Spectrophotometer

Abstract

The spectroscopic measurement device (1) comprises: a collimating optical system (15) for collimating object light from a measurement point (a) of a sample (S); a photodetector (21) having a light receiving surface on which a plurality of pixels are arranged in a predetermined direction; a conjugate plane imaging optical system (11) disposed between the sample and the collimating optical system and used to form a surface optically conjugate with the surface of the sample; an amplitude type diffraction grating (13) disposed on the conjugate surface, the amplitude type diffraction grating (13) being obtained by providing a plurality of openings in a light shielding member, the light incident surface or the light exit surface of the light shielding member being formed of a material having a light shielding rate higher than the light shielding rate of silicon in the wavelength range of the object light; an optical path length difference imparting optical system (16) for splitting the collimated object light into a first light beam and a second light beam and imparting an optical path length difference; and an interference optical system (17) for causing the first light beam and the second light beam, to which the optical path length difference is imparted, to interfere with each other to form an interference image on the light receiving surface along the predetermined direction.

Description

Technical Field

[0001] The present invention relates to a spectrophotometric device. Background Art

[0002] It is known that there is a method for qualitatively or quantitatively determining the components (glucose, cholesterol, etc. in the blood) present in the inspected part of the organism by irradiating light to the inspected part of the organism to measure the spectral characteristics of the object light such as the transmitted light, diffused light, scattered light, etc. emitted from the inspected part as mid-infrared light. As a method for measuring the spectral characteristics of the object light, there is the following method: after the object light is made into a parallel beam by an objective lens, it is introduced into an optical system for imparting an optical path length difference, so that the object light is divided into two beams and an optical path difference is set between the two beams, so that the two beams interfere to obtain interference light, and the spectral characteristics are obtained according to the intensity change of the interference light relative to the optical path length difference of the two beams. As an optical system for imparting an optical path length difference, an optical system obtained by arranging a fixed mirror and a movable mirror is used in the past. The object light that becomes a parallel beam is reflected by these mirrors, so that the two beams interfere and the movable mirror is moved along the optical axis direction, thereby imparting an optical path length difference to the two beams (for example, Patent Document 1).

[0003] In addition, Patent Document 2 proposes a method of measuring the intensity change of interference light at one time without using a moving mechanism of a movable mirror.

[0004] In patent document 2, an optical system is provided with an optical path length difference composed of two flat mirrors (reference mirror and tilt mirror) arranged in an array and having different inclinations of the reflecting surfaces. The reference mirror and the tilt mirror are arranged in an array along an axis perpendicular to a plane including the traveling direction of the object light incident on the reference mirror and the traveling direction of the object light after being reflected by the reference mirror, and the reflecting surface of the tilt mirror rotates around the axis. The object light that becomes a parallel beam is reflected by the respective reflecting surfaces of the reference mirror and the tilt mirror, and is converged in the direction of the axis through the imaging optical system, and is converged on the same line segment perpendicular to the axis. On the line segment (imaging line segment), an interference image is formed based on the light reflected by the reference mirror (reference reflected light) and the light reflected by the tilt mirror (tilted reflected light). Since the reflecting surface of the tilt mirror is inclined relative to the reflecting surface of the reference mirror, a continuous optical path length difference corresponding to the angle formed by the two reflecting surfaces is generated between the reference reflected light and the tilt reflected light. Therefore, by detecting the light intensity change of the interference image on the imaging line segment, an interference pattern showing the intensity change of the interference light relative to the optical path length difference of the two light beams is obtained. The spectral characteristics of the object light can be obtained by Fourier transforming the interference pattern.

[0005] Patent documents 3 to 5 propose the use of an amplitude-type diffraction grating to improve the clarity of the interference image. In the spectroscopic measurement device described in Patent document 3, a conjugate plane imaging optical system is used to form a surface optically conjugate with the surface (object plane) of the sample, and an amplitude-type diffraction grating is arranged on the conjugate surface. The amplitude-type diffraction grating is obtained by periodically setting openings in a light shielding plate composed of, for example, a single crystal of silicon. It is expected that the clarity of the interference image will be improved by arranging these multiple openings in a direction parallel to the imaging line segment. In addition, Patent document 4 describes that the clarity of the interference light is improved by setting multiple openings at a predetermined period in a direction perpendicular to the above-mentioned imaging line segment. And, Patent document 5 describes that in a spectroscopic measurement device using a fixed mirror and a movable mirror as described in Patent document 1, the clarity of the interference light is improved by using an amplitude-type diffraction grating with openings similar to Patent document 4.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2008-309706

[0009] Patent Document 2: International Publication No. 2012 / 033096

[0010] Patent Document 3: International Publication No. 2021 / 044979

[0011] Patent Document 4: International Publication No. 2017 / 007024

[0012] Patent Document 5: Japanese Patent Application Publication No. 2016-142522 Summary of the invention

[0013] Problem that the invention aims to solve

[0014] However, it is known that even if an interference image is formed from object light of a sample using a spectroscopic measurement apparatus such as those described in Patent Documents 3 to 5, the clarity of the interference light is not necessarily sufficiently high.

[0015] The problem to be solved by the present invention is to improve the clarity of the interference image of object light emitted from a sample as mid-infrared light.

[0016] Solutions for solving problems

[0017] The spectrophotometer according to the present invention, which has been made to solve the above-mentioned problems, is characterized by comprising:

[0018] a collimating optical system that collimates object light emitted from a measurement point on the surface of the sample;

[0019] A photodetector having a light receiving surface on which a plurality of pixels are arranged in a linear manner;

[0020] A conjugate surface imaging optical system, which is disposed between the sample and the collimating optical system and is used to form a surface optically conjugate with the surface of the sample between the collimating optical system;

[0021] an amplitude-type diffraction grating disposed on the conjugate surface, the amplitude-type diffraction grating being formed by providing a plurality of openings in a light-shielding member, wherein the light-shielding member has a light-exiting surface for emitting the object light, the light-exiting surface being formed of a material having an emissivity lower than that of silicon, and / or the light-exiting surface being formed of a material having a reflectivity higher than that of silicon in a wavelength range of the object light, and an anti-reflection process being applied to the light-exiting surface;

[0022] an optical path length difference imparting optical system that splits the object light collimated by the collimating optical system into a first light beam and a second light beam and imparts an optical path length difference between the first light beam and the second light beam; and

[0023] The interference optical system causes the first light beam and the second light beam, to which the optical path length difference is given by the optical path length difference giving optical system, to interfere with each other, thereby forming an interference image on the light receiving surface.

[0024] Regarding the amplitude type diffraction grating, the entire amplitude type diffraction grating may be composed of a material having a light shielding rate higher than that of silicon in the wavelength range of the object light, or only the light incident surface or the light exit surface may be formed of a material having a light shielding rate higher than that of silicon in the wavelength range. Furthermore, both the light incident surface and the light exit surface may be formed of a material having a light shielding rate higher than that of silicon.

[0025] The fact that the object light cannot be completely blocked by the light shielding portion of the amplitude grating and a part of the object light passes through the light shielding portion is considered to be one of the factors that cause the sharpness of the interference light to be low in the spectrophotometric measuring devices described in Patent Documents 3 to 5. In particular, when the wavelength range of the object light is in the infrared region, more of the object light passes through the light shielding portion.

