JP6477360B2 - Photometric device - Google Patents

Description

  The present invention relates to a photometric device that measures light emitted from a screen of a liquid crystal display device, for example.

  A spectral radiance meter is a photometric device that includes a spectroscopic unit, and that splits light from a measurement target by the spectroscopic unit and measures the luminance, saturation, spectral characteristics, and the like of the light. The spectroscopic unit is configured by a diffraction grating, a prism, or the like, and these optical elements have strong polarization dependence. In the case of a reflection type diffraction grating, the diffraction efficiency of the diffraction grating varies depending on the polarization direction of linearly polarized light. For this reason, when the light emitted from the measurement object is linearly polarized light (for example, light emitted from the screen of the liquid crystal display device), a correct measurement value cannot be obtained due to polarization dependency. Therefore, a depolarizing element is arranged on the incident side of the spectroscopic unit, and light from which linearly polarized light has been eliminated by the depolarizing element is incident on the spectroscopic unit (see, for example, Patent Document 1 and Patent Document 2).

JP 2001-264166 A Japanese Patent No. 2995985

  Patent Document 1 uses a fiber bundle as a depolarizing element. The light incident on each fiber constituting the fiber bundle is repeatedly reflected in each fiber and guided to the spectroscopic unit. This reflection eliminates linearly polarized light.

  The fiber generally has a circular cross section as viewed from the traveling direction of the light, but the present inventor has a small depolarization effect in the case of a light guide member having a circular cross section, and the linearly polarized light emitted from the measurement object is small. It has been found that the measured value varies depending on the polarization direction.

  An object of this invention is to provide the photometry apparatus which can prevent that a measured value produces dispersion | variation according to the polarization state of the light which the measurement object radiate | emitted.

  The photometric device according to the present invention that achieves the above object has four side surfaces, and has a square or rectangular cross section when viewed from the traveling direction of the light with respect to the light emitted from the measurement object. A light guide member disposed along a predetermined optical axis that reflects and guides the light from the four side surfaces, and performs a predetermined process on the light guided by the light guide member. A processing unit having polarization dependence, and a light receiving unit that receives the light subjected to the predetermined processing, and the light guide member is not disposed along the predetermined optical axis. In the linearly polarized light incident on the processing unit, when the predetermined processing is performed by the processing unit and the vibration direction of the electric field of the linearly polarized light that maximizes the amount of light transmitted to the light receiving unit is the maximum direction, the maximum direction The angle formed by the direction of each normal of the four side surfaces But so as to respectively 45 °, wherein the light guide member is disposed.

  According to the photometric device according to the present invention, the amount of light transmitted to the light receiving unit can be adjusted regardless of the direction of vibration of the electric field of the light emitted from the measurement object (hereinafter referred to as the polarization direction). Can be the same. Therefore, it is possible to prevent the measurement values from varying depending on the polarization state of the light emitted from the measurement object. The light guide member is, for example, a quadrangular prism or a truncated pyramid made of glass or transparent resin, called a light pipe, a glass rod, or the like.

  As a mode in which the light guide member is arranged so that the angle formed between the maximum direction and the normal direction is 45 degrees, there are a first mode to a third mode.

  A 1st aspect is a case where a process part is a diffraction grating. That is, in the first aspect, the processing unit includes a diffraction grating that splits the light guided by the light guide member, and the diffraction grating has a plurality of score lines extending in a first direction, It has a structure arranged with a gap in a second direction orthogonal to the first direction, and the angle formed by the first direction and the direction of the normal is 45 degrees. As described above, the light guide member is arranged. In the case of a reflective diffraction grating, the maximum amount of light transmitted to the light receiving unit means that the diffraction efficiency of the diffraction grating is maximum. In the case of a transmissive diffraction grating, the maximum amount of light transmitted to the light receiving unit means that the transmittance of the diffraction grating is maximum.

  The second mode is a case where the processing unit is a triangular prism. That is, in the second aspect, the processing unit includes a triangular prism that includes an incident surface on which the light guided by the light guide member is incident and an exit surface that emits the light, and that splits the light. Each of the incident surface and the exit surface includes a first side orthogonal to the light traveling direction and a second side inclined with respect to the light traveling direction, and the normal line The light guide member is arranged so that an angle formed between the first side and the first side is 45 degrees. In the case of a triangular prism, the maximum amount of light transmitted to the light receiving unit means the maximum transmittance of the incident surface and the output surface.

  The third aspect is a case where the processing unit is a dichroic prism. That is, in the third aspect, the processing unit is configured to reflect and transmit a predetermined wavelength component of the light guided by the light guide member and transmit a wavelength component other than the predetermined wavelength component. Including a dichroic prism that divides the light, wherein the reflection / transmission surface includes a first side orthogonal to the traveling direction of the light and a second side inclined with respect to the traveling direction of the light. In addition, the light guide member is arranged so that an angle formed by the first side and the normal is 45 degrees. In the case of a dichroic prism, the maximum amount of light transmitted to the light receiving unit means that the transmittance of the transmission / reflection surface is maximum.

The said structure WHEREIN: The said light guide member has a linear shape, and satisfy | fills following formula (1).

  Here, θp indicates arcsin (sin θ / np), L1 indicates the length of the light guide member in the optical axis direction, L2 indicates the length of one side of the square when the cross section is square, When the cross section is rectangular, it indicates the length of the long side, and θ is incident on the incident end surface when the end surface of the light guide member on the side where the light is incident on the light guide member is the incident end surface. The maximum value of the incident angle of light is shown, and np shows the refractive index of the light guide member.

  If the number of times the light is reflected on the side surface of the light guide member increases, the depolarization effect increases. According to this configuration, the light having the maximum incident angle to the incident end face can be reflected at least twice.

  In the above configuration, the P-polarized light component and S of the light are formed on the four side surfaces and when the light is emitted from the light guide member, compared to when the light is incident on the light guide member. A coating film that further increases the phase difference from the polarization component is further provided.

  If the phase difference between the P-polarized component and the S-polarized component of the light incident on the light guide member can be increased, the depolarization effect is increased. According to this configuration, the phase difference between the P-polarized light component and the S-polarized light component can be increased by the coating film, so that the depolarization effect can be further increased.

  If the length of the light guide member in the optical axis direction is increased, the phase difference between the P-polarized component and the S-polarized component can be increased, but the photometric device is increased in size. According to this configuration, since the phase difference between the P-polarized component and the S-polarized component can be increased by the coat film, even if the length of the light guide member in the optical axis direction is small (that is, the photometric device is downsized). ), A depolarization effect can be obtained.

  The said structure WHEREIN: The said coating film is a single layer, The refractive index of the said coating film is made larger than the refractive index of the said light guide member.

