WO2007026791A1

WO2007026791A1 - Polarization compensation optical system

Info

Publication number: WO2007026791A1
Application number: PCT/JP2006/317153
Authority: WO
Inventors: Kumiko Matsui
Original assignee: Nikon Corporation
Priority date: 2005-08-29
Filing date: 2006-08-24
Publication date: 2007-03-08

Abstract

A polarization compensation optical system includes a polarization compensation optical element capable of accurately compensating a rotation and phase difference of the polarization direction of the polarization optical system even when an Objective lens is exchanged. The polarization compensation optical system includes: an illumination optical system having a polarizer (P) and applying an illumination light to an object via the polarizer; and an image formation optical system for forming an image by converging light from the object and passing it through an analyzer (A). Polarization compensation optical elements (C1, C2) for compensating the ration and phase difference of the polarization direction caused by the optical element arranged between the polarizer (P) and the analyzer (A) are arranged between the polarizer (P) and the object (4) or between the object (4) and the analyzer (A).

Description

Technical description Polarization compensation optics Technical field

The present invention relates to a polarization compensation optical system that uses polarized light. Background art

In a microscope optical system that uses linearly polarized light, the polarization direction of the linearly polarized light rotates and becomes elliptically polarized by the action of various coatings applied to the lens refractive surfaces and lenses that make up the microscope optical system. The contrast of the obtained image has the problem that the S / N deteriorates. This problem is particularly noticeable when the number of refractive surfaces of the lens is large, the refractive power of the refractive surface is strong, or the antireflection film applied to the refractive surface is multilayered. This is a problem with high NA objective lenses. In order to solve these problems, polarization-compensating optics that compensates for elliptical polarization of linearly polarized light by combining a lens with zero refractive power and a 1 Z 2 wavelength phase plate that has almost the same polarization characteristics as a microscope optical system. Devices are known (see, for example, Japanese Examined Patent Publication No. 3 7 1 5 7 8 2).

However, in the disclosed example of Japanese Examined Patent Publication No. 3 7-5 7 8 2, it is necessary to accurately arrange one or more bulky elements at predetermined positions in the optical path of the microscope. It is not easy to exchange the polarization compensation optical element by changing the lens. In addition, the polarization compensation optical element must be fixed, and as a result, when a specific objective lens is used, the polarization direction rotation and elliptical polarization caused by the microscope optical system can be compensated. In the case of replacement, there is a problem that the contrast and S / N of the obtained image are not sufficient due to insufficient compensation. Disclosure of the invention

The present invention has been made in view of the above problems, and a polarization compensation optical system including a polarization compensation optical element capable of highly accurately compensating for the rotation of the polarization direction and the phase difference of the polarization optical system even when the objective lens is replaced. The purpose is to provide.

In order to solve the above-described problem, a first aspect of the present invention includes a polarizer, an illumination optical system that irradiates illumination light to the object through the polarizer, and collects light from the object. A polarization optical system that forms an image through the analyzer and compensates for the rotation of the polarization direction and the phase difference generated by the optical element disposed between the polarizer and the analyzer. A polarization compensation optical system is provided, wherein an compensation optical element is disposed between at least one of the polarizer and the object, or between the object and the analyzer. In addition, the second aspect of the present invention includes a polarizer, an illumination optical system that irradiates an object with illumination light that has passed through the polarizer, and the light from the object is condensed. An imaging optical system that passes through the deflection element and forms an image through the analyzer, and rotates in the polarization direction generated by the optical element disposed between the polarizer and the analyzer. And a polarization compensation optical element that compensates for the phase difference is disposed between at least one of the polarizer and the deflection element or between the deflection element and the analyzer. provide.

The third aspect of the present invention includes an illumination optical system that irradiates an object with polarized light as illumination light, and a condensing optical system that collects light from the object via an analyzer, An optical element from the object of the collecting optical system to the analyzer, and a polarization compensating optical element that compensates for a rotation and a phase difference of a polarization direction generated by the optical element of the illumination optical system, the illumination optical system or the object And a polarization compensation optical system, wherein the polarization compensation optical system is disposed in at least one of the analyzer and the analyzer.

