WO2015177974A1

WO2015177974A1 - Spectral sensor

Info

Publication number: WO2015177974A1
Application number: PCT/JP2015/002303
Authority: WO
Inventors: 吉原　孝明
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2014-05-19
Filing date: 2015-05-01
Publication date: 2015-11-26
Also published as: JP2015219153A

Abstract

　A spectral separation part (3) includes a MEMS mirror (30) for holding a diffraction grating (35). A first photodetector (5) receives a specific order of diffracted light from the diffraction grating (35). A second photoreceptor (7) is capable of receiving zero-order diffracted light from the diffraction grating (35). A signal processing device (10) obtains the deflection angle of a movable part (23) on the basis of the detection timing of the zero-order diffracted light and the oscillation frequency of a movable part (32), and performs one-to-one correlation of a wavelength stored in advance corresponding to the deflection angle and a signal of the first photoreceptor (5) obtained at the deflection angle. The MEMS mirror (30) is provided with a support part (31), the movable part (32) on an inside of the support part (31), a pair of torsion spring parts (33) on either side of the movable part (32) and connecting the support part (31) and the movable part (32), and a mirror part (34) formed on a surface side of the movable part (32). A drive part (4) is provided integrally with the MEMS mirror (30), and drives the movable part (32).

Description

Spectrum sensor

The present invention relates to a spectrum sensor, and more particularly to a spectrum sensor that measures an intensity distribution for each wavelength of light.

Conventionally, a laser scanning microscope has been proposed as having a configuration that enables spectroscopic measurement (for example, Japanese Patent Application Publication No. 2004-212600 (hereinafter referred to as “Document 1”)).

The laser scanning microscope described in Document 1 includes a second detection unit as a configuration for performing spectroscopic measurement of fluorescence from a specimen separately from the first detection unit. The second detection unit includes an imaging lens, a pinhole, a collimator lens, a planar diffraction grating, a condenser lens, a slit, a photoelectric conversion element, a correction processing unit, and a control unit. Yes. The plane diffraction grating splits incident light and reflects the light flux at different angles for each wavelength. The planar diffraction grating is provided with a motor as drive means. An encoder that outputs a signal corresponding to the rotation angle of the planar diffraction grating is connected to the motor.

In the configuration for performing the above-described spectroscopic measurement, it is difficult to reduce the size of the planar diffraction grating because it requires relatively large components such as a motor and an encoder.

An object of the present invention is to provide a spectrum sensor that can be miniaturized.

The spectrum sensor of the present invention includes a housing having an opening, a collimating lens, a spectrum separation unit, a first light receiving element, and a first diaphragm. The collimating lens is disposed so as to close the opening of the housing. The spectrum separation unit is housed in the casing and includes a diffraction grating. The spectrum separation unit is configured by a MEMS mirror that separates light emitted from the collimating lens into a plurality of spectra. The first light receiving element is housed in the housing. The first diaphragm is disposed on the light receiving surface side of the first light receiving element and is housed in the housing, and has a first slit through which light having a predetermined wavelength band passes. The spectrum sensor further includes a second light receiving element, a second diaphragm, a signal processing device, and a drive unit. The second light receiving element is disposed so as to be able to receive 0th-order diffracted light among the light diffracted by the diffraction grating provided in the movable part of the MEMS mirror, and is housed in the housing. The second diaphragm is disposed on the light receiving surface side of the second light receiving element and is housed in the housing, and has a second slit through which light in the predetermined wavelength band passes. The first light receiving element is disposed so as to be able to receive diffracted light of a specified order other than the 0th order among the light diffracted by the diffraction grating. The signal processing device corresponds to a swing angle of the movable part or a swing angle thereof based on at least the timing when the second-order diffracted light is detected by the second light receiving element and the vibration frequency of the movable part. An arithmetic unit for obtaining the time to perform The signal processing device is configured to correlate the wavelength stored in advance corresponding to the deflection angle of the movable part and the signal of the first light receiving element obtained at the deflection angle on a one-to-one basis. . The MEMS mirror includes a frame-shaped support part, the movable part arranged inside the support part, and a pair of twists arranged so as to sandwich the movable part and connecting the support part and the movable part. A spring part, and a mirror part formed on the surface side of the movable part. The diffraction grating is formed on the surface of the mirror portion. The drive unit is housed in the housing, and is provided integrally with the MEMS mirror so as to drive the movable unit.

The spectrum sensor of the present invention can be downsized.

The drawings illustrate one or more embodiments in accordance with the present teachings, but are by way of example and not limitation. In the drawings, like numerals refer to the same or similar elements.
FIG. 1 is a schematic configuration diagram of a spectrum sensor according to an embodiment. FIG. 2 is a schematic perspective view in which a main part of the spectrum sensor according to the embodiment is partially broken. FIG. 3 is a schematic plan view of the MEMS mirror in the spectrum sensor of the embodiment. 4 is a schematic cross-sectional view taken along the line X1-X1 of FIG. 5 is a schematic cross-sectional view taken along the line X2-Y2 of FIG. FIG. 6 is an operation explanatory diagram of the spectrum sensor of the embodiment. FIG. 7 is an operation explanatory diagram of the spectrum sensor of the embodiment. FIG. 8 is an operation explanatory diagram of the spectrum sensor of the embodiment. FIG. 9 is an operation explanatory diagram of the spectrum sensor of the embodiment. FIG. 10 is an operation explanatory diagram of the spectrum sensor of the embodiment.

