Mirror moving mechanism and interferometer

Abstract

Provided are a mirror movement mechanism and an interferometer provided with the mirror movement mechanism, the mirror movement mechanism being capable of ensuring a large amount of movement while achieving miniaturization and suppressing shake during movement. The mirror moving mechanism is characterized by comprising: a moving mirror having a reflecting surface; an inner cylinder having an inner surface supporting the moving mirror and an outer surface having a first threaded groove extending around a central axis; the inner surface of the outer cylinder is provided with a second thread groove screwed with the first thread groove; and a drive unit that moves the inner cylinder in the direction of the central axis by rotationally driving the inner cylinder with the central axis as a rotation axis.

Description

Technical Field

[0001] The present invention relates to a mirror moving mechanism and an interferometer. Background Art

[0002] In Patent Document 1, an optical module for spectroscopic analysis is disclosed. The spectroscopic analysis obtains spectral information of light emitted or absorbed by a specimen, and analyzes components in the specimen based on the spectral information. The optical module includes a mirror unit, a beam splitter unit, a light incident portion, a first photodetector, a second light source, and a second photodetector. The mirror unit includes a movable mirror that moves in a predetermined direction and a fixed mirror whose position is fixed. In such an optical module, an interference optical system for measuring light and laser to be incident is constituted by the beam splitter unit, the movable mirror, and the fixed mirror.

[0003] The measurement light incident from the first light source via the measurement object passes through the light incident portion and is split by the beam splitter unit. A part of the split measurement light is reflected by the movable mirror and returns to the beam splitter unit. The remaining part of the split measurement light is reflected by the fixed mirror and returns to the beam splitter unit. A part and the remaining part of the measurement light returning to the beam splitter unit are detected as interference light by the first photodetector.

[0004] On the other hand, the laser emitted from the second light source is split by the beam splitter unit. A part of the split laser is reflected by the movable mirror and returns to the beam splitter unit. The remaining part of the split laser is reflected by the fixed mirror and returns to the beam splitter unit. A part and the remaining part of the laser returning to the beam splitter unit are detected as interference light by the second photodetector.

[0005] In such an optical module, the position of the movable mirror is measured based on the detection result of the interference light of the laser. Then, based on the measurement result of the position of the movable mirror and the detection result of the interference light of the measurement light, spectroscopic analysis of the measurement object can be performed. Specifically, by obtaining the intensity of the measurement light at each position of the movable mirror, a waveform called an interferogram is obtained. By performing Fourier transform on the interferogram, spectral information of the measurement object can be obtained. Therefore, the optical module described in Patent Document 1 is used for FTIR (Fourier transform infrared spectrometer).

[0006] In Patent Document 2, an optical microelectromechanical system (optical MEMS device) is disclosed for use in an FTIR spectrometer. The optical MEMS device includes a movable corner cube reflector, a fixed mirror, and a MEMS actuator. Since the optical MEMS device can achieve a large optical path delay (optical path difference), the resolution range of the FTIR spectrometer can be expanded.

[0007] Patent Document 1: International Publication No. 2019 / 009404

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2012-524295

[0009] In the optical module described in Patent Document 1, a movable mirror is driven by an electrostatic actuator. In order to achieve high precision of the acquired spectral information, it is important that the light incident on the movable mirror and the light emitted therefrom do not shift in a direction orthogonal to the propagation direction as the movable mirror is driven. In other words, it is important that the wobbling is small. Therefore, it is required to improve the translatability of the movement of the movable mirror. However, in the optical module described in Patent Document 1, the translatability of the movable mirror is not sufficiently considered, and there is room for research.

[0010] On the other hand, it is important to sufficiently ensure the movement amount of the movable mirror in terms of improving the wavelength resolution (wave number resolution) of the acquired spectral information. However, in order to improve the translatability of the movable mirror and sufficiently ensure the movement amount, it is necessary to increase the size of the drive unit that moves the movable mirror.

[0011] In addition, in the optical MEMS device described in Patent Document 2, a MEMS actuator is used. Although the MEMS actuator is easily miniaturized, it cannot sufficiently ensure the movement amount.

[0012] Therefore, it has become a technical problem to realize a mirror movement mechanism that suppresses the increase in the size of the drive unit that moves the movable mirror, suppresses wobbling during movement, and can ensure a large movement amount. Summary of the Invention

[0013] The mirror movement mechanism according to an application example of the present invention includes:

[0014] A movable mirror having a reflecting surface;

[0015] An inner cylinder that supports the movable mirror on its inner surface and has a first thread groove extending around a central axis on its outer surface;

[0016] An outer cylinder having a second thread groove that engages with the first thread groove on its inner surface; and

[0017] A drive unit that rotates the inner cylinder around the central axis to move the inner cylinder in the direction of the central axis.

[0018] The interferometer according to an application example of the present invention includes:

[0019] The mirror movement mechanism according to an application example of the present invention that reflects the analysis light; and

[0020] An analysis optical system that outputs a first light reception signal including information from the sample by performing interference of light including the analysis light reflected by the mirror movement mechanism and the analysis light passing through the sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 FIG. 1 is a schematic structural diagram showing a spectroscopic device as an interferometer according to a first embodiment.

[0022] Figure 2 FIG. 2 is a functional block diagram showing the main parts of Figure 1 an analysis unit, a length measurement unit, a periodic signal generation unit, and an arithmetic unit.

[0023] Figure 3 FIG. 3 is a perspective view showing a structural example of a vibration element shown in Figure 1 FIG. 4.

[0024] Figure 4 FIG. 5 is a perspective view showing another structural example of the vibration element shown in Figure 1 FIG. 6.

[0025] Figure 5 FIG. 7 is a perspective view showing a mirror moving mechanism (mirror moving mechanism according to the first embodiment) shown in Figure 1 FIG. 8.

[0026] Figure 6 FIG. 9 is a cross-sectional view of the mirror moving mechanism shown in Figure 5 FIG. 10.

[0027] Figure 7 FIG. 11 is a diagram showing an example of a first light reception signal F(t) and a moving mirror position signal X(t) obtained by the spectroscopic device shown in Figure 1 FIG. 12.

[0028] Figure 8 FIG. 13 is a diagram showing an example of an interferogram F(x).

[0029] Figure 9 FIG. 14 is an example of a spectral pattern SP0 obtained by performing spectral analysis on a sample.

[0030] Figure 10 FIG. 15 is a cross-sectional view of a mirror moving mechanism according to a first modification of the first embodiment.

[0031] Figure 11 FIG. 16 is a cross-sectional view of a mirror moving mechanism according to a second modification of the first embodiment.

[0032] Figure 12 FIG. 17 is a cross-sectional view of a mirror moving mechanism according to a third modification of the first embodiment.

[0033] Figure 13 FIG. 18 is a cross-sectional view of a mirror moving mechanism according to a fourth modification of the first embodiment.

[0034] Figure 14 This is a cross-sectional view showing a mirror moving mechanism according to a fifth modification of the first embodiment.

[0035] Figure 15 is Figure 14 a partially enlarged view of the shown mirror moving mechanism.

[0036] Figure 16 This is a cross-sectional view showing a mirror moving mechanism according to a sixth modification of the first embodiment.

[0037] Figure 17 This is a cross-sectional view showing a mirror moving mechanism according to a seventh modification of the first embodiment.

[0038] Figure 18 This is a cross-sectional view showing a mirror moving mechanism according to a seventh modification of the first embodiment.

[0039] Figure 19 This is a cross-sectional view showing a mirror moving mechanism according to an eighth modification of the first embodiment.

[0040] Figure 20 This is a cross-sectional view showing a mirror moving mechanism according to a ninth modification of the first embodiment.

[0041] Figure 21 is a front view of the shown mirror moving mechanism viewed from the positive side of the X-axis Figure 20 shown.

[0042] Figure 22 This is a cross-sectional view showing a mirror moving mechanism according to the second embodiment.

[0043] Figure 23 schematically shows Figure 22 a perspective view of the spline shaft shown and a second linear groove provided on the inner surface of the inner cylinder.

[0044] Figure 24 This is a cross-sectional view showing a mirror moving mechanism according to a modification of the second embodiment.

[0045] Figure 25 This is a schematic structural diagram of a shape measurement device as an interferometer according to the third embodiment.

[0046] Figure 26 shows Figure 25 a functional block diagram of each main part of the analysis unit, the length measurement unit, the periodic signal generation unit, and the arithmetic unit.

[0047] Description of Reference Numerals

[0048] 1... Mirror moving mechanism, 3... Analytical optical system, 4... Length measuring optical system, 6... Periodic signal generation unit, 7... Operation unit, 9... Specimen, 12... Optical modulator, 30... Vibration element, 32... Beam splitter, 33... Moving mirror, 34... Fixed mirror, 35... Condensing lens, 36... First light receiving element, 37... Condensing lens, 41... Second light source, 42... Beam splitter, 45... Second light receiving element, 46... 1 / 2 wavelength plate, 47... 1 / 4 wavelength plate, 48... 1 / 4 wavelength plate, 49... Analyzer, 51... First light source, 54... Beam splitter, 55... Condensing lens, 56... Neutral density filter, 62... Oscillation circuit, 72... Moving mirror position operation unit, 74... Light intensity operation unit, 76... Fourier transform unit, 78... Shape calculation unit, 80... Driving unit, 81... Inner cylinder, 82... Wall part, 83... Outer cylinder, 84... Preloading part, 85... Connecting part, 86... Bearing, 100... Spectroscopic device, 200... Shape measuring device, 300... Analysis part, 330... Corner cube prism, 332... Reflective surface, 333... Reflective surface, 334... Substrate, 336... Incident surface, 338... Retroreflective surface, 400... Length measuring part, 401... Base part, 402... First vibrating arm, 403... Second vibrating arm, 404... Electrode, 405... Electrode, 406... Light reflecting surface, 431... Vibration piece, 432... Groove, 433... Pad, 434... Diffraction grating, 435... Pad, 436... Vibration direction, 441... Optical path changing mirror, 442... Optical path changing mirror, 722... Pretreatment part, 724... Demodulation processing part, 726... Moving mirror position signal output part, 812... First thread groove, 812a... Tooth surface, 814... First linear groove, 816... Second linear groove, 822... Through hole, 831... Window part, 832... Second thread groove, 832a... Tooth surface, 833... Screw hole, 834... Guide groove, 842... Elastic body, 844... Magnet, 846... Magnetic body, 852... Shaft, 854... Circular plate part, 856... Protrusion, 862... Power conversion part, 863... Worm gear, 864... Spline shaft, 866... External teeth, 867... Flexible shaft, 4311... Surface, 4312... Back surface, AX... Central axis, F(t)... First light receiving signal, F(x)... Interference pattern, L1... Analytical light, L1a... Analytical light, L1b... Analytical light, L2... Length measuring light, L2a... Length measuring light, L2b... Length measuring light, M... Motor, S2... Second light receiving signal, SP0... Spectral pattern, Sd... Element drive signal, Ss... Reference signal, X(t)... Moving mirror position signal, X9... Absorption peak. Detailed implementation mode

[0049] Hereinafter, the mirror moving mechanism and the interferometer of the present invention will be described in detail based on the embodiments shown in the drawings.