According to the present invention, it is possible to provide a polarization compensation optical system including a polarization compensation optical element capable of compensating for the rotation of the polarization direction and the phase difference of the polarization optical system with high accuracy even when the objective lens is replaced. Brief Description of Drawings

FIG. 1 is a schematic configuration diagram of a transmission illumination type polarization microscope which is a polarization compensation optical system according to the first embodiment of the present invention.

2A and 2B are a schematic diagram showing rotation of the polarization direction in the optical system and a schematic diagram showing ovalization, respectively.

3A and 3B schematically show examples of the configuration of the polarization compensating optical element, FIG. 3A is a schematic diagram of an example of a split type phase plate, and FIG. 3B is a schematic diagram of an example of a gradient phase plate. It is.

FIGS. 4A-4C are schematic views showing the effects of the first configuration method of the structural birefringent member. FIGS. 5A-5C are schematic views showing the effects of the second configuration method of the structural birefringent member. FIG. 6 is a schematic configuration diagram showing a modification of the first embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a polarization compensation optical system (an epi-illumination polarization microscope) according to the second embodiment of the present invention.

FIG. 8 is a schematic configuration diagram of a modified example of the second embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)

FIG. 1 is a schematic configuration diagram of a polarization compensation optical system according to a first embodiment of the present invention. In this first embodiment, a transmission illumination type polarization microscope is taken as a representative example of a polarization compensation optical system, and a polarization compensation optical system that compensates for the rotation of the polarization direction and the phase difference generated in the optical system is described. To do.

In FIG. 1, illumination light from a light source 1 is collected by a collector lens 2 and then illuminates a specimen 4 placed on a slide glass (not shown) via a condenser lens 3. The light from the illuminated specimen 4 is collected by the objective lens 5, A magnified image 6 is formed. The observer observes the magnified image 6 with the naked eye through an eyepiece (not shown). A polarizer P is disposed in the optical path between the collector lens 2 and the condenser lens 3, and an analyzer A is disposed in the optical path between the objective lens 5 and the magnified image 6. The polarizer P and the analyzer A are generally arranged so that their transmission directions are orthogonal to each other (arrangement of crossed Nicols). The illumination light for illuminating the object is not limited to the polarized light transmitted through the polarizer P, but may be polarized light generated by reflecting the polarizer, or a laser light source that directly generates polarized light from the light source.

In such a configuration, if the specimen 4 is not placed on the slide glass, the field of view is dark. In this state, for example, when a thin specimen 4 such as a mineral is placed, the tissue structure becomes bright and dark due to the difference in the polarization state of each part of the specimen 4 and is visualized. In such a polarizing microscope, in order to detect a slight change in the polarization state due to the sample and detect it with high accuracy, it is necessary to avoid as much as possible the disturbance of the polarization state that occurs in the optical system other than the sample.

However, there are many optical systems such as condenser lens 3 and objective lens 5 between polarizer Ρ and analyzer 、, and it is assumed that polarizer P and analyzer A are arranged in a crossed nicols. However, the extinction ratio is lowered by the disturbance of the polarization state by the optical system, and the detection capability of the microscope is lowered. This is more noticeable for high-power objective lenses 5. The main causes are the large number of lens refracting surfaces arranged in the objective lens 5, the large refraction angle by the lens surface, and the polarization characteristics such as the antireflection coating applied to the lens surface.

The characteristics of these coats are generally designed to be optimal when light is incident perpendicular to the coat, and when the light passing through the lens has a large angle, such as a high magnification objective lens 5 Causes rotation of the polarization direction as shown in Fig. 2A in regions other than the X-axis and y-axis (when incident light is polarized in the y-axis direction). This is because the reflectance of the P-polarized component and the S-polarized component of the incident linearly polarized light differs depending on the incident angle. As a result, the light exiting the lens is converted into the incident linearly polarized light. Rotate against. In addition, when a multilayer antireflection film is frequently used on the lens surface, there is a phase difference between the P-polarized component and the S-polarized component, which not only rotates the linearly polarized light, but also in Fig. 2B. It becomes elliptically polarized light as shown. As shown in Fig. 2A and Fig. 2B, elliptical polarization by rotating the polarization direction and generating a phase difference lowers the extinction ratio of the polarization microscope and lowers the contrast and SZN of the image.