Hereinafter, the spectrum sensor of the present embodiment will be described with reference to FIGS.

The spectrum sensor 100 is a sensor that measures the distribution of intensity for each wavelength of light. In short, the spectrum sensor 100 is a sensor that measures the relative spectral distribution as a function of wavelength. The spectrum sensor 100 has sensitivity in a predetermined wavelength band, for example. As the predetermined wavelength band, a wavelength range of visible light is set. The wavelength range of visible light in this specification is 400 nm to 800 nm. The wavelength resolution of the spectrum sensor 100 can be set to 10 nm, for example.

The spectrum sensor 100 includes a housing 1 having an opening 11, a collimating lens 2, a spectrum separating unit 3, a first light receiving element 5, and a first diaphragm 6. The collimating lens 2 is disposed so as to close the opening 11 of the housing 1. The spectrum separation unit 3 is housed in the housing 1 and includes a diffraction grating 35. The spectrum separation unit 3 includes a MEMS (Micro Electro Mechanical System) mirror 30 that separates light emitted from the collimating lens 2 into a plurality of spectra. The first light receiving element 5 is housed in the housing 1. The first diaphragm 6 is disposed on the light receiving surface 51 side of the first light receiving element 5 and is housed in the housing 1 and has a first slit 61 that allows light in a predetermined wavelength band to pass through. The spectrum sensor 100 further includes a second light receiving element 7, a second diaphragm 8, a signal processing device 10, and a drive unit 4. The second light receiving element 7 is disposed and accommodated in the housing 1 so as to be able to receive 0th-order diffracted light among the light diffracted by the diffraction grating 35 provided in the movable portion 32 of the MEMS mirror 30. . The second diaphragm 8 is disposed on the light receiving surface 71 side of the second light receiving element 7 and is housed in the housing 1, and has a second slit 81 that allows light in a predetermined wavelength band to pass through. The first light receiving element 5 is arranged so as to be able to receive diffracted light of a specified order other than the 0th order among the light diffracted by the diffraction grating 35. The signal processing device 10 corresponds to the deflection angle of the movable portion 32 or the deflection angle thereof based on at least the timing when the second-order diffracted light is detected by the second light receiving element 7 and the vibration frequency of the movable portion 32. The calculating part 18 which calculates | requires the time to perform is provided. The signal processing apparatus 10 is configured to associate the wavelength stored in advance corresponding to the deflection angle of the movable unit 32 with the signal of the first light receiving element 5 obtained at the deflection angle, on a one-to-one basis. . The MEMS mirror 30 is a pair of a frame-shaped support part 31, a movable part 32 arranged inside the support part 31, and a pair of parts arranged so as to sandwich the movable part 32 and connecting the support part 31 and the movable part 32. A torsion spring portion 33 and a mirror portion 34 formed on the surface 32a side of the movable portion 32 are provided. The diffraction grating 35 is formed on the surface of the mirror portion 34. The drive unit 4 is housed in the housing 1 and is provided integrally with the MEMS mirror 30 so as to drive the movable unit 32. Therefore, the spectrum sensor 100 can be downsized.

It is preferable that the spectrum sensor 100 further includes a storage unit 9 and a signal processing device 10. The storage unit 9 stores in advance the relationship between the deflection angle of the movable unit 32 and the wavelength of light incident on the first light receiving element 5. The signal processing apparatus 10 includes a calculation unit 18 that obtains the deflection angle of the movable unit 32 based on at least the timing when the second-order diffracted light is detected by the second light receiving element 7 and the vibration frequency of the movable unit 32. . The signal processing device 10 is configured to associate the wavelength read from the storage unit 9 with the signal of the first light receiving element 5 on a one-to-one basis based on the deflection angle obtained by the calculation unit 18. The deflection angle means a rotation angle when the movable portion 32 rotates from a horizontal posture parallel to the support portion 31.

The second light receiving element 7 is preferably disposed at a position for receiving the 0th-order diffracted light when the swing angle of the movable portion 32 in the prescribed rotation direction of the movable portion 32 (see FIG. 7) is maximized. . Thereby, the spectrum sensor 100 can improve the measurement accuracy of the deflection angle of the movable part 32. Therefore, the spectrum sensor 100 can improve the measurement accuracy of the spectrum. The prescribed rotation direction is a counterclockwise direction in FIG.

The MEMS mirror 30 preferably includes a detection unit 36 that detects the timing at which the swing angle of the movable unit 32 becomes 0 degrees. In this case, the calculation unit 18 is based on the timing at which the 0th-order diffracted light is detected by the second light receiving element 7, the vibration frequency of the movable unit 32, and the timing detected by the detection unit 36. It is preferable that the deflection angle is determined. Thereby, the spectrum sensor 100 can further improve the measurement accuracy of the deflection angle of the movable part 32. Therefore, the spectrum sensor 100 can further improve the spectrum measurement accuracy.

