JPWO2008010316A1 - Polarizer and microscope using the polarizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel polarizer that is not affected by polarization state conversion derived from a lens or the like (deletion) when used in a polarization microscope, not a linear polarizer, and a novel polarization An object of the present invention is to provide a polarizing microscope that ideally blocks light when a sample having no polarization conversion effect is observed. The above problem is unavoidable when the lens is composed of a curved surface that is rotationally symmetric with respect to the optical axis, whereas the polarization axis is linear. Therefore, the above problem can be fundamentally solved by using a polarizer having a transmission axis that is rotationally symmetric with respect to the optical axis as in the case of the lens. That is, the above-mentioned problem can be solved by making the polarizer used in the polarizing microscope a polarizer having a concentric transmission axis or a polarizer having a radial transmission axis. [Selection] Figure 6

Description

  The present invention relates to a polarizer and a microscope using the polarizer. More specifically, the present invention uses a polarizer designed to have a concentric transmission axis, a polarizer designed to have a transmission axis radially, and a combination of such polarizers. This is related to a microscope that can effectively extract and observe only the components.

  A polarizer is an element having an action of transmitting only a polarized component along the transmission axis of incident light, and is widely used for measuring a polarization state, a microscope using polarized light, sunglasses, and the like (for example, Patent 3486355). Issue no.). A normal polarizer has a unidirectional transmission axis indicated by a straight line and a unidirectional blocking axis perpendicular thereto.

  A polarizing microscope is used for the purpose of observing an observation object composed of a transparent substance, for example, a living cell under a microscope. This uses the refractive index change or birefringence of the object to be observed, and is used when it is desired to observe living cells without staining. In this polarization microscope, a polarizer for irradiating an observation target with polarized light and a polarizer (analyzer) for adjusting the brightness of an observation image according to the direction of polarization are generally used. For example, when the polarization axes of the irradiation-side polarizer and the observation-side polarizer are orthogonal to each other, only the portion having the polarization conversion effect to be observed is observed brightly. Based on such a principle, a polarizing microscope may be able to observe the internal structure of a transparent body that cannot normally be seen. A polarizing microscope having such a characteristic has conventionally been used with a polarizer having a transmission axis that is linearly unidirectional.

  For example, Japanese Patent No. 2828451 (Patent Document 1) states that “a cold mirror film that reflects infrared rays of incident light and transmits visible light is coated on one surface of the glass substrate, and the incident non-polarized light is applied. A polarizer comprising: a polarizing beam splitter film that divides the light beam into two linearly polarized light beams whose polarization planes are orthogonal to each other, and is coated on the other surface of the glass substrate (Claim 8). And a polarizing microscope using the polarizer is disclosed. Again, in the polarizing microscope disclosed in the above document, it is intended to use one or a plurality of polarizers having a linear polarization axis.

  However, when a polarizer having a linear polarization axis is used for the irradiation side polarizer and the observation side polarizer, the objective lens has a curved surface, so that the polarization state of the light is changed by the objective lens. After all, there was a problem that even if there was no observation sample, it could not be completely darkened. In particular, in a polarizing microscope using an objective lens having a high magnification, there is a problem that the above-described polarization conversion occurs remarkably. That is, it has been difficult to achieve a high extinction ratio with a polarization microscope using a polarizer having a linear polarization axis as in the prior art.

  The polarization rotation phenomenon associated with the lens transmission described above is that the transmittance on an inclined surface that is not perpendicular to the traveling direction of light differs between a p-wave whose incident surface is parallel to the vibration direction of the electric field and an s-wave perpendicular to this. Is one of the causes. In addition, a deviation in phase between the p wave and the s wave caused by a multilayer film such as an antireflection film provided on the lens surface also causes a change in the polarization state. By generating different transmittance and phase difference between the p-wave and s-wave on the lens surface in this way, light containing both wave components changes from linearly polarized light to elliptically polarized light, and the principal axis direction rotates. End up. For this reason, for example, when the irradiation-side polarizer and the observation-side polarizer are used with their transmission axes orthogonal to each other, even a portion where the observation sample does not exist cannot be made a completely dark portion. There is a problem in that the detection of the weak polarization conversion effect resulting from this is obstructed.

Furthermore, in the polarization observation using the linearly polarized light as the irradiation light, the optical characteristics of the observation sample having an optical anisotropy axis in the direction parallel and perpendicular to the irradiated polarization axis could not be observed. For this reason, when performing polarization observation, it is often the case that samples are evaluated by comparing multiple observation results set in at least two directions of the polarization direction of the irradiated light. It contributed to the increase of the process.
Japanese Patent No. 2828451

  The present invention uses a polarizer having a rotationally symmetric polarization axis instead of a linear polarization axis, so that when used in a polarization microscope, the present invention is affected by the deviation of the polarization plane derived from a lens or the like. An object of the present invention is to provide a novel polarizer that is difficult.

  An object of the present invention is to provide a polarizing microscope that uses a novel polarizer and blocks light with a high extinction ratio when there is no sample.

  An object of this invention is to provide the polarization microscope which can acquire the observation image without direction dependence by one observation.

  An object of the present invention is to provide a polarizing microscope capable of effectively observing minute defects, scratches, fiber structures, and the like.