[0050] First embodiment

[0051] First, the interferometer according to the first embodiment will be described.

[0052] Figure 1 FIG. 1 is a schematic configuration diagram of a beam splitting device 100 as an interferometer according to the first embodiment. Figure 2 FIG. 2 is Figure 1 a functional block diagram showing the main parts of the analysis unit 300, the length measurement unit 400, the periodic signal generation unit 6, and the arithmetic unit 7.

[0053] In Figure 1 the beam splitting device 100 shown in FIG. 1, the incident analysis light L1 is irradiated onto a sample 9 as a test object, and the analysis light L1 emitted from the sample 9 passes through a Michelson interference optical system. Then, while moving the movable mirror to change the optical path length inside the interference optical system, the intensity change of the obtained interference light is detected, and the result is calculated to obtain an interferogram. By performing a Fourier transform on the obtained interferogram, a spectral pattern (spectral information) including information from the sample 9 can be obtained. By selecting the wavelength of the analysis light L1, Figure 1 the beam splitting device 100 shown in FIG. 1 can be applied to, for example, FT-IR (Fourier transform infrared spectroscopy), FT-NIR (Fourier transform near-infrared spectroscopy), FT-VIS (Fourier transform visible spectroscopy), FT-UV (Fourier transform ultraviolet spectroscopy), FT-THz (Fourier transform terahertz spectroscopy), etc. for the sample 9.

[0054] As Figure 1 shown in FIG. 3, the beam splitting device 100 includes: an analysis unit 300 having an analysis optical system 3 and a mirror moving mechanism 1 (the mirror moving mechanism according to the first embodiment); a length measurement unit 400 having a length measurement optical system 4; a periodic signal generation unit 6; and an arithmetic unit 7.

[0055] The analysis optical system 3 irradiates the analysis light L1 onto the sample 9, and while changing the optical path length of the analysis light L1, divides and mixes the analysis light L1 to generate interference, so as to extract the component from the sample from the analysis light L1. In the length measurement optical system 4, a length measurement light L2 as a laser is used to measure the change in the optical path length of the analysis light L1.

[0056] The periodic signal generation unit 6 outputs a reference signal Ss to the arithmetic unit 7. The arithmetic unit 7 obtains a waveform representing the intensity of the interference light with respect to the optical path length, that is, the above-mentioned interferogram, based on the signal representing the intensity of the interference light output from the analysis optical system 3 and the signal representing the change in the optical path length output from the length measurement optical system 4. In addition, the arithmetic unit 7 performs a Fourier transform on the interferogram to obtain a spectral pattern.

[0057] 1.1 Analysis optical system

[0058] The analysis optical system 3 includes a first light source 51, a beam splitter 54, a condenser lens 55, and a neutral density filter 56. In addition, in the analysis optical system 3, a part of these optical elements may be omitted, other optical elements may be added, or they may be replaced with other optical elements.

[0059] The first light source 51 is, for example, a light source that emits the analysis light L1 by condensing white light, that is, broad light. The wavelength region of the analysis light L1, that is, the type of the first light source 51, is appropriately selected according to the purpose of the spectral analysis of the sample 9. In the case of performing infrared spectral analysis, examples of the first light source 51 include a halogen lamp, an infrared lamp, a tungsten lamp, etc. In the case of performing visible spectral analysis, examples of the first light source 51 include a halogen lamp, etc. In the case of performing ultraviolet spectral analysis, examples of the first light source 51 include a deuterium lamp, a UV-LED (ultraviolet light-emitting diode), etc.

[0060] In addition, by selecting a wavelength of 100 nm or more and less than 760 nm for the analysis light L1, a spectroscopic device 100 capable of performing ultraviolet spectral analysis or visible spectral analysis can be realized. Further, by selecting a wavelength of 760 nm or more and 20 μm or less for the analysis light L1, a spectroscopic device 100 capable of performing infrared spectral analysis or near-infrared spectral analysis can be realized. Moreover, by selecting a wavelength of 30 μm or more and 3 mm or less for the analysis light L1, a spectroscopic device 100 capable of performing terahertz spectral analysis can be realized.

[0061] In addition, the first light source 51 may be provided outside the spectroscopic device 100. In this case, the analysis light L1 emitted from the first light source 51 provided outside is only required to be introduced into the spectroscopic device 100. On the other hand, as in the present embodiment, by the spectroscopic device 100 including the first light source 51, the alignment accuracy between the first light source 51 and the beam splitter 54 can be particularly improved, and the loss of the analysis light L1 due to misalignment can be suppressed to a minimum.

[0062] In addition, the first light source 51 may be a laser source that emits laser light. By using a laser source as the first light source 51, a spectroscopic device 100 capable of realizing laser-excited spectral analysis such as Fourier-type Raman spectral analysis and Fourier-type fluorescence spectral analysis for the sample 9 can be obtained. In addition, in this case, the structure of the analysis optical system 3 can be changed from the above structure. As the laser source, a known light source used in Raman spectroscopy and fluorescence spectroscopy is used.

[0063] The analysis light L1 passes through the beam splitter 54, is condensed by the condenser lens 55, and irradiates the specimen 9. At the specimen 9, the analysis light L1 is reflected and returns to the beam splitter 54. Thus, spectral analysis based on the reflected light emitted from the specimen 9, that is, analysis based on the reflection spectrometry, can be performed. In addition, by changing the optical path of the analysis optical system 3, spectral analysis based on the transmitted light passing through the specimen 9, that is, analysis based on the transmission spectrometry, can be performed.

[0064] The beam splitter 54 uses, for example, a non-polarizing beam splitter, but a polarizing beam splitter may also be used. In this case, the required wavelength plates are appropriately added.

[0065] The condenser lens 55 condenses the analysis light L1 and reduces the spot size of the analysis light L1 irradiated onto the specimen 9. In addition, the condenser lens 55 condenses the diffused light emitted from the specimen 9. Thus, local analysis can be performed. If local analysis is not required, the condenser lens 55 can also be omitted.

[0066] The analysis light L1 emitted from the specimen 9 includes a component originating from the specimen generated by the interaction with the specimen 9. The component originating from the specimen is a component generated by the analysis light L1 acting on the specimen 9, and as the acting modes, absorption, reflection, scattering, luminescence, etc. of light of a specific wavelength by the specimen 9 can be cited. This analysis light L1 passes through the condenser lens 55, is reflected by the beam splitter 54, and passes through the neutral density filter 56. The neutral density filter 56 selectively attenuates light of a predetermined wavelength. Thus, the S / N ratio (signal-to-noise ratio) of the component originating from the specimen can be improved, and spectral analysis can be performed with higher accuracy. As the neutral density filter 56, for example, a notch filter having an optical density (OD value) of 6.0 or more can be cited.

[0067] In addition, the analysis optical system 3 includes a beam splitter 32 (light splitting unit), a fixed mirror 34 (fixed reflection unit), a condenser lens 35, and a first light receiving element 36 that constitute a Michelson interference optical system. In addition, in the analysis optical system 3, a part of these optical elements can be omitted, optical elements other than these can be provided, or these optical elements can be replaced with other optical elements.

[0068] The beam splitter 32 is a non-polarizing beam splitter that splits the analysis light L1 into two analysis lights L1a and L1b. Specifically, the beam splitter 32 reflects a part of the analysis light L1 as the analysis light L1a toward the moving mirror 33 and transmits the other part of the analysis light L1 as the analysis light L1b toward the fixed mirror 34, thereby splitting the analysis light L1 into two.

[0069] As the type of the beam splitter 32, for example, in addition to Figure 1In addition to the prism-type element (cube-type element) shown, a plate-type element, a stacked-type element, etc. can also be cited. In the case of using the plate-type beam splitter 32, since wavelength dispersion occurs in the analysis light L1a and the analysis light L1b, a wavelength dispersion compensation plate may be disposed between the beam splitter 32 and the fixed mirror 34 as needed. The wavelength dispersion compensation plate is an optical element that compensates for the wavelength dispersion caused by the optical path length difference of the glass material. In the present embodiment, since a prism-type element is used as the beam splitter 32, this wavelength dispersion compensation plate is not required. The prism-type element is an element in which optical thin films are sandwiched between prisms. In addition, the stacked-type element is an element in which optical thin films are sandwiched between two transparent flat plates. Similarly to the prism-type element, the stacked-type element can also eliminate the need for a wavelength dispersion compensation plate. In addition, in the prism-type element and the stacked-type element, the optical thin films are not exposed, so the long-term reliability of the beam splitter 32 can be improved.

[0070] In addition, the beam splitter 32 transmits the analysis light L1a reflected by the movable mirror 33 toward the first light receiving element 36, and reflects the analysis light L1b reflected by the fixed mirror 34 toward the first light receiving element 36. Therefore, the beam splitter 32 mixes the divided analysis lights L1a and L1b.

[0071] The movable mirror 33 is a mirror that moves along the incident direction of the analysis light L1a with respect to the beam splitter 32 and reflects the analysis light L1a. The movable mirror 33 is moved reciprocally in the incident direction of the analysis light L1a by a drive unit 80. The phase of the analysis light L1a reflected by the movable mirror 33 changes according to the position of the movable mirror 33. Thereby, the movable mirror 33 adds phase information derived from the position of the movable mirror 33 to the analysis light L1a. The phase information derived from the position of the movable mirror 33 is the change in the phase added to the analysis light L1a according to the position of the movable mirror 33.

[0072] The movable mirror 33 is assembled to the mirror moving mechanism 1. The mirror moving mechanism 1 includes: the movable mirror 33 having a reflection surface 332; an inner cylinder 81 that supports the movable mirror 33; an outer cylinder 83 disposed outside the inner cylinder 81; and a drive unit 80 that moves the inner cylinder 81 by rotationally driving the inner cylinder 81.

[0073] By the mirror moving mechanism 1, the movable mirror 33 can be translated along the incident direction of the analysis light L1a with high precision and by a target moving amount. Thereby, when the movable mirror 33 moves, generation of angular deviation (deflection angle) accompanied by the shaking of the movable mirror 33 can be suppressed, and a large moving amount can be ensured. As a result, a spectroscopic device 100 (interferometer) that can suppress the influence of angular deviation on the analysis result and can improve the wavelength resolution (wave number resolution) of spectral information can be realized. In addition, the mirror moving mechanism 1 can be easily miniaturized. In addition, the mirror moving mechanism 1 will be described in detail later.

[0074] The fixed mirror 34 is a mirror that is fixed in position relative to the beam splitter 32 and reflects the analysis light L1b. The analysis light L1b reflected by the fixed mirror 34 is mixed with the analysis light L1a in the beam splitter 32 and received by the first light receiving element 36 as interference light. In the analysis optical system 3, an optical path difference is generated between the optical path of the analysis light L1a and the optical path of the analysis light L1b according to the position of the moving mirror 33. The fixed mirror 34 can be a flat mirror, a corner cube prism, or a corner cube mirror. Among them, by using a corner cube prism, a corner cube mirror, etc. having retroreflectivity for the fixed mirror 34, it is possible to suppress a decrease in the S / N ratio of the interference signal due to the angular deviation (deviation angle) accompanying the arrangement of the fixed mirror 34, and it is possible to suppress the influence on the analysis result.