The spectrum sensor 100 preferably includes a drive circuit 45 that applies a drive voltage to the drive unit 4, and a timing control unit 55 that controls the operation timing of each of the drive circuit 45 and the signal processing device 10.

Each component of the spectrum sensor 100 will be described in detail below.

As shown in FIG. 1, the spectrum sensor 100 includes a housing 1 having an opening 11, a spectrum separation unit 3, a drive unit 4 (see FIG. 3), a first light receiving element 5, a first diaphragm 6, and a second light reception. The element 7 and the second diaphragm 8 are accommodated. For example, the housing 1 may have only the opening 11. The spectrum sensor 100 is preferably arranged such that the collimating lens 2 closes the opening 11 of the housing 1 and the internal space of the housing 1 is in a reduced pressure atmosphere. As a result, the spectrum sensor 100 can increase the swing angle of the movable portion 32 while reducing power consumption compared to the case where the internal space of the housing 1 is atmospheric pressure.

The spectrum sensor 100 is not limited to the case where the internal space of the housing 1 is a reduced pressure atmosphere, and may be an inert gas atmosphere. The spectrum sensor 100 can improve stability over time such as measurement accuracy by setting the internal space of the housing 1 to a reduced pressure atmosphere or an inert gas atmosphere. As the inert gas, for example, N ₂ gas, Ar gas, or the like can be employed.

The housing 1 is formed in a box shape. The casing 1 adopts a rectangular box shape as a box shape. In the example of FIGS. 1 and 2, the housing 1 has a bottom portion 1a, a plurality (four in the example of FIG. 2) side portions 1b, and an upper portion 1c. The opening 11 is formed so as to penetrate in the thickness direction of the wall 12 of the housing 1 (upper part 1c in the example of FIG. 1). The opening shape of the opening 11 is preferably, for example, a circular shape. In addition, the housing | casing 1 may have the bottom part 1a, the side part 1b which consists of one surrounding wall, and the upper part 1c.

The housing 1 is preferably formed of, for example, a black resin. Thereby, the spectrum sensor 100 can reduce stray light reaching the first light receiving element 5 and the second light receiving element 7 respectively. Therefore, the spectrum sensor 100 can improve the S / N ratio of the outputs of the first light receiving element 5 and the second light receiving element 7. The housing 1 is not limited to black resin, and may be formed of metal, for example. In this case, for example, the spectrum sensor 100 may coat the inner surface side of the housing 1 with a black coating material, or may form black alumite.

Further, the spectrum sensor 100 may be configured such that the inner surface of the housing 1 is a rough surface that scatters stray light. Thereby, the spectrum sensor 100 can reduce stray light reaching the light receiving surface 51 of the first light receiving element 5 and the light receiving surface 71 of the second light receiving element 7.

The collimating lens 2 is configured so that light incident from the outside of the spectrum sensor 100 becomes a parallel light beam. In other words, the collimating lens 2 is configured to convert incident light into parallel light. More specifically, the collimating lens 2 can be composed of, for example, a biconvex lens 21 and a plano-concave lens 22.

The MEMS mirror 30 is manufactured using MEMS manufacturing technology. The structure of the MEMS mirror 30 will be described with reference to FIGS.

The MEMS mirror 30 has a support portion 31, a movable portion 32, and a pair of torsion spring portions 33 formed from a substrate 300. As the substrate 300, an SOI substrate in which a silicon layer 313 is formed on a silicon oxide film 312 on a silicon substrate 311 is used. The silicon oxide film 312 can be composed of, for example, a buried oxide film. The surface of the silicon layer 313 of the SOI substrate is a (100) plane. In the SOI substrate, for example, the thickness of the silicon substrate 311, the silicon oxide film 312, and the silicon layer 313 can be set to 400 μm, 1 μm, and 30 μm, respectively. The silicon substrate 311 and the silicon layer 313 have conductivity. The silicon oxide film 312 constitutes an insulating film having electrical insulation.

It is preferable that the outer peripheral shape of the support portion 31 is a rectangle (right-angled quadrilateral). Thereby, in the manufacturing method of the MEMS mirror 30, it becomes possible to improve the workability | operativity of the dicing process which isolate | separates into the individual MEMS mirror 30 from the wafer in which the several MEMS mirror 30 was formed. When the substrate 300 is an SOI substrate, the wafer serving as the basis of the substrate 300 is an SOI wafer. The chip size of the MEMS mirror 30 can be set to 4 mm × 4 mm, for example.

The support portion 31 adopts a rectangular frame shape as the frame shape. The support portion 31 is formed of a silicon substrate 311, a silicon oxide film 312, and a silicon layer 313 among the SOI substrate.

The MEMS mirror 30 has a movable portion 32 and a pair of torsion spring portions 33 formed on the first surface 301 side in the thickness direction of the substrate 300. The first surface 301 of the substrate 300 is constituted by the surface of the silicon layer 313. The movable portion 32 and the pair of torsion spring portions 33 are formed from a silicon layer 313 of the SOI substrate. Accordingly, the movable portion 32 and the pair of torsion spring portions 33 are sufficiently thinner than the support portion 31.