[0026] Therefore, in the spectrophotometric measuring device involved in the present invention, an amplitude type diffraction grating is used in which an opening is set in a light shielding member formed of a material whose light absorptivity and reflectivity in the wavelength range of the object light are higher than the absorptivity and reflectivity of silicon. As a material whose light absorptivity is higher than the absorptivity of silicon, for example, quartz glass and various organic compounds are cited. In addition, as a material whose light reflectivity is higher than the reflectivity of silicon, for example, aluminum and gold are cited. In addition, it is not limited to pure metals, and any metal can be used as long as it has free electrons. For example, a material composed of stainless steel or the like can also be used.

[0027] In addition, the spectrophotometer according to the present invention can adopt the following structure:

[0028] The shading component comprises: a reflecting component, which is arranged on the light incident surface side and is composed of a material whose reflectivity of light in the wavelength range of the object light is higher than the reflectivity of silicon; and an absorbing component, which is arranged on the light emitting surface side and is composed of a material whose absorptivity of light in the wavelength range of the object light is higher than the absorptivity of silicon.

[0029] When the wavelength range of the object light is in the infrared region, a light shielding member (absorption member) composed of quartz glass with a thickness of about 0.1 mm is generally used, thereby being able to absorb the object light incident on the light shielding portion. However, when the intensity of the object light increases, it is difficult for the light shielding member composed only of quartz glass to completely absorb the object light incident on the light shielding portion. In the above-mentioned spectrophotometric measuring device, a reflection member is arranged on the light incident surface side of the absorption member, and the object light is reflected by the reflection member, so that the object light passing through the light shielding portion of the light shielding member can be further reduced.

[0030] In addition, the spectrophotometer according to the present invention can adopt the following structure:

[0031] A reinforcing member is further provided, the reinforcing member being used to reinforce the light shielding member.

[0032] As described above, when the wavelength range of the object light is in the infrared region, a shading member made of quartz glass with a thickness of about 0.1 mm is usually used, thereby absorbing the object light incident on the shading portion. However, such a thin member is easily damaged due to insufficient strength, and operation becomes difficult. In the above-mentioned spectrophotometric measurement device, sufficient strength can be achieved by providing a reinforcing member. In addition, the reinforcing member can adopt any shape as long as it can improve the strength of the shading member. Specifically, for example, it can be a member provided with a plurality of openings like the shading member, or it can be a frame-shaped member that reinforces the periphery of the shading member.

[0033] In the spectrophotometer according to the present invention,

[0034] Preferably, when the light emitting surface of the light shielding member is formed of a material having a reflectivity higher than that of silicon in the wavelength range of the object light, the light emitting surface is subjected to an anti-reflection process.

[0035] In the anti-reflection processing, various structures can be used, such as a structure in which a large number of structures below the wavelength of object light are arranged (sub-wavelength structure), a structure obtained by performing sandblasting to make the light emitting surface a rough surface, and a structure obtained by setting an inclination on the light emitting surface to suppress direct reflection generated by the light emitting surface.

[0036] There are thermal photodetectors and quantum photodetectors for measuring mid-infrared rays. In thermal photodetectors, a material having a resistance that depends on temperature is used, and mid-infrared rays as the measurement object are incident on the material, and the intensity of the mid-infrared rays is measured by measuring the resistance value of the material. On the other hand, in quantum photodetectors, incident mid-infrared rays are photoelectrically converted to generate electrical signals for detection. Quantum photodetectors have higher sensitivity than thermal photodetectors, but on the other hand, they require a cooling mechanism for suppressing the generation of thermal noise, and are therefore generally expensive. Therefore, in conventional spectrophotometric measurement devices, thermal photodetectors are used more frequently in order to suppress the cost of the device. However, in thermal photodetectors, incident mid-infrared rays are thermally coupled to the sensor to generate heat, and therefore, radiated light is generated due to the heat. The fact that the radiated light is reflected by the amplitude-type diffraction grating and then incident on the photodetector again also becomes a factor that reduces the clarity of the interference image. In particular, when the light exit surface is formed of a material with high reflectivity such as metal as described above, light emitted from the light detector is directly reflected by the light exit surface and then enters the light detector again. In the above-mentioned spectrophotometric measuring device, by using an amplitude-type diffraction grating that has been subjected to anti-reflection processing on the light exit surface, the clarity of the interference light can be improved compared to the past.

[0037] Effects of the Invention

[0038] By using the spectroscopic measurement device according to the present invention, the clarity of the interference image of object light can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic structural diagram of Example 1 of the spectrophotometer according to the present invention.

[0040] Figure 2 This is a top view of the spectrophotometer of Example 1.

[0041] Figure 3 This is a diagram showing the structure of a multi-slit of the spectroscopic measurement device of Example 1.

[0042] Figure 4 This is a diagram showing the arrangement of pixels of a two-dimensional detector of the spectrophotometer of Example 1.

[0043] Figure 5 This is a diagram showing the results of an experiment using a conventional spectrophotometer.

[0044] Figure 6 This is an image acquired in an experiment using a conventional spectrophotometer.

[0045] Figure 7 This is a diagram showing the results of measuring the change in contrast of the interference image with respect to the temperature of the sample while changing the orientation of the slit.

[0046] Figure 8 It is a schematic structural diagram of Example 2 of the spectrophotometer according to the present invention.

[0047] Fig. 9 It is a top view of the spectrophotometer of Example 2.

[0048] Fig.10 It is a side view of the spectrophotometer of Example 2.

[0049] Fig.11 This is a diagram showing the structure of a two-dimensional slit of a spectroscopic measurement device according to Example 2.

[0050] Fig.12 It is a schematic structural diagram of Example 3 of the spectrophotometer according to the present invention.

[0051] Fig.13 This is a diagram showing the structure of a phase shifter of the spectroscopic measurement device of the second embodiment.

[0052] Fig.14 It is a diagram showing the structure of a two-dimensional slit according to a modified example.

[0053] Fig.15 It is a diagram for explaining an embodiment of an amplitude type diffraction grating of a spectrometer according to the present invention. DETAILED DESCRIPTION

[0054] Several preferred embodiments of the spectrophotometer according to the present invention will be described below with reference to the accompanying drawings.

[0055] (Example 1)

[0056] exist Figure 1 Schematic diagram of the structure of the spectrophotometer 1 according to the first embodiment is shown in FIG. Figure 21 is a top view of the spectroscopic measuring device 1. The spectroscopic measuring device 1 includes an imaging lens 11, a multi-slit 13, an objective lens 15, a phase shifter 16, an imaging lens 17, and a two-dimensional detector 18 in the order close to the sample S. In the spectroscopic measuring device 1 of Example 1, a conjugate plane imaging optical system is formed between the sample S, the imaging lens 11, and the multi-slit 13. In addition, an imaging type two-dimensional Fourier spectroscopic optical system is formed between the multi-slit 13, the objective lens 15, the phase shifter 16, the imaging lens 17, and the two-dimensional detector 18. The spectroscopic measuring device 1 also includes a control / processing unit 25, which has the functions of a calculation unit and a processing unit. The calculation unit obtains an interference pattern based on the detection signal of the two-dimensional detector 18, mathematically performs Fourier transformation on the interference pattern to obtain the spectral characteristics (spectrum) of the relative intensity of each wavelength of the radiated light, and the processing unit images the calculation result of the calculation unit, etc.