According to this configuration, the phase difference between the P-polarized component and the S-polarized component can be increased.
Another aspect of the photometric device according to the present invention has four side surfaces, and has a square or rectangular cross section when viewed from the traveling direction of the light with respect to the light emitted from the measurement object. A light guide member disposed along a predetermined optical axis that reflects and guides the light from the four side surfaces; and a predetermined process on the light guided by the light guide member. A processing unit having polarization dependence; and a light receiving unit that receives the light subjected to the predetermined processing, and the processing is performed along the predetermined optical axis in a state where the light guide member is not disposed. In the linearly polarized light incident on the part, when the predetermined processing is performed by the processing unit and the vibration direction of the electric field of the linearly polarized light that maximizes the amount of light transmitted to the light receiving unit is the maximum direction, the maximum direction, The angle formed by the normal direction of each of the four side surfaces is The light guide members are arranged so as to be 45 degrees each, the light guide member is a light pipe or an optical fiber, and the light emitted from the measurement object is P in the light guide member. The incident light has an incident end face that is not separated into a polarized light component and an S polarized light component, and the light incident from the incident end face is totally reflected by the four side surfaces to guide the light. A phase difference is generated between the polarization component and the S polarization component.

  According to the present invention, the measurement value can be stabilized regardless of the polarization state of the light emitted from the measurement object.

It is a schematic diagram which shows the structure of the photometry apparatus which concerns on this embodiment. It is a schematic diagram which shows the cross section of the light pipe seen from the advancing direction (Z direction) of light. It is a schematic diagram which shows a diffraction grating. In this embodiment, it is explanatory drawing explaining the relationship between the cross section of the light pipe seen from the advancing direction (Z direction) of light, and the linearly polarized light reflected by the side surface of a light pipe. It is a graph which shows the relationship between an incident angle and a phase, when the light of wavelength 546nm reflects in the boundary of quartz glass and air. It is a side view of a light pipe. In a comparative example, it is explanatory drawing explaining the relationship between the light of a linearly polarized light, and the cross section of the light pipe seen from the advancing direction (Z direction) of light. It is a schematic diagram which shows the structure of the photometry apparatus which concerns on a 1st modification. In the 1st modification, it is a mimetic diagram showing a cross section of a light pipe and an entrance plane of a triangular prism side by side seen from the advancing direction (Z direction) of light. It is a schematic diagram which shows the structure of the photometry apparatus which concerns on a 2nd modification. In the 2nd modification, it is a mimetic diagram showing a cross section of a light pipe and a reflective transmissive surface of a dichroic prism arranged from the advancing direction (Z direction) of light. It is explanatory drawing explaining a light pipe bundle. It is a schematic diagram which shows the cross section of the light pipe with which the coating film was formed in the side surface. It is a table | surface which shows the conditions of a sample provided with the coating film of a single layer. It is a graph which shows the relationship between an incident angle and a phase difference about the sample provided with the coating film of a single layer. It is a table | surface which shows the conditions of a sample provided with a three-layer coating film. It is a graph which shows the relationship between an incident angle and a phase difference about the sample provided with a three-layer coating film. It is a schematic diagram which shows the model of the photometry apparatus for calculating the concrete value which shows a depolarization effect. It is a graph which shows an example of the light quantity fluctuation | variation computed using the model of the photometry apparatus shown in FIG. It is a table | surface which shows the depolarization effect in case the coating film is not formed in the side surface of a light pipe. It is a table | surface which shows the depolarization effect in case the single layer coating film is formed in the side surface of a light pipe. It is a table | surface which shows the depolarization effect in case the three-layer coating film is formed in the side surface of a light pipe.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the structure which attached | subjected the same code | symbol shows that it is the same structure, The description is abbreviate | omitted about the content which has already demonstrated the structure.

  FIG. 1 is a schematic diagram showing the configuration of a photometric device 1a according to this embodiment. The photometric device 1a is, for example, a spectral radiance meter, and measures the luminance, saturation, spectral characteristics, and the like of the light R by dispersing the linearly polarized light R emitted from the measurement object 10. The linearly polarized light R emitted from the measurement object 10 is, for example, light emitted from the screen of the liquid crystal display device. Linearly polarized light may be simply referred to as linearly polarized light.

  The photometric device 1 a includes an objective lens 2, a light pipe 3, and a polychromator 4. A monochromator may be used instead of the polychromator 4. The objective lens 2 and the light pipe 3 are arranged on the optical path from the measurement object 10 to the polychromator 4. The traveling direction of the light R between the measurement object 10 and the polychromator 4 is the Z direction. Of the two directions orthogonal to the Z direction, one is the X direction (direction perpendicular to the paper surface) and the other is the Y direction. The X direction and the Y direction are orthogonal to each other.

  The objective lens 2 condenses the linearly polarized light R emitted from the measurement object 10 and forms a light source image on the incident end face 30 of the light pipe 3. In the case of a liquid crystal display device, the light source image is an image of a light source of the liquid crystal display device.

  The light pipe 3 is a specific example of a light guide member. FIG. 2 is a schematic diagram showing a cross section of the light pipe 3 as viewed from the Z direction. 1 and 2, the light pipe 3 has a regular quadrangular prism shape defined by four side surfaces 32 and two end surfaces (an incident end surface 30 and an output end surface 31). The material of the light pipe 3 is, for example, quartz glass, optical glass, or transparent resin, and these materials are selected according to the purpose.

  The light R collected by the objective lens 2 is incident on the incident end face 30 and is repeatedly reflected on the side face 32, thereby being guided in the light pipe 3 and emitted from the exit end face 31. The number of reflections is determined according to the incident angle of the light R incident on the incident end face 30. Virtually, many light source images are formed on the incident end face 30, and each light source image illuminates the outgoing end face 31, whereby the illuminance of the outgoing end face 31 becomes uniform.

  Thus, the light pipe 3 has four side surfaces 32 and has a square cross section when viewed from the Z direction (the traveling direction of the light R) with respect to the linearly polarized light R emitted from the measurement object 10. The light R is reflected by the four side surfaces 32 and guided.

  The cross-sectional shape of the light pipe 3 is not limited to a square but may be a rectangle.

  The three-dimensional shape of the light pipe 3 is not limited to a regular quadrangular prism, and may be, for example, a quadrangular prism whose cross section gradually decreases from the incident end face 30 toward the exit end face 31. In this way, the size of the emission end face 31 can be reduced. If the size of the emission end face 31 is reduced, the wavelength resolution of the polychromator 4 can be improved.

  Although the light pipe 3 is used as the light guide member, an optical fiber may be used as the light guide member.

  With reference to FIG. 1, the polychromator 4 includes an imaging optical system 5, a diffraction grating 6, and a linear array sensor 7. The entrance aperture 40 of the polychromator 4 faces the exit end face 31 of the light pipe 3, and the light R emitted from the exit end face 31 enters the imaging optical system 5 through the entrance opening 40 and forms an image. The light is collimated by the optical system 5 into parallel light. The parallel light R enters the diffraction grating 6.