The outer peripheral shape of the movable part 32 is rectangular. The movable part 32 has a thickness set to 30 μm. The mirror part 34 has a rectangular outer peripheral shape. The mirror part 34 can be comprised by the reflective film formed on the silicon layer 313, for example. Al is adopted as the material of the reflective film. The material of the reflective film is not limited to Al, and for example, Ag, Al—Si, Au, or the like may be employed. The thickness of the mirror part 34 can be set to 500 nm, for example.

The torsion spring portion 33 is a torsion bar that can be torsionally deformed. The torsion spring portion 33 has a thickness of 30 μm and a width of 5 μm.

The movable part 32 is rotatable about a pair of torsion spring parts 33 supported by the support part 31 as a rotation axis. More specifically, the movable portion 32 is rotatable with respect to the support portion 31 around a straight line including the axis of the pair of torsion spring portions 33. Here, the movable portion 32 has the first position (see θm in FIG. 6) at which the maximum deflection angle is obtained in the clockwise direction and the maximum deflection angle in the counterclockwise direction, with the pair of torsion spring portions 33 as the rotation axes. It can reciprocate between the second position (see θm− in FIG. 7). As shown in FIG. 1, the deflection angle in the present specification is based on the position of the movable portion 32 that is not driven, and the clockwise direction is a positive angle and the counterclockwise direction is a negative angle. . In the present specification, the direction in which the pair of torsion springs 33 are arranged in the movable portion 32 is defined as a first direction D1, and the direction perpendicular to the first direction D1 in the movable portion 32 is defined as a second direction D2. To do. 6 and 7, the first light receiving element 5 and the second light receiving element 7 are provided between the collimating lens 2 and the movable portion 32. The first light receiving element 5 is arranged on the first end side of the movable portion 32 on the first side (right side in the drawing) in the second direction D2, while the second light receiving element 7 is arranged in the second direction D2. It is arranged on the second end side of the movable part 32 on the second side (left side in the figure). In this case, the clockwise direction is a direction in which the first end portion of the movable portion 32 is separated from the first light receiving element 5 side and the second end portion of the movable portion 32 is closer to the first light receiving element 5 side. The counterclockwise direction is a direction in which the first end portion of the movable portion 32 approaches the first light receiving element 5 side and the second end portion of the movable portion 32 moves away from the first light receiving element 5 side. Thus, the movable part 32 is rotatable about the pair of torsion spring parts 33 arranged in the first direction D1 as the rotation axis.

The diffraction grating 35 is a reflective diffraction grating that diffracts the light emitted from the collimating lens 2 and reflects it at different angles for each wavelength. In short, the diffraction grating 35 is configured to emit each wavelength component of light contained in incident light in a direction corresponding to each wavelength.

The diffraction grating 35 has a plurality of grooves 35b arranged in the second direction D2. More specifically, in the diffraction grating 35, a plurality of grooves 35b are periodically formed in the second direction D2. Each groove 35b is formed along the first direction D1.

The diffraction grating 35 emits diffracted light of each order (the order of diffraction) when the light emitted from the collimating lens 2 enters. In FIGS. 1, 6 and 7, the light L entering and exiting the collimating lens 2 is schematically described by broken lines. In addition, the range in which the 0th-order diffracted light (reflected light) DL0 is emitted is schematically illustrated by an elongated band shape indicated by a dashed line. In addition, the emission ranges of the first-order diffracted light DL1 and the −1st-order diffracted light DL1- are schematically described in fan shapes indicated by alternate long and short dash lines. The spectrum sensor 100 preferably employs the first-order diffracted light DL1 as the diffracted light having a specified order other than the 0th order from the viewpoint of increasing sensitivity.

As shown in FIG. 4, in the diffraction grating 35, the shape of the groove 35b in the cross section orthogonal to the first direction D1 is a sawtooth shape. Accordingly, the diffraction grating 35 can further increase the diffraction efficiency of the first-order diffracted light DL1 as compared with the case where the shape of the groove 35b in the cross section orthogonal to the first direction D1 is rectangular. In the diffraction grating 35, the period d of the groove 35b is the grating period. The period d of the groove 35b can be set in a range of about 500 nm to 2000 nm, for example. Further, the depth of the groove 35b can be set, for example, in the range of about 10 nm to 100 nm. The blaze angle of the groove 35b can be set to 7 degrees, for example.

The spectrum sensor 100 rotates the diffraction grating 35 by rotating the movable part 32 of the MEMS mirror 30, thereby changing the wavelength of the light incident on the light receiving surface 51 of the first light receiving element 5, and the light intensity for each wavelength. Can be measured (see the first-order diffracted light DL1 in FIGS. 1, 6 and 7). In this case, since the wavelength of the light incident on the light receiving surface 51 depends on the swing angle of the movable part 32, the swing angle of the movable part 32 is specified in order to specify the wavelength of the light incident on the light receiving surface 51. There is a need. A configuration for specifying the deflection angle of the movable portion 32 will be described later.

The microactuator constituting the drive unit 4 is an electrostatic actuator that drives the movable unit 32 by electrostatic force, and is preferably formed integrally with the MEMS mirror 30.