[0057] Light (object light) emitted in various directions from a large number of measurement points arranged on the surface of the sample S is converged by the imaging lens 11 to the position of the multi-slit 13. The surface of the imaging lens 11 that is optically conjugate with the surface of the sample S is formed at the position of the multi-slit 13. The imaging lens 11 is equivalent to the conjugate surface imaging optical system in the present invention. Figure 2 In FIG. 1 , one measurement point among a large number of measurement points is shown as measurement point a1.

[0058] The phase shifter 16 is arranged at an angle of about 45° relative to the optical axis of the incident object light, and has a fixed mirror portion 16a and a movable mirror portion 16b arranged at the upper and lower parts in the vertical direction. The movable mirror portion 16b is moved in the direction indicated by the arrow by a driving mechanism not shown in the figure. The fixed mirror portion 16a and the movable mirror portion 16b can also be arranged on either side of the upper or lower side, but here, the movable mirror portion 16b is arranged on the upper side and the fixed mirror portion 16a is arranged on the lower side. The fixed mirror portion and the movable mirror portion can also be arranged on the left and right, but in this case, when the movable mirror portion is moved significantly, there is a situation where the fixed mirror portion is in the shadow of the movable mirror portion, resulting in the light toward the two-dimensional detector being blocked, so it is preferably arranged in the upper and lower directions. The phase shifter 16 is equivalent to the optical path length difference imparting optical system in the present invention.

[0059] The imaging lens 17 interferes the object light reflected by the fixed mirror portion 16a and the movable mirror portion 16b and converges the object light onto the light receiving surface of the two-dimensional detector 18. The imaging lens 17 corresponds to the interference optical system in the present invention.

[0060] The multi-slit 13 is equivalent to the amplitude-type diffraction grating in the present invention. The multi-slit 13 is obtained by etching a single crystal of silicon to form an opening 132, forming a sub-wavelength structure (SWC) in which quadrangular pyramid-shaped protrusions 133 are arranged at a period less than the wavelength of the object light emitted from the sample S, and evaporating gold on the surface. Figure 3 As shown in FIG. 1 , in the multi-slit 13, a plurality of strip-shaped openings 132 are periodically arranged in one direction (first axis direction) of a rectangular plate-shaped substrate 131 having light-shielding properties for the mid-infrared light to be measured. In addition, a cooling member 14 (see FIG. 1 ) for cooling the multi-slit 13 is arranged on the side periphery of the multi-slit 13. Figure 2 .exist Figure 1 and Figure 3 As the cooling member 14, for example, a Peltier element or a member having a flow path for circulating a refrigerant fluid therein can be used.

[0061] Similar to the spectrometers described in Patent Documents 4 and 5, the length W1 of the opening 132 in the first axis direction and the period L1 of the adjacent openings 132 in the first axis direction are designed to satisfy the following equations (1) and (2), respectively.

[0062] W1=P1×2 / (m+1)…(1)

[0063] L1=P1×2 / m…(2)

[0064] Here, P1 is the interval between pixels 181 in the first axis direction of the two-dimensional detector 18 , and m is the optical magnification of the optical system composed of the multi-slit 13 , the objective lens 15 , the phase shifter 16 , the imaging lens 17 , and the two-dimensional detector 18 .

[0065] In the cross section including the vertical axis of the phase shifter 16, the object light is irradiated to the fixed mirror portion 16a and the movable mirror portion 16b, but in the cross section including the horizontal axis, the object light is irradiated only to the fixed mirror portion 16a or the movable mirror portion 16b. That is, when viewed in the cross section including the vertical axis, the optical path length difference changes and the interference intensity changes with the movement of the movable mirror portion 16b, but when viewed in the cross section including the horizontal axis, there is no optical path length difference and the interference intensity does not change. Therefore, in Example 1, a multi-slit 13 having a combination of an opening portion and a light shielding portion that cancel each other out for eliminating the phase between bright spots (measurement points) is arranged in the vertical axis direction (first axis direction).

[0066] like Figure 4As shown, the two-dimensional detector 18 is composed of a plurality of pixels arranged in a grid shape (a period P1 in the first axis direction and a period P2 in the second axis direction. In the present embodiment, P1=P2). The two-dimensional detector 18 is a thermal photodetector. A thermal photodetector converts the heat generated by thermally coupling the incident mid-infrared rays with the sensor into an electrical signal for detection. Specifically, thermal detectors include, for example, microbolometer array sensors. In order to prevent the radiated light caused by the heat generated inside the two-dimensional detector 18 from being emitted to the outside, a cooling member 19 (in Figure 1 and Figure 4 As the cooling member 19, for example, a Peltier element or a member having a flow path for circulating a refrigerant fluid inside can be used.

[0067] The processing unit 25 obtains an interference pattern from the light intensity distribution of the interference image obtained by the two-dimensional detector 18, and acquires a spectrum at the measurement point by Fourier transforming the interference pattern.

[0068] In the spectroscopic measurement device 1 of the first embodiment, object light emitted from a large number of measurement points located on the surface of the sample S is condensed by the imaging lens 11 to the position of the multi-slit 13. The object light that has passed through the opening 132 of the multi-slit 13 is collimated by the objective lens 15 and then incident on the fixed mirror portion 16a and the movable mirror portion 16b of the phase shifter 16. In the first embodiment, the movable mirror portion 16b is moved, thereby giving an optical path length difference between the object light reflected by the fixed mirror portion 16a and the object light reflected by the movable mirror portion 16b, and an image is formed on the light receiving surface of the two-dimensional detector 18 through the imaging lens 17.

[0069] exist Figure 2 In order to illustrate the optical path of the object light in an easy-to-understand manner, only the optical path of the object light emitted from a measuring point a1 on the surface of the sample S is shown. However, in fact, interference light is formed by the object light emitted from multiple measuring points a two-dimensionally distributed on the surface of the sample S, and the interference light is incident on each light receiving element two-dimensionally arranged on the light receiving surface of the two-dimensional detector 18.

[0070] In particular, the spectrophotometric device 1 of the first embodiment is characterized by a structure of a multi-slit 13 (a structure in which a sub-wavelength structure is formed on a surface facing a detector and gold is vapor-deposited), a cooling member 14 for cooling the multi-slit 13, and a cooling member 19 for cooling a light-receiving surface of a two-dimensional detector 18. The spectrophotometric device 1 of the first embodiment has all three structures as a preferred specific embodiment of the present invention, but a structure having only a part of these three features may be adopted.

[0071] Here, the above three features are explained.

[0072] In order to investigate the factors that caused the sharpness of the interference image to not increase in the conventional spectrophotometric device, the inventors of the present invention conducted the following experiment: after heating or cooling a black body to a plurality of different temperatures at room temperature, the radiation emitted from the black body at each temperature was measured to confirm the change in the brightness amplitude of the interference image. The magnitude of the brightness amplitude is equivalent to the height of the center burst in the interference pattern. As a conventional spectrophotometric device, a device having a structure obtained by removing the above three features from the spectrophotometric device 1 of the above-mentioned embodiment was used.

