can be changed.

  Hereinafter, the configuration of the lens stand 62 will be specifically described. At one end on the base 84 of the lens stand 62, a fixed support column 83 having rigidity and a support table 91 provided so as to be fitted to the front surface of the fixed support column 83 are attached. The fixed support 83 supports the lens module 1, and the support base 91 supports the stage 61 on which the object 6 is placed.

  The fixed column 83 includes a rotation mechanism 82 at the top. A rotation shaft is engaged with the hole of the rotation mechanism 82. Thereby, the rotation support | pillar 81 can be rotated (inclined) around a horizontal axis. A slider 92 that can slide in the Z-axis direction is attached to the rotating support column 81. A camera mounting portion 93 is fixed to the slider 92. The lens module 1 is attached to the camera attachment portion 93 along the Z-axis direction.

  On the other hand, when the user operates the adjustment knob 94, the stage 61 is set at a predetermined position in the Z-axis direction. That is, the height of the upper surface of the stage 61 is set to match the height of the rotation shaft of the rotation column 81 when viewed from the X-axis direction.

  A method for inclining the rotating column 81 of the lens stand 62 will be described. FIG. 14 shows a state in which the rotating column 81 of the lens stand 62 is fixed along the Z axis without being inclined. On the other hand, FIG. 15 is a schematic view showing a state in which the rotation support 81 of the lens stand 62 is inclined at a desired angle. By using the stand device having the configuration as shown in FIG. 14, the vertical height of the slider 92 and the vertical height of the stage 61 are adjusted even when observing the object 6 having different heights. Thus, the focal position of the camera 5 connected to the lens module 1 and the observation point of the object 6 can be matched.

  FIG. 16 is an exemplary view when imaging is performed with the rotation support 81 of the lens stand 62 tilted. FIG. 16A is an illustration of an image obtained by imaging the object 6 when the up-down direction imaged by the camera 5 is the depth direction of FIG. From left to right, when the lens module 1 is tilted leftward by tilting the rotation support column 81, when standing upright, when tilting rightward, images taken at respective positions are shown.

  On the other hand, FIG. 16B is an illustration of an image obtained by capturing the object 6 when the up-down direction captured by the camera 5 is the direction in which the lens module 1 in FIG. 15 is inclined. From left to right, when the lens module 1 is tilted leftward by tilting the rotation support column 81, when standing upright, when tilting rightward, images taken at respective positions are shown. Compared to FIG. 16 (a), the object 6 can be imaged from an angle different by 90 degrees, and the imaging position can be changed according to the user's needs.

  FIG. 16C is an illustration of an image obtained by capturing the object 6 when the stage 61 is also rotated 90 degrees with respect to FIG. From left to right, when the lens module 1 is tilted leftward by tilting the rotation support column 81, when standing upright, when tilting rightward, images taken at respective positions are shown. Compared to FIG. 16A, the object 6 can be imaged from a different angle, and the imaging position can be changed according to the user's needs.

  As described above, according to the present embodiment, when differential interference observation is performed, the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 have a parallel Nicol positional relationship, The interference DIC prism 15 is arranged so that the two polarization axis directions orthogonal to each other are approximately 45 degrees with respect to the polarization axis direction of the polarizer 21, and the λ / 4 wavelength plate 7 is placed on the high-speed axis. Or it arrange | positions so that a low-speed axis may be about 45 degree | times with the polarization-axis direction of the polarizer 21. FIG. By configuring the optical system in this way, the light reflected by the flat portion of the object 6 cancels each other when passing through the analyzer 9, so that the original purpose of differential interference observation such as recognition of minute defects can be achieved. Easier to achieve. That is, in the case where differential interference observation is performed even though the low-magnification objective lens 4 and the λ / 4 wavelength plate 7 are mounted on the lens module 1 as in the case of normal observation, a flat portion without defects. Since an observation image that darkens and an uneven portion with defects becomes bright can be acquired, a minute defect can be detected more reliably.

  When performing normal observation, the polarization axis of the polarizer 21 is arranged so that the polarization axis of the polarizer 21 and the polarization axis of the analyzer 9 are in a crossed Nicols positional relationship, and the differential interference DIC prism 15 is removed. It is possible to perform normal observation without flare.

  The present invention is not limited to the above-described embodiments, and various changes and improvements can be made within the scope of the present invention. For example, the high-speed axis of the λ / 4 wave plate 7 is arranged so as to be approximately 45 degrees with the polarization axis direction of the polarizer 21, but the low-speed axis is arranged so as to be approximately 45 degrees with the polarization axis direction of the polarizer 21. Needless to say.