As shown in FIG. 3, for example, the drive unit 4 is paired with a pair of movable electrodes 41 formed on both sides of the movable unit 32 in the second direction D2 and a pair of movable electrodes 41 formed on the support unit 31. 1 and a pair of fixed electrodes 42 facing each other. That is, the drive unit 4 that is an electrostatic actuator includes two sets of the movable electrode 41 and the fixed electrode 42 that face each other. In the drive unit 4, the movable electrode 41 and the fixed electrode 42 are formed from the silicon layer 313. The drive unit 4 drives the movable unit 32 by an electrostatic force generated between the movable electrode 41 and the fixed electrode 42.

The movable electrode 41 and the fixed electrode 42 are preferably comb-shaped. The comb-shaped movable electrode 41 includes a plurality of comb teeth projecting along the second direction D2 from the facing surface of the comb bone portion 41a formed along the first direction D1 and the support portion 31 of the comb bone portion 41a. Part 41b. The plurality of comb teeth 41b of the movable electrode 41 are formed side by side in the first direction D1. The comb-shaped fixed electrode 42 includes a plurality of comb teeth projecting along the second direction D2 from the facing surfaces of the comb bone portion 42a formed along the first direction D1 and the movable portion 32 of the comb bone portion 42a. Part 42b. The plurality of comb-tooth portions 42b of the fixed electrode 42 are formed side by side in the first direction D1.

The comb-shaped movable electrode 41 and the comb-shaped fixed electrode 42 are arranged so as to be intertwined with each other. More specifically, in the driving unit 4, the comb bone portions 41 a and 42 a of the movable electrode 41 and the fixed electrode 42 face each other, and the comb tooth portions 41 b of the movable electrode 41 and the fixed electrode 42 of the movable electrode 41 in the first direction D <b> 1. The comb tooth portions 42b are alternately arranged. What is necessary is just to set suitably the clearance gap between the comb-tooth part 41b and the comb-tooth part 42b which adjoin in the 1st direction D1, for example in the range of about 5 micrometers-20 micrometers. The drive unit 4 generates an electrostatic force that acts in the direction of attracting between the movable electrode 41 and the fixed electrode 42 when a voltage is applied between the movable electrode 41 and the fixed electrode 42.

The MEMS mirror 30 is tilted although the movable part 32 is not in a horizontal posture even in a stationary state but is slightly inclined due to the internal stress of the movable part 32 and the pair of torsion spring parts 33. For this reason, for example, when a pulse voltage is applied between the movable electrode 41 and the fixed electrode 42, the MEMS mirror 30 causes the movable portion 32 to move in the thickness direction of the support portion 31 even from a stationary state. A driving force in the direction along is applied. As a result, the MEMS mirror 30 rotates while the movable portion 32 twists the pair of torsion spring portions 33 around the pair of torsion spring portions 33 as rotation axes. Then, when the driving force between the movable electrode 41 and the fixed electrode 42 is released when the MEMS mirror 30 is in such a posture that the comb tooth portion 41b and the comb tooth portion 42b are completely overlapped, 32 continues to rotate while twisting the pair of torsion spring portions 33 by inertial force. Then, when the inertial force in the rotation direction of the movable part 32 and the restoring force of the pair of torsion spring parts 33 become equal, the MEMS mirror 30 stops the rotation of the movable part 32. At this time, when a pulse voltage is applied again between the movable electrode 41 and the fixed electrode 42 to generate an electrostatic force, the movable portion 32 causes the restoring force of the pair of torsion spring portions 33 and the drive portion 4 to move. Rotation in the direction opposite to that until then is started. The movable portion 32 repeats rotation by the driving force of the driving portion 4 and the restoring force of the pair of torsion spring portions 33. Thereby, the drive part 4 can reciprocately rotate the movable part 32 by making a pair of torsion spring part 33 into a rotating shaft. In short, the drive unit 4 can swing the movable unit 32 around the pair of torsion springs 33 as the rotation axis.

The MEMS mirror 30 is driven with a resonance phenomenon by applying a pulse voltage having a frequency approximately twice the resonance frequency of the vibration system including the movable portion 32 and the pair of torsion spring portions 33. . As a result, the MEMS mirror 30 can have a larger deflection angle than when driven at a frequency that does not cause a resonance phenomenon.

The drive voltage of the MEMS mirror 30 can be set in the range of about 20 to 50V, for example.

For example, the MEMS mirror 30 preferably has a resonance frequency of the vibration system of 1 kHz or less, and preferably 200 Hz or less. The resonance frequency of the vibration system including the movable portion 32 and the pair of torsion spring portions 33 is determined by the shape of the movable portion 32, the mass of the movable portion 32, the spring constant of each torsion spring portion 33, and the like. The resonance frequency is the resonance frequency of the torsional vibration mode. Since the MEMS mirror 30 is formed with the movable portion 32 and each torsion spring portion 33 from the silicon layer 313 of the SOI substrate, the movable portion 32 and each torsion spring portion 33 are compared with the case where the substrate 300 is a silicon substrate. It becomes possible to increase the accuracy of the thickness. Thereby, the MEMS mirror 30 can improve the accuracy of the resonance frequency of the vibration system including the movable portion 32 and the pair of torsion spring portions 33.