  The first aspect of the present invention basically provides a polarizer having a concentric or radial transmission axis, not a polarizer having parallel polarization planes. Basically, these polarizers are polarized light using an irradiation side polarizer and an observation side polarizer having a concentric transmission axis or a radial transmission axis (and thus a blocking axis being concentric). Useful for microscopes. That is, in a polarizing microscope, a local disturbance (polarization conversion) of the polarization state occurs due to a lens such as an objective lens. Of course, in a microscope other than the polarization microscope, local disturbance of the polarization state does not cause any problem, and even in the polarization microscope, the light due to the polarization state conversion by the lens is small. However, when observing a sample with a slight polarization conversion effect, such as when using a polarizing microscope to observe a biological sample, the polarization conversion effect of the slight lens itself affects the detection limit of weak signal light. . In the present invention, basically, the irradiation-side polarizer and the observation-side polarizer each have a concentric transmission axis or a radial transmission axis (and therefore a blocking axis is concentric). The microscope is basically an axially symmetric optical system, apart from causes that can eliminate the assembly error and the photoelastic effect due to the residual stress of the lens. In such a system, light having concentric polarization is not converted into light having radial polarization when passing through a lens or space, and vice versa, so if the polarizer of the present invention is used, the lens A polarizing microscope that is not affected by the above can be obtained.

That is, the 1st side surface of this invention is related with the polarizer by which a transmission axis is provided concentrically. A preferred embodiment of the first aspect of the present invention is the polarizer according to the above, wherein a plurality of the transmission axes are provided concentrically from one center. Such a polarizer may be manufactured by, for example, a self-cloning method using a substrate having a plurality of concavities and convexities on the surface. That is, for example, the layers constituting the polarizer have a plurality of concentric periodic structures, and such layers may be formed in multiple layers. Further, the polarizer provided with the transmission axes concentrically may be a polarizer having a layer in which a radial periodic structure is formed in multiple stages from the center to the outer edge. A preferred embodiment of the first aspect of the present invention relates to the polarizer described in any one of the above, which is constituted by a self-cloning photonic crystal. As a specific example of a polarizer having transmission axes concentrically arranged, a SiO ₂ layer having a concentric periodic structure composed of a self-cloning photonic crystal composed of a plurality of layers, each layer having a period of 232 nm. The thickness of the layer is 58 nm, the thickness of the Ta ₂ O ₅ layer is 81 nm, 40 layers of SiO ₂ layers and Ta ₂ O ₅ layers are alternately stacked, and the input light having a wavelength of 520 nm or more and 540 nm or less is Examples thereof include a polarizer that transmits polarized light having an electric field component parallel to the tangent line of the circumference of each concentric circle. As another specific example of the polarizer having transmission axes concentrically arranged, the polarizer is composed of a self-cloning photonic crystal composed of a plurality of layers, has a radial periodic structure, and has a substrate pitch of 245 nm and SiO 2 ₂ is 145 nm, Ta ₂ O ₅ is 125 nm, and there are 27 layers of polarizers.

The aspect different from the above of the first aspect of the present invention relates to a polarizer in which the transmission axis is provided radially from one point (therefore, the cutoff axis is concentric). A preferred embodiment of this embodiment has a layer in which a radial periodic structure is formed in multiple stages from the center to the outer edge, and further relates to the polarizer described above which is constituted by a self-cloning photonic crystal. More specifically, the layers constituting the polarizer have a periodic structure, and in order to keep the interval between the periodically formed periodic structures within a certain range, the radiating periodicity is formed in multiple stages from the center to the outer edge. Examples include a structure formed. More specifically, a polarizer having a transmission axis radially provided from one point is composed of a self-cloning photonic crystal composed of a plurality of layers, and each layer has a radial periodic structure with a period of 232 nm. , SiO ₂ layer thickness is 58 nm, Ta ₂ O ₅ layer thickness is 81 nm, 40 layers of SiO ₂ layers and Ta ₂ O ₅ layers are alternately stacked, and the input light has a wavelength of 520 nm or more and 540 nm or less On the other hand, there is a polarizer that transmits polarized light having an electric field component perpendicular to the tangent of the circumference of each concentric circle. As a polarizer having a transmission axis that is radially provided from one point, it is composed of a self-cloning photonic crystal composed of a plurality of layers, has a concentric periodic structure from the center, a substrate pitch of 245 nm, and SiO ₂ of 145 nm. , Ta ₂ O ₅ is 125 nm and there are 27 layers of polarizers.

  According to a second aspect of the present invention, there is provided a light source; a first polarizer that transmits light from the light source, a transmission axis that is provided concentrically with the optical axis as a center; and transmission through the first polarizer. An observation sample stage on which a sample irradiated with the irradiated light is mounted; an objective lens through which light transmitted through the sample mounted on the observation sample stage or light reflected from the sample mounted on the observation sample stage transmits; The present invention relates to a polarizing microscope including: a second polarizer that transmits light that has passed through the objective lens, and whose transmission axis is provided radially about the optical axis. The “second polarizer in which the transmission axis is provided radially from the optical axis” is preferably the polarizer described above in which the transmission axis is provided radially from the center of the polarizer. That is, the above-described polarizer can be used as appropriate as the first polarizer and the second polarizer.

  That is, in the conventional polarizing microscope, a polarizer having a linear polarization axis is used, so that a high extinction ratio cannot be obtained due to the influence of the lens. In the polarizing microscope of the present invention, a polarizer having a transmission axis concentrically provided and a polarizer having a transmission axis provided radially around the optical axis are used in combination. The extinction ratio can be obtained.

  Another aspect of the second aspect of the present invention is a light source; a first polarizer that transmits light from the light source and that has a transmission axis radially formed around the optical axis; and the first An observation sample stage on which the sample irradiated with the light transmitted through the polarizer is irradiated; light transmitted through the sample mounted on the observation sample stage or light reflected from the sample mounted on the observation sample stage is transmitted , An objective lens; and a second polarizer that transmits light transmitted through the objective lens and has a transmission axis provided concentrically around the optical axis.

  The aspect different from the above of the second aspect of the present invention is the light source; the light from the light source is transmitted; the transmission axis is provided radially around the optical axis or concentrically centered around the optical axis. 1 polarizer; an observation sample stage on which a sample irradiated with light transmitted through the first polarizer is mounted; light transmitted through a sample mounted on the observation sample stage, or mounted on the observation sample stage An objective lens that transmits light reflected from the sample to be transmitted; an optical rotator that transmits light transmitted through the objective lens; an optical rotator that orthogonally crosses the polarization principal axis direction; and a first polarized light that transmits light transmitted through the optical rotator And a second polarizer having a transmission axis similar to that of the polarizer.