Therefore, in the polarization compensation optical system (transmission illumination type polarization microscope) according to the first embodiment, the condenser 3 of the illumination optical system in FIG. 1 is used for the purpose of compensating for the rotation of the polarization direction and the phase difference caused by the optical system. A polarization compensation optical element C 1 is inserted near the front focal plane to compensate for the rotation of the polarization direction and the phase difference caused by the optical system between the polarizer P and the condenser lens 3. In addition, the polarization compensation optical element C 2 compensates for the rotation and phase difference of the polarization direction caused by the optical system between the objective lens 5 and the analyzer A in the optical path between the objective lens 5 and the analyzer A of the imaging optical system. It is configured by inserting.

As shown in FIG. 3A, the polarization compensation optical elements C 1 and C 2 divide the effective diameter of the optical system in the circumferential direction and the radial direction, and divide the respective divided regions (for example, 1 a ~ Lh, 2a ~ 2h) is a so-called split type phase plate in which phase plates corresponding to the rotation of the polarization direction and the phase difference are arranged. The axis of each phase plate in the split phase plate (fast axis or slow axis) is arranged in different directions depending on the characteristics of the optical system. 3A and 3B illustrate the polarization compensation optical systems C 1 and C 2 in the same drawing. However, the phase difference of the phase plate and the direction of the axis of the phase plate are shown in FIG. It differs depending on the characteristics of the optical system in which 1 and C 2 are inserted.

Assuming that the phase difference between the phase plates 1 a to lh and 2 a to 2 h of the phase compensation optical element C 1 that is a split type phase plate is δ 1 a to 3 1 h and δ 2 a to d 2 h The phase difference between the light beams passing through each of the divided regions is the rotation and position of the polarization direction caused by the optical elements from the polarizer P to the condenser lens 3 except for the phase compensation optical element C 1 in FIG. Designed to compensate for all phase differences. Similarly, the divided regions la to lh and 2a to 2h of the phase compensation optical element C2, which is a split type phase plate, are used. If the phase difference of each phase plate is (5 1 a to (? 1 h, (5 2 a to 3 2 h), the phase difference is It is designed to compensate for all rotations and phase differences in the polarization direction caused by the optical elements from the objective lens 5 except the phase compensation optical element C 2 to the analyzer A.

Note that the number of divisions and the shape of the polarization compensating optical elements C 1 and C 2 are not limited to those shown in FIG. 3A, and any number of divisions and shapes can be used. It is also possible to provide a region that does not give a phase difference to a part of the divided region, that is, has no effect as a phase plate.

In addition, the polarization compensation optical elements C 1 and C 2 can be composed of gradient phase plates. Here, the gradient phase plate means that the effective diameter of the optical system is divided like the split type phase plate in FIG. 3A, and the phase difference δ 1 a to δ 1 h and δ 2 a to Instead of adding <5 2 h, the phase difference within the effective diameter of the optical system and the axial direction are gradually changed as shown in Fig. 3B so as not to have the boundary of the segmented area like the segmented phase plate. It is a thing. In the split phase plate in Fig. 3A, the polarization in the split region is compensated on the average by the representative value in that region, whereas in the case of the radial phase plate in Fig. 3B, the arbitrary phase within the effective diameter is set. On the other hand, it is possible to optimally compensate for rotations and phase differences in slightly different polarization directions at all coordinate points.

As a result, the light beam that has passed through the optical system of the transmission illumination type polarization microscope shown in FIG. 1 (with no specimen placed) has a polarization direction rotation or phase difference depending on the polarization characteristics of the optical system. Since it is compensated by l, and C 2, a high extinction ratio can be secured, and a magnified image 6 with good contrast can be formed when the specimen 4 is observed.