  The diffraction grating 6 splits the light R guided by the light pipe 3. The diffraction grating 6 is a reflection type, and the light R incident on the diffraction grating 6 is diffracted and reflected by the diffraction grating 6. FIG. 3 is a schematic diagram showing the diffraction grating 6. The diffraction grating 6 has a plurality of score lines 60 extending in the first direction. The score line 60 is also referred to as a groove. The plurality of engraved lines 60 are arranged at a predetermined interval in a second direction orthogonal to the first direction.

  The diffraction grating 6 is a specific example of a processing unit having polarization dependency that performs a predetermined process on the light R guided by the light pipe 3.

  Referring to FIG. 1, the light R reflected by the diffraction grating 6 again enters the imaging optical system 5, and the wavelength dispersion of the light source image on the light receiving surface 70 of the linear array sensor 7 by the imaging optical system 5. It is formed as an image.

  The linear array sensor 7 is a specific example of a light receiving unit that receives the light R that has been subjected to predetermined processing by the processing unit. The linear array sensor 7 includes a plurality of photoelectric conversion elements arranged along one direction. The photoelectric conversion element is, for example, a silicon photodiode (SPD). The linear array sensor 7 generates an electric signal representing the intensity level of each wavelength by photoelectrically converting the wavelength dispersion image of the light source image formed on the light receiving surface 70 by each of the plurality of photoelectric conversion elements.

  Referring to FIG. 1, when linearly polarized light is incident on the polychromator 4 along a predetermined optical axis without the light pipe 3 being disposed, the reflective diffraction grating 6 has a direction in which the score line 60 extends. The diffraction efficiency of the diffraction grating 6 is maximized (ie, the amount of light transmitted to the linear array sensor 7 is maximized) with respect to linearly polarized light having a polarization direction parallel or perpendicular to the (X direction). Whether the diffraction efficiency of the diffraction grating 6 is maximized with respect to linearly polarized light in any direction depends on the characteristics of the diffraction grating (shape, groove pitch, etc.), the wavelength of the linearly polarized light, and the like. The predetermined optical axis coincides with the optical axis AX of the light pipe 3 (FIG. 6). The light pipe 3 is arranged along a predetermined optical axis. The polarization direction means the direction of vibration of the electric field. The polarization direction that appears below also has this meaning.

  The linearly polarized light incident on the polychromator 4 along the predetermined optical axis has the maximum reflectivity of the diffraction grating 6 when the polarization direction is the X direction or the Y direction, and the four side surfaces 32 of the light pipe 3. The light pipe 3 is arranged so that the angle θ1 formed by the direction of each normal N and the X direction and the angle θ2 formed by the normal N and the Y direction are 45 degrees. .

  Thus, in the state where the light guide member (light pipe 3) is not disposed, the linearly polarized light incident on the processing unit (polychromator 4) along the predetermined optical axis is subjected to predetermined processing in the processing unit, When the polarization direction of the linearly polarized light (electric field vibration direction) that maximizes the amount of light transmitted to the light receiving unit (linear array sensor 7) is the maximum direction, the maximum direction and the direction of the normal N of each of the four side surfaces 32 The light guide members are arranged so that the angles formed by and are each 45 degrees (or approximately 45 degrees).

  According to the photometric device 1a according to the present embodiment including the light pipe 3 arranged in this manner, the output end face 31 (the light R incident on the incident end face 30 (FIG. 1) is in any polarization state. With respect to the light R emitted from FIG. 1), the linear polarization component with the polarization direction in the X direction can be 50%, and the linear polarization component with the polarization direction in the Y direction can be 50%. Accordingly, the diffraction efficiency of the diffraction grating 6 can be made the same regardless of the polarization state of the linearly polarized light R emitted from the measurement object 10.

  This will be described in detail below. FIG. 4 illustrates the relationship between the cross section of the light pipe 3 viewed from the Z direction (the traveling direction of the light R) and the linearly polarized light R reflected by the side surface 32 of the light pipe 3 in the present embodiment. FIG. The direction of the arrow indicating the linearly polarized light R indicates the polarization direction. The linearly polarized light R is composed of a P-polarized component RP and an S-polarized component RS. The direction of the P-polarized component RP is the direction of the normal N, and the direction of the S-polarized component RS is a direction orthogonal to the normal N in the side surface 32.

  P-polarized light and S-polarized light will be briefly described. When light is reflected and refracted on a plane serving as a boundary between two media, a plane including incident light, reflected light, and refracted light is defined as an incident surface. The polarized light whose electric field vibration direction is in the incident plane is P-polarized light, and the polarized light whose electric field vibration direction is perpendicular to the incident plane is S-polarized light.

  With reference to FIGS. 1 and 4, the linearly polarized light R incident on the incident end face 30 is repeatedly reflected by the side face 32 of the light pipe 3 and is emitted from the emission end face 31. When light R is incident on the boundary between the high refractive index medium (here, the light pipe 3) and the low refractive index medium (here, air) from the high refractive index medium side at an incident angle greater than the critical angle. The light R is totally reflected.

  When the light R is totally reflected, a phase change occurs in each of the P-polarized component RP and the S-polarized component RS of the light R. The value of the phase change of the P-polarized component RP is different from the value of the phase change of the S-polarized component RS, and the value of the phase change of each of the P-polarized component RP and the S-polarized component RS differs depending on the incident angle. This will be specifically described with reference to FIG.

  FIG. 5 shows the relationship between the incident angle and the phase change of reflected light when light having a wavelength of 546 nm is reflected at the boundary between quartz glass (refractive index n = 1.46) and air (refractive index n = 1). It is a graph to show. The horizontal axis of the graph is the incident angle, and the unit is degrees. The vertical axis of the graph is phase, and the unit is degree.

  When the incident angle exceeds about 43 degrees, the light is totally reflected. It can be seen that the phase change value of the P polarization component RP is different from the phase change value of the S polarization component RS, and the phase change values of the P polarization component RP and the S polarization component RS differ depending on the incident angle. . In the present embodiment, the polarization of the linearly polarized light R is canceled using the phase difference between the P-polarized component RP and the S-polarized component RS. This will be described with reference to FIG.

  FIG. 6 is a side view of the light pipe 3. AX indicates the optical axis of the light pipe 3. L1 is the length of the light pipe 3 in the optical axis direction. L2 is the length of one side of the longitudinal section (square) of the light pipe 3. θ is the maximum value of the incident angle of the linearly polarized light R incident on the incident end face 30.

  The NA of the objective lens 2 (FIG. 1) is 0.2, the refractive index n of the light pipe 3 is 1.46, L1 is 200 mm, and L2 is 1 mm. θ is about 11.5 degrees, the maximum angle formed by the light R with the optical axis AX within the light pipe 3 is about 7.9 degrees, and the incident angle of the light R on the side surface 32 is about 82. 1 to 90 degrees. The state in which the light R incident on the incident end face 30 is emitted from the emission end face 31 under the above conditions will be described with reference to FIG.