  That is, by providing the optical rotator, the plane of polarization is shifted by 90 degrees, so that the function of the polarizing microscope described above can be achieved by one type (preferably one) polarizer. That is, “a second polarizer having a transmission axis similar to that of the first polarizer” means, for example, a polarizer in which the first polarizer is provided concentrically with the transmission axis being centered on the optical axis. In this case, the polarizers may be exactly the same polarizers, or the transmission axes may be provided concentrically around the optical axis, and the first polarizers may be provided radially around the optical axis. In the case of a polarizer, the polarizers may be exactly the same or may be polarizers whose transmission axes are provided radially around the optical axis.

  The aspect different from the above of the second aspect of the present invention is the light source; the light from the light source is transmitted; the transmission axis is provided radially around the optical axis or concentrically centered around the optical axis. A polarizer of 1; an optical rotator that transmits light transmitted through the first polarizer, an orthogonal polarization axis direction; an observation sample stage that mounts a sample irradiated with light transmitted through the optical rotator; An objective lens through which light transmitted through the sample mounted on the observation sample stage or light reflected from the sample mounted on the observation sample stage transmits; first polarized light through which light transmitted through the optical rotator transmits; And a second polarizer having a transmission axis similar to that of the polarizer.

  In a preferred aspect of the polarizing microscope according to the second aspect of the present invention, a condensing lens for condensing light from the light source is provided between the light source and the first polarizer; The child is disposed between the light source and the observation sample and is disposed at a pupil position of the condenser lens; the second polarizer is disposed at a pupil position of the objective lens; This relates to a polarizing microscope.

  In the polarizing microscope of the present invention according to this aspect, the linearly polarized light in all directions is equal by disposing a polarizer having a rotationally symmetric polarization axis at the pupil position of the condenser lens and the objective lens, or at a position conjugate with them. Since the mixed light is incident on the sample, an observation image having no direction dependency can be acquired by one observation. In this polarizing microscope, when the sample surface is a transparent body, the light passing through one point of the concentric circular polarizer arranged at the front stage of the observation sample is reflected by the radial polarizer arranged at the rear stage of the observation sample. It is blocked by gathering at one corresponding point. On the other hand, when the observation sample has a non-uniform component, more components are transmitted according to the heterogeneity. Therefore, as the inhomogeneous point in the observation sample is smaller, the transmittance tends to increase, and an observation image in which high-frequency components are emphasized as a whole can be obtained. Therefore, the polarizing microscope according to this aspect is suitable for observing minute defects, scratches, fibrous structures, and the like.

  The microscope according to the third aspect of the present invention includes a polarizer having a concentric transmission axis and a radial polarizer having a transmission axis at the pupil position of the condenser lens and the pupil position of the objective lens. The present invention relates to a microscope characterized in that an image with a higher resolution can be obtained with a more structural body. In other words, this microscope includes, for example, a polarizer having a concentric transmission axis at the pupil position of the condenser lens and a polarizer having a radial transmission axis at the pupil position of the objective lens. Alternatively, this microscope includes, for example, a polarizer having a radial transmission axis at the pupil position of the condenser lens and a polarizer having a concentric transmission axis at the pupil position of the objective lens. As demonstrated by the examples described later, the pupil position of the condenser lens and the pupil position of the objective lens have either a concentric polarizer with a transmission axis and a polarizer with a radial transmission axis. The higher the resolution, the higher the resolution. In addition, as a microscope of this aspect, the configuration of a normal microscope can be appropriately adopted as the configuration other than the polarizer.

  According to the present invention, it is possible to provide a novel polarizer in which the transmission axis is not concentric, or the transmission axis is radial (and thus the cutoff axis is concentric), instead of a polarizer having parallel polarization planes. They can be effectively used in the above-described polarizing microscope and the like.

  According to the present invention, the irradiation-side polarizer and the observation-side polarizer each have a concentric transmission axis or a radial transmission axis (thus, the blocking axis is concentric), so that an objective lens, etc. It is possible to provide a polarizing microscope that is not affected by the distortion of the polarization plane caused by the lens and that blocks light when there is no sample.

  According to the present invention, it is possible to provide a polarization microscope capable of acquiring an observation image having no direction dependency by one observation.

  According to the present invention, it is possible to provide a polarization microscope that can effectively observe minute defects, scratches, fibrous structures, and the like.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing the direction of the transmission axis in a polarizer in which transmission axes are provided concentrically. As shown in FIG. 1, the first aspect of the present invention relates to a polarizer in which transmission axes are provided concentrically. Such a polarizer may be manufactured by, for example, a self-cloning method using a substrate having a plurality of concavities and convexities on the surface. That is, for example, the layers constituting the polarizer have a plurality of concentric periodic structures, and such layers may be formed in multiple layers. FIG. 2 is a diagram showing the direction of the transmission axis in a polarizer in which the transmission axis is provided radially from one point. As shown in FIG. 2, in a polarizer in which the transmission axis is provided radially from one point, the transmission axis is provided radially at a ratio equal to the transmission axis from one point (preferably the center of gravity of the polarizer). Since the transmission axis and the blocking axis are orthogonal, the blocking axis of such a polarizer is concentric.