The polarization compensation optical elements C1 and C2 can be formed of a structural birefringent optical member, a resin phase plate, or a photonic crystal.

A structural birefringent optical member uses the fact that a grating with a sufficiently smaller pitch than the wavelength acts as a phase plate or a polarizing plate. By changing the grating pitch, etc. Arbitrary phase difference and phase axis can be given. A divided phase plate as shown in FIG. 3A can be realized by changing the lattice direction, pitch, etc. for each of the divided regions 1 a to lh and 2 a to 2 h in FIG. 3A. In addition, as shown in FIG. 3B, a gradient phase plate can be realized by changing the grating direction pitch so that the phase axis and the phase difference within the effective diameter of the optical system gradually change.

In addition, a normal resin phase plate uses a resin birefringence to provide a phase axis and phase difference. By joining resin phase plates with different phase axes and phase differences, Fig. 3A A split type phase plate as shown can be realized. In addition, with resin, it is possible to continuously vary the phase axis and phase difference with a single resin phase plate by controlling the tensile stress in each direction when creating the resin phase plate. The gradient phase plate shown in Fig. 3B can be realized.

Photonic crystals are optical functional crystals with a three-dimensional structure. By changing the three-dimensional structural parameters, it is possible to create arbitrary optical characteristics such as phase difference and phase axis. When making a split phase plate as shown in Fig. 3A using this photonic crystal, it is possible to make a phase plate with a wide-band wavelength characteristic because of the high degree of design freedom. Effective for color observation optical system with white light source. Further, as shown in Fig. 3B, a gradient phase plate can be realized by changing the parameters of the three-dimensional structure so that the phase axis and the phase difference within the effective diameter of the optical system gradually change.

Since the polarization compensation optical elements C 1 and C 2 have the same action and effect on the optical system, the polarization compensation optical element C 1 will be described as a representative.

The polarization compensation optical element C 1 will be described in detail with respect to the rotation of the polarization direction and the compensation of the phase difference in the case where the polarization compensation optical element C 1 is composed of a structural birefringence optical member. There are two ways to construct the polarization compensation optical element C 1 with a structural birefringent optical member.

"First Configuration Method"

The first configuration method consists of one-side structural birefringence with compensation for rotation in the polarization direction and compensation for phase difference. This is achieved with an optical member. In Figure 4A-4C, the incident linearly polarized light polarized in the y-axis direction becomes elliptically polarized due to the rotation of the polarization direction generated in the optical system and the phase difference <5, and the state shown by the ellipse in Figure 4A Become. At this time, a rectangle ABCD circumscribing the ellipse is drawn. This rectangle ABCD is selected so that the diagonal corner AC exists on the y-axis. Then, the direction 0 of the fast axis (y ′ axis in the figure) of the structural birefringent optical member is selected so that A x ′ / A y ′ = tan S.

As shown in Fig. 4B, when light passes through a structural birefringent optical member formed so as to compensate for the phase difference δ, the elliptical light is converted into linearly polarized light M whose polarization direction is the direction of the arrow. The Furthermore, as shown in Fig. 4C, by adding the characteristics of a 1 Z 2 wavelength phase plate (giving a phase difference π) to the structural birefringent optical member, the linearly polarized light が is given a phase difference of π and Converted. As a result, the linearly polarized light Ν is polarized in the same y-axis direction as the incident linearly polarized light. In this way, by forming the structural birefringent optical member so as to give phase differences δ and π, the light elliptically polarized in the optical system (Fig. 4 Α) is converted into the original incident linearly polarized light (Fig. 4C) It becomes possible to return.

This first configuration method can be achieved by configuring a single structural birefringent optical member to compensate for a phase difference obtained by adding two types of phase differences δ and 7 及び.