[0073] Figure 5 is a graph showing the results of the above experiment. As shown in the graph, in the conventional spectrophotometer, the brightness amplitude of the interference light obtained when the black body is heated to about 35°C, which is close to room temperature, becomes extremely small. In addition, when a gas cell filled with DME gas is placed on the surface of the cold storage material and a mid-infrared image of the surface of the cold storage material is captured, as shown in FIG. Figure 6 As shown in FIG. 1 , the brightness at the position of the light shielding portion is higher than the brightness at the position of the opening portion. It can be considered that, Figure 5 and Figure 6 The results shown suggest that light of the same magnitude as that of radiation from a black body heated to approximately 35° C. enters the two-dimensional detector from the light shielding portion of the slit, and a portion of the light is radiation from the slit.

[0074] The following describes an experiment conducted to confirm in more detail the light incident from the light shielding portion of the slit. In this experiment, a slit made by evaporating gold on the surface of a silicon single crystal was used, and a structure ( Figure 7 The above-mentioned usual case) and the structure in which the gold vapor deposition surface is arranged on the sample S side (light incident surface) ( Figure 7 In each structure of the pseudo-invisible multi-slit) described above, the brightness amplitude of the interference light emitted from the black body heated to multiple different temperatures is measured.

[0075] exist Figure 7 The results of the above experiment are shown in FIG. Figure 7As shown in the figure, it can be seen that in the structure where the gold vapor deposition surface is arranged on the two-dimensional detector side, the contrast becomes minimum when the temperature of the black body is heated to 35°C. On the contrary, in the structure where the gold vapor deposition surface is arranged on the sample S side, the contrast becomes minimum when the temperature of the black body is 25°C. When the material of the slit used to constitute the surface facing the two-dimensional detector is changed, the temperature at which the brightness amplitude becomes minimum changes. Since the emissivity (radiance) of gold is lower than that of silicon, in the case of only radiated light from the slit, for the structure where the gold vapor deposition surface is arranged toward the two-dimensional detector side, the light incident on the two-dimensional detector should be less, and the temperature at which the brightness amplitude becomes minimum should be lower. However, in fact, as described above, when the gold vapor deposition surface is arranged toward the two-dimensional detector side, the temperature at which the brightness amplitude becomes minimum is higher. When considering that the light reflectivity of silicon is lower than that of gold and that a thermal type two-dimensional detector is used as the two-dimensional detector, it can be considered that the radiant light caused by the heat generated inside the two-dimensional detector is reflected by the light shielding portion of the slit and it enters the two-dimensional detector again, which is another factor of the light emitted from the slit.

[0076] As described above, the light radiated from the substrate of the slit and the light emitted from the two-dimensional detector and reflected by the light shielding portion of the slit are considered to be factors for the light emitted from the light shielding portion of the slit. In the spectrophotometric measurement device 1 of Example 1, as the substrate 131 of the multi-slit 13, a substrate with gold vapor-deposited on the surface on the two-dimensional detector 18 side is used, thereby reducing the emissivity (suppressing the radiation light of the slit itself) compared with a substrate composed of a single crystal of silicon. In addition, a sub-wavelength structure (SWC) formed by arranging convex portions 133 at a period less than the wavelength of the object light emitted from the sample S is formed on the surface, thereby reducing the reflectivity (reflection of the radiation light from the two-dimensional detector 18). In addition, by cooling the multi-slit 13 using the cooling member 14, the radiation light of the multi-slit 13 itself is further suppressed. In addition, by cooling the light receiving surface of the two-dimensional detector 18 using the cooling member 19, the radiation light caused by the heat generated inside the two-dimensional detector 18 is also suppressed. By using at least part of these features, the clarity of the interference light can be improved compared with the conventional spectrophotometric measurement device. For example, a structure may be adopted in which the reflection of the radiated light from the two-dimensional detector 18 is reduced by using the pseudo-invisible multi-slit instead of the multi-slit 13 of the first embodiment, and the radiated light of the slit itself is suppressed by cooling the multi-slit 13 with the cooling member 14 .

[0077] (Example 2)

[0078] The spectrophotometer 100 of Example 2 is also used to obtain the spectroscopic spectrum of mid-infrared light emitted from the sample as the analysis object, similarly to Example 1. In the spectrophotometer 100 of Example 2, the interference pattern of object light emitted from each measurement point a1 distributed along the first axis direction on the surface of the sample S is obtained.

[0079] exist Figure 8 Schematic diagram of the structure of the spectrophotometer 100 according to the second embodiment is shown in FIG. Fig. 9 and Fig.10 1 and 2 are a top view and a side view of the spectrophotometer 100. The spectrophotometer 100 includes an imaging lens 111, a two-dimensional slit 113, an objective lens 115, a phase shifter 116, a cylindrical lens 117, and a two-dimensional detector 118 in the order close to the sample S. In addition, the spectrophotometer 100 includes a control / processing unit 125, which has the functions of a calculation unit and a processing unit. The calculation unit obtains an interference pattern based on the detection signal of the two-dimensional detector 118, mathematically performs Fourier transformation on the interference pattern to obtain the spectral characteristics (spectrum) of the relative intensity of each wavelength of the radiated light, and the processing unit images the calculation results of the calculation unit.

[0080] Object light emitted in various directions from each measuring point arranged on the surface of the sample S is converged by the imaging lens 111 to the position of the two-dimensional slit 113. A surface of the imaging lens 111 that is optically conjugate with the surface of the sample S is formed at the position of the two-dimensional slit 113. The imaging lens 111 is equivalent to the conjugate surface imaging optical system in the present invention.

[0081] The two-dimensional slit 113 is equivalent to the amplitude-type diffraction grating in the present invention. Fig.11 As shown in the front view and the side view in FIG, in the two-dimensional slit 113, a plurality of openings 1132 are periodically arranged along two orthogonal directions (first axis direction and second axis direction) of a rectangular plate-shaped substrate 1131 having light shielding properties for mid-infrared light to be measured. In the first axis direction, similar to the spectrophotometric measurement apparatus described in Patent Documents 4 and 5, the length W1 of the opening 1132 in the first axis direction and the period L1 of the adjacent openings 1132 in the first axis direction are designed to satisfy the following equations (1) and (2), respectively.

[0082] W1=P1×2 / (m+1)…(1)

[0083] L1=P1×2 / m…(2)

[0084] Here, P1 is the pixel spacing in the first axis direction of the two-dimensional detector 118 , and m is the optical magnification of the optical system composed of the two-dimensional slit 113 , the objective lens 115 , the phase shifter 116 , the cylindrical lens 117 , and the two-dimensional detector 118 .

[0085] In the second axis direction, similar to the spectrophotometer described in Patent Document 3, the length W2 of the opening 1132 in the second axis direction and the period L2 of adjacent openings 1132 in the second axis direction are designed to satisfy the following equations (3) and (4).

[0086] W2={(λ C ×f) / 2×Δλ×h}×P2…(3)

[0087] L2=2×{(λ C ×f) / 2×Δλ×h}×P2…(4)

[0088] Here, λ C is the wavelength contained in the object light, f is the focal length of the objective lens 115, Δλ is the difference in optical path length between a first beam of object light that has passed through the first transmission section 116a (hereinafter referred to) and a second beam of object light that has passed through the second transmission section 116b (hereinafter referred to) and is incident on adjacent pixels in the second axis direction in the two-dimensional detector 118, and h is the distance from the phase shifter 116 to the light receiving surface of the two-dimensional detector 118. By providing the openings 1132 that satisfy the above-mentioned equations (3) and (4), the phases of the object light that has passed through the adjacent openings 1132 are made consistent.