  In FIG. 4, consider linearly polarized light R whose polarization direction is the Y direction. In this case, for the linearly polarized light R reflected by the side surface 32, the P-polarized component RP is 50% and the S-polarized component RS is 50%.

  What is important here is that the linearly polarized light R whose polarization direction is the Y direction is always reflected by 50% of the P-polarized component RP and 50% of the S-polarized component RS, regardless of where the side surface 32 is reflected. It is to become.

  When the incident angle of the light R on the side surface 32 is 82.1 degrees, the phase difference between the P-polarized component RP and the S-polarized component RS is about 11.4 degrees as shown in FIG. In this case, the linearly polarized light R incident on the incident end face 30 is reflected from the side face 32 27 times and emitted from the emission end face 31. For the emitted light R, the phase difference between the P-polarized component RP and the S-polarized component RS is about 309 degrees (= about 11.4 degrees × 27 times). When the phase difference is 90 degrees, it becomes circularly polarized light, and when the phase difference is 180 degrees, the polarization direction changes by 90 degrees.

  When the incident angle of the light R on the side surface 32 is 90 degrees, the direction of the light R is the direction of the optical axis AX, so that the light R is not reflected by the side surface 32 and is incident on the incident end surface 30. The light R is emitted from the emission end face 31 while maintaining the polarization direction.

  As described above, the phase difference continuously changes from about 309 degrees to 0 degrees in accordance with the incident angle (= about 82.1 degrees to 90 degrees) of the light R to the side surface 32. As a result, the light R in which various polarization states are mixed is emitted from the emission end face 31. In this case, in the entire light R emitted from the emission end face 31, the linearly polarized light component whose polarization direction is the Y direction is about 56%, and the linearly polarized light component whose polarization direction is the X direction is about 44%. Since the difference in the ratio of these polarization components is small, it can be said that the polarization is eliminated.

  Ideally, there is no difference in the proportion of these polarization components (that is, the linear polarization component whose polarization direction is the Y direction is 50%, and the linear polarization component whose polarization direction is the X direction is 50%). The maximum angle formed by the direction in which the light R is reflected in the light pipe 3 and the optical axis AX is increased (in other words, the NA of the objective lens 2 is increased), or the optical axis direction of the light pipe 3 If the length L1 of the light pipe 3 is increased or the length L2 of one side of the longitudinal section (square) of the light pipe 3 is decreased, the linearly polarized light component whose polarization direction is the Y direction and the linearly polarized light whose polarization direction is the X direction It is possible to eliminate the difference in ratio with the components.

  Referring to FIG. 4, when the angle θ2 formed by the polarization direction of linearly polarized light R and the direction of normal N is 45 degrees, the depolarization effect becomes the largest. As the angle θ2 decreases from 45 degrees, the depolarization effect gradually decreases. When the angle θ2 is 0 degree, that is, when the polarization direction of the linearly polarized light R and the direction of the normal line N are parallel, the depolarization effect is lost, and the linearly polarized light R is maintained in polarization. Then, the light is emitted from the emission end face 31.

  When the angle θ2 is 0 degree, the linearly polarized light R has no difference between the linearly polarized light component whose polarization direction is Y direction is 50% and the linearly polarized light component whose polarization direction is X direction is 50%. Accordingly, even if there is no depolarization effect, in the entire light R emitted from the emission end face 31, the linear polarization component with the polarization direction in the Y direction is 50% and the linear polarization component with the polarization direction in the X direction is 50%. be able to.

  When the angle θ2 is smaller than 45 degrees and larger than 0 degrees, as the angle θ2 becomes smaller, the proportion of the linearly polarized light component in the Y direction gradually decreases from 100% and approaches 50%, and the polarization direction becomes X The ratio of the linearly polarized light component in the direction gradually increases from 0% and approaches 50%. Therefore, even if the depolarization effect gradually decreases as the angle θ2 approaches 45 degrees from 0 degrees, the linear polarization component whose polarization direction is the Y direction is 50% in the entire light R emitted from the emission end face 31, The linearly polarized light component whose polarization direction is the X direction can be 50%.

  As described above, the photometric device 1a according to the present embodiment uses the light R emitted from the emission end face 31 regardless of the polarization state of the linearly polarized light R incident on the incidence end face 30. The linear polarization component whose polarization direction is the Y direction can be 50%, and the linear polarization component whose polarization direction is the X direction can be 50%. In the polychromator 4, the amount of light transmitted to the light receiving unit (linear array sensor 7) becomes maximum when linearly polarized light whose polarization direction is the X direction or the Y direction is incident. Therefore, in this embodiment, the amount of light transmitted to the light receiving unit (linear array sensor 7) can be made the same regardless of the polarization state of the light R emitted from the measurement object 10. Therefore, according to the present embodiment, it is possible to prevent the measurement value from varying depending on the polarization state of the linearly polarized light R emitted from the measurement object 10 (that is, not limited to linearly polarized light in various directions). Therefore, it is possible to prevent variations in measured values not only for circularly polarized light and elliptically polarized light, but also for partially polarized light as well as partially polarized light), and as a result, affected by the polarization state of the light R. Stable measurement is possible.

  Further, in the present embodiment, since the light pipe 3 having a linear shape is used, it is easier to predict the depolarization effect by simulation compared to the case of using a bent fiber.

  Although the light pipe 3 having a square cross section when viewed from the traveling direction of the light R has been described, the same applies to the light pipe 3 having a rectangular cross section when viewed from the traveling direction of the light R. That is, even in the case of the light pipe 3 having a rectangular cross section when viewed from the traveling direction of the light R, the light R that is incident on the incident end face 30 is emitted from the exit end face 31 regardless of the polarization state. For R, the linear polarization component with the polarization direction in the Y direction can be 50%, and the linear polarization component with the polarization direction in the X direction can be 50%.

  For comparison with the present embodiment, it will be described that the depolarization effect is small when the light pipe 3a has a circular cross section when viewed from the traveling direction (Z direction) of the light R as shown in FIG. FIG. 7 is an explanatory diagram for explaining the relationship between linearly polarized light R and the cross section of the light pipe 3a viewed from the traveling direction of the light R in the comparative example. The polarization direction of the linearly polarized light R is the Y direction.

  On the side surface 32a of the light pipe 3a, the angle formed by the polarization direction of the linearly polarized light R and the direction of the normal line N is 45 degrees. For the linearly polarized light R reflected at the point P1, the P-polarized component RP is 50% and the S-polarized component RS is 50% as in the present embodiment. Therefore, the linearly polarized light R reflected at the point P1 is emitted from the light pipe 3a in a state where the polarization is eliminated, as in the present embodiment.