  In FIG. 5, the λ / 4 wavelength plate 7 is shown slightly tilted with respect to the optical axis, but the inclination of the λ / 4 wavelength plate 7 should be larger than the NA (numerical aperture) of the objective lens 4. Is preferred. Since the objective lens 4 guides light within the NA range to the camera 5, the direct reflected light directly reflected by the λ / 4 wavelength plate 7 reaches the camera 5 by tilting the λ / 4 wavelength plate 7 slightly. No worries. However, if it is tilted too much, the distance between the objective lens 4 and the object 6 is shortened and the usability is deteriorated.

DESCRIPTION OF SYMBOLS 1 Lens module 2 Coaxial epi-illumination unit 3 Light source 4 Objective lens 5 Camera 6 Target object 7 (lambda) / 4 wavelength plate (polarization conversion member)
8 Half mirror (light transmission member)
9 Analyzer (analyzer)
15 DIC prism for differential interference (birefringent optical member)
21 Polarizer
61 stage (mounting part)
81 Rotating strut 82 Rotating mechanism 83 Fixed strut 84 Base

Claims (6)

A polarizer that polarizes light from the light source;
A light transmissive member that reflects a part of the light that has passed through the polarizer, guides it to the object along the light receiving axis direction of the camera that can be coupled, and transmits a part of the reflected light from the object; ,
A birefringent optical member capable of separating and detaching the light reflected by the light transmitting member into light of two polarization axis directions orthogonal to each other and having no phase difference ; and
An objective lens that condenses the light that has passed through the birefringent optical member and irradiates the object;
A polarization conversion member that converts the polarization state of the light that has passed through the objective lens;
An analyzer that polarizes part of the reflected light from the object that has passed through the light transmitting member;
The polarizer and the analyzer, Yes disposed so that the polarization axes direction is flat line to each other,
The birefringent optical member relative to the polarization axis of the polarizer, Yes in the two directions of the polarization axes are disposed so that both 4 5 degrees,
Lens module, wherein the polarization conversion member, which has a fast axis or slow axis, any of the axes are arranged such that the polarization axis direction and 4 5 ° of the polarizer. The analyzer is fixed;
Said birefringent optical element, said two polarization axes directions perpendicular to each other, the relative polarization axis of the analyzer with 4 5 degrees to become the birefringent optical element a first that can be inserted as An opening,
Polarization axis direction with each other on a flat Komata polarization axis direction of the polarizer the analyzer and further comprising a second opening capable of inserting the polarizer such that vertically into The lens module according to claim 1.   The lens module according to claim 2, wherein the polarizer inserted into the second opening is capable of changing an angle of a polarization axis.   The lens module according to any one of claims 1 to 3, wherein the polarization conversion member is disposed between the objective lens and an object. The lens module according to any one of claims 1 to 4,
A rotating column that is mounted so that the lens module can be moved up and down;
A rotation mechanism that supports the rotation column so that the rotation column can be rotated around a horizontal rotation axis;
A fixed support column in which the rotation mechanism is provided above;
A base on which the fixed column is erected;
A magnifying observation apparatus, comprising: a mounting portion that is provided on the fixed column or the base and on which an object is mounted. A polarizer that polarizes light from the light source;
A light transmissive member that reflects a part of the light that has passed through the polarizer, guides it to the object along the light receiving axis direction of the camera that can be coupled, and transmits a part of the reflected light from the object; ,
A birefringent optical member capable of separating and detaching the light reflected by the light transmitting member into light of two polarization axis directions orthogonal to each other and having no phase difference ; and
An objective lens that condenses the light that has passed through the birefringent optical member and irradiates the object;
A polarization conversion member that converts the polarization state of the light that has passed through the objective lens;
A magnification observation method for magnifying and observing using a lens module having an analyzer that polarizes part of reflected light from the object that has passed through the light transmitting member,
Wherein the polarizer and the analyzer, the polarization axis direction can switch whether a or vertical a flat line to each other,
It said birefringent optical element, with respect to the polarization axis of the polarizer, arranged said as two directions of the polarization axes is 4 5 times none,
Wherein the polarizer and the analyzer, when the polarization axis direction is disposed such that the flat line with each other, the polarization conversion member, the polarization axis direction of any axis is the polarizer having a fast axis or slow axis And an enlarged observation method characterized by being arranged so as to be 45 degrees.