[0089] The two-dimensional slit 113 in the second embodiment is obtained in the same manner as the slit 13 in the first embodiment: the opening 1132 is formed by etching a single crystal of silicon, such as Fig.11 As shown in the figure, a sub-wavelength structure (SWC) is formed by arranging quadrangular pyramidal protrusions 1133 at a period less than the wavelength of the object light emitted from the sample S, and gold is evaporated on the surface. The surface on which the protrusions 1133 are formed is arranged on the side of the two-dimensional detector 118. In addition, a cooling member 114 (at the periphery of the two-dimensional slit 113) for cooling the two-dimensional slit 113 is installed. Figures 9 to 11 As the cooling member 114, for example, a Peltier element similar to that in the first embodiment or a member having a flow path for circulating a refrigerant fluid therein can be used.

[0090] The objective lens 115 collimates the light that has passed through the opening 1132 of the two-dimensional slit 113. The objective lens 115 corresponds to the collimating optical system in the present invention.

[0091] The phase shifter 116 is composed of a first transmission part 116a and a second transmission part 116b made of a material that is transmissive to mid-infrared light, and the two are arranged in a row in the second axis direction. The first transmission part 116a is an optical component in the shape of a rectangular plate with a fixed thickness, in which the light incident surface is parallel to the light exit surface. The second transmission part 116b is an optical component in the shape of a trapezoid when viewed from above, in which the thickness continuously changes along the second axis, and has a light incident surface inclined relative to the light incident surface of the first transmission part 116a, and a light exit surface on the same plane as the light exit surface of the first transmission part 116a. The phase shifter 116 is equivalent to the optical system for imparting optical path length difference in the present invention.

[0092] The cylindrical lens 117 is a semi-cylindrical member made of a material that is transmissive to mid-infrared light. The cylindrical lens 117 is configured with the convex side facing the phase shifter 116 side and the flat surface facing the two-dimensional detector 118 side, and the semi-circular cross section is located at a position orthogonal to the second axis. The cylindrical lens 117 is equivalent to the interference optical system in the present invention.

[0093] The two-dimensional detector 118 is similar to the first embodiment, and is composed of a plurality of pixels arranged in a grid pattern (a period P1 in the first axis direction and a period P2 in the second axis direction. In this embodiment, P1=P2). In the second embodiment, a thermal photodetector is used as the two-dimensional detector 118, similar to the first embodiment. In order to prevent the radiation light generated by the heat inside the two-dimensional detector 118 from being emitted to the outside, a cooling member 119 (at the Fig. 9 and Fig.10 As the cooling member 119, for example, a Peltier element similar to that in the first embodiment or a member having a flow path for circulating a refrigerant fluid inside can be used.

[0094] The control / processing unit 125 obtains an interference pattern from the light intensity distribution of the interference image obtained by the two-dimensional detector 118 , and acquires a spectrum at the measurement point by Fourier transforming the interference pattern.

[0095] In the spectrophotometric measurement device 100 of the second embodiment, object light as mid-infrared light emitted from a measurement point a1 located on the surface of the sample S is condensed by the imaging lens 111 to the position of the two-dimensional slit 113. The object light having passed through the opening 1132 of the two-dimensional slit 113 is collimated by the objective lens 115 and is incident on the first transmission section 116a and the second transmission section 116b of the phase shifter 116. As described above, the light incident surface of the second transmission section 116b is inclined relative to the light incident surface of the first transmission section 116a, and the light exit surfaces of the first transmission section 116a and the second transmission section 116b are located on the same plane, so that a continuous optical path length difference is given along the second axis between the object light (first light beam) having passed through the first transmission section 116a and the object light (second light beam) having passed through the second transmission section 116b. The object light that has passed through the first transmission portion 116 a and the object light that has passed through the second transmission portion 116 b are condensed in the first axis direction by the cylindrical lens 117 , and are imaged on the light receiving surface of the two-dimensional detector 118 as linear interference images along the second axis.

[0096] exist Figure 8 to Figure 10 In order to show the optical path of the object light in an easily understandable manner, only the optical path of the object light emitted from one measuring point a1 on the surface of the sample S is shown, but in fact, according to the object light emitted from a plurality of measuring points arranged in the first axis direction with respect to the measuring point a1, linear interference images are formed in the first axis direction on the light receiving surface of the two-dimensional detector 118. Therefore, in the spectroscopic measurement device 100 of the second embodiment, the interference images formed by the object light emitted from a plurality of measuring points arranged along the first axis on the surface of the sample S can be detected simultaneously by the two-dimensional detector 118.

[0097] Similar to the first embodiment, the spectrophotometric device 100 of the second embodiment also has the features of: the structure of the two-dimensional slit 113, the cooling member 114 for cooling the two-dimensional slit 113, and the cooling member 119 for cooling the two-dimensional detector 118. Therefore, the sharpness of the interference image can be improved in the same manner as in the first embodiment. The spectrophotometric device 100 of the second embodiment also has all these three structures as another preferred specific form of the present invention, but a structure having only a part of these three features can also be adopted. For example, the following structure can be adopted: by replacing the two-dimensional slit 113 of the second embodiment with a pseudo-invisible multi-slit having openings two-dimensionally provided in the same manner as the two-dimensional slit 113, the reflection of the radiated light from the two-dimensional detector 118 is reduced, and by cooling the two-dimensional slit 113 with the cooling member 114, the radiated light of the slit itself is suppressed.

[0098] (Example 3)

[0099] The spectroscopic measurement device 200 of Example 3 acquires an interference pattern of object light emitted from a measurement point a1 on the surface of a sample S.

[0100] exist Fig.12 2 shows a schematic structure of a spectrophotometric device 200 of Example 3. The spectrophotometric device 200 includes an imaging lens 211, a two-dimensional slit 213, an objective lens 215, a phase shifter 216, and a two-dimensional detector 218 in the order close to the sample S. In addition, the control / processing unit 225 is provided. The control / processing unit 225 has the functions of a calculation unit and a processing unit. The calculation unit obtains an interference pattern based on the detection signal of the two-dimensional detector 218, mathematically performs Fourier transformation on the interference pattern to obtain the spectral characteristics (spectrum) of the relative intensity of each wavelength of the radiated light, and the processing unit images the calculation results of the calculation unit.

[0101] Object light emitted in various directions from each measurement point arranged on the surface of the sample S is converged by the imaging lens 211 to the position of the two-dimensional slit 213. A surface of the imaging lens 211 that is optically conjugate with the surface of the sample S is formed at the position of the two-dimensional slit 213. The imaging lens 211 is equivalent to the conjugate surface imaging optical system in the present invention.

[0102] The two-dimensional slit 213 corresponds to the amplitude type diffraction grating in the present invention. The two-dimensional slit 213 is obtained by two-dimensionally arranging openings, similarly to the two-dimensional slit 113 of Example 2, and a cooling member 214 is attached to the side periphery thereof.

[0103] The objective lens 215 collimates the light that has passed through the opening 1132 of the two-dimensional slit 213. The objective lens 215 corresponds to the collimating optical system in the present invention.

[0104] The phase shifter 216 is equivalent to the optical path length difference imparting optical system and the interference optical system in the present invention. The phase shifter 216 has a reference mirror 216a and a tilt mirror 216b. The reference mirror 216a and the tilt mirror 216b are arranged in a vertical direction (x-axis direction). The tilt mirror 216b is arranged so that its reflection surface is parallel to a virtual surface obtained by rotating the reflection surface of the reference mirror 216a around the x-axis by a specified angle θx and around an axis (y-axis) in the horizontal direction by a specified angle θy. As a result, the reflection surface of the tilt mirror 216b is tilted relative to the reflection surface of the reference mirror 216a in the y-axis direction and the z-axis direction.