[0075] The condenser lens 35 condenses the interference light, that is, the mixed analysis lights L1a and L1b, onto the first light receiving element 36. Depending on the area of the light receiving portion of the first light receiving element 36, the condenser lens 35 may be omitted.

[0076] The first light receiving element 36 receives the interference light and obtains its intensity. Then, a signal showing the temporal change of the intensity is output as the first light receiving signal F(t). This first light receiving signal F(t) includes a component derived from the sample generated by the interaction between the analysis light L1 and the sample 9 and the phase information derived from the position of the above-mentioned moving mirror 33.

[0077] As the first light receiving element 36, for example, a photodiode, a phototransistor, a photomultiplier tube (PMT), etc. can be cited. Among them, as the photodiode, for example, an InGaAs-based photodiode, an Si-based photodiode, an avalanche photodiode, etc. can be cited.

[0078] 1.2. Length measurement optical system

[0079] The length measurement optical system 4 is a Michelson interference optical system, and includes a second light source 41, a beam splitter 42, an optical modulator 12, second light receiving elements 45, a 1 / 2 wavelength plate 46, a 1 / 4 wavelength plate 47, a 1 / 4 wavelength plate 48, a polarizer 49, and optical path changing mirrors 441 and 442. In addition, in the length measurement optical system 4, some of these optical elements may be omitted, other optical elements may be provided, or these optical elements may be replaced with other optical elements. The length measurement optical system 4 outputs the phase information derived from the position of the moving mirror 33 and the frequency information derived from the moving speed to the arithmetic unit 7 by heterodyne interferometry. In this specification, these information are referred to as "length measurement components".

[0080] The second light source 41 preferably uses a light source that emits light with a relatively narrow spectral linewidth. As the second light source 41, for example, gas lasers such as He-Ne lasers and Ar lasers, semiconductor laser elements such as DFB-LD (Distributed FeedBack - Laser Diode), FBG-LD (Fiber Bragg Grating - Laser Diode), VCSEL (Vertical Cavity Surface Emitting Laser), and FP-LD (Fabry-Perot Laser Diode), and crystal lasers such as YAG (Yttrium Aluminum Garnet) can be cited.

[0081] The second light source 41 is particularly preferably a semiconductor laser element. Thereby, miniaturization, light weight, and low power consumption of the beam splitter device 100 can be achieved.

[0082] The beam splitter 42 is a polarization beam splitter that transmits P-polarized light and reflects S-polarized light. The 1 / 2 wavelength plate 46 is arranged in a state where its optical axis is rotated with respect to the polarization axis of the length measurement light L2. Thereby, when the length measurement light L2 passes through the 1 / 2 wavelength plate 46, it becomes linearly polarized light including P-polarized light and S-polarized light, and is split into two, namely P-polarized light and S-polarized light, by the beam splitter 42.

[0083] The length measurement light L2a as S-polarized light is converted into circularly polarized light by the 1 / 4 wavelength plate 48 and is incident on the optical modulator 12. The optical modulator 12 adds a modulation component to the length measurement light L2a by reflecting the length measurement light L2a. The modulation component is a change in frequency generated when the length measurement light L2a is reflected by the vibrating element 30. The reflected length measurement light L2a returns to the beam splitter 42. At this time, the length measurement light L2a is converted into P-polarized light by the 1 / 4 wavelength plate 48.

[0084] On the other hand, the length measurement light L2b as P-polarized light is converted into circularly polarized light by the 1 / 4 wavelength plate 47 and is incident on the moving mirror 33 via the optical path changing mirrors 441 and 442. The length measurement light L2b is incident on the same reflection surface 332 as the analysis light L1a and is reflected by it. Thereby, the length measurement light L2b changes in phase according to the position of the moving mirror 33. The length measurement light L2b reflected by the moving mirror 33 returns to the beam splitter 42 via the optical path changing mirrors 441 and 442.

[0085] In the present embodiment, as described above, the analysis light L1a and the length measurement light L2b are incident on the same reflecting surface 332 of the movable mirror 33. In this case, the phase information added to the analysis light L1a and the phase information added to the length measurement light L2b become information from the position of the same reflecting surface 332. Therefore, the correlation of the phase information of both can be further improved, and the accuracy of the finally obtained analysis result can be improved.

[0086] In addition, the beam splitter 42 mixes the length measurement light L2a returned from the optical modulator 12 and the length measurement light L2b reflected by the movable mirror 33. The mixed length measurement lights L2a and L2b pass through the analyzer 49 and are incident on the second light receiving element 45.

[0087] As the optical modulator 12, for example, an optical modulator disclosed in Japanese Patent Application Laid-Open No. 2022-38156 can be cited. In the present embodiment, the optical modulator 12 has a vibrating element 30. The vibrating element 30 vibrates according to the element drive signal Sd and reflects the length measurement light L2a. Thereby, the optical modulator 12 overlaps the modulation component with respect to the length measurement light L2a. In addition, the optical modulator 12 may be an optical frequency shifter. For example, it may be an AOM (acousto-optic modulator) or an EOM (electro-optic modulator).

[0088] As the vibrating element 30, for example, a crystal oscillator, a silicon oscillator, a ceramic oscillator, etc. can be cited. Since these oscillators utilize the mechanical resonance phenomenon, they have a high Q value, and stabilization of the natural vibration frequency can be easily achieved. Thereby, the S / N ratio of the modulation component applied by the optical modulator 12 to the length measurement light L2a can be improved, and the accuracy of the reference signal Ss can be improved. As a result, the position of the movable mirror 33 can be obtained with high precision, and finally, the spectroscopic device 100 capable of generating a spectral pattern with high accuracy on the wavelength axis (wave number axis) can be realized.

[0089] As the crystal oscillator, for example, a crystal AT oscillator, an SC-cut crystal oscillator, a tuning fork type crystal oscillator, a surface acoustic wave element of a crystal, etc. can be cited. The oscillation frequency of the crystal oscillator is, for example, about 1 kHz to several hundred MHz.

[0090] A silicon oscillator is an oscillator including a single crystal silicon wafer and a piezoelectric film manufactured from a single crystal silicon substrate using MEMS technology. MEMS (Micro Electro Mechanical Systems) is a microelectromechanical system. As the shape of the single crystal silicon wafer, for example, a cantilever shape such as a two-legged tuning fork type or a three-legged tuning fork type, a double-supported beam shape, etc. can be cited. The oscillation frequency of the silicon oscillator is, for example, about 1 kHz to several hundred MHz.

[0091] A ceramic oscillator is an oscillator that includes a piezoelectric ceramic sheet and electrodes fabricated by sintering a piezoelectric ceramic. Examples of the piezoelectric ceramic include lead zirconate titanate (PZT) and barium titanate (BTO). The oscillation frequency of the ceramic oscillator is, for example, on the order of several hundreds of kHz to several tens of MHz.

[0092] Figure 3 is a perspective view showing Figure 1 a structural example of the vibration element 30 shown in

[0093] Figure 3 The vibration element 30 shown in

[0094] includes a plate-shaped vibrating piece 431 and a diffraction grating 434 provided on the vibrating piece 431. Figure 3 The vibrating piece 431 shown in

[0095] is a crystal AT oscillator that performs thickness-shear vibration along the vibration direction 436 in the high-frequency region of the MHz band. In addition, a diffraction grating 434 is provided on the surface of the vibrating piece 431. The diffraction grating 434 includes grooves 432 having a component that intersects the vibration direction 436, that is, a plurality of linear grooves 432 extending in a direction intersecting the vibration direction 436.

[0096] The vibrating piece 431 has a size such that, for example, the long side is 0.50 mm or more and 10.0 mm or less. In addition, the thickness of the vibrating piece 431 is, for example, 0.10 mm or more and 2.0 mm or less. As an example, the shape of the vibrating piece 431 is a square with one side being 1.6 mm and its thickness being 0.35 mm.

[0097] The diffraction grating 434 has a size such that, for example, the long side is 0.20 mm or more and 3.0 mm or less. In addition, the thickness of the diffraction grating 434 is, for example, 0.003 mm or more and 0.50 mm or less.

[0098] In the present embodiment, the vibrating piece 431 performs thickness-shear vibration. However, as shown by the vibration direction 436 in Figure 3 this vibration is in-plane vibration. Therefore, even if light is incident perpendicularly to the surface of the vibrating piece 431 alone, optical modulation cannot be performed. Therefore, in the vibration element 30, optical modulation can be performed by providing the diffraction grating 434 on the vibrating piece 431.

[0099] As an example, Figure 3 the diffraction grating 434 shown is a blazed diffraction grating. A blazed diffraction grating refers to a grating whose cross-sectional shape is stepped. In addition, the shape of the diffraction grating 434 is not limited to this.

[0100] Figure 4 is Figure 1 a perspective view of another structural example of the vibrating element 30 shown. In addition, in Figure 4 three axes orthogonal to each other, the A-axis, the B-axis, and the C-axis are set and shown by arrows. The front end side of the arrow is set as "positive", and the base end side of the arrow is set as "negative". Additionally, for example, the two directions of the positive side and the negative side of the A-axis are referred to as the "A-axis direction". The B-axis direction and the C-axis direction are the same respectively.

[0101] Figure 4 the vibrating element 30 shown is a tuning fork type crystal oscillator. Figure 4 The vibrating element 30 shown has a vibrating substrate, and the vibrating substrate has a base portion 401, a first vibrating arm 402, and a second vibrating arm 403. Since the manufacturing technology of such a tuning fork type crystal oscillator has been established, it is easily obtained and the oscillation is also stable. Therefore, the tuning fork type crystal oscillator is suitable as the vibrating element 30. In addition, the vibrating element 30 has electrodes 404, 405, and a light reflecting surface 406 provided on the vibrating substrate.

[0102] The base portion 401 is a portion extending along the A-axis. The first vibrating arm 402 is a portion extending from the end portion on the negative side of the A-axis of the base portion 401 toward the positive side of the B-axis. The second vibrating arm 403 is a portion extending from the end portion on the positive side of the A-axis of the base portion 401 toward the positive side of the B-axis.

[0103] The electrode 404 is a conductive film provided on the side surfaces parallel to the A-B plane in the first vibrating arm 402 and the second vibrating arm 403. In addition, although not shown in Figure 4 the electrode 404 is provided on the opposing side surfaces respectively, and by applying voltages with different polarities, the first vibrating arm 402 and the second vibrating arm 403 are driven.

[0104] The electrode 405 is a conductive film provided on the side surfaces intersecting the A-B plane in the first vibrating arm 402 and the second vibrating arm 403. In addition, although not shown in Figure 4 the electrode 405 is also provided on the opposing side surfaces respectively, and by applying voltages with different polarities, the first vibrating arm 402 and the second vibrating arm 403 are driven.