  In the side surface 32a of the light pipe 3a, an angle formed between the polarization direction of the linearly polarized light R and the direction of the normal line N is 0 degree at the point P2. For the linearly polarized light R reflected at the point P2, the P-polarized component RP is 100% and the S-polarized component RS is 0%. Therefore, the linearly polarized light R reflected at the point P2 is emitted from the light pipe 3a while maintaining the polarization.

  On the side surface 32a of the light pipe 3a, an angle formed between the polarization direction of the linearly polarized light R and the direction of the normal line N is 90 degrees. For the linearly polarized light R reflected at the point P3, the P-polarized component RP is 0% and the S-polarized component RS is 100%. Therefore, the linearly polarized light R reflected at the point P3 is emitted from the light pipe 3a while maintaining the polarization.

  As described above, in the comparative example, with respect to linearly polarized light R whose polarization direction is the Y direction, the polarization is not eliminated depending on the location of the side surface 32a where the light R is reflected (for example, point P2 or point P3). R is emitted from the light pipe 3a while maintaining polarization. Therefore, the comparative example has a smaller depolarization effect than the present embodiment. When viewed from the traveling direction of the light R, the light pipe having a hexagonal, octagonal, or rhombic cross section also has a smaller depolarization effect than the present embodiment for the same reason.

With reference to FIG. 6, in this embodiment, the light pipe 3 has a linear shape and satisfies the following formula (1).

  θp represents arcsin (sin θ / np). np represents the refractive index of the light pipe 3. As already described, L1 indicates the length of the light pipe 3 in the optical axis direction, and L2 indicates the length of one side of the cross section (square) of the light pipe 3 viewed from the traveling direction of the light R (note that When the cross section of the light pipe 3 viewed from the traveling direction of the light R is rectangular, it indicates the length of the long side), and θ indicates the maximum value of the incident angle of the light R incident on the incident end face 30.

  As described above, if the number of times the light R is reflected on the side surface 32 of the light pipe 3 increases, the phase difference between the P-polarized component RP and the S-polarized component RS increases, and the depolarization effect increases. The left side of Expression (1) indicates the approximate number of times the light R is reflected by the side surface 32 of the light pipe 3 when the incident angle of the light R incident on the incident end face 30 is the maximum. If the formula (1) is satisfied, the light R having the maximum incident angle to the incident end face 30 can be reflected at least twice.

  The light pipe 3 (light guide member) is made of a transparent material, has a quadrangular prism shape or a truncated pyramid shape, and satisfies np × cos θp ≧ 1. Thereby, the reflection at the side surface 32 of the light pipe 3 becomes total reflection.

  A first modification and a second modification of this embodiment will be described. FIG. 8 is a schematic diagram showing the configuration of the photometric device 1b according to the first modification. The photometric device 1 b is different from the photometric device 1 a shown in FIG. 1 in that a spectroscopic device 8 is provided instead of the polychromator 4.

  The spectroscopic device 8 includes a collimator lens 81, a triangular prism 82, and a linear array sensor 7. The incident aperture 80 of the spectroscopic device 8 faces the exit end face 31 of the light pipe 3, and the light R emitted from the exit end face 31 enters the collimator lens 81 through the entrance opening 80, and is collimated by the collimator lens 81. It becomes parallel light. The collimated light R travels to the triangular prism 82.

  The triangular prism 82 includes an entrance surface 84 and an exit surface 85. The collimated light R enters the incident surface 84, is split by the triangular prism, and exits from the exit surface 85. The triangular prism 82 is a specific example of a processing unit having polarization dependency that performs a predetermined process on the light R guided by the light pipe 3.

  The light R emitted from the emission surface 85 enters the imaging optical system 83 and is imaged as a wavelength dispersion image of the light source image on the light receiving surface 70 of the linear array sensor 7 by the imaging optical system 83. Since the linear array sensor 7 has already been described, the description of the linear array sensor 7 is omitted.

  FIG. 9 is a schematic diagram showing the cross section of the light pipe 3 and the incident surface 84 of the triangular prism 82 side by side as viewed from the traveling direction (Z direction) of the light R in the first modification. 8 and 9, the incident surface 84 includes two first sides 86 that are orthogonal to the traveling direction of the light R, and two second sides that are inclined with respect to the traveling direction of the light R. 87. Although not shown, the reflection surface 85 similarly includes two first sides orthogonal to the traveling direction of the light R and two second sides inclined with respect to the traveling direction of the light R.

  The direction of the first side 86 is set to the X direction. The light pipe 3 is arranged so that the angle formed by the direction of the normal N and the first side 86 (that is, the angle θ1 formed by the direction of the normal N and the X direction) is 45 degrees. ing.

  Since the transmittance of the interface of the triangular prism 82 (that is, the incident surface 84 and the output surface 85) differs between P-polarized light and S-polarized light, the triangular prism 82 has polarization dependency. The linear polarization of the polarization direction of either the polarization direction of P-polarized light (here in the YZ plane) or the polarization direction of S-polarized light (here, the X direction) maximizes the transmittance at the interface of the triangular prism 82 (that is, The amount of light sent to the linear array sensor 7 is maximized). Therefore, the spectroscopic device 8 maximizes the amount of light transmitted to the linear array sensor 7 when the polarization direction of the incident linearly polarized light is the X direction or the Y direction. Therefore, the polarization dependence can be reduced for the same reason as the photometric device 1a shown in FIG.

  As described above, according to the photometric device 1b according to the first modification, the transmittance at the interface of the triangular prism 82 can be made the same regardless of the polarization state of the light R emitted from the measurement object 10. . Therefore, according to the photometric device 1b according to the first modification, it is possible to prevent the measurement values from varying depending on the polarization state of the light R emitted from the measurement object 10, as with the photometric device 1a.

  FIG. 10 is a schematic diagram showing a configuration of a photometric device 1c according to the second modification. The photometric device 1 c is different from the photometric device 1 a shown in FIG. 1 in that a spectroscopic device 9 is provided instead of the polychromator 4. The photometric device 1c is, for example, an XYZ tristimulus color measuring device.

  The spectroscopic device 9 includes a collimator lens 91, a dichroic prism 92, and optical sensors 93, 94, 95. The incident opening 90 of the spectroscopic device 9 faces the emission end face 31 of the light pipe 3, and the light R emitted from the emission end face 31 enters the collimator lens 91 through the incident opening 90, and is collimated by the collimator lens 91. It becomes parallel light. The collimated light R travels to the dichroic prism 92.

  The dichroic prism 92 includes reflection / transmission surfaces 96 and 97. The reflection / transmission surfaces 96 and 97 each include an interference film, reflect a predetermined wavelength component of the light R converted into parallel light, and transmit a wavelength component other than the predetermined wavelength component. As a result, the light R is split into the first wavelength component, the second wavelength component, and the third wavelength component, and is emitted from the dichroic prism 92. The dichroic prism 92 is a specific example of a processing unit having polarization dependency that performs a predetermined process on the light R guided by the light pipe 3.