  FIG. 3 shows a schematic diagram of a polarizer having a transmission axis in a concentric or radial manner by a self-cloning photonic crystal. FIG. 3A shows an example of a polarizer in which transmission axes are provided concentrically. FIG. 3B shows an example of a polarizer in which the transmission axis is provided radially from one point. FIG. 3C shows an example of a polarizer having a layer in which radial periodic structures are formed in multiple stages. FIG. 4 is a diagram illustrating an example of a self-cloning photonic crystal. As shown in FIG. 4, a self-cloning photonic crystal is generally formed by stacking a large number of layers having a specific periodic structure, and electric field oscillations in a direction parallel to a surface irregularity groove and a direction perpendicular thereto, respectively. Different transmission characteristics can be designed for polarized light having For example, as shown in FIG. 4, polarized light having electric field vibration parallel to the groove can be reflected and polarized light having electric field vibration perpendicular to the groove can be transmitted. Further, by adjusting the pitch of the unevenness and the film thickness of the multilayer film, it is possible to transmit only the polarized light having the electric field vibration parallel to the groove, contrary to FIG. Therefore, according to the self-cloning method, a polarizer having a shape as shown in FIGS. 3A and 3B can be manufactured.

  The one shown in FIG. 3 (c) is designed so that the radial periodic structure is divided into three stages so that the center to the outer edge are divided into three equal parts, but the polarizer of the present invention is limited to this. It may be two steps or four steps or more. In a preferred embodiment of such a polarizer, the layers constituting the polarizer have a periodic structure, and the periodic structure of the radial type is formed in a multi-stage for the purpose of keeping the interval between the radially formed periodic structures within a certain range. Is formed. The size of the polarizer is not particularly limited, but is preferably a size that can be used as a lens for a polarizing microscope.

Examples of the polarizer as described above include, for example, JP-A-10-335758, JP-A-2000-258645, JP-A-2001-74554, JP-A-2001-249235, and JP-A-2004-45779. It can be made as appropriate using the manufacturing technique disclosed in. A desirable method for producing self-cloning photonic crystals is described below. Quartz is used as the substrate material, and periodic irregularities with a pitch of about half the operating wavelength are formed using a photolithography process. A photonic crystal can be obtained by forming a film using a sputtering apparatus. The material for forming the film can be appropriately selected from materials that can be sputtered, such as SiO ₂ , Nb ₂ O ₅ , or Ta ₂ O ₅ . For example, when self-cloning a multilayer film using SiO ₂ and Nb ₂ O ₅ , a voltage is applied at a gas pressure of about 0.5 Pa while flowing Ar and oxygen gas at a partial pressure of 4: 1 in the film forming apparatus. Application and sputtering may be performed. By applying a substrate bias at the same time, film formation and etching can be performed simultaneously, thereby realizing self-cloning film formation. The power applied to the substrate bias is desirably 10% or less of the film forming power.

As demonstrated by the examples described later, for example, using a quartz substrate, the substrate pitch (one period of unevenness) is 232 nm, the thickness of the SiO ₂ layer is 58 nm, and the thickness of the Ta ₂ O ₅ layer is 81 nm. When 40 layers were laminated, it was possible to obtain a polarizer that transmits only polarized light having an electric field component parallel to the irregularities at a wavelength of 520 to 540 nm (an extinction ratio of 40 dB or more). That is, in this case, when the substrate groove is concentric, a transmission axis having a concentric shape can be obtained. On the other hand, if the substrate groove is radial, the transmission axis can be made radial. For example, even a polarizer having a layer in which a radial periodic structure is formed in multiple stages from the center to the outer edge can be obtained with a radial transmission axis. As described above, the groove provided in the substrate and the polarizer having the transmission axis parallel to each other are appropriately configured based on this embodiment by appropriately changing the groove shape of the substrate, the substrate pitch, the material constituting each layer, the film thickness of each layer, and the like. It can be manufactured by adjusting. The substrate pitch is not particularly limited, but may be appropriately adjusted within about half the wavelength of incident light, for example, in the range of 50 nm to 600 nm, preferably in the range of 100 nm to 500 nm. What is necessary is just to adjust the thickness of each layer which comprises the polarizer which consists of a self-cloning crystal | crystallization suitably from 20 nm or more and 150 nm or less, for example. In addition, each layer is preferably configured such that two different types of layers form one pair and a plurality of such pairs are stacked. Examples of the number of such pairs (number of layers) include 10 to 200 layers, and may be 20 to 100 layers.

On the other hand, as demonstrated in the examples to be described later, even when the same material is used, when the substrate pitch is 245 nm, SiO ₂ is 145 nm, Ta ₂ O ₅ is 125 nm, and each has 27 layers, the wavelength is 520 to 550 nm, and it is perpendicular to the unevenness. Obtains a polarizer that transmits only polarized light having an electric field component. In this case, when the substrate groove is concentric, a polarizer having a radial transmission axis is obtained, and when the substrate groove is radial, a transmission axis having a concentric circle is obtained. For example, even a polarizer having a layer in which a radial periodic structure is formed in multiple stages from the center to the outer edge, a transmission axis having a concentric shape can be obtained. In this way, the grooves provided in the substrate and the polarizer whose transmission axes are orthogonal to each other adjust the groove shape of the substrate, the substrate pitch, the material constituting each layer, the film thickness of each layer, etc., as appropriate based on this embodiment. Can be manufactured. The substrate pitch is not particularly limited, but may be appropriately adjusted within about half the wavelength of incident light, for example, in the range of 50 nm to 600 nm, preferably in the range of 100 nm to 500 nm. What is necessary is just to adjust the thickness of each layer which comprises the polarizer which consists of a self-cloning crystal | crystallization suitably from 20 nm or more and 150 nm or less, for example. In addition, each layer is preferably configured such that two different types of layers form one pair and a plurality of such pairs are stacked. Examples of the number of such pairs (number of layers) include 10 to 200 layers, and may be 20 to 100 layers.

  In addition to the self-cloning photonic crystal, for example, a polarizer having a transmission axis radially can be realized by a wire grid polarizer having a shape as shown in FIG. FIG. 5 is a schematic diagram of a wire grid type polarizer. However, the self-cloning photonic crystal is preferable because it can be manufactured with high accuracy and can exhibit the polarization adjustment function.