[0105] The light reflecting surface 406 is set on the side surfaces of the first vibrating arm 402 and the second vibrating arm 403 that intersect the A-B plane, and has the function of reflecting the length measuring light L2a. The side surface refers to the surface that extends along the extending directions of the first vibrating arm 402 and the second vibrating arm 403. Figure 4 The illustrated light reflecting surface 406 is set on the surface of the electrode 405 in particular among the side surfaces of the first vibrating arm 402. The electrode 405 provided on the first vibrating arm 402 also has the function as the light reflecting surface 406. In addition, a light reflecting film (not shown) may be provided separately from the electrode 405.

[0106] The tuning fork type crystal oscillator uses a crystal wafer cut out from a crystal substrate. As the crystal substrate used in the manufacture of the tuning fork type crystal oscillator, for example, a crystal Z-cut flat plate or the like can be cited. In Figure 4 it, an X-axis parallel to the A-axis, a Y'-axis parallel to the B-axis, and a Z'-axis parallel to the C-axis are set. The crystal Z-cut flat plate is, for example, a substrate cut out from a single crystal of a crystal in such a way that the X-axis is the electrical axis, the Y'-axis is the mechanical axis, and the Z'-axis is the optical axis. Specifically, in the orthogonal coordinate system composed of the X-axis, the Y'-axis, and the Z'-axis, a substrate having a main surface obtained by tilting the X-Y' plane formed by the X-axis and the Y'-axis about the X-axis in the counterclockwise direction by about 1° to 5° is cut out from the single crystal of the crystal, and is preferably used as the crystal substrate. Then, by etching such a crystal substrate, Figure 4 the crystal wafer used for the vibrating element 30 shown is obtained. The etching may be wet etching or dry etching.

[0107] On the other hand, the light reflecting surface 406 may be set on the surface of the electrode 404. In this case, the signals applied to the respective electrodes are adjusted so that the tuning fork type crystal oscillator performs out-of-plane vibration. Specifically, it is sufficient to excite a mode (including parasitic components) that performs out-of-plane vibration.

[0108] The second light receiving element 45 receives the mixed length measuring lights L2a and L2b as interference light, and acquires its intensity. Then, a signal showing the time change of the intensity is output as the second light receiving signal S2. This second light receiving signal S2 includes a length measuring component derived from the position of the moving mirror 33.

[0109] As the second light receiving element 45, for example, a photodiode, a phototransistor, or the like can be cited.

[0110] As described above, the optical elements included in each optical system have been described. However, for the optical elements that require light to be incident, an antireflection treatment is preferably performed. Thereby, the S / N ratios of the first light receiving signal F(t) and the second light receiving signal S2 can be improved.

[0111] 1.3. Periodic signal generation section

[0112] Figure 2 The periodic signal generation unit 6 shown generates a periodic signal and outputs it as a reference signal Ss. In the present embodiment, the periodic signal generation unit 6 includes an oscillation circuit 62.

[0113] As the oscillation circuit 62, for example, an oscillation circuit disclosed in Japanese Unexamined Patent Application Publication No. 2022-38156 can be cited. The oscillation circuit 62 operates with the vibration element 30 as a signal source and generates a periodic signal with high precision. Thus, the oscillation circuit 62 outputs a highly accurate element drive signal Sd and a reference signal Ss. Then, in the case of being disturbed, the element drive signal Sd and the reference signal Ss are affected by each other in the same way. As a result, the modulation component added via the vibration element 30 driven by the element drive signal Sd and the reference signal Ss are also affected by each other in the same way. Therefore, when the second light-receiving signal S2 and the reference signal Ss are supplied to the operation in the operation unit 7, during the operation, the influence of the interference included in both can be canceled or reduced with each other. As a result, in the operation unit 7, even if disturbed, the position of the moving mirror 33 can be obtained with high precision.

[0114] In addition, the oscillation circuit disclosed in the above publication is a circuit using an inverter IC, but a Colpitts oscillation circuit can be used instead.

[0115] Furthermore, the periodic signal generation unit 6 is not particularly limited as long as it has a function of generating a periodic signal. For example, it can also be a signal generator, a function generator, etc.

[0116] 1.4. Mirror Moving Mechanism

[0117] Figure 5 is a perspective view showing Figure 1 the mirror moving mechanism 1 (the mirror moving mechanism according to the first embodiment) shown. Figure 6 is Figure 5 a cross-sectional view of the mirror moving mechanism 1 shown. In addition, in each drawing of the present application, the X-axis, Y-axis, and Z-axis are set as three mutually orthogonal axes. Each axis is shown by an arrow, the front end side of the arrow is set as "positive", and the base end side of the arrow is set as "negative". In the following description, for example, the so-called "X-axis direction" includes both the positive direction and the negative direction of the X-axis. The same applies to the Y-axis direction and the Z-axis direction. In addition, in the following description, the positive side of the Z-axis is also particularly referred to as "up", and the negative side of the Z-axis is also referred to as "down".

[0118] Figure 5 The mirror moving mechanism 1 shown includes a moving mirror 33, an inner cylinder 81, an outer cylinder 83, and a drive unit 80. The moving mirror 33 has a reflection surface 332. As Figure 6As shown, the inner cylinder 81 supports the movable mirror 33 on its inner surface. For example, the whole or a part of its outer surface has a first thread groove 812 extending around the central axis AX. The outer cylinder 83 has a second thread groove 832 on the whole or a part of its inner surface. The first thread groove 812 and the second thread groove 832 are screwed together with each other. The driving part 80 rotates the inner cylinder 81 around the central axis AX as the rotation axis, screws the first thread groove 812 into the second thread groove 832, and moves the inner cylinder 81 in the direction of the central axis AX.

[0119] The first thread groove 812 and the second thread groove 832 extend spirally around the central axis AX. When such thread grooves are screwed together with each other, the state where the first thread groove 812 is in contact with the second thread groove 832 is maintained for the whole circumference around the central axis AX or a larger part thereof. In addition, this state is also maintained when the inner cylinder 81 is rotationally driven. Therefore, when the inner cylinder 81 is rotationally driven, the inner cylinder 81 can be moved while suppressing the wobbling of the inner cylinder 81 relative to the outer cylinder 83 to the minimum. As a result, the translatability of the movement of the movable mirror 33 can be improved, and the generation of the angular deviation (tilt angle) of the movable mirror 33 can be suppressed.

[0120] In addition, by the mirror moving mechanism 1, it is possible to suppress the wobbling during the movement of the movable mirror 33 without using a large guiding mechanism or the like. Therefore, it is possible to realize the mirror moving mechanism 1 which is easily miniaturized. As a result, it is possible to realize an interferometer in which miniaturization, light weight, and low cost are achieved.

[0121] Moreover, according to the structure as described above, for example, compared with a mirror moving mechanism using MEMS (Micro Electro Mechanical Systems), it is possible to easily increase the movement amount of the movable mirror 33. Therefore, it is possible to easily improve the wavelength resolution (wavenumber resolution) of the spectral pattern that can be obtained in the spectroscopic device 100 (interferometer).

[0122] The length of the inner cylinder 81 in the direction of the central axis AX is shorter than that of the outer cylinder 83. Therefore, even if the inner cylinder 81 is moved in the X-axis direction by the driving part 80, it is easy to maintain the state where the first thread groove 812 is screwed into the second thread groove 832. Thereby, it is possible to ensure sufficiently long the movement distance of the movable mirror 33.

[0123] In addition, it is preferable that the length of the outer cylinder 83 in the direction of the central axis AX is longer than the distance by which the driving part 80 moves the inner cylinder 81. Thereby, it is possible to screw the first thread groove 812 into the second thread groove 832 in the entire area of the movement amount of the movable mirror 33. As a result, it is possible to suppress the generation of the tilt angle in the entire area of the movement amount of the movable mirror 33.

[0124] There is no particular limitation on the constituent material of the inner cylinder 81 and the constituent material of the outer cylinder 83. For example, metal materials, ceramic materials, glass materials, resin materials, etc. can be cited. In addition, it can also be a composite material including at least one of these materials. Among them, a metal material is preferably used. Since the metal material has high rigidity and hardness, the translatability of the movement of the moving mirror 33 can be particularly improved. As the metal material, for example, stainless steel, aluminum alloy, titanium alloy, etc. can be cited.

[0125] Figure 6 The moving mirror 33 shown has a substrate 334 and a reflecting surface 332 provided on one surface of the substrate 334. As the substrate 334, for example, a glass plate, a resin plate, a metal plate, etc. can be cited. The reflecting surface 332 can be, for example, the surface of a metal film formed on the substrate 334, or the surface of the substrate 334 that has been mirror-polished. With such a structure, after the reflecting surface 332 is provided on the substrate 334 in advance, the moving mirror 33 can be manufactured through the installation step, so that a reflecting surface 332 with high surface accuracy can be obtained. In addition, the substrate 334 can also be omitted. In this case, the surface of the wall portion 82 or the surface of a metal film formed on the wall portion 82, etc. can also be the reflecting surface 332.

[0126] There is no particular limitation on the method of supporting the moving mirror 33 with respect to the wall portion 82. For example, the moving mirror 33 is supported on the wall portion 82 via an adhesive or an adhesive sheet.

[0127] In addition, a stray light suppression treatment can be performed on the inner surface of the inner cylinder 81 as needed. As the stray light suppression treatment, for example, an anodic oxidation film (acid-resistant aluminum) treatment, an anti-reflection sheet attachment treatment, a flocked paper attachment treatment, etc. can be cited. Thereby, the generation of stray light accompanied by diffuse reflection can be suppressed. As a result, the reduction of the S / N ratio of the interference signal accompanied by stray light can be suppressed.

[0128] The central axis AX extends along the X axis. Moreover, the inner cylinder 81 has a cylindrical shape with the central axis AX as the axis. A wall portion 82 intersecting the central axis AX is fixed to the inner surface of the inner cylinder 81. If the wall portion 82 is fixed to the inner surface of the inner cylinder 81, there is no particular limitation on its position, but Figure 6In the middle part of the inner cylinder 81 disposed in the direction of the central axis AX. And, the movable mirror 33 is supported by this wall portion 82. According to such a structure, even when dust is generated due to the screwing together of the first thread groove 812 and the second thread groove 832, the generated dust is not easily attached to the reflecting surface 332 of the movable mirror 33. That is, since the distance between the end portion of the inner cylinder 81 in the X-axis direction and the movable mirror 33 can be sufficiently ensured, the probability that the dust generated by the screwing adheres to the movable mirror 33 can be reduced. In addition, by providing the wall portion 82 in the middle part of the inner cylinder 81, even when the inner cylinder 81 swings relative to the outer cylinder 83, specifically, when the inner cylinder 81 swings about the Y-axis, an unexpected displacement width of the reflecting surface 332 can be suppressed. Thereby, a decrease in the S / N ratio of the interference signal accompanying a decrease in the reflectivity of the reflecting surface 332 and a displacement of the reflecting surface 332 caused by the swing can be suppressed. In addition, the so-called middle part means a range of 40% or more and 60% or less of the total length from the end portion of the inner cylinder 81.