  The first wavelength component emitted from the dichroic prism 92 is received by the optical sensor 93. The second wavelength component emitted from the dichroic prism 92 is received by the optical sensor 94. The third wavelength component emitted from the dichroic prism 92 is received by the optical sensor 95. The optical sensors 93, 94, and 95 are, for example, silicon photodiodes (SPD).

  FIG. 11 is a schematic diagram showing the cross section of the light pipe 3 and the reflection / transmission surface 96 of the dichroic prism 92 as seen from the traveling direction of the light R (Z direction) in the second modification. Referring to FIGS. 10 and 11, the reflection / transmission surface 96 is orthogonal to the traveling direction of the light R, similarly to the incident surface 84 and the emission surface 85 of the first modification shown in FIGS. 8 and 9. It includes two first sides 98 and two second sides 99 that are inclined with respect to the traveling direction of the light R. Although not shown, the reflection / transmission surface 97 similarly includes two first sides orthogonal to the traveling direction of the light R and two second sides inclined with respect to the traveling direction of the light R. .

  As in the first modification, the direction of the first side 98 is set to the X direction. The light pipe 3 is arranged so that the angle formed by the direction of the normal N and the first side 98 (that is, the angle θ1 formed by the direction of the normal N and the X direction) is 45 degrees. ing.

  Since the transmittance and reflectance of the reflection / transmission surfaces 96 and 97 of the dichroic prism 92 are different between the P-polarized light and the S-polarized light, the dichroic prism 92 has polarization dependency. The linearly polarized light in the polarization direction of either the polarization direction of P-polarized light (here in the YZ plane) or the polarization direction of S-polarized light (here, X direction) is reflected by the reflection / transmission surfaces 96, 97 of the dichroic prism 92, or The transmittance is maximized (that is, the amount of light transmitted to the optical sensors 93, 94, 95 is maximized). Therefore, the spectroscopic device 9 maximizes the amount of light transmitted to the optical sensors 93, 94, and 95 when the polarization direction of the incident linearly polarized light is the X direction or the Y direction. Therefore, the polarization dependence can be reduced for the same reason as the photometric device 1a shown in FIG.

  As described above, according to the photometric device 1c according to the second modification, the transmittances of the reflection / transmission surfaces 96 and 97 of the dichroic prism 92 are the same regardless of the polarization state of the light R emitted from the measurement object 10. Can be. Therefore, according to the photometric device 1c according to the second modification, similarly to the photometric device 1a, it is possible to prevent the measurement values from varying depending on the polarization state of the light R emitted from the measurement object 10.

  Additional configurations 1 to 7 that can be added to the photometric device 1a according to the present embodiment, the photometric device 1b according to the first modification, and the photometric device 1c according to the second modification will be described.

  As shown in FIG. 12, the additional configuration 1 uses a light pipe bundle 300 formed by bundling a plurality of ultrafine light pipes 3 instead of the light pipe 3. FIG. 12 is an explanatory diagram for explaining the light pipe bundle 300. The light pipe bundle 300 has a structure in which a plurality of light pipes 3 are bundled and these are hardened with resin or the like. One end face of the light pipe bundle 300 is an incident end face 301 on which the light R is incident, and the other end face is an outgoing end face 302 that emits the light R.

  The incident end face 301 has a circular shape, and the outgoing end face 302 has a rectangular shape. Such a shape is realized by gradually twisting the light pipe bundle 300 from the incident end face 301 toward the outgoing end face 302. Since the shape of the emission end surface 302 is rectangular, the shape of the emission end surface 302 is a slit shape. Thereby, for example, the wavelength resolution of the polychromator 4 shown in FIG. 1 can be improved.

  For each of the plurality of light pipes 3 constituting the light pipe bundle 300, the light pipe is set so that an angle formed between the X direction or the Y direction and the direction of the normal N (FIG. 2) is 45 degrees. A bundle 300 is arranged.

  Since the light pipe bundle 300 includes a plurality of light pipes 3, the length L2 of one side of the cross section (square) of each light pipe 3 can be reduced. Therefore, the number of reflections on the side surface 32 of the light pipe 3 increases, and the depolarization effect can be further enhanced.

  The additional configuration 2 uses a diffusion plate or a birefringent crystal together with the light pipe 3. This will be described with reference to FIG. A diffusing plate or a birefringent crystal is disposed in the optical path between the exit end face 31 and the entrance aperture 40. According to the additional configuration 2, the depolarization effect can be further increased.

  In the additional configuration 3, all of the light R incident on the incident end face 30 (FIGS. 1, 8, and 10) of the light pipe 3 is totally reflected by the side surface 32 of the light pipe 3. This can be realized by appropriately setting the aperture diameter for the aperture stop of the objective lens 2. According to the additional configuration 3, the light amount loss in the light pipe 3 can be reduced.

  The additional configuration 4 includes a relay lens and a field stop. This will be described with reference to FIG. A relay lens is disposed in the optical path between the objective lens 2 and the incident end face 30 of the light pipe 3. The relay lens condenses the light R that has passed through the objective lens 2. An image plane formed by the objective lens 2 is formed between the objective lens 2 and the relay lens. A plurality of switchable field stops (each of the field stops having a different aperture size) is disposed at a position where the image plane is formed. According to the additional configuration 4, the measurement range of the measurement object 10 can be switched.

  In the additional configuration 5, a rectangular opening that shields a part of the emission end face 31 is disposed on the emission end face 31 (FIGS. 1 and 8) side of the light pipe 3. This rectangular opening is used as a slit. According to the additional configuration 5, the wavelength resolution of the polychromator 4 (FIG. 1) and the spectroscopic device 8 (FIG. 8) can be improved.

  In the additional configuration 6, a cylinder lens is disposed between the exit end face 31 and the entrance opening 40 of the light pipe 3 shown in FIG. 1 and between the exit end face 31 and the entrance opening 80 of the light pipe 3 shown in FIG. The size of the image of the emission end face 31 is adjusted by the cylinder lens. According to the additional configuration 6, the wavelength resolution of the polychromator 4 (FIG. 1) and the spectroscopic device 8 (FIG. 8) can be improved.

  The additional configuration 7 will be described using the photometric device 1a shown in FIG. In the additional configuration 7, a coat film 33 is formed on the entire surface of the four side surfaces 32 of the light pipe 3, as shown in FIG. The coating film 33 can be formed by vacuum vapor deposition, sputtering, or the like, as in a general optical thin film. The coat film 33 has a function of increasing the phase difference between the P-polarized component RP and the S-polarized component RS that are generated at the time of reflection on the side surface 32 of the light pipe 3. As described above, if the phase difference between the P-polarized component RP and the S-polarized component RS can be increased, the depolarization effect is increased. According to the additional configuration 7, the coat film 33 can increase the phase difference between the P-polarized component RP and the S-polarized component RS. Therefore, if the additional configuration 7 is added to the photometric device 1a, the depolarization effect can be further increased. The same applies to the photometric device 1b (FIG. 8) and the photometric device 1c (FIG. 10).