  Next, a polarizing microscope according to the second aspect of the present invention will be described. According to a second aspect of the present invention, there is provided a light source; a first polarizer that transmits light from the light source, a transmission axis that is provided concentrically with the optical axis as a center; and transmission through the first polarizer. An observation sample stage on which a sample irradiated with the irradiated light is mounted; an objective lens through which light transmitted through the sample mounted on the observation sample stage or light reflected from the sample mounted on the observation sample stage transmits; The present invention relates to a polarizing microscope including: a second polarizer that transmits light that has passed through the objective lens and that has a transmission axis that is provided radially around the optical axis. The optical axis means an axis through which light passes in a polarizing microscope. In the polarizing microscope of the present invention, a polarizer having a transmission axis concentrically provided and a polarizer having a transmission axis provided radially around the optical axis are used in combination. An extinction ratio can be obtained.

  Another aspect of the second aspect of the present invention is a light source; a first polarizer that transmits light from the light source and that has a transmission axis radially formed around the optical axis; and the first An observation sample stage on which the sample irradiated with the light transmitted through the polarizer is irradiated; light transmitted through the sample mounted on the observation sample stage or light reflected from the sample mounted on the observation sample stage is transmitted , An objective lens; and a second polarizer that transmits light transmitted through the objective lens and has a transmission axis provided concentrically around the optical axis. When light from the light source passes through the first polarizer, the plane of polarization is adjusted. The light transmitted through the first polarizer is irradiated onto the sample on the observation sample stage. The light transmitted through the observation sample or the light reflected from the observation sample passes through the objective lens. The light that has passed through the objective lens passes through the second polarizer. And the light which permeate | transmitted the 2nd polarizer will be observed through an objective lens etc. suitably.

  FIG. 6 shows an apparatus configuration example of a polarizing microscope. In the microscope (11) of FIG. 6, the light collected and horizontally output by the condenser lens (13) in the lamp house (12) is bent upward by the mirror (14) at the bottom of the microscope, and the irradiation side polarizer. (15), condenser lens (16), observation sample (17), objective lens (18), observation side polarizer (analyzer) (19) are passed in this order. Then, an image is obtained through the eyepiece lens (20). This microscope has a transmissive configuration. One of the irradiation side polarizer (15) and the observation side polarizer (analyzer) (19) is a polarizer having a concentric transmission axis as shown in FIG. 1, and the rest are as shown in FIG. It is a polarizer having a radial transmission axis. 3A, FIG. 3B, and FIG. 3C are schematic views in the case where a polarizer having a transmission axis in a concentric or radial manner is realized by a self-cloning photonic crystal polarizer. As shown. In the irradiation side polarizer (15), when the light having a predetermined transmission pattern reaches the observation side polarizer without adjusting the polarization plane, the observation side polarizer (analyzer) (19 ) Will be blocked. However, only the component whose polarization plane is shifted by the observation sample (17) is observed. Of course, a microscope having a configuration other than that shown in FIG. 6 such as a reflection type may be used. A highly sensitive polarization microscope that is not affected by the polarization conversion by the lens is provided by providing a polarizer with transmission axes arranged concentrically or radially at the position of the irradiation side polarizer and the observation side polarizer in FIG. can do.

  FIG. 7 is a diagram showing an example of a polarization microscope in which an optical rotator composed of a crystal rotator or a liquid crystal is inserted between an irradiation side polarizer and an observation side polarizer. As shown in FIG. 7, by inserting an optical rotator composed of a crystal rotator or a liquid crystal between the irradiation side polarizer and the observation side polarizer, the extinction state between the two polarizers can be reduced to some extent. The amount of light transmitted through the observation side polarizer can be relaxed and contribute to preliminary positioning for observation.

  FIG. 8 is a diagram illustrating an example of a polarization microscope in which an optical rotator (Faraday element) using a Faraday effect is provided between an irradiation side polarizer and an observation side polarizer. As shown in FIG. 8, the irradiation-side polarizer and the observation-side polarizer can be shared by one polarizer (22) through the Faraday element (21). As described above, for example, when a polarizer having a concentric transmission axis is used as the irradiation side polarizer, the light transmitted through the sample surface without the observation sample reaches the observation side polarizer without being converted in polarization state. Therefore, it can be blocked by a polarizer having a transmission axis radially. As the optical rotator of the present invention, any known optical rotator can be used as long as it has a function of orthogonally crossing the polarization main axis direction. 283635, Toshiaki Sugawara, “Lightwave Optics”, Corona, 1998, p. 223), and those having such functions and composed of crystal or liquid crystal. That is, the polarizing microscope of the embodiment shown in FIG. 8 includes a light source; a first polarizer that transmits light from the light source and whose transmission axis is provided radially or concentrically; and transmits the first polarizer. An observation sample stage on which a sample irradiated with the irradiated light is mounted; an objective lens through which light transmitted through the sample mounted on the observation sample stage or light reflected from the sample mounted on the observation sample stage transmits; An optical rotator that transmits light transmitted through the objective lens and that has orthogonal polarization main axis directions; a second polarizer that transmits the light transmitted through the optical rotator and has a transmission axis similar to that of the first polarizer; A polarizing microscope.