The detection unit 36 includes a pair of movable electrodes 37 formed on both sides in the second direction D2 in the movable unit 32, and a pair of fixed electrodes 38 formed on the support unit 31 and facing the pair of movable electrodes 37, respectively. A capacitive sensor is preferred. As a result, the spectrum sensor 100 detects the timing at which the swing angle of the movable portion 32 becomes 0 degrees by a capacitive sensor having a simple structure including the pair of movable electrodes 37 and the pair of fixed electrodes 38. It becomes possible.

The movable electrode 37 and the fixed electrode 38 are preferably comb-shaped. The comb-shaped movable electrode 37 includes a plurality of comb teeth projecting along the second direction D2 from the facing surface of the comb bone portion 37a formed along the first direction D1 and the support portion 31 of the comb bone portion 37a. Part 37b. The plurality of comb teeth portions 37b of the movable electrode 37 are formed side by side in the first direction D1. The comb-shaped fixed electrode 38 includes a plurality of comb teeth projecting along the second direction D2 from the facing surface of the comb bone portion 38a formed along the first direction D1 and the movable portion 32 of the comb bone portion 38a. Part 38b. The plurality of comb-tooth portions 38b of the fixed electrode 38 are formed side by side in the first direction D1.

The comb-shaped movable electrode 37 and the comb-shaped fixed electrode 38 are arranged so as to be intertwined with each other. More specifically, in the detection unit 36, the

comb bone portions

37 a and 38 a of the movable electrode 37 and the fixed electrode 38 are opposed to each other, and the comb teeth 37 b and the fixed electrode 38 of the movable electrode 37 in the first direction D <b> 1. The comb tooth portions 38b are alternately arranged. What is necessary is just to set suitably the clearance gap between the comb-tooth part 37b and the comb-tooth part 38b which adjoin in the 1st direction D1, for example in the range of about 5 micrometers-20 micrometers.

In the MEMS mirror 30, a first pad electrode 39a, a second pad electrode 39b, and a third pad electrode 39c are formed on the surface 31a side of the support portion 31. The first pad electrode 39a, the second pad electrode 39b, and the third pad electrode 39c have a square shape in plan view. The first pad electrode 39a, the second pad electrode 39b, and the third pad electrode 39c are made of a metal film. The metal film is an Al—Si film. The thicknesses of the first pad electrode 39a, the second pad electrode 39b, and the third pad electrode 39c are set to 500 nm.

In the MEMS mirror 30, the movable electrode 41 of the driving unit 4 and the first pad electrode 39a are electrically connected. In the MEMS mirror 30, the fixed electrode 42 of the driving unit 4 and the second pad electrode 39b are electrically connected. In the MEMS mirror 30, the movable electrode 37 of the detector 36 and the first pad electrode 39a are electrically connected. In the MEMS mirror 30, the fixed electrode 38 of the detection unit 36 and the third pad electrode 39c are electrically connected. In the present specification, the movable electrode 41 of the drive unit 4 is referred to as a first movable electrode, the fixed electrode 42 of the drive unit 4 is referred to as a first fixed electrode, and the movable electrode 37 of the detection unit 36 is referred to as a second movable electrode. In other words, the fixed electrode 38 of the detection unit 36 can be referred to as a second fixed electrode.

A plurality of grooves 314 having a depth reaching the silicon oxide film 312 from the surface of the silicon layer 313 are formed in the support portion 31. Thereby, in the MEMS mirror 30, the movable electrode 41 and the fixed electrode 42 of the drive unit 4 are electrically insulated, and the movable electrode 37 and the fixed electrode 38 of the detection unit 36 are electrically insulated. As shown in FIG. 3, the MEMS mirror 30 has fixed electrodes 42 formed at four locations, and the upper two fixed electrodes 42 and the lower two fixed electrodes 42 in FIG. They are electrically connected by wiring such as conductive wires.

In the MEMS mirror 30, by applying a driving voltage between the movable electrode 41 and the fixed electrode 42 facing each other, an electrostatic force is generated between the movable electrode 41 and the fixed electrode 42 facing each other, and the movable portion 32. However, the pair of torsion spring portions 33 rotate around the rotation axis. Therefore, in the MEMS mirror 30, by applying a pulse voltage of a predetermined frequency between the movable electrode 41 and the fixed electrode 42 facing each other, an electrostatic force can be periodically generated, and the movable part 32 is continuously formed. Can be rotated back and forth. In short, the MEMS mirror 30 can swing the movable portion 32 around the pair of torsion spring portions 33 as rotation axes. More specifically, the predetermined frequency is preferably about twice the resonance frequency. The MEMS mirror 30 has a movable portion 32 and a pair of torsion spring portions 33 as rotation axes within an angular range (swing range) determined by a maximum clockwise swing angle θm and a maximum counterclockwise swing angle θm−. Can be swung. The maximum deflection angle θm in the clockwise direction can be set to +15 degrees, for example. Further, the maximum deflection angle θm− in the counterclockwise direction can be set to −15 degrees, for example.