"Second Configuration Method"

The second construction method is a method comprising at least two (front and back) structural birefringent optical members. In Fig. 5 Α-5C, the incident linearly polarized light polarized in the y-axis direction is the polarization direction rotation and phase difference generated in the optical system (elliptical polarization by 5 and the state shown by the ellipse in Fig. 5A. The angle formed by the axis of the original linearly polarized light (y axis) and the long axis of the elliptically polarized light (fast axis: y ′ axis) is 0. Here, the first structural birefringent optical member has a phase difference of π / If it is configured to give 2, elliptically polarized light that has passed through the first structural birefringent optical member is converted to linearly polarized light 角度 having an angle with respect to the y ′ axis. When the orientation of the fast axis (y '' axis) of the second structural birefringent optical component is set to 0 '= (θ + α) / 2 and the phase difference π is given, the second Transmitted through the birefringent member Light with linearly polarized light ○ is converted into light with linearly polarized light P parallel to the y-axis, and can be returned to the direction of incident linearly polarized light.

As described above, the first structural birefringent optical member has a characteristic that gives a phase difference of π （2 (that is, the same characteristic as a quarter-wave phase plate). By adopting a structure that gives a phase difference of 7 mm (that is, the same characteristics as a 1 Z 2 wavelength phase plate), the light that has been ellipticalized by the optical system can be returned to the original incident linearly polarized light. The second configuration method is characterized by being easy to manufacture because it can compensate for the rotation of the polarization direction and the phase difference by combining the 1/4 wavelength plate and 1/2 wavelength plate. Have.

In FIG. 1, the polarization compensating optical elements C 1 and C 2 can be arranged at arbitrary positions in the respective optical systems. However, in the illumination optical system, the pupil position of the illumination optical system (that is, It is desirable to place it near the front focal plane of condenser lens 3. Also, in the imaging optical system, it can be placed near the rear focal plane of the objective lens 5. However, if the polarization compensation optical element C2 is a split type phase plate, the structure near the boundary of the split region gives the imaging performance. It is necessary to consider aberration deterioration.

In addition, since the polarization compensation optical element of the present embodiment has a parallel plate-like thin plate shape, the polarization compensation optical element can be easily inserted into and removed from the optical path. For example, the polarization compensation optical element can be easily replaced even when the lens is changed during magnification switching. be able to. In addition, since it is not necessary to incorporate the lens system, a normal lens can be used as it is.

In both the first and second configuration methods, the required phase difference can be configured by superimposing a plurality of structural birefringent optical members and the like. That is, when the phase difference in region 2 a in Fig. 3 とする is δ 2 a,

6 2 a = 5 2 al + (5 2 a 2 + 5 2 a 3 +-· + + δ 2 a (n-1) + δ 2 an This can be realized by superposing n divided structural birefringent optical members having respective phase differences so that the total becomes δ 2 a, provided that the phase of the n structural birefringent optical members is the same. All axes are in the same direction is there. The same applies to a gradient phase plate as well as a split phase plate. The above configuration is not limited to the structural birefringent optical member, and a resin phase plate or a photonic crystal can also be used.

(Modification of the first embodiment)

FIG. 6 shows a modification of the first embodiment of the present invention. This modification is an example in which one polarization compensation optical element is used in the transmission illumination type polarization microscope of FIG. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

In FIG. 6, the polarization compensation optical element C is arranged in the illumination optical system in the transmission illumination type polarization microscope. The polarization compensating optical element C is disposed near the front focal plane of the condenser lens 3. The polarization compensating optical element C has a characteristic for compensating for the rotation of the polarization direction and the phase difference of the entire optical system in a state where the sample 4 is excluded. With this configuration, a single polarization compensation optical element C can be used to compensate for the rotation and phase difference in the polarization direction of the entire optical system. Note that the polarization compensation optical element C can use either the first method or the second method of forming the structural birefringent optical member. Resin phase plates and photonic crystals can also be used in the same manner. The illumination light for illuminating the object is not limited to the polarized light transmitted through the polarizer P, but may be polarized light generated by reflecting the polarizer, or a laser light source that directly generates polarized light from the light source.