  That is, by providing the optical rotator, the plane of polarization is shifted by 90 degrees, so that the function of the polarizing microscope described above can be achieved by one type (preferably one) polarizer. That is, “a second polarizer having a transmission axis similar to that of the first polarizer” means, for example, a polarizer in which the first polarizer is provided concentrically with the transmission axis being centered on the optical axis. In this case, the polarizers may be exactly the same polarizers, or the transmission axes may be provided concentrically around the optical axis, and the first polarizers may be provided radially around the optical axis. In the case of a polarizer, the polarizers may be exactly the same or may be polarizers whose transmission axes are provided radially around the optical axis. However, the Faraday rotator using magnetism has the property of rotating twice when the light transmitted through the Faraday rotator is reflected and then transmitted again from the opposite side. On the other hand, in the case of an optical rotator made of crystal or liquid crystal, once the optical rotator is transmitted and the optical rotator is transmitted from the opposite side, the optical rotation is canceled because the optical rotation is reversed from that transmitted from the forward side. Disappear. Therefore, when the irradiation light to the sample and the observation light from the sample pass through the same path as in a reflection microscope, it is preferable to use a Faraday rotator using magnetism. On the other hand, any type of optical rotator can be used in a transmission-type polarization microscope in which the paths of irradiation light and observation light are completely separated. That is, it is preferable to use a Faraday rotator in a reflective polarization microscope as shown in FIG.

  Such a polarizing microscope also includes a light source; a first polarizer that transmits light from the light source, and whose transmission axis is provided radially around the optical axis or concentrically around the optical axis; An optical rotator that transmits light transmitted through one polarizer and that has orthogonal polarization principal axis directions; an observation sample stage that mounts a sample irradiated with light transmitted through the optical rotator; and a sample that is mounted on the observation sample stage An objective lens that transmits light transmitted through the observation sample stage or light reflected from a sample mounted on the observation sample stage; and has a transmission axis similar to that of the first polarizer that transmits light transmitted through the optical rotator A polarizing microscope comprising: a second polarizer;

  Hereinafter, it will be described how the light that has passed through the concentric circles or radial polarizers arranged at the pupil position of the condenser lens in front of the sample is subjected to the image plane. A light beam that has passed through the entire surface of the condenser lens pupil position in the same direction is condensed at one point on the image plane. Therefore, the light that illuminates a point on the image plane is a collection of light that has passed through all the surfaces of the concentric or radial polarizers, and is light of any polarization orientation. When no object is present on the image plane, these lights reach radial or concentric polarizers arranged at the pupil position of the objective lens, and these polarizers are transmitted perpendicular to the polarization direction of each light beam. Since it has an axis, all light is blocked.

On the other hand, when a scatterer is present on the sample surface, the light beam that has passed through one point on the condenser lens pupil position has a spread on the pupil plane of the objective lens (that is, the Fourier plane) instead of a single point after entering the scatterer. Form a luminous flux. Hereinafter, in order to consider the case where the sample has birefringence, that is, the light beam that has passed through the sample has a polarization component that is orthogonal to that before passing, the case where the polarization direction does not change before and after passing through the sample Consider two states. All states can be expressed by a combination of these two states.
First, consider the case where the polarization orientation does not change before and after passing through the sample. The component light beam penetrating the sample in a straight line is completely blocked at the point where it reaches the radial or concentric polarizer placed at the pupil position of the objective lens, since the polarization direction and the transmission axis of the polarizer are orthogonal. . However, in addition to the light beam penetrating the sample linearly, diffracted light is generated according to the fineness of the sample, so that the light reaching the objective lens pupil position irradiates a wide area. In a region other than the central portion, the polarization direction of the light beam and the transmission axis are deviated from orthogonal, and a component that is not blocked is generated according to the amount of deviation. Further, the amount of deviation between the polarization direction of the light beam and the orthogonal direction of the polarizer transmission axis increases as the spread of the light beam increases, that is, as the component away from the center of the light beam increases. Furthermore, the spread of the luminous flux increases as the spatial frequency component of the scatterer increases, that is, as the scatterer becomes finer. Therefore, it can be seen that the non-blocking component becomes larger as the sample becomes finer. When the sample is sufficiently fine, that is, when the diffracted light by the sample spreads over the entire objective lens pupil position, the transmittance is 50%. This is shown in FIG. FIG. 9 is a graph showing the relationship between the transmittance and the spatial frequency component of the sample when there is no polarization conversion by the sample.

  Next, consider the case where the polarization orientation changes by 90 degrees before and after passing through the sample. In this case, since the light beam penetrating the sample linearly is polarized light parallel to the transmission axis of the polarizer at the objective lens pupil position, it passes through 100%. As the sample becomes smaller, diffracted light is present around the light beam, so that a component that does not transmit is generated. That is, as the sample is finer, the blocking component increases. When the sample is sufficiently fine, the diffracted light from the sample spreads over the entire objective lens pupil position, so that the transmittance is 50%. This is shown in FIG. FIG. 10 is a graph showing the relationship between the transmittance and the spatial frequency component of the sample when the polarization direction is changed by 90 degrees by the sample.

From the above consideration, when there is nothing on the sample surface, a complete dark part is obtained, and when the object on the sample surface is sufficiently fine, 50% light transmission is possible regardless of whether the object has birefringence or not. On the other hand, if the object is completely uniform, the transmittance corresponding to the birefringence of the object can be obtained. Therefore, an observation image having a sensitivity corresponding to not only the presence / absence of birefringence but also the fineness of the sample can be obtained.

  In a preferred aspect of the polarizing microscope of the present invention, a condensing lens for condensing light from the light source is provided between the light source and the first polarizer; the first polarizer includes the light source and The polarizing microscope according to any one of the above, wherein the second polarizer is disposed at a pupil position of the objective lens between the observation samples and at the pupil position of the condenser lens. In this specification, the “pupil position of the condenser lens” means the focal position of the condenser lens. On the other hand, the “pupil position of the objective lens” means the focal position of the objective lens.