The MEMS mirror 30 is applied with a drive voltage between the movable electrode 41 and the fixed electrode 42 facing each other when a drive voltage is applied between the first pad electrode 39a and the second pad electrode 39b.

In the MEMS mirror 30, a detection voltage having a higher frequency than the drive voltage of the drive unit 4 is applied between the movable electrode 37 and the fixed electrode 38 facing each other in the detection unit 36.

The detection unit 36 has a capacitance of a capacitor including the movable electrode 37 and the fixed electrode 38 according to a change in the relative position of the movable unit 32 with respect to the support unit 31 (that is, a change in the deflection angle of the movable unit 32). Changes, and the current value based on the detection voltage of the current flowing through the detection unit 36 changes. This current value becomes the largest when the deflection angle of the movable part 32 is 0 degree. Therefore, the signal processing apparatus 10 can know the timing at which the deflection angle of the movable unit 32 becomes 0 degrees by monitoring the current flowing through the detection unit 36.

In the MEMS mirror 30, it is preferable that the center line of the movable part 32 along the thickness direction of the movable part 32 is on the optical axis 201 of the collimator lens 2 in a state where the swing angle of the movable part 32 is 0 degree.

An example of the manufacturing method of the MEMS mirror 30 will be briefly described below.

In manufacturing the MEMS mirror 30, first, a substrate 300 made of an SOI substrate is prepared, and then an unevenness 321 (see FIG. 4) corresponding to the shape of the diffraction grating 35 is formed on the first surface 301 of the substrate 300. A formation process is performed. The uneven shape is a texture structure. The uneven shape can be formed using, for example, a photolithography technique and an etching technique. The concavo-convex shape can also be formed using an imprint technique and an etching technique.

After the unevenness forming step, a metal film forming step is performed. In the metal film forming step, a metal film is formed on the first surface 301 side of the substrate 300 using a sputtering method, a vapor deposition method, or the like.

The first patterning step is performed after the metal film forming step. In the first patterning step, the metal film is patterned so that the first pad electrode 39a, the second pad electrode 39b, the third pad electrode 39c, and the mirror part 34 are formed from the metal film. At this time, a diffraction grating 35 is formed on the surface side of the mirror portion 34.

After the first patterning step, a second patterning step for patterning the silicon layer 313 of the SOI substrate is performed. In the second patterning step, of the silicon layer 313, the movable portion 32, the pair of torsion spring portions 33, the support portion 31, the pair of movable electrodes 41, the pair of fixed electrodes 42, the pair of movable electrodes 37, and the pair of fixed electrodes 38. The silicon layer 313 is patterned so as to leave a portion corresponding to. In the second patterning step, unnecessary portions of the silicon layer 313 are etched using a photolithography technique and an etching technique. In the second patterning step, the silicon oxide film 312 is used as an etching stopper layer.

After the second patterning step, a third patterning step for patterning the silicon substrate 311 is performed. In the third patterning step, the silicon substrate 311 is patterned so that a portion of the silicon substrate 311 corresponding to the support portion 31 remains. In the third patterning step, unnecessary portions of the silicon substrate 311 are etched using photolithography technology and etching technology. In the third patterning step, the silicon oxide film 312 is used as an etching stopper layer.

After the third patterning step, a fourth patterning step for patterning the silicon oxide film 312 is performed. The MEMS mirror 30 is obtained by performing the fourth patterning step.

In manufacturing the MEMS mirror 30, the process until the completion of the fourth patterning process is performed at the wafer level and then the dicing process is performed to divide the MEMS mirror 30 into individual MEMS mirrors 30.

The MEMS mirror 30 is mounted on the first support substrate 401. The first support substrate 401 can be configured by, for example, a printed circuit board. The first support substrate 401 is positioned with respect to the housing 1 within the housing 1. The first support substrate 401 is preferably positioned with respect to the housing 1 by being fixed to the housing 1, for example.

The first light receiving element 5 is preferably composed of a photodiode. Thereby, the first light receiving element 5 can be reduced in size and improved in response. What is necessary is just to change the material and structure of the 1st light receiving element 5 according to the wavelength, light quantity, etc. of the light received with the 1st light receiving element 5. FIG.

The first light receiving element 5 is arranged in the housing 1 so as to receive the first-order diffracted light DL1 from the diffraction grating 35. More specifically, in the spectrum sensor 100, the first light receiving element 5 is arranged so that the first-order diffracted light DL 1 is received by the first light receiving element 5 regardless of the deflection angle of the movable portion 32. In the example of FIG. 1, the first light receiving element 5 is configured to receive only the first-order diffracted light DL <b> 1 regardless of the deflection angle of the movable portion 32. The diffraction angle of the first-order diffracted light DL1 is a function of the wavelength of the light. In the spectrum sensor 100, the first light receiving element 5 is arranged so that the optical axis 501 of the first light receiving element 5 and the center line of the emission range of the primary light DL1 are aligned when the swing angle of the movable part 32 is 0 degree. It is preferable. The first light receiving element 5 is a photoelectric conversion element, and outputs a signal (hereinafter referred to as “photoelectric conversion signal”) corresponding to the light intensity of the light incident on the light receiving surface 51. In the example of FIG. 1, the spectrum sensor 100 further includes an output unit 65, and the signal processing device 10 is configured to output a light intensity signal obtained from the photoelectric conversion signal via the output unit 65. Note that the output unit 65 may be included in the signal processing device 10. For example, when the signal processing device 10 is configured by a microcomputer, the output unit 65 may be a digital output port of the signal processing device 10.