(Second embodiment)

FIG. 7 is a schematic configuration diagram of a polarization compensating optical system according to the second embodiment of the present invention. In the present second embodiment, an epi-illumination polarization microscope will be taken up, and a polarization compensation optical system that compensates for the rotation of the polarization direction and the phase difference generated in the optical system will be described.

In FIG. 7, the illumination light from the light source 1 1 is collected by the collector lens 1 2 and then passes through the polarizer P and the polarization compensation optical element C 1 and enters the beam splitter BS. 5 illuminates the specimen 14 placed on the glass slide (not shown) through the objective lens 15. The light from the illuminated specimen 1 4 It is condensed by the object lens 15 to form an enlarged image 16. The observer observes the magnified image 16 with the naked eye through an eyepiece (not shown). A polarization compensation optical element C 2 and an analyzer A are arranged in the optical path between the objective lens 15 and the magnified image 16, respectively. The polarizer P and the analyzer A are generally arranged so that their transmission directions are orthogonal to each other (that is, the crossed Nicols arrangement). The illumination light for illuminating the object is not limited to the polarized light transmitted through the polarizer P, but may be polarized light generated by reflecting the polarizer, or a laser light source that directly generates polarized light from the light source.

As the polarization compensation optical elements C 1 and C 2, either the first configuration method or the second configuration method of the structural birefringence optical member similar to the first embodiment can be used. Resin phase plates and photonic crystals can also be used in the same way. In this way, an epi-illumination polarization microscope is constructed. The operation and effect are the same as those in the first embodiment, and a description thereof will be omitted.

(Modification of the second embodiment)

FIG. 8 shows a modification of the second embodiment of the present invention. This modification is an example in which one polarization compensation optical element is used in the incident-light illumination type polarization microscope of FIG. The same components as those of the second embodiment are denoted by the same reference numerals and the description thereof is omitted. '

In FIG. 8, the polarization compensation optical element C is arranged in the illumination optical system in the epi-illumination polarization microscope. The polarization compensating optical element C is disposed between the polarizer P and the beam splitter BS. The polarization compensating optical element C has a characteristic for compensating for the rotation and phase difference of the polarization direction of the entire optical system of the epi-illumination polarization microscope in the state excluding the specimen 14. With this configuration, it is possible to compensate for the rotation and the phase difference of the polarization direction of the optical system with a single polarization compensation optical element C. The polarization compensating optical element C can use either the first configuration method or the second configuration method of the structural birefringent optical member. Resin phase plates and photonic crystals can also be used in the same manner. The polarization compensation optical element C can be placed anywhere on the polarizer P and the analyzer A. However, as shown in Fig. 8, the illumination optics PI

Positioning between the 12-system polarizer P and the beam splitter B S is desirable because it can reduce the effect on the imaging performance of the coupling part of the split phase plate. The illumination light for illuminating the object is not limited to the polarized light transmitted through the polarizer P, but may be polarized light generated by reflecting the polarizer, or a laser light source that directly generates polarized light from the light source.

In the above-described embodiment, the case where the present invention is applied to a typical polarizing microscope optical system has been described. However, the present invention is not limited to this, and any optical system using polarized light, such as an ellipsometer or differential interference microscope, It is possible to compensate for the polarization characteristics of the optical system itself. Further, the above-described embodiment is merely an example, and is not limited to the above-described configuration and shape, and can be appropriately modified and changed within the scope of the present invention. '

Claims

I

13 Scope of request l. Illumination optical system for irradiating an object with illumination light through a polarizer;

An imaging optical system that collects light from the object and forms an image via an analyzer; and is disposed between at least one of the polarizer and the object or between the object and the analyzer, A polarization compensation optical system comprising a polarization compensation optical element for compensating for a rotation and a phase difference of a polarization direction generated by an optical element disposed between a polarizer and the analyzer.

2. An illumination optical system that irradiates an object with illumination light via a polarizer via a deflection element, and imaging optics that collects the light from the object and forms an image via the deflection element and an analyzer. The system,

Polarized light generated by an optical element disposed between the polarizer and the deflector or at least one between the deflector and the analyzer, and disposed between the polarizer and the analyzer. A polarization compensation optical system comprising: a polarization compensation optical element that compensates for direction rotation and phase difference.