[0129] Figure 5 The outer cylinder 83 shown has a window portion 831 penetrating the outer surface and the inner surface. The outer surface of the inner cylinder 81 can be exposed through the window portion 831.

[0130] In the present embodiment, a first linear groove 814 is provided on the outer surface of the inner cylinder 81. The first linear groove 814 intersects the first thread groove 812. More specifically, the first linear groove 814 extends parallel to the central axis AX. In addition, the first linear groove 814 may be inclined with respect to the central axis AX.

[0131] Figure 1 The drive unit 80 shown has a motor M and a power conversion unit 862. The motor M generates rotational power. Figure 5 The power conversion unit 862 shown is constituted by a worm wheel 863 connected to the output shaft of the motor M, and transmits the rotational power to the inner cylinder 81. Specifically, the worm wheel 863 is screwed to the first linear groove 814 exposed from the window portion 831. Thereby, the rotation of the worm wheel 863 can be transmitted to the inner cylinder 81. Therefore, the movable mirror 33 can be moved by an arbitrary amount corresponding to the rotation amount of the worm wheel 863. That is, the drive unit 80 converts the rotational power of the motor M into a translational motion of the movable mirror 33. In addition, when the power conversion unit 862 is constituted by the worm wheel 863, the reduction ratio of the power conversion unit 862 can be increased, and the backlash can be suppressed to a small value. Thereby, since it is not necessary to add a speed reducer or the like, the drive unit 80 can be easily miniaturized, and the position accuracy of the movable mirror 33 can be easily improved.

[0132] The motor M generates rotational power in a predetermined rotational direction and rotational speed. As the motor M, for example, a stepping motor, a DC motor, an ultrasonic (piezoelectric) motor, etc. can be cited.

[0133] Among them, in the present embodiment, a DC motor is preferably used. Even if the DC motor is small, it can generate sufficient torque, so it can contribute to the miniaturization of the mirror moving mechanism 1. In addition, as the DC motor, a brushed DC motor, a brushless DC motor, etc. can be cited, but a brushless DC motor is preferably used. The brushless DC motor can easily control the rotation speed based on the applied voltage, so it can easily control the moving speed of the moving mirror 33.

[0134] In the present embodiment, as described above, the analysis light L1a and the length measurement light L2b are incident on the reflection surface 332 of the moving mirror 33. It is preferable that the incident positions of the analysis light L1a and the length measurement light L2b are different from each other. Thereby, it is possible to prevent the situation where both lights are mixed and present.

[0135] In addition, the incident position of the length measurement light L2b can also be set at the intersection of the reflection surface 332 and the central axis AX. Even if the inner cylinder 81 is rotationally driven, this intersection is not easily displaced in the X-axis direction. That is, even if the reflection surface 332 is slightly inclined with respect to the central axis AX, near the intersection, the displacement is suppressed to be small. In addition, the length measurement light L2b is continuously irradiated to the same position of the reflection surface 332. Therefore, compared with the case where it is irradiated to various positions as the reflection surface 332 rotates, the possibility that the reflectivity unexpectedly changes due to dirt or the like becomes smaller. Therefore, by setting the incident position of the length measurement light L2b as the intersection, it is possible to suppress a decrease in the S / N ratio of the length measurement component caused by the displacement of the reflection surface 332. In addition, setting the incident position of the length measurement light L2b as the intersection means a state where the intersection of the reflection surface 332 and the central axis AX is included in the irradiation range of the length measurement light L2b.

[0136] The outer cylinder 83 has screw holes 833. The screw holes 833 are used to fix the outer cylinder 83 to a substrate or the like (not shown) using screws (not shown). The number of screw holes 833 is not particularly limited, but if it is considered to stably fix the outer cylinder 83, it is preferably 3 or more.

[0137] In addition, the drive unit 80 only needs to have a function of rotationally driving the inner cylinder 81 around the central axis AX, and its structure is not limited to the above.

[0138] 1.5. Operation Unit

[0139] Figure 2 The operation unit 7 shown has a moving mirror position operation unit 72, a light intensity operation unit 74, and a Fourier transform unit 76. The functions exerted by these functional units are realized by hardware having, for example, a processor, a memory, an external interface, an input unit, a display unit, etc. Specifically, it is realized by the processor reading and executing a program stored in the memory. In addition, these components can communicate with each other through an external bus.

[0140] As a processor, for example, a CPU (Central Processing Unit), a DSP (Digital Signal Processor), etc. can be cited. In addition, instead of the method of executing software by these processors, a method of implementing the above functions using an FPGA (Field-Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), etc. can be adopted.

[0141] As a memory, for example, an HDD (Hard Disk Drive), an SSD (Solid State Drive), an EEPROM (Electrically Erasable Programmable Read-Only Memory), a ROM (Read-Only Memory), a RAM (Random Access Memory), etc. can be cited.

[0142] As an external interface, for example, digital input / output ports such as a USB (Universal Serial Bus), an Ethernet (registered trademark) port, etc. can be cited.

[0143] As an input unit, for example, various input devices such as a keyboard, a mouse, a touch panel, a touchpad, etc. can be cited. As a display unit, for example, a liquid crystal display panel, an organic EL (Electro Luminescence) display panel, etc. can be cited. In addition, the input unit and the display unit can be provided as needed and can also be omitted.

[0144] 1.5.1. Moving Mirror Position Calculation Unit

[0145] Figure 2The shown moving mirror position calculation unit 72 determines the position of the moving mirror 33 by heterodyne interferometry, and based on the result, generates a moving mirror position signal X(t). Specifically, the length measurement optical system 4 is provided with an optical modulator 12, and a modulation component can be added to the length measurement light L2a. Then, when the length measurement lights L2a and L2b interfere with each other, the length measurement component derived from the position of the moving mirror 33 can be obtained with high precision according to the obtained interference light. Then, the calculation unit 7 can accurately calculate the moving mirror position signal X(t) based on the length measurement component. According to the heterodyne interferometry, when extracting the length measurement component, it is not easily affected by interference, especially not easily affected by stray light with frequencies that become noise, and is given high robustness.

[0146] Figure 2 The shown moving mirror position calculation unit 72 has a pre-processing unit 722, a demodulation processing unit 724, and a moving mirror position signal output unit 726. The pre-processing unit 722 and the demodulation processing unit 724 can apply, for example, the pre-processing unit and the demodulation unit disclosed in Japanese Patent Laid-Open No. 2022-38156.

[0147] The pre-processing unit 722 performs pre-processing on the second light reception signal S2 based on the reference signal Ss. The demodulation processing unit 724 demodulates the length measurement component derived from the position of the moving mirror 33 based on the pre-processed signal output from the pre-processing unit 722 and based on the reference signal Ss. That is, the demodulation processing unit 724 demodulates the length measurement component based on the reference signal Ss, which is a periodic signal generated by the periodic signal generation unit 6, and the second light reception signal S2.

[0148] The moving mirror position signal output unit 726 generates and outputs a moving mirror position signal X(t) based on the length measurement component of the moving mirror 33 demodulated by the demodulation processing unit 724. The moving mirror position signal X(t) obtained by this method is a signal representing the position of the moving mirror 33 that changes at each moment, and captures the displacement of the moving mirror 33 at intervals sufficiently narrower than the wavelength of the length measurement light L2. For example, when the wavelength of the length measurement light L2 is several hundred nm, the position resolution of the moving mirror position signal X(t) can reach less than 10 nm. Therefore, in the light intensity calculation unit 74, high-precision digital data of the interference pattern F(x) can be generated.

[0149] Figure 7 is a diagram showing Figure 1 an example of the first light reception signal F(t) and the moving mirror position signal X(t) obtained by the Figure 7 shown spectroscopic device 100. The horizontal axis is time t, and the vertical axis is the intensity of the interference light incident on the first light reception element 36 or the position of the moving mirror 33.

[0150] Figure 7The shown moving mirror position signal X(t) is an image of a signal that continuously detects changes in the position of the moving mirror 33 and achieves high position resolution. By generating the interference pattern F(x) based on such a moving mirror position signal X(t), an interference pattern F(x) with a larger number of data points is obtained. A larger number of data points means a shorter sampling interval and higher precision for the interference pattern F(x). Therefore, a spectral pattern with high wavelength resolution (wave number resolution) can ultimately be acquired.

[0151] In addition, by being able to shorten the sampling interval, even when using analysis light L1 with a shorter wavelength (larger wave number), an interference pattern F(x) with sufficient data points can be obtained. Thereby, a spectral pattern over a wider wavelength range (wider wave number range), that is, a spectral pattern with a wider frequency band, can be acquired.

[0152] 1.5.2. Light intensity calculation unit

[0153] The light intensity calculation unit 74 generates a waveform (interference pattern F(x)) representing the intensity of the interference light with respect to the position of the moving mirror 33 based on the first light reception signal F(t) and the moving mirror position signal X(t).

[0154] As described above, the first light reception signal F(t) includes a component originating from the specimen and the phase information originating from the moving mirror 33. In the light intensity calculation unit 74, based on the moving mirror position signal X(t), the intensity of the first light reception signal F(t) is extracted. Then, the light intensity calculation unit 74 generates the interference pattern F(x) based on the position of the moving mirror 33 obtained from the moving mirror position signal X(t) and the intensity of the first light reception signal F(t). In addition, the interference pattern F(x) is shown as a function of the optical path difference between the reflected light at the moving mirror 33 and the reflected light at the fixed mirror 34 in the analysis optical system 3 and the intensity of the interference light received by the first light receiving element 36 (the intensity of the first light reception signal F(t)).

[0155] Figure 8 is a diagram showing an example of the interference pattern F(x). Figure 8 The horizontal axis of is the optical path difference of the analysis optical system 3, and the vertical axis is the intensity of the interference light. In addition, the optical path difference of the analysis optical system 3 refers to the difference between the optical path lengths of the beam splitter 32 and the moving mirror 33 and the optical path lengths of the beam splitter 32 and the fixed mirror 34. In Figure 8 the optical path difference zero is set as the origin of the horizontal axis.

[0156] 1.5.3. Fourier transform unit

[0157] The Fourier transform unit 76 performs a Fourier transform on the interference pattern F(x). Thereby, a spectral pattern including the information inherent to the specimen 9 is acquired.

[0158] Figure 9This is an example of the spectral pattern SP0 obtained by performing spectral analysis on the specimen 9. The spectral pattern SP0 is an example of the reflection spectrum of the specimen 9.

[0159] In Figure 9 In the spectral pattern SP0 shown, the component originating from the specimen generated when the analysis light L1 acts on the specimen 9 is reflected as the absorption peak X9. According to the spectroscopic device 100, the characteristics of the specimen 9, such as material, structure, component amount, etc., can be analyzed based on the spectral pattern SP0.