  In the polarizing microscope of the present invention according to this aspect, the linearly polarized light in all directions is equal by disposing a polarizer having a rotationally symmetric polarization axis at the pupil position of the condenser lens and the objective lens, or at a position conjugate with them. Since the mixed light is incident on the sample, an observation image having no direction dependency can be acquired by one observation. In this polarizing microscope, when the sample surface is a transparent body, the light passing through one point of the concentric circular polarizer arranged at the front stage of the observation sample is reflected by the radial polarizer arranged at the rear stage of the observation sample. It is blocked by gathering at one corresponding point. On the other hand, when the observation sample has a non-uniform component, more components are transmitted according to the heterogeneity. Therefore, as the inhomogeneous point in the observation sample is smaller, the transmittance tends to increase, and an observation image in which high-frequency components are emphasized as a whole can be obtained. Therefore, the polarizing microscope according to this aspect is suitable for observing minute defects, scratches, fibrous structures, and the like.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples. In addition, the present invention can be appropriately modified according to known techniques, and known techniques can be incorporated as appropriate.

1. Substrate preparation A substrate for preparing a polarizer was prepared. Specifically, the quartz substrate was subjected to ion beam exposure, and a plurality of rectangular irregularities were provided so as to be concentric. The obtained substrate is shown in FIG. That is, FIG. 11 is a conceptual diagram of the substrate obtained in Example 1. Note that the width of the unevenness may be about half the normal wavelength, and the depth may be about half the wavelength.

Specifically, a self-cloning photonic crystal of SiO ₂ and Ta ₂ O ₅ was prepared using a quartz substrate provided with a plurality of concentric grooves. Forty layers were laminated with a substrate pitch (one period of unevenness) of 232 nm, SiO ₂ of 58 nm, and Ta ₂ O ₅ of 81 nm. In this way, it was possible to obtain a polarizer that transmits only polarized light having an electric field component parallel to the unevenness at a wavelength of 520 to 540 nm (an extinction ratio of 40 dB or more). A polarizer was manufactured using a quartz substrate having a plurality of grooves extending radially from the center of the substrate. This polarizer also had a radial transmission axis.

On the other hand, 27 layers of polarizers each having a substrate pitch of 245 nm, SiO ₂ of 145 nm, and Ta ₂ O ₅ of 125 nm were manufactured using the same material. A polarizer that transmits only polarized light having an electric field component perpendicular to the unevenness at a wavelength of 520 to 550 nm could be obtained. A polarizer having an extinction ratio of 40 dB or more was obtained. When the substrate groove is concentric, a polarizer having a radial transmission axis can be obtained. When the substrate groove having a radial shape is used, a polarizer having a concentric transmission axis can be obtained.

2. Film Formation Process Film formation was performed by the autocloning method using the substrate shown in FIG. Specifically, the substrate shown in FIG. 11 is installed in a sputtering apparatus, and (a) deposition of film-forming particles, (b) plasma etching with Ar ions, and (c) surface constituent particles popped out by etching. By continuing the three phenomena of re-adhesion in a balanced manner at the same time, the outermost surface layer with a stable triangular wave shape was maintained. FIG. 12 is a schematic diagram of an apparatus used for autocloning and a schematic diagram of the autocloning method. Silicon dioxide and tantalum oxide (Ta ₂ O ₅ ) were alternately formed. FIG. 13 shows a conceptual diagram of the obtained polarizer. FIG. 14 shows a photograph replacing the drawing of the obtained polarizer. As shown in FIG. 14, a polarizer was actually obtained based on this method.

3. Characteristic evaluation The characteristic of the obtained polarizer was measured. FIG. 15 is a graph replaced with a drawing showing the spectral characteristic evaluation results of the prototype self-cloning photonic crystal polarizer. In the measurement, a measurement sample having a linear groove formed simultaneously with a substrate having a groove concentrically was used. A TE wave having an electric field vibration component parallel to the concave and convex grooves shows a transmittance of 0.1% or less in a band of 500 nm or less, and a TM wave having an electric field vibration component orthogonal to the concave and convex grooves is 90 in a band of 405 nm or more. % Indicates a high transmittance, and it has a high polarization separation function. It should be noted that the band operating as a polarizer can be variously adjusted by changing the pitch of the concavo-convex grooves or the lamination period of the multilayer film. From the above data, it can be seen that a polarization function having a concentric cut-off axis and a radial transmission axis is realized with a prototype polarizer having concentric grooves.

4). Simulation FIG. 16 shows the result of simulating an image obtained when scatterers of various shapes are arranged on the observation surface with the polarizing microscope of the present invention. FIG. 16A is a diagram showing an image observed with a polarizing microscope for scatterers having the same edge sharpness and different sizes. FIG. 16B is a diagram showing an image observed with a polarization microscope with respect to scatterers having the same size but different edge sharpness. From FIG. 16 (a), it can be seen that the brightness of the obtained image increases as the object becomes smaller if the polarizing microscope of the present invention is used. Moreover, it can be seen from FIG. 16B that the sharper the edge, the higher the luminance of the obtained image.

  The polarizer of the present invention can be widely used not only in a polarizing microscope but also in the optical element industry. On the other hand, the polarizing microscope of the present invention is used effectively as a microscope because it is effectively used for observation of biological samples.