  If the length L1 of the light pipe 3 in the optical axis direction is increased, the phase difference between the P-polarized component RP and the S-polarized component RS can be increased, but the photometric device 1a is increased in size. According to the additional configuration 7, since the coat film 33 can increase the phase difference between the P-polarized component RP and the S-polarized component RS, even if the length L1 of the light pipe 3 in the optical axis direction is small (that is, the photometric device). Even if the size of 1a is reduced, a depolarization effect can be obtained. The same applies to the photometric device 1b (FIG. 8) and the photometric device 1c (FIG. 10).

  Hereinafter, the depolarization effect will be described by comparing a sample including the single-layer coat film 33, a sample including the three-layer coat film 33, and a sample not including the coat film 33. FIG. 14 is a table showing conditions for a sample including a single-layer coating film 33. The substrate corresponds to the light pipe 3. The material of the coat film 33 is ZrO2.

  In each case where the wavelength of light is 380 nm, 580 nm, and 780 nm, the phase difference between the P-polarized component RP and the S-polarized component RS was calculated for the sample including the single-layer coating film 33. The reason for setting the wavelengths to 380 nm, 580 nm, and 780 nm is that the measurement wavelength range of the photometric device is 380 to 780 nm. The calculation results are shown in FIG. FIG. 15 is a graph showing the relationship between the incident angle and the phase difference for the sample including the single-layer coating film 33. The horizontal axis of the graph is the incident angle of light, and the unit is degrees. The vertical axis of the graph is the phase difference between the P-polarized component RP and the S-polarized component RS, and the unit is degrees.

  A sample including the single-layer coat film 33 is compared with a sample not including the coat film 33 shown in FIG. Compared with the sample without the coating film 33, the sample with the single-layer coating film 33 has a P-polarized light in any of the cases where the incident angle is 80 to 90 degrees and the light wavelength is 380 nm, 580 nm, or 780 nm. It was found that the phase difference between the component RP and the S-polarized component RS has changed greatly. Therefore, when the length L1 of the light pipe 3 in the optical axis direction is the same, when the single-layer coating film 33 is formed on the side surface 32 of the light pipe 3, the coating film 33 is formed on the side surface 32 of the light pipe 3. It can be said that the depolarization effect is large as compared with the case where it is not formed.

  In order to increase the phase difference between the P-polarized component RP and the S-polarized component RS in the single-layer coat film 33, the refractive index of the coat film 33 (first layer) is set to the refractive index of the light guide member (substrate). It may be larger than the rate.

  FIG. 16 is a table showing the conditions of a sample having a three-layer coating film 33. The substrate corresponds to the light pipe 3. The coat film 33 includes a first layer formed on the substrate, a second layer formed on the first layer, and a third layer formed on the second layer. The material of the first layer is Al2O3. The material of the second layer is TiO2. The material of the third layer is MgF2.

  For each of the light wavelengths of 380 nm, 580 nm, and 780 nm, the phase difference between the P-polarized component RP and the S-polarized component RS was calculated for the sample having the three-layer coating film 33. The calculation results are shown in FIG. FIG. 17 is a graph showing the relationship between the incident angle and the phase difference for the sample including the three-layer coating film 33. The horizontal and vertical axes of the graph are the same as in FIG.

  The sample including the three-layer coating film 33 is compared with the sample including the single-layer coating film 33. When considering a sample including the single-layer coating film 33 shown in FIG. 15, when the incident angle is 80 to 90 degrees and the light wavelength is 380 nm and 780 nm, the phase difference changes rapidly. It was found that when the wavelength was 580 nm, the phase difference changed gradually. Therefore, it was found that the sample including the single-layer coating film 33 is not well balanced in the change of the phase difference when viewed over the entire wavelength (380 nm to 780 nm).

  On the other hand, when the sample including the three-layer coating film 33 shown in FIG. 17 is considered, the phase difference is obtained when the incident angle is 80 to 90 degrees and the light wavelength is 380 nm, 580 nm, or 780 nm. Was found to change rapidly. Therefore, it was found that the sample including the three-layer coating film 33 has a good balance of change in phase difference when viewed over the entire wavelength (380 nm to 780 nm). Therefore, when the three-layer coating film 33 is formed on the side surface 32 of the light pipe 3, the depolarization effect is improved as compared with the case where the single-layer coating film 33 is formed on the side surface 32 of the light pipe 3. Predictable to be high.

  As described above, the depolarization effect is greatest when the three-layer coating film 33 is formed on the side surface 32 of the light pipe 3, and the single-layer coating film 33 is formed on the side surface 32 of the light pipe 3. The case where the coating film 33 is not formed on the side surface 32 of the light pipe 3 can be predicted to be the next largest. In order to support this, the following simulation was performed.

  In this simulation, specific values indicating the depolarization effect were calculated for each of the sample with the single-layer coating film 33, the sample with the three-layer coating film 33, and the sample without the coating film 33. FIG. 18 is a schematic diagram illustrating a model of the photometric device 400 for calculating a specific value indicating the depolarization effect.

  The photometric device 400 includes a linearly polarizing plate 401, an objective lens 402, a light pipe 3, a collimating lens 403, a linearly polarizing plate 405, and a light receiver 406. The cross section of the light pipe 3 is as shown in FIG.

  The light emitted from the light source 406 to be measured is composed of linearly polarized light having various polarization directions. The light emitted from the light source 406 enters the linearly polarizing plate 401, and only linearly polarized light having a predetermined polarization direction passes through the linearly polarizing plate 401. The linearly polarized light transmitted through the linear polarizing plate 401 is incident on the incident end face 30 of the light pipe 3 collected by the objective lens 402. The light incident on the incident end face 30 is reflected by the side surface 32 of the light pipe 3 and emitted from the emission end face 31 as described in the photometric device 1a of the present embodiment.

  The light emitted from the emission end face 31 is converted into parallel light by the collimator lens 403. The parallel light enters the linear polarizing plate 404 and the light that has been transmitted through the linear polarizing plate 404 is received by the light receiver 405.

  The NA of the objective lens 402 is 0.2, the incident angle of light incident on the incident end face 30 is minus about 11.5 degrees to about 11.5 degrees, and the material of the light pipe 3 is quartz glass (refractive index n = 1.46), and the cross-sectional shape of the light pipe 3 is a square of 1 mm × 1 mm.