[0160] This spectral pattern SP0 is generated by performing a Fourier transform on the interferogram F(x). Since the interferogram F(x) is an electric field amplitude waveform obtained by taking the position of the moving mirror 33 as a parameter, the spectral pattern SP0 obtained by performing a Fourier transform on it has wavelength information. The position of the moving mirror 33 is directly related to the wave number accuracy of the spectral pattern SP0. Therefore, according to the spectroscopic device 100 according to the present embodiment, the position of the moving mirror 33 can be obtained more accurately, so that a spectral pattern SP0 with high accuracy on the wavelength axis (wave number axis) can be generated. In addition, according to the present embodiment, it is possible to suppress a decrease in the S / N ratio of the first light receiving signal F(t) due to the shaking when the moving mirror 33 moves and a decrease in the S / N ratio of the second light receiving signal S2, and it is possible to suppress a decrease in the accuracy of the spectral pattern SP0.

[0161] 2. Modification Example of the First Embodiment

[0162] Next, a modification example of the first embodiment will be described. In the following description, the description will focus on the differences from the first embodiment, and the description of the same matters will be omitted.

[0163] Figure 10 is a cross-sectional view showing the mirror moving mechanism 1 according to the first modification example of the first embodiment. In addition, in Figure 10 the same reference numerals are assigned to the same structures as those in the first embodiment.

[0164] The first modification example is the same as the first embodiment except that the moving mirror 33 has a corner prism 330 instead of the substrate 334.

[0165] Figure 10The corner prism 330 shown has an incident surface 336 and a retroreflective surface 338. The incident surface 336 is the surface where the analysis light L1a and the length measurement light L2b are incident, and is composed of a flat surface. When light is incident on the incident surface 336, it enters the corner prism 330, is reflected by the retroreflective surface 338, and exits again from the incident surface 336. The retroreflective surface 338 is composed of the surface of the corner of a cube and generates three internal reflections. As a result, the light exiting from the incident surface 336 can return in the same direction as the incident direction. As a result, even in the case of a large deflection angle, the positions where the reflected analysis light L1a and length measurement light L2b return are not likely to change, so that the loss of light intensity due to the deflection angle can be suppressed to the minimum.

[0166] Such a corner prism 330 has retroreflectivity regardless of, for example, the incident angle of light with respect to the incident surface 336. In addition, in the corner prism 330, retroreflectivity can be achieved by one component.

[0167] In addition, a corner reflector can be used instead of the corner prism 330. The corner reflector is also called a hollow retroreflector and has the same retroreflectivity as the corner prism 330. In addition, as the corner reflector, for example, there are a mounted reflector in which three reflectors are fixed to a mounting member, a replicated reflector in which a mirror material such as metal is formed on a replicated member having three mutually orthogonal surfaces, and the like.

[0168] Figure 11 It is a cross-sectional view showing the mirror moving mechanism 1 according to the second modification of the first embodiment. In addition, in Figure 11 For the same structures as those in the first embodiment, the same reference numerals are given.

[0169] The second modification is the same as the first embodiment except that reflective surfaces 332 and 333 are provided on both surfaces of the substrate 334.

[0170] Figure 11 The wall portion 82 shown has a through hole 822 that penetrates a portion intersecting the central axis AX. As a result, light can be irradiated onto both surfaces of the substrate 334. Therefore, in Figure 11 the substrate 334 shown, a reflective surface 332 is provided on one surface and a reflective surface 333 is provided on the other surface. According to such a mirror moving mechanism 1, for example, the analysis light L1a can be incident on the reflective surface 332 and the length measurement light L2b can be incident on the reflective surface 333. As a result, there is no need for Figure 1 the optical elements for detouring the length measurement light L2b as shown, and the structure of the length measurement optical system 4 can be simplified.

[0171] In addition, since the wall portion 82 has a through hole 822, when an adhesive is applied between the substrate 334 and the wall portion 82, the excess adhesive can be extruded toward the through hole 822 side. Thereby, the thickness of the adhesive can be made uniform. As a result, the arrangement accuracy of the reflecting surfaces 332 and 333 with respect to the wall portion 82 can be improved.

[0172] Figure 12 FIG. is a cross-sectional view showing a mirror moving mechanism 1 according to a third modification of the first embodiment. In addition, in Figure 12 structures identical to those of the first embodiment are denoted by the same reference numerals.

[0173] The third modification is the same as the first embodiment except that the diameter of the moving mirror 33 is smaller than the beam diameter of the length measuring light L2b incident on the reflecting surface 332.

[0174] Figure 12 The moving mirror 33 shown has a substrate 334. Figure 12 The diameter of the substrate 334 shown is set smaller than the beam diameter of the length measuring light L2b incident on the reflecting surface 332. As a result, the length measuring light L2b reflected by the reflecting surface 332 has a beam diameter reduced to the diameter of the substrate 334. As a result, Figure 12 the moving mirror 33 shown has a function of an aperture that reduces the beam diameter. Thereby, the beam diameter can be reduced without providing an aperture in another place, and thus the number of optical elements constituting the length measuring optical system 4 can be reduced.

[0175] Figure 13 FIG. is a cross-sectional view showing a mirror moving mechanism 1 according to a fourth modification of the first embodiment. In addition, in Figure 13 structures identical to those of the first embodiment are denoted by the same reference numerals.

[0176] The fourth modification is the same as the first embodiment except that the length of the inner cylinder 81 in the direction of the central axis AX is equal to or greater than the length of the outer cylinder 83.

[0177] Figure 13 Both end portions of the inner cylinder 81 in the direction of the central axis AX shown project from the outer cylinder 83. According to such a structure, even when dust is generated due to the screwing together of the first thread groove 812 and the second thread groove 832, the generated dust is less likely to adhere to the reflecting surface 332 of the moving mirror 33.

[0178] Figure 14 FIG. is a cross-sectional view showing a mirror moving mechanism 1 according to a fifth modification of the first embodiment. Figure 15 is Figure 14 a partial enlarged view of the mirror moving mechanism 1 shown. In addition, in Figure 14and Figure 15 In the drawings, the same reference numerals are given to the same structures as those of the first embodiment.

[0179] The fifth modification is the same as the first embodiment, except that it includes a preloading portion 84 having an elastomer 842.

[0180] Figure 14 The mirror moving mechanism 1 shown includes a preloading portion 84 that preloads the inner cylinder 81 in the direction of the central axis AX. Figure 14 The preloading portion 84 shown has an elastomer 842. When the elastomer 842 is compressed in the X-axis direction, a resilient force that rebounds is generated. As the elastomer 842, for example, a helical spring, a leaf spring, rubber, an elastomer, etc. can be cited. The end portion of the elastomer 842 on the negative side of the X-axis is fixed to the outside, and the end portion on the positive side of the X-axis abuts against the inner cylinder 81. Moreover, the length of the elastomer 842 is set so as to be maintained in a state of being compressed in the X-axis direction as compared with the natural state regardless of the position of the inner cylinder 81. As a result, the elastomer 842 preloads the inner cylinder 81 in the direction of the central axis AX. As a result, as Figure 15 shown, the state in which the tooth surfaces of the first thread groove 812 and the second thread groove 832 are in contact can be maintained. Thereby, generation of backlash accompanying the gap between the tooth surfaces can be suppressed, and generation of angular deviation (deflection angle) of the movable mirror 33 can be suppressed.

[0181] Figure 16 is a cross-sectional view showing the mirror moving mechanism 1 according to the sixth modification of the first embodiment. In addition, in Figure 16 the drawings, the same reference numerals are given to the same structures as those of the first embodiment.

[0182] The sixth modification is the same as the first embodiment, except that it includes a preloading portion 84 having a magnet 844 and a magnetic body 846.

[0183] Figure 16 The mirror moving mechanism 1 shown also includes a preloading portion 84 that preloads the inner cylinder 81 in the direction of the central axis AX. Figure 16 The preloading portion 84 shown has a magnet 844 and a magnetic body 846. The magnet 844 is, for example, a permanent magnet or an electromagnet, and is fixed to the outside of the mirror moving mechanism 1. The magnetic body 846 generates magnetic forces such as magnetic attraction and magnetic repulsion with the magnet 844. The magnetic body 846 is, for example, a magnetic metal, a metal oxide, a magnet, etc. As Figure 15 shown, these magnetic attraction and magnetic repulsion forces maintain the state in which the tooth surfaces of the first thread groove 812 and the second thread groove 832 are in contact. Thereby, generation of backlash accompanying the gap between the tooth surfaces can be suppressed.

[0184] Figure 17 and Figure 18 is a cross-sectional view showing the mirror moving mechanism 1 according to the seventh modification of the first embodiment. In addition, in Figure 17 and Figure 18 , the same reference numerals are given to the same structures as those in the first embodiment.

[0185] The seventh modification is the same as the first embodiment except that the cross-sectional shapes of the respective thread teeth of the first thread groove 812 and the second thread groove 832 are different.

[0186] Figure 17 The cross-sectional shapes of the thread teeth of the first thread groove 812 and the second thread groove 832 shown in Figure 18 are each substantially right-angled triangles, and are set such that a part of the tooth surface (the tooth surface 812a of the first thread groove 812 and the tooth surface 832a of the second thread groove 832) is substantially orthogonal to the X axis. In addition, Figure 17 and Figure 18 the cross-sectional shapes of the thread teeth of the first thread groove 812 and the second thread groove 832 shown in

[0187] are each substantially rectangles, and are set such that a part of the tooth surface (the tooth surface 812a of the first thread groove 812 and the tooth surface 832a of the second thread groove 832) is substantially orthogonal to the X axis. Moreover, as shown in

[0188] Figure 19 is a cross-sectional view showing the mirror moving mechanism 1 according to the eighth modification of the first embodiment. In addition, in Figure 19 , the same reference numerals are given to the same structures as those in the first embodiment.

[0189] The eighth modification is the same as the first embodiment except that Figure 19 as shown, the second thread groove 832 does not reach the X-axis positive-side end of the outer cylinder 83.

[0190] According to such a structure, the inner cylinder 81 cannot move to the end on the positive X-axis side of the outer cylinder 83. Therefore, it is possible to prevent the inner cylinder 81 from coming off from the end on the positive X-axis side of the outer cylinder 83.

[0191] Figure 20 It is a cross-sectional view showing the mirror moving mechanism 1 according to the ninth modification of the first embodiment. Figure 21 It is viewed from the positive X-axis side Figure 20 The front view of the shown mirror moving mechanism 1.

[0192] The ninth modification is the same as the first embodiment except that a connecting portion 85 that connects the wall portion 82 and the moving mirror 33 is provided.

[0193] Figure 20 The shown mirror moving mechanism 1 includes a connecting portion 85. The connecting portion 85 connects the wall portion 82 and the moving mirror 33. Specifically, the connecting portion 85 is composed of a shaft 852 and a circular plate portion 854. The shaft 852 passes through the central portion of the wall portion 82 and extends along the X-axis. The circular plate portion 854 is connected to the end on the positive X-axis side of the shaft 852 and extends in the Y-Z plane. The end on the negative X-axis side of the shaft 852 is fixed to the wall portion 82 via a bearing 86. The bearing 86 supports the shaft 852 so as to be rotatable about the central axis AX. The circular plate portion 854 supports the moving mirror 33. In addition, a part of the outer edge of the circular plate portion 854 constitutes a protruding portion 856 that protrudes outward. On the other hand, on the inner surface of the outer cylinder 83, a guide groove 834 extending in the X-axis direction is provided so as to cross the second thread groove 832. And, as Figure 21 shown, the protruding portion 856 is fitted into the guide groove 834.