FIG. 1 is a diagram illustrating the direction of the transmission axis in a polarizer in which transmission axes are provided concentrically. FIG. 2 is a diagram showing the direction of the transmission axis in a polarizer in which the transmission axis is provided radially from one point. FIG. 3 shows a schematic diagram of a polarizer having a transmission axis in a concentric or radial manner by a self-cloning photonic crystal. FIG. 3A shows an example of a polarizer in which transmission axes are provided concentrically. FIG. 3B shows an example of a polarizer in which the transmission axis is provided radially from one point. FIG. 3C shows an example of a polarizer in which the transmission axis is provided in multiple stages radially from the center of the polarizer. FIG. 4 is a diagram illustrating an example of a self-cloning photonic crystal. FIG. 5 is a schematic diagram of a wire grid type polarizer. FIG. 6 shows an apparatus configuration example of a polarizing microscope. FIG. 7 is a diagram showing an example of a polarization microscope in which an optical rotator composed of a crystal rotator or a liquid crystal is inserted between an irradiation side polarizer and an observation side polarizer. FIG. 8 is a diagram illustrating an example of a polarization microscope in which an optical rotator (Faraday element) using a Faraday effect is provided between an irradiation side polarizer and an observation side polarizer. FIG. 9 is a graph showing the relationship between the transmittance and the spatial frequency component of the sample when there is no polarization conversion by the sample. FIG. 10 is a graph showing the relationship between the transmittance and the spatial frequency component of the sample when the polarization direction is changed by 90 degrees by the sample. FIG. 11 is a conceptual diagram of a substrate obtained in Example 1. FIG. 12 is a schematic diagram of an apparatus used for autocloning and a schematic diagram of the autocloning method. Silicon dioxide and tantalum oxide (Ta ₂ O ₅ ) were alternately formed. FIG. 13 shows a conceptual diagram of the obtained polarizer. FIG. 14 shows a photograph replacing the drawing of the obtained polarizer. FIG. 15 is a graph replaced with a drawing showing the spectral characteristic evaluation results of the prototype self-cloning photonic crystal polarizer. FIG. 16 shows the result of simulating an image obtained when scatterers having various shapes are arranged on the observation surface in the polarizing microscope of the present invention. FIG. 16A is a diagram showing an image observed with a polarizing microscope for scatterers having the same edge sharpness and different sizes. FIG. 16B is a diagram showing an image observed with a polarization microscope with respect to scatterers having the same size but different edge sharpness.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Polarizing microscope 12 Lamphouse 13 Condensing lens 14 Mirror 15 Irradiation side polarizer 16 Condenser lens 17 Observation sample 18 Objective lens 19 Observation side polarizer (analyzer)
20 Eyepiece 21 Faraday Element 22 Polarizer

Claims (15)

  A polarizer in which transmission axes are provided concentrically.   The polarizer of Claim 1 comprised by the self-cloning photonic crystal.   A polarizer whose transmission axis is provided radially from one point.   The polarizer of Claim 3 comprised by the self-cloning photonic crystal. With a light source;
A first polarizer that transmits light from the light source and has a transmission axis provided concentrically around the optical axis;
An observation sample stage on which a sample irradiated with light transmitted through the first polarizer is mounted;
An objective lens that transmits light transmitted through a sample mounted on the observation sample stage or light reflected from a sample mounted on the observation sample stage;
A second polarizer that transmits light that has passed through the objective lens, and whose transmission axis is provided radially about the optical axis;
A polarizing microscope. A condensing lens for condensing light from the light source between the light source and the first polarizer;
The first polarizer is:
Between the light source and the observation sample and disposed at a pupil position of the condenser lens;
The second polarizer is:
Disposed at the pupil position of the objective lens;
The polarizing microscope according to claim 5. With a light source;
A first polarizer that transmits light from the light source and whose transmission axis is provided radially about the optical axis;
An observation sample stage on which a sample irradiated with light transmitted through the first polarizer is mounted;
An objective lens that transmits light transmitted through a sample mounted on the observation sample stage or light reflected from a sample mounted on the observation sample stage;
A second polarizer that transmits light that has passed through the objective lens and that is provided concentrically with a transmission axis centered on the optical axis;
A polarizing microscope. A condensing lens for condensing light from the light source between the light source and the first polarizer;
The first polarizer is:
Between the light source and the observation sample and disposed at a pupil position of the condenser lens;
The second polarizer is:
Disposed at the pupil position of the objective lens;
The polarizing microscope according to claim 7. With a light source;
A first polarizer that transmits light from the light source, and whose transmission axis is provided radially around the optical axis or concentrically around the optical axis;
An observation sample stage on which a sample irradiated with light transmitted through the first polarizer is mounted;
An objective lens that transmits light transmitted through a sample mounted on the observation sample stage or light reflected from a sample mounted on the observation sample stage;
An optical rotator that transmits the light transmitted through the objective lens and that orthogonally crosses the polarization main axis direction;
A second polarizer having a transmission axis similar to that of the first polarizer, through which the light transmitted through the optical rotator is transmitted;
A polarizing microscope. A condensing lens for condensing light from the light source between the light source and the first polarizer;
The first polarizer is:
Between the light source and the observation sample and disposed at a pupil position of the condenser lens;
The second polarizer is:
Disposed at the pupil position of the objective lens;
The polarizing microscope according to claim 9.   The polarizing microscope according to claim 9, wherein the first polarizer and the second polarizer are the same polarizer. With a light source;
A first polarizer that transmits light from the light source, and whose transmission axis is provided radially around the optical axis or concentrically around the optical axis;
An optical rotator that transmits the light transmitted through the first polarizer and that orthogonally crosses the polarization main axis direction;
An observation sample stage carrying a sample irradiated with light transmitted through the optical rotator;
An objective lens that transmits light transmitted through a sample mounted on the observation sample stage or light reflected from a sample mounted on the observation sample stage;
A second polarizer having a transmission axis similar to that of the first polarizer, through which the light transmitted through the optical rotator is transmitted;
A polarizing microscope. A condensing lens for condensing light from the light source between the light source and the first polarizer;
The first polarizer is:
Between the light source and the observation sample and disposed at a pupil position of the condenser lens;
The second polarizer is:
Disposed at the pupil position of the objective lens;
The polarizing microscope according to claim 12.   The polarizing microscope according to claim 12, wherein the first polarizer and the second polarizer are the same polarizer. At the pupil position of the condenser lens and the pupil position of the objective lens, either a polarizer with a concentric transmission axis or a polarizer with a radial transmission axis is provided, and a finer structure can obtain a higher resolution image. Features a microscope.

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