  For this model, θ was about 7.9 degrees, and the number of reflections calculated using equation (1) was as follows. When the length L1 of the light pipe 3 in the optical axis direction is 25 mm, 50 mm, 100 mm, and 200 mm, the number of reflections is 3.5 times, 6.9 times, 13.8 times, and 27.7 times, respectively. It was.

  When the transmission axis of the linear polarizing plate 404 was set in the Y direction and the linear polarizing plate 401 was rotated once, the variation in the amount of light received by the light receiver 405 was obtained. For example, FIG. 19 shows fluctuations in the amount of light when the single-layer coating film 33 is formed on the side surface 32 of the light pipe 3. The wavelength was 580 nm, and the length L1 of the light pipe 3 in the optical axis direction was 25 mm, 50 mm, 100 mm, and 200 mm. The horizontal axis of the graph indicates the rotation angle of the linearly polarizing plate 401, and the unit is degrees. The vertical axis of the graph is the relative value of the amount of light received by the light receiver 405. The variation in the amount of light became a curve that draws a cos curve with the rotation angle of the linear polarizing plate 401 at a cycle of 180 degrees.

In this light amount fluctuation, the maximum value of the light amount is set to max, and the minimum value of the light amount is set to min.
Depolarization effect = {(max−min) / (max + min)} × 100

  According to this equation, when the polarization is not eliminated at all (min = 0), the depolarization effect is 100%, and when the polarization is completely eliminated (max = min), the depolarization effect is 0%. .

  The length L1 of the light pipe 3 in the optical axis direction is set to 25 mm, 50 mm, 100 mm, and 200 mm, and the wavelength of light emitted from the light source 406 is set to 380 nm, 480 nm, 580 nm, 680 nm, and 780 nm. 3, when the single-layer coating film 33 is formed on the side surface 32 of the light pipe 3, or when the three-layer coating film 33 is formed on the side surface 32 of the light pipe 3. The depolarization effect was calculated. The conditions for the single-layer coating film 33 were the conditions shown in FIG. 14, and the conditions for the three-layer coating film 33 were the conditions shown in FIG.

  FIG. 20 is a table showing the depolarization effect when the coating film 33 is not formed on the side surface 32 of the light pipe 3. FIG. 21 is a table showing the depolarization effect when the single-layer coating film 33 is formed on the side surface 32 of the light pipe 3. FIG. 22 is a table showing the depolarization effect when the three-layer coating film 33 is formed on the side surface 32 of the light pipe 3.

  The results when the single-layer coating film 33 described in FIG. 19 is formed on the side surface 32 of the light pipe 3 are the values shown in the column of wavelength 580 nm in FIG. 21 (13.5%, 5 .6%, 2.7%, 1.5%).

  As can be seen from FIGS. 20 to 22, it was found that the depolarization effect increases as the length L1 of the light pipe 3 in the optical axis direction increases. Further, when the length L1 of the light pipe 3 in the optical axis direction is equal, the depolarization effect is greatest when the three-layer coating film 33 is formed on the side surface 32 of the light pipe 3, and the single-layer coating. It was found that the case where the film 33 was formed on the side surface 32 of the light pipe 3 was the next largest, and the case where the coat film 33 was not formed on the side surface 32 of the light pipe 3 was the next largest.

1a, 1b, 1c Photometric device 3 Light pipe 4 Polychromator 6 Diffraction grating 7 Linear array sensor 10 Measurement object 30 Entrance end face 31 Exit end face 32 Side face 33 Coat film 60 Engraving line R Light RP P polarization component RS S polarization component

Claims (8)

It has four side surfaces, and has a square or rectangular cross section when viewed from the traveling direction of the light with respect to the light emitted from the measurement object, and reflects the light on the four side surfaces. A light guide member disposed along a predetermined optical axis for guiding light;
A polarization-dependent processing unit that performs a predetermined process on the light guided by the light guide member;
A light receiving unit that receives the light subjected to the predetermined processing,
In the state where the light guide member is not arranged, the linearly polarized light incident on the processing unit along the predetermined optical axis is subjected to the predetermined processing by the processing unit, and the amount of light transmitted to the light receiving unit is maximum. When the vibration direction of the electric field of the linearly polarized light becomes the maximum direction, the angles formed by the maximum direction and the normal directions of the four side surfaces are 45 degrees, respectively. A light guide member is arranged ,
The light guide member is a light pipe or an optical fiber,
The light guide member has an incident end face on which the light emitted from the measurement object is incident without being separated into a P-polarized component and an S-polarized component, and the light incident from the incident end face is A photometric device characterized in that a phase difference is produced between the P-polarized component and the S-polarized component of the light by being totally reflected on a side surface and guided . The processing unit includes a diffraction grating that splits the light guided by the light guide member,
The diffraction grating has a structure in which a plurality of score lines extending in a first direction are arranged at intervals in a second direction orthogonal to the first direction;
The photometric device according to claim 1, wherein the light guide member is arranged so that an angle formed between the first direction and the normal direction is 45 degrees. The processing unit includes an incident surface on which the light guided by the light guide member is incident and an output surface from which the light is emitted, and includes a triangular prism that splits the light.
The entrance surface and the exit surface each include a first side orthogonal to the traveling direction of the light and a second side inclined with respect to the traveling direction of the light,
The photometric device according to claim 1, wherein the light guide member is arranged so that an angle formed by the normal line and the first side is 45 degrees. The processing unit includes a reflection / transmission surface that reflects a predetermined wavelength component of the light guided by the light guide member and transmits a wavelength component other than the predetermined wavelength component, and dichroic divides the light. With a prism,
The reflection / transmission surface includes a first side perpendicular to the traveling direction of the light and a second side inclined with respect to the traveling direction of the light,
The photometric device according to claim 1, wherein the light guide member is arranged so that an angle formed by the first side and the normal is 45 degrees. The photometric device according to any one of claims 1 to 4, wherein the light guide member has a linear shape and satisfies the following formula (1).


(Where, theta] p represents an arcsin (sinθ / np), L1 represents an optical axis direction of the length of the light guide member, L2, when the cross section is square, the length of one side of the square shown, when the cross section is rectangular, the length of the long side, theta, when the end face of the light guide member on the side where the light is incident on the light guide member and said entrance end face, the incident end face (The maximum value of the incident angle of the incident light is shown, and np is the refractive index of the light guide member.) Formed on four of the side, than when the light is incident on the light guide member, towards when the light is emitted from the light guide member is the said P-polarized component of the light S-polarized light component The photometric device according to any one of claims 1 to 5, further comprising a coat film that increases a phase difference between the first and second layers. The coating film is a single layer,
The photometric device according to claim 6, wherein a refractive index of the coating film is larger than a refractive index of the light guide member.   The photometric device according to any one of claims 1 to 7, wherein the light guide member is made of a transparent material and has a quadrangular prism shape or a truncated pyramid shape.