[0194] According to such a structure, even if the inner cylinder 81 is rotationally driven, the moving mirror 33 does not rotate. That is, even if the inner cylinder 81 is rotationally driven, the power is not transmitted to the connecting portion 85 supported by the bearing 86. In addition, since the protruding portion 856 is fitted into the guide groove 834, it is possible to suppress the rotation of the connecting portion 85 about the central axis AX, and the connecting portion 85 can move in the X-axis direction. Therefore, it is possible to move in the X-axis direction while suppressing the rotation of the moving mirror 33, and the analysis light L1a and the length measuring light L2b are always irradiated to the same position on the reflection surface 332. As a result, it is possible to eliminate the adverse conditions that may occur along with the rotation of the moving mirror 33. Specifically, it is possible to suppress the unexpected change in the respective reflection intensities of the analysis light L1a and the length measuring light L2b along with the rotation of the moving mirror 33.

[0195] In each of the above modifications, the same effects as those of the first embodiment can also be obtained.

[0196] 3. Second Embodiment

[0197] Next, the mirror moving mechanism according to the second embodiment will be described.

[0198] Figure 22 It is a cross-sectional view showing the mirror moving mechanism 1 according to the second embodiment. Figure 23 It schematically shows Figure 22 A perspective view of the spline shaft 864 shown and the second linear groove 816 provided on the inner surface of the inner cylinder 81.

[0199] Hereinafter, the second embodiment will be described. In the following description, the differences from the first embodiment will be mainly described, and the same matters will be omitted. In addition, in Figure 22 and Figure 23 matters identical to those of the first embodiment are denoted by the same reference numerals.

[0200] The second embodiment is the same as the first embodiment except for the structure of the drive unit 80.

[0201] Figure 22 The drive unit 80 shown has a motor M and a power conversion unit 862. Figure 22 The power conversion unit 862 shown is constituted by a spline shaft 864 connected to the output shaft of the motor M, and transmits the rotational power of the motor M to the inner cylinder 81. Specifically, as Figure 23 shown, a second linear groove 816 extending parallel to the central axis AX is provided on the inner surface of the inner cylinder 81. In addition, as Figure 23 shown, the spline shaft 864 has external teeth 866 on its outer surface. By meshing the external teeth 866 with the second linear groove 816, rotational power is transmitted from the spline shaft 864 to the inner cylinder 81. On the other hand, the second linear groove 816 extends relatively long in the direction of the central axis AX. Therefore, the spline shaft 864 can transmit rotational power and slide in the direction of the central axis AX. Thereby, the inner cylinder 81 is rotationally driven and can move in the direction of the central axis AX. In addition, the spline shaft 864 may be another spline shaft for a ball spline or the like. Similarly, the inner cylinder 81 having the second linear groove 816 may be another spline bearing.

[0202] As Figure 22 the motor M shown, it is particularly preferable to use a stepping motor. The stepping motor is easy to control the rotation angle even at low speeds. Therefore, for example, even when the reduction ratio of the power conversion unit 862 is small, appropriate rotational power can be generated.

[0203] In the second embodiment as described above, the same effects as those of the first embodiment can also be obtained.

[0204] 4. Modification Example of the Second Embodiment

[0205] Next, a modification of the second embodiment will be described.

[0206] Hereinafter, a modification of the second embodiment will be described. In the following description, the differences from the second embodiment will be mainly described, and the description of the same matters will be omitted.

[0207] Figure 24 is a cross-sectional view showing the mirror moving mechanism 1 according to the modification of the second embodiment. In addition, in Figure 24 structures identical to those of the second embodiment are denoted by the same reference numerals.

[0208] The modification is the same as the second embodiment except that a flexible shaft 867 is used.

[0209] Figure 24 The power conversion unit 862 shown has a spline shaft 864 and a flexible shaft 867. The flexible shaft 867 is a shaft that connects the output shaft of the motor M and the spline shaft 864. Since the flexible shaft 867 has flexibility, rotational power can be transmitted even if it does not extend linearly. Therefore, by using the flexible shaft 867, the degree of freedom in arranging the motor M can be increased. As a result, miniaturization of the mirror moving mechanism 1 can be achieved, and the degree of freedom in design can be improved.

[0210] In the modification as described above, the same effects as those of the second embodiment are obtained.

[0211] 5. Third Embodiment

[0212] Next, an interferometer according to the third embodiment will be described.

[0213] Figure 25 is a schematic configuration diagram showing a shape measurement device 200 as an interferometer according to the third embodiment. Figure 26 is a block diagram showing Figure 25 the functions of the main parts of the analysis unit 300, the length measurement unit 400, the periodic signal generation unit 6, and the arithmetic unit 7.

[0214] Hereinafter, the third embodiment will be described. In the following description, the differences from the first embodiment will be mainly described, and the description of the same matters will be omitted. In addition, in Figure 25 and Figure 26 matters identical to those of the first embodiment are denoted by the same reference numerals.

[0215] The spectroscopic device 100 according to the first embodiment is a device that irradiates the analysis light L1 emitted from the first light source 51 onto the specimen 9 and performs spectroscopic analysis of the specimen 9. In contrast, the shape measurement device 200 according to the third embodiment is a device that irradiates the analysis light L1 onto the specimen 9 and measures the shape of the surface and inside of the specimen 9. Figure 25 The shape measurement device 200 shown is the same as the Figure 1 spectroscopic device 100 shown except for the structure of the analysis optical system 3.

[0216] Figure 25 The analysis optical system 3 shown includes a first light source 51, a beam splitter 32, a condenser lens 35, a condenser lens 37, and a first light receiving element 36.

[0217] Figure 25 Examples of the first light source 51 shown include not only white light sources such as SLD (Super Luminescent Diode) and LED (Light Emitting Diode), but also wavelength scanning light sources, various lamps listed in the first embodiment, etc. Preferably, a broadband light source called a low coherence light source is used.

[0218] The analysis light L1 emitted from the first light source 51 is split into two by the beam splitter 32. Figure 25 The beam splitter 32 shown reflects a part of the analysis light L1 as the analysis light L1a toward the moving mirror 33 and transmits the other part of the analysis light L1 as the analysis light L1b toward the specimen 9. The analysis light L1b is condensed by the condenser lens 37 and irradiated onto the specimen 9.

[0219] In addition, the beam splitter 32 transmits the analysis light L1a reflected by the moving mirror 33 toward the first light receiving element 36 and reflects the analysis light L1b reflected by the specimen 9 toward the first light receiving element 36. Therefore, the beam splitter 32 mixes the split analysis lights L1a and L1b and forms interference light.

[0220] The first light receiving element 36 receives the interference light and obtains its intensity. Then, a signal showing the time change of the intensity is output as the first light receiving signal F(t). This first light receiving signal F(t) includes a component derived from the specimen generated by the interaction between the analysis light L1b and the specimen 9 and the phase information from the above-mentioned moving mirror 33. The component derived from the specimen is, for example, a change in the phase added to the analysis light L1b according to the surface shape of the specimen 9.

[0221] As the first light-receiving element 36, for example, in addition to a photodiode, a phototransistor, etc., image sensors such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal Oxide Semiconductor) can also be cited. By using an image sensor, a two-dimensional distribution of the first light-receiving signal F(t) can be acquired. Thereby, the surface shape of the specimen 9 can be measured two-dimensionally.

[0222] Figure 25 The length-measuring optical system 4, the periodic signal generation unit 6, and the mirror moving mechanism 1 shown in Figure 1 are the same.

[0223] Figure 26 The arithmetic unit 7 shown in has a moving mirror position arithmetic unit 72, a light intensity arithmetic unit 74, and a shape calculation unit 78.

[0224] Figure 26 Similar to the first embodiment, the light intensity arithmetic unit 74 shown generates a waveform (interference pattern F(x)) representing the intensity of the first light-receiving signal F(t) at each position of the moving mirror 33 based on the first light-receiving signal F(t) and the moving mirror position signal X(t). Figure 26 The shape calculation unit 78 shown calculates the surface shape and internal shape of the specimen 9 based on this waveform. Specific analysis methods are known under names such as white light interferometry and time-domain OCT (Optical Coherence Tomography).

[0225] In addition, in Figure 25 the case where the analysis light L1b is reflected by the specimen 9 is illustrated, but in the case where the specimen 9 transmits the analysis light L1b, Figure 25 the shape measurement device 200 shown can measure the internal shape (internal structure) of the specimen 9. Specific analysis methods are known under names such as optical coherence tomography.

[0226] In the third embodiment as described above, the same effects as those of the first embodiment can also be obtained. That is, according to the third embodiment, the effects of the mirror moving mechanism 1 can be enjoyed, and thus a shape measurement device 200 that can achieve high-precision measurement of analysis results such as the surface shape and internal shape of the specimen 9 can be realized.

[0227] 6. Effects achieved by the respective embodiments

[0228] The mirror moving mechanism 1 according to each of the embodiments and each of the modified examples includes a movable mirror 33, an inner cylinder 81, an outer cylinder 83, and a drive unit 80. The movable mirror 33 has a reflecting surface 332. The inner cylinder 81 supports the movable mirror 33 on its inner surface and has a first thread groove 812 extending around the central axis AX on its outer surface. The outer cylinder 83 has a second thread groove 832 on its inner surface that engages with the first thread groove 812. The drive unit 80 can move the inner cylinder 81 in the direction of the central axis AX by rotationally driving the inner cylinder 81 about the central axis AX as the rotation axis.

[0229] According to such a structure, the state where the first thread groove 812 and the second thread groove 832 are in contact is maintained for the entire circumference or a majority of the circumference around the central axis AX. Therefore, when the inner cylinder 81 is rotationally driven, the wobbling of the inner cylinder 81 relative to the outer cylinder 83 can be suppressed to a minimum. As a result, the translatability of the movement of the movable mirror 33 can be improved, and the generation of angular deviation (deflection angle) of the movable mirror 33 can be suppressed. In addition, a large movement amount of the movable mirror 33 can be ensured. Moreover, since there is no need to use a large guiding mechanism or the like, miniaturization of the mirror moving mechanism 1 can be achieved.

[0230] In addition, it is preferable that the length of the outer cylinder 83 in the direction of the central axis AX is longer than the distance by which the drive unit 80 moves the inner cylinder 81.

[0231] According to such a structure, the first thread groove 812 and the second thread groove 832 can be engaged throughout the entire region of the movement amount of the movable mirror 33. As a result, the generation of deflection angle can be suppressed throughout the entire region of the movement amount of the movable mirror 33.

[0232] In addition, it is preferable that the movable mirror 33 is supported at the middle portion of the length of the inner cylinder 81 in the direction of the central axis AX.

[0233] According to such a structure, even when dust is generated due to the engagement of the first thread groove 812 and the second thread groove 832, the generated dust is not easily attached to the reflecting surface 332 of the movable mirror 33. Thereby, a decrease in the S / N ratio of the interference signal due to a decrease in the reflectivity of the reflecting surface 332 can be suppressed.