[0105] When θx=α° and θy=β°, the traveling direction of the inclined reflected light is offset by 2α° in the y-axis direction relative to the traveling direction of the reference reflected light by tilting in the y-axis direction (rotation around the x-axis), and an optical path length difference is generated between the reference reflected light and the inclined reflected light according to the offset angle. In addition, the traveling direction of the inclined reflected light is tilted in the z-axis direction by tilting in the z-axis direction (rotation around the y-axis), and the inclined reflected light intersects with the reference reflected light at a position away from the phase shifter 216 by a predetermined distance. The distance from the phase shifter 216 to the position where the two reflected lights intersect is determined by the angle θy=β°, and the light receiving surface of the detector 218 is arranged at such a position.

[0106] The two-dimensional detector 218 is the same as in Examples 1 and 2, in that a plurality of pixels are arranged in a grid pattern (a period P1 in the first axis direction and a period P2 in the second axis direction. In the present embodiment, P1=P2). In Example 3, as in Examples 1 and 2, a thermal photodetector is used as the two-dimensional detector 218. In order to prevent the radiation light caused by the heat generated inside the two-dimensional detector 218 from being emitted to the outside, a cooling member is used to cool the light-receiving surface. As the cooling member 219, for example, a Peltier element similar to that in Examples 1 and 2 or a member having a flow path for circulating a refrigerant fluid inside can be used.

[0107] The processing unit 225 obtains an interference pattern from the light intensity distribution of the interference image obtained by the two-dimensional detector 218, and acquires a spectrum of the measurement point by Fourier transforming the interference pattern.

[0108] In the spectrophotometric measuring device 200 of the third embodiment, the object light as the mid-infrared light emitted from a measuring point a1 located on the surface of the sample S is converged by the imaging lens 211 to the position of the two-dimensional slit 213. The object light that has passed through the opening of the two-dimensional slit 213 is collimated by the objective lens 215 and then incident on the reference mirror 216a and the tilt mirror 216b of the phase shifter 216. The object light reflected by the reference mirror 216a and the object light reflected by the tilt mirror 216b are incident on the light receiving surface of the two-dimensional detector 218 in a planar shape, and a part of each incident area overlaps. As described above, since there is a difference in optical path length between the reference reflected light and the tilted reflected light, an interference image is formed in the area (overlapping area DA) where the light reflected by the two mirrors overlaps and is incident. Therefore, the interference pattern of the measuring point a1 can be obtained by detecting the light intensity distribution of the interference image, and the spectral characteristics of the measuring point a1 can be obtained by Fourier transforming the interference pattern.

[0109] Similar to the first and second embodiments, the spectrophotometric measurement device 200 of the third embodiment also has the features of: the structure of the two-dimensional slit 213, the cooling member 214 for cooling the two-dimensional slit 213, and the cooling member 219 for cooling the two-dimensional detector 218. Therefore, the sharpness of the interference image can be improved in the same way as in the first and second embodiments. The spectrophotometric measurement device 200 of the third embodiment also has all these three structures as another preferred specific form of the present invention, but it is also possible to adopt a structure having only a part of these three features. For example, the following structure can be adopted: by replacing the two-dimensional slit 213 of the third embodiment with a pseudo-invisible multi-slit having openings two-dimensionally provided in the same manner as the two-dimensional slit 213, the reflection of the radiated light from the two-dimensional detector 218 is reduced, and by cooling the two-dimensional slit 213 with the cooling member 214, the radiated light of the slit itself is suppressed.

[0110] The above-described first to third embodiments are all preferred examples of the present invention and can be appropriately modified according to the gist of the present invention.

[0111] In the above-mentioned Embodiments 2 and 3, the two-dimensional slits 113 and 213 are used in which the openings are arranged in a grid pattern. Fig.14 As shown, it is also possible to use a two-dimensional slit 323 in which a group of openings 3232 having different lengths and periods in the second axis direction are arranged in an array in the first axis direction of a substrate 3231. In the two-dimensional slits 113 and 213 in the above-mentioned embodiments 2 and 3, the length and period in the second axis direction are determined for a wavelength λ contained in the object light. In all linear interference images obtained from a plurality of measurement points arranged in the first axis direction when these two-dimensional slits 113 and 213 are used, it is mainly the light of wavelength λ that reinforces each other. On the other hand, in Fig.14 In the two-dimensional slit 313 shown, the groups of openings 3232 arranged in a row in the first axis direction are designed to transmit k wavelengths λ contained in the object light. n Since the lights (n=1, 2, . . . ) reinforce each other independently, interference images with enhanced interference degrees of different wavelengths can be detected from linear interference images obtained from a plurality of measurement points arranged in the first axis direction.

[0112] Furthermore, a slit having openings arranged one-dimensionally only in the second axis direction may be used when obtaining an interference image from only one measurement point on the surface of the sample S. In this case, a line detector having a plurality of pixels arranged only in the second axis direction may be used.

[0113] Furthermore, in the above-mentioned embodiments, as the multi-slits 13, 113, and the two-dimensional slits 213, 313 used as the amplitude-type diffraction grating, slits in which the openings 132, 1132, 2132, and 3132 are formed by etching a substrate such as a silicon single crystal, are used, but the amplitude-type diffraction grating may be a diffraction grating in which the light-transmitting portion and the light-shielding portion are alternately arranged one-dimensionally or two-dimensionally, and may not be provided in a physically open portion. For example, a mask made of a material that transmits light in the wavelength range of the object light emitted from a measurement point on the surface of a sample may be applied to the surface of a substrate made of a material that transmits light in the wavelength range of the object light, and having openings arranged one-dimensionally or two-dimensionally, thereby making it possible to form multi-slits and two-dimensional slits.

[0114] In the above-mentioned embodiment, a structure in which gold is vapor-deposited on the surface of a single crystal of silicon is used, but a structure in which a metal other than gold (such as aluminum) is vapor-deposited can also be used. Alternatively, a structure consisting only of a metal such as gold can also be used. In addition, it is not limited to pure metals, and a structure in which a material such as stainless steel having free electrons is vapor-deposited, or a structure consisting of stainless steel, etc. can also be used. In the above-mentioned embodiment, reflection based on the multi-slit 13 or the two-dimensional slit 113, 213 is suppressed by providing a subwavelength structure on the surface facing the two-dimensional detector 18, 118, 218, but other structures can also be used. For example, the surface of the slit 13, the two-dimensional slit 113, 213 facing the two-dimensional detector 18, 118, 218 can also be sandblasted to form a rough surface, or the surface facing the two-dimensional detector 18, 118, 218 can be tilted to reflect light in a direction different from the two-dimensional detector 18, 118, 218. Alternatively, the surface can be changed to a subwavelength structure and a suitable anti-reflection film can be formed on the surface. When forming an antireflection film, it is preferable to use a structure composed of a material having an emissivity lower than that of silicon, or to adopt a structure for cooling an amplitude type diffraction grating on which the antireflection film is formed.