3. an illumination optical system that illuminates the object with polarized illumination light;

A condensing optical system for condensing light from the object via an analyzer;

Polarization direction generated by the optical element from the object to the analyzer of the condensing optical system and the optical element of the illumination optical system, disposed in at least one of the illumination optical system or the object and the analyzer A polarization compensation optical system comprising: a polarization compensation optical element that compensates for the rotation and phase difference. 4. The polarization-compensating optical element is at least one divisional phase plate formed by arranging each phase axis of a plurality of regions having different phase differences in a predetermined direction. P

14. The polarization compensation optical system according to claim 1, wherein

5. The polarization compensating optical system according to claim 4, wherein the phase plate is formed of a structural birefringent optical member.

6. The polarization compensation optical system according to claim 4, wherein the phase plate is formed of a photonic crystal.

7. The polarization compensating optical element is formed by arranging and connecting the respective phase axes of the plurality of 1 Z 4 wavelength plates corresponding to the plurality of regions having different phase differences in a predetermined direction. The first divided-type phase plate formed and the phase axes of the plurality of half-wave plates corresponding to the plurality of regions having different phase differences are arranged and bonded in a predetermined direction. 4. The polarization compensation optical system according to claim 1, wherein the polarization compensation optical system is formed of a plurality of layers including a second divided phase plate formed in the above manner. 5.

8. The polarization compensating optical system according to claim 7, wherein the 1 Z 4 wavelength plate and the 1/2 wavelength plate are formed of a structural birefringent optical member.

9. The polarization compensation optical system according to claim 7, wherein the 1 Z 4 wavelength plate and the 12 wavelength plate are formed of a photonic crystal.

The polarization compensation optical system according to any one of claims 1 to 3, wherein the polarization compensation optical element is at least one gradient phase plate.

11. The polarization compensating optical system according to claim 10, wherein the gradient phase plate is formed of a structural birefringent optical member.

12. The polarization compensating optical system according to claim 10, wherein the gradient phase plate is formed of a photonic crystal.

1 3. The effective diameter is divided into a plurality of regions in the circumferential direction and the radial direction, each divided region has a phase axis in a different direction toward a predetermined direction, and at least 1 so as to give a different phase difference. A polarization-compensating optical element that compensates for the rotation of the polarization direction and the phase difference, characterized in that a phase plate made of layer members is disposed.

14. The phase plate is a first divided type phase formed by arranging and joining the respective phase axes of a plurality of quarter wavelength plates corresponding to the respective divided regions in a predetermined direction. And a second divided type phase plate formed by arranging and joining the respective phase axes of the plurality of 1 Z 2 wavelength plates corresponding to the respective divided regions in a predetermined direction. The polarization compensating optical element according to claim 13, wherein the polarization compensating optical element is formed of a plurality of layers.

15. The polarization compensating optical element according to claim 14, wherein the phase plate, the 1/4 wavelength plate, and the 1/2 wavelength plate are formed of a structural birefringence optical member.

16. The polarization-compensating optical element according to claim 14, wherein the phase plate, the 1-wave plate, and the 12-wave plate are formed of a photonic crystal.

17. The polarization compensating optical element according to claim 13, wherein the phase plate is formed of a structural birefringent optical member.

18. The polarization compensating optical element according to claim 13, wherein the phase plate is made of a photonic crystal.

1 9. A gradient phase plate composed of at least one layer member formed so that the phase axis and the phase difference within the effective diameter gradually change in a predetermined direction in the radial direction and the circumferential direction. A polarization-compensating optical element that compensates for the rotation and phase difference of the polarization direction.

20. The polarization compensating optical element according to claim 19, wherein the gradient phase plate is formed of a structural birefringent optical member.

21. The polarization compensating optical element according to claim 19, wherein the gradient phase plate is formed of a photonic crystal.