[0234] In addition, the mirror moving mechanism 1 according to each of the embodiments and each of the modified examples may include a wall portion 82 that is fixed to the inner surface of the inner cylinder 81 and intersects the central axis AX. Moreover, the movable mirror 33 may be supported by the wall portion 82.

[0235] According to such a structure, the wall portion 82 and the movable mirror 33 can be prepared separately, so a reflecting surface 332 with high surface accuracy can be obtained.

[0236] In addition, the mirror moving mechanism 1 according to each of the above-described embodiments and modifications may also include a preloading portion 84 that preloads the inner cylinder 81 in the direction of the central axis AX.

[0237] According to such a structure, the state where the tooth surfaces of the first thread groove 812 and the second thread groove 832 are in contact can be maintained. As a result, the generation of backlash due to the clearance between the tooth surfaces can be suppressed, and the generation of angular deviation (deflection angle) of the moving mirror 33 can be suppressed.

[0238] Alternatively, the preloading portion 84 may be configured to preload the inner cylinder 81 by the elastic force generated in the elastic body 842.

[0239] According to such a structure, the state where the tooth surfaces of the first thread groove 812 and the second thread groove 832 are in contact can be maintained by the elastic force.

[0240] Alternatively, the preloading portion 84 may be configured to preload the inner cylinder 81 by the magnetic force generated by the magnet 844.

[0241] According to such a structure, the state where the tooth surfaces of the first thread groove 812 and the second thread groove 832 are in contact can be maintained by the magnetic force.

[0242] In addition, it is preferable that the angle formed by the tooth surface 812a of the first thread groove 812 and a plane orthogonal to the central axis AX, and the angle formed by the tooth surface 832a of the second thread groove 832 and the plane are 15° or less.

[0243] According to such a structure, the effect of suppressing the offset of the inner cylinder 81 in the direction of the central axis AX can be obtained more reliably.

[0244] In addition, it is preferable that the moving mirror 33 has retroreflectivity.

[0245] According to such a structure, the light incident on the moving mirror 33 can be returned in the same direction as the incident direction. As a result, even when the deflection angle is large, the positions where the reflected analysis light L1a and the length measurement light L2b return are not likely to change, and thus the loss of light intensity due to the deflection angle can be suppressed to a minimum.

[0246] In addition, the mirror moving mechanism 1 according to each of the above-described embodiments and modifications may also include: a wall portion 82 fixed to the inner surface of the inner cylinder 81; a connecting portion 85 that connects the wall portion 82 and the moving mirror 33; and a bearing 86 that prevents the connecting portion 85 from rotating when the inner cylinder 81 is rotationally driven.

[0247] According to such a structure, it is possible to move in the X-axis direction while suppressing the rotation of the moving mirror 33, and analyze that the analysis light L1a and the length measurement light L2b always irradiate the same position on the reflecting surface 332. As a result, it is possible to eliminate the adverse conditions that may occur along with the rotation of the moving mirror 33. Specifically, it is possible to suppress the unexpected change in the respective reflection intensities of the analysis light L1a and the length measurement light L2b along with the rotation of the moving mirror 33.

[0248] In addition, the moving mirror 33 may also have a substrate 334 and reflecting surfaces 332 and 333 provided on both sides of the substrate 334.

[0249] According to such a structure, for example, it is possible to make the analysis light L1a incident on the reflecting surface 332 and make the length measurement light L2b incident on the reflecting surface 333. As a result, for example, optical elements for making the length measurement light L2b detour are not required, and the structure of the length measurement optical system 4 can be simplified.

[0250] In addition, the inner cylinder 81 may also have a first linear groove 814 that intersects the first thread groove 812 on its outer surface. Moreover, the drive unit 80 may also have: a motor M; and a worm wheel 863, which is connected to the motor M and meshes with the first linear groove 814.

[0251] According to such a structure, it is possible to increase the reduction ratio of the power conversion unit 862 and suppress backlash less. As a result, since it is not necessary to add a speed reducer or the like, it is possible to easily miniaturize the drive unit 80 and easily improve the position accuracy of the moving mirror 33.

[0252] In addition, it is preferable that the motor M is a DC motor.

[0253] According to such a structure, it is possible to contribute to the miniaturization of the mirror moving mechanism 1.

[0254] In addition, the inner cylinder 81 may also have a second linear groove 816 that extends parallel to the central axis AX on its inner surface. Moreover, the drive unit 80 may also have: a motor M; and a spline shaft 864, which is connected to the motor M and slides relative to the inner cylinder 81.

[0255] According to such a structure, the inner cylinder 81 is rotationally driven and can move in the direction of the central axis AX.

[0256] In addition, the drive unit 80 may also have a flexible shaft 867 that transmits the rotational power of the motor M to the spline shaft 864.

[0257] According to such a structure, the degree of freedom in the arrangement of the motor M can be improved. As a result, it is possible to miniaturize the mirror moving mechanism 1 and improve the degree of freedom in design.

[0258] In addition, the interferometer (the spectroscopic device 100 or the shape measurement device 200) according to the above-described embodiment includes: a mirror moving mechanism 1 according to the above-described embodiment or each modification that reflects the analysis light L1a; and an analysis optical system 3. The analysis optical system 3 outputs a first light reception signal F(t) including information derived from the specimen 9 by performing interference of light including the analysis light L1a reflected by the mirror moving mechanism 1 and the analysis light L1b that has passed through the specimen 9.

[0259] With such a configuration, it is possible to realize a miniaturized, lightweight, and low-cost interferometer. In addition, it is possible to improve the translatability of the movement of the moving mirror 33 and suppress the occurrence of angular deviation (tilt angle) of the moving mirror 33. Therefore, when the interferometer is applied to the spectroscopic device 100 or the shape measurement device 200, a highly accurate analysis result can be obtained.

[0260] In addition, the interferometer (the spectroscopic device 100 or the shape measurement device 200) according to the above-described embodiment may further include a length measurement optical system 4. The length measurement optical system 4 causes the length measurement light L2b (laser) to enter the reflection surface 332 and performs interference of light including the reflected length measurement light L2b, thereby outputting a second light reception signal S2 including information indicating the position of the moving mirror 33.

[0261] With such a configuration, an interferogram F(x) with a larger number of data points can be obtained. A larger number of data points means a shorter sampling interval and higher accuracy of the interferogram F(x). Therefore, ultimately, a spectral pattern with high wavelength resolution (wave number resolution) can be acquired. In addition, even when using analysis light L1 with a shorter wavelength (larger wave number), an interferogram F(x) with a sufficient number of data points can be obtained. Thus, a spectral pattern with a wider wavelength range (wider wave number range), that is, a wider-band spectral pattern, can be acquired.

[0262] As described above, the mirror moving mechanism and the interferometer of the present invention have been described based on the illustrated embodiments, but the mirror moving mechanism and the interferometer of the present invention are not limited to the above-described embodiments and each modification, and the structure of each part can be replaced by any constituent, and any other constituent can also be added.

[0263] In addition, the mirror moving mechanism and the interferometer of the present invention may also include a combination of two or more of the above-described embodiments and their modifications. Moreover, each functional part included in the interferometer of the present invention can be divided into a plurality of elements, and a plurality of functional parts can also be integrated into one.

[0264] In addition, in the above-described embodiments, a Michelson interference optical system is used, but an interference optical system of other types may also be used.

[0265] Moreover, the arrangement of the specimen is not limited to the illustrated arrangement. Since the component derived from the specimen is generated by causing the analysis light to act on the specimen, the specimen can be arranged at any position as long as the analysis light emitted from the specimen can be incident on the position of the first light receiving element.

Claims

1. A reflector moving mechanism, characterized in that: have: a movable mirror having a reflective surface; An inner cylinder, which supports the movable mirror on its inner surface and has a first thread groove extending around a central axis on its outer surface; An outer cylinder having a second thread groove on its inner surface that is threadedly engaged with the first thread groove; as well as The driving unit drives the inner cylinder to rotate about the central axis as a rotation axis, thereby moving the inner cylinder in the direction of the central axis.

2. The reflector moving mechanism according to claim 1, characterized in that: The length of the outer cylinder in the direction of the central axis is longer than a distance that the inner cylinder is moved by the driving unit.

3. The reflector moving mechanism according to claim 1 or 2, characterized in that: The movable mirror is supported at an intermediate portion of the length of the inner cylinder in the direction of the central axis.

4. The reflector moving mechanism according to claim 1 or 2, characterized in that: The mirror moving mechanism includes a wall portion, the wall portion being fixed to the inner surface of the inner cylinder and intersecting the central axis. The movable mirror is supported by the wall portion.

5. The reflector moving mechanism according to claim 1 or 2, characterized in that: The mirror moving mechanism includes a pre-pressing portion configured to pre-press the inner cylinder in the direction of the central axis.

6. The reflector moving mechanism according to claim 5, characterized in that: The pre-compression portion pre-compresses the inner tube by an elastic force generated in the elastic body.

7. The reflector moving mechanism according to claim 5, characterized in that: The pre-pressing portion pre-presses the inner tube by a magnetic force generated by a magnet.

8. The reflector moving mechanism according to claim 5, characterized in that: An angle formed by a tooth surface of the first thread groove and a plane perpendicular to the central axis, and an angle formed by a tooth surface of the second thread groove and the plane are 15° or less.

9. The reflector moving mechanism according to claim 1 or 2, characterized in that: The movable mirror has retro-reflective properties.

10. The reflector moving mechanism according to claim 1 or 2, characterized in that: have: A wall portion, fixed to the inner surface of the inner cylinder; a connecting portion connecting the wall portion and the movable mirror; and The bearing prevents the connection portion from rotating when the inner cylinder is driven to rotate.

11. The reflector moving mechanism according to claim 1 or 2, characterized in that: The movable mirror has: substrate; and The reflecting surface is arranged on two surfaces of the substrate.

12. The reflector moving mechanism according to claim 1 or 2, characterized in that: The inner tube has a first linear groove intersecting the first thread groove on the outer surface. The driving unit has: Motors; and The worm wheel is connected to the motor and is threadedly engaged with the first linear groove.

13. The reflector moving mechanism according to claim 12, characterized in that: The motor is a DC motor.

14. The reflector moving mechanism according to claim 1 or 2, characterized in that: The inner cylinder has a second linear groove extending parallel to the central axis on the inner surface. The driving unit has: Motors; and A spline shaft is connected to the motor and slides relative to the inner cylinder.

15. The reflector moving mechanism according to claim 14, characterized in that: The driving portion includes a flexible shaft that transmits the rotational power of the motor to the spline shaft.

16. An interferometer, characterized in that: have: The mirror moving mechanism according to claim 1 or 2 for reflecting the analysis light; and The analysis optical system causes interference of the analysis light reflected by the mirror moving mechanism and the analysis light passing through the sample, thereby outputting a first light reception signal including information derived from the sample.

17. The interferometer according to claim 16, characterized in that The interferometer further includes a length measuring optical system that causes laser light to be incident on the reflecting surface, performs interference of light including the reflected laser light, and outputs a second light receiving signal including information indicating the position of the movable mirror.

Images