[0115] In the above-mentioned embodiments, a thermal type detector is used as the two-dimensional detector 18, 118, 218, but a quantum type two-dimensional detector may also be used. As a quantum type two-dimensional detector, for example, an MCT detector, an InSb type detector, a CCD detector or a CMOS detector may be used. In these quantum type detectors, the incident infrared rays are photoelectrically converted to generate an electrical signal, and the electrical signal is detected, so it is considered that it is not easy to generate radiated light from the detector. However, in the quantum type detector, a cooling mechanism for suppressing the generation of thermal noise is required, and the device becomes expensive. Therefore, in the case of suppressing the cost of the device, it is preferred to use a thermal type two-dimensional detector 18, 118, 218 as in the above-mentioned embodiments.

[0116] (Embodiment of Amplitude-Type Diffraction Grating)

[0117] Reference Fig.15 The following will describe eight embodiments of amplitude-type diffraction gratings 41 to 48 that can be used in the spectrophotometric measurement device of the present invention. The amplitude-type diffraction grating described below may be a multi-slit structure (a structure in which the openings are arranged one-dimensionally) as used in the first embodiment, or a two-dimensional slit structure (a structure in which the openings are arranged two-dimensionally) as used in the second and third embodiments. Alternatively, as described above, a structure may be obtained by applying a mask made of a material that does not transmit light in the wavelength range of the object light and has openings one-dimensionally or two-dimensionally to the surface of a substrate made of a material that transmits light in the wavelength range of the object light.

[0118] (1) First Embodiment

[0119] The amplitude type diffraction grating 41 of the first embodiment is obtained by forming a light shielding member with a member (absorption member) 411 made of a material having a light absorptivity greater than that of silicon in the wavelength range of object light and providing a plurality of openings in the light shielding member. As such a material, for example, quartz glass or various organic compounds can be used.

[0120] In the amplitude type diffraction grating 41, since the absorption member 411 made of a material having a higher light absorption rate than that of silicon is used, more object light emitted from the sample and incident on the light shielding portion of the amplitude type diffraction grating 41 is absorbed (shielded) than in the conventional case where a light shielding member made of a single crystal of silicon is used, and the clarity of the interference image can be improved compared to the conventional case. In addition, even when radiated light is emitted from the photodetector, the radiated light is absorbed by the absorption member 411. Therefore, there is no case where the radiated light from the photodetector is incident on the photodetector again and the clarity of the interference light is deteriorated.

[0121] When the wavelength range of the object light is in the infrared region, it is usually possible to fully absorb the object light incident on the shading portion by using an absorption member made of quartz glass with a thickness of about 0.1 mm. Among the materials with high light absorption rates such as those mentioned above, there are many materials with high emissivity, but if the thickness is about 0.1 mm, the amount of radiated light is small, so it will not have a significant impact on the clarity of the interference image. However, when the intensity of the object light is high, it is necessary to make the absorption member 411 thicker in order to absorb the object light incident on the shading portion of the amplitude type diffraction grating 41. In this case, the amount of radiated light emitted from the absorption member 411 becomes larger, and there is a possibility of reducing the clarity of the interference image. In such a case, a structure having a diffraction grating cooling portion for cooling the amplitude type diffraction grating 41 can be adopted. Alternatively, a photodetector configured to selectively cool only the pixels on which the light passing through the shading portion is incident among the multiple pixels of the photodetector can be used.

[0122] In the above-mentioned embodiment, a structure for cooling the photodetector is described, but it is not realistic to cool the photodetector to absolute zero. That is, even if the photodetector is cooled, some radiation light will be emitted. Generally speaking, an attempt is made to improve the sharpness of the interference image of the object light by reducing the amount of light incident on the pixel corresponding to the shading portion of the amplitude-type diffraction grating 41 and increasing the difference between the amount of light incident on the pixel corresponding to the opening portion, but in the case where the intensity of the object light is weak, it is also considered to reverse this relationship. That is, it is considered to actively emit radiation light by heating the amplitude-type diffraction grating 41, so as to increase the amount of light incident on the pixel corresponding to the shading portion and increase the difference between the amount of light incident on the pixel corresponding to the opening portion. Alternatively, a structure may be adopted in which a temperature control mechanism is provided to heat and / or cool the amplitude type diffraction grating 41, and a temperature change unit is provided to change the temperature at which the amplitude type diffraction grating 41 is heated and / or cooled by the temperature control mechanism, so as to adjust the temperature of the amplitude type diffraction grating 41 so as to maximize the clarity of the interference image of the object light. In the following embodiments, only the cooling of the amplitude type diffraction grating is described separately, but in the following embodiments, as in the present embodiment, a structure that includes a temperature control mechanism and a temperature change unit and can heat the amplitude type diffraction grating may be appropriately adopted.

[0123] (2) Second Embodiment

[0124] The amplitude type diffraction grating 42 of the second embodiment is obtained by arranging a member (reflection member) 422 made of a material (for example, a metal such as gold, which is the same in the following embodiments) having a reflectance higher than the reflectance of silicon in the wavelength range of the incident object light on the light incident surface side of the incident object light, and arranging an absorption member 421 on the light exit surface side from which the object light is emitted. In the amplitude type diffraction grating 42, most of the object light incident on the light shielding portion of the amplitude type diffraction grating 41 is reflected by the reflection member 422, so even when the intensity of the object light is high, it is not necessary to make the absorption member 421 thicker. With respect to the amplitude type diffraction grating 42, a thin absorption member 421 of about 0.1 mm can be used, so the amount of radiation light emitted from the absorption member 421 is sufficiently small, but a diffraction grating cooling portion may be further provided to improve the clarity of interference light.

[0125] (3) Third Embodiment

[0126] The amplitude type diffraction grating 43 of the third embodiment is obtained by combining a plate-shaped member (silicon member) 433 composed of a single crystal of silicon with an absorption member 431. As described above, in most cases, although the object light incident on the light shielding portion can be absorbed by the absorption member 431 with a thickness of about 0.1 mm, it is easy to be damaged due to its low strength and becomes difficult to operate. In the third embodiment, the absorption member 431 is reinforced by combining the silicon member 433 so that it can have sufficient strength. Here, an example is illustrated in which the silicon member used as a light shielding member in the previous amplitude type diffraction grating is directly used as a reinforcing member, but the material and shape of the reinforcing member can be appropriately changed. For example, a frame-shaped member that reinforces the periphery of the absorption member 431 can also be used.

[0127] (4) Fourth Embodiment

[0128] The amplitude type diffraction grating 44 of the fourth embodiment is obtained by combining the second embodiment and the third embodiment, and is provided with a silicon member 443, a reflection member 442, and an absorption member 441 in order from the side where the object light is incident. In the amplitude type diffraction grating 44, both the effects obtained by the second embodiment and the third embodiment are obtained.

[0129] (5) Fifth Embodiment

[0130] The amplitude type diffraction grating 45 of the fifth embodiment is also obtained by combining the second embodiment and the third embodiment, and a reflection member 452, a silicon member 453, and an absorption member 451 are arranged in order from the side where the object light is incident. In this amplitude type diffraction grating 45, both the effects obtained by the second embodiment and the third embodiment are obtained.

[0131] (6) Sixth Embodiment

[0132] The amplitude type diffraction grating 46 of the sixth embodiment is obtained by arranging a reflective member 462 on the side where the object light is incident, and arranging a silicon member 463 on the side where the object light is emitted. In the amplitude type diffraction grating 46, the object light is reflected at a high reflectivity at the light shielding portion of the reflective member 462, so that the object light hardly reaches the light shielding portion of the silicon member 463, and therefore, an interference image with a higher clarity than that of a conventional amplitude type diffraction grating composed only of a silicon member can be obtained.

[0133] In the amplitude-type diffraction grating 46, a single crystal of silicon is exposed on the side of the exit surface of the object light. Silicon is a material with large thermal radiation (high emissivity), so the higher the temperature, the more radiation light is emitted from the silicon component 463. When the radiation light is incident on the photodetector, the clarity of the interference image decreases. In addition, silicon is a material with high reflectivity, so when the radiation light is emitted from the photodetector, there is a possibility that the light is reflected by the amplitude-type diffraction grating 46 and enters the photodetector again. When the reflected light is incident on the photodetector, the clarity of the interference image decreases. Therefore, when the amplitude-type diffraction grating 46 of this embodiment is used, it is preferable to adopt a structure having a cooling unit for cooling the amplitude-type diffraction grating 46 and / or the photodetector.

[0134] (7) Seventh Embodiment

[0135] The amplitude type diffraction grating 47 of the seventh embodiment is obtained by arranging a silicon member 473 on the side where the object light is incident, and arranging a reflective member 472 on the side where the object light is emitted. In the amplitude type diffraction grating 47, even if the object light passes through the light shielding portion (the portion other than the opening portion) of the silicon member 473, it is reflected by the light shielding portion of the reflective member 472, so that an interference image with higher clarity than that of a conventional amplitude type diffraction grating composed only of a silicon member can be obtained.

[0136] In the amplitude type diffraction grating 47, as in a thermal type photodetector, when light in the same wavelength range (infrared region) as the wavelength range of the object light is radiated (thermal radiation) from the photodetector, there is a possibility that the light is directly reflected by the reflective member and enters the photodetector again. Therefore, when the amplitude type diffraction grating 47 is used in combination with a thermal type photodetector or the like, it is preferable to adopt a structure that cools the photodetector to suppress thermal radiation.

[0137] (8) Eighth Embodiment

[0138] The amplitude type diffraction grating 48 of the eighth embodiment is obtained by configuring a silicon component 483 on the side where the object light is incident, configuring a reflective component 482 on the side where the object light is emitted, and providing an anti-reflection portion 484 on the surface (light exit surface) of the reflective component 482. The anti-reflection portion 484 can be a structure that suppresses direct reflection of the incident light, and various structures can be used. Specifically, for example, the anti-reflection portion 484 can be provided by providing a sub-wavelength structure (SWC) described in the above embodiment on the light exit surface side of the anti-reflection portion 484, or by performing sandblasting on the light exit surface, or by tilting the light exit surface, etc.

[0139] In the amplitude type diffraction grating 48 of the eighth embodiment, even when radiated light is emitted from the photodetector, the radiated light can be prevented from re-entering the photodetector by the anti-reflection portion 484. In addition, since a metal such as gold, i.e., a material with low emissivity, is located on the light exit surface side, the heat radiation from the amplitude type diffraction grating 48 is also small. Therefore, a sufficiently high definition interference image can be obtained without cooling the amplitude type diffraction grating 48 and the photodetector. Of course, the following structure can also be adopted: a structure for cooling the amplitude type diffraction grating 48 and / or the photodetector is further provided to further improve the definition of the interference image of the object light.

[0140] Description of Reference Numerals

[0141] 1: spectrophotometric device; 11: imaging lens; 13: multi-slit; 131, 131: substrate; 132, 132: opening; 133: convex portion; 14: cooling member; 15: objective lens; 16: phase shifter; 16a: fixed mirror portion; 16b: movable mirror portion; 18: two-dimensional detector; 181: pixel; 19: cooling member; 25: control / processing unit; 100: spectrophotometric device; 111: imaging lens; 113: multi-slit; 1131: substrate; 1132: opening; 1133: convex portion; 114: cooling member; 115: objective lens; 117: cylindrical lens; 116: phase shifter; 116a: first transmission portion; 116b: second transmission portion; 118: two-dimensional detector; 119: cooling member; 125: control / processing unit 200: spectrometer; 211: imaging lens; 213: two-dimensional slit; 2131: substrate; 2132: opening; 214: cooling member; 215: objective lens; 216: phase shifter; 216a: reference mirror; 216b: tilt mirror; 218: two-dimensional detector; 219: cooling member; 225: control / processing unit; 313: two-dimensional slit; 3131: substrate; 3132: opening; 3133: convex portion; 41-48: amplitude-type diffraction grating; 411, 421, 431, 441, 451: absorption member; 422, 432, 442, 452, 462, 472, 482: reflection member; 443, 453, 463, 473, 483: silicon member; 484: anti-reflection unit; S: sample.

Claims

1. A spectrophotometric measuring device, characterized in that: have: a collimating optical system that collimates object light emitted from a measurement point on the surface of the sample; a photodetector having a light receiving surface on which a plurality of pixels are arranged in a predetermined direction; A conjugate surface imaging optical system, which is disposed between the sample and the collimating optical system and is used to form a surface optically conjugate with the surface of the sample between the collimating optical system; an amplitude-type diffraction grating disposed on the conjugate surface, the amplitude-type diffraction grating being obtained by providing a plurality of openings in a light-shielding member along a direction corresponding to the prescribed direction, wherein a light-exiting surface of the light-shielding member from which the object light is emitted is composed of a material having an emissivity lower than that of silicon, and / or the light-exiting surface is composed of a material having a reflectivity higher than that of silicon in a wavelength range of the object light and an anti-reflection process is applied to the light-exiting surface; an optical path length difference imparting optical system that splits the object light collimated by the collimating optical system into a first light beam and a second light beam and imparts an optical path length difference between the first light beam and the second light beam; and The interference optical system causes the first light beam and the second light beam, to which the optical path length difference is given by the optical path length difference giving optical system, to interfere with each other, thereby forming an interference image on the light receiving surface along the predetermined direction.

2. The spectrophotometer according to claim 1, wherein: The shading component comprises: a reflecting component, which is arranged on the light incident surface side where the object light is incident, and is composed of a material whose reflectivity of light in the wavelength range of the object light is higher than the reflectivity of silicon; and an absorbing component, which is arranged on the light emitting surface side and is composed of a material whose absorptivity of light in the wavelength range of the object light is higher than the absorptivity of silicon.

3. The spectrophotometer according to claim 1, wherein: A reinforcing member is further provided, the reinforcing member being used to reinforce the light shielding member.

4. The spectrophotometer according to claim 1, wherein: The material having a reflectivity higher than that of silicon is gold.

5. The spectrophotometer according to claim 4, wherein: The anti-reflection processing is performed by arranging convex portions on the light emitting surface at a period not larger than the wavelength range of the object light.

6. The spectrophotometer according to claim 1, wherein: A diffraction grating temperature control unit is further provided, and the diffraction grating temperature control unit heats or cools the amplitude type diffraction grating.

7. The spectrophotometer according to claim 1, wherein: A detector cooling unit is further provided for cooling a light incident surface of the photodetector.

8. The spectrophotometer according to claim 1, wherein: The object light is mid-infrared light, The photodetector detects heat generated by thermally coupling incident mid-infrared rays to the sensor by converting the heat into an electrical signal.

Images