Since the first light receiving element 5 receives the first-order diffracted light DL1 in the spectrum sensor 100, the first light-receiving element 5 can be downsized as compared with the case where the second-order or higher order diffracted light is received. In addition, the amount of light received by the first light receiving element 5 can be increased.

The first light receiving element 5 is mounted on the second support substrate 402. The second support substrate 402 can be configured by, for example, a printed circuit board. The second support substrate 402 is positioned with respect to the housing 1 within the housing 1. The second support substrate 402 is preferably positioned with respect to the housing 1 by being fixed to the housing 1, for example.

The shape of the first slit 61 in the first diaphragm 6 is preferably a linear shape, for example. The first diaphragm 6 is preferably arranged so that the longitudinal direction of the first slit 61 is in the direction along the first direction D1.

The distance between the first diaphragm 6 and the center of the diffraction grating 35 can be set to 5 mm, for example. Here, the width of the first slit 61 can be appropriately set according to the desired wavelength resolution of the spectrum sensor 100. For example, when the wavelength resolution is 10 nm, it can be set to 0.065 mm. In the first diaphragm 6, the center of the first slit 61 is preferably on the optical axis 501 of the first light receiving element 5.

The first diaphragm 6 can be constituted by, for example, a first light shielding film arranged so as to cover the light receiving surface 51 of the first light receiving element 5. Thereby, the first diaphragm 6 can be formed integrally with the first light receiving element 5. The first light shielding film shields light. In the first diaphragm 6, the opening formed in the first light shielding film constitutes the first slit 61. As a material of the first light shielding film, for example, a metal or the like can be employed. The first light shielding film can be formed using, for example, a vapor deposition method, a sputtering method, a CVD method, a plating method, or the like. The first light-shielding film is preferably made of a material having a high light absorption rate from the viewpoint of reducing stray light due to multiple reflection of light, and may be formed of a material other than metal.

Since the spectrum sensor 100 includes the first diaphragm 6, the wavelength of the first-order diffracted light DL1 received by the first light receiving element 5 changes according to the deflection angle (rotation angle) of the movable part 32. Therefore, the relationship between the deflection angle of the movable part 32 and the output of the first light receiving element 5 is, for example, as shown in the schematic diagram of FIG. FIG. 8 shows three curves with the deflection angle as a function, but these three curves have a one-to-one correspondence with the three spectra with the wavelength as a function. In other words, in FIG. 8, the deflection angle can be converted into a wavelength, and the leftmost curve of the three curves corresponds to the spectrum having the center wavelength λ1, and the middle curve is the spectrum having the center wavelength λ2. The rightmost curve corresponds to the spectrum having the center wavelength λ3.

The second light receiving element 7 is preferably composed of a photodiode. As a result, the second light receiving element 7 can be reduced in size and improved in response. The material and configuration of the second light receiving element 7 may be changed according to the wavelength, light amount, etc. of the light received by the second light receiving element 7.

The second light receiving element 7 is arranged so as to be able to receive the reflected light which is the 0th-order diffracted light DL0 from the diffraction grating 35 (see FIG. 7). More specifically, the spectrum sensor 100 receives the 0th-order diffracted light by the second light receiving element 7 when the deflection angle of the movable portion 32 in the prescribed rotational direction of the movable portion 32 is the negative maximum deflection angle θm−. Thus, the second light receiving element 7 is arranged. In other words, the spectrum sensor 100 receives the second-order diffracted light DL0 so that it receives the 0th-order diffracted light DL0 when the movable part 32 is at a position (see FIG. 7) at which the negative maximum deflection angle θm− is obtained in the specified rotational direction. The position of the light receiving element 7 is set. The spectrum sensor 100 emits the optical axis 701 of the second light receiving element 7 and the 0th-order diffracted light DL0 when the deflection angle of the movable portion 32 in the prescribed rotational direction of the movable portion 32 is the negative maximum deflection angle θm−. It is preferable that the second light receiving element 7 is arranged so as to be aligned with the center line of the range. The “position where the negative maximum deflection angle θm−” is not only a position where the negative maximum deflection angle θm− is strictly, but also a deflection angle whose absolute value is about 1 degree smaller than the negative maximum deflection angle θm−. To the position. Therefore, the position of the second light receiving element 7 can be in the range of −15 degrees to −14 degrees of the position where the negative maximum deflection angle θm− is obtained, for example. The second light receiving element 7 is a photoelectric conversion element, and outputs a signal (photoelectric conversion signal) corresponding to the light intensity of the light incident on the light receiving surface 71.

The second light receiving element 7 is mounted on the third support substrate 403. The third support substrate 403 can be constituted by a printed circuit board, for example. The third support substrate 403 is positioned with respect to the housing 1 within the housing 1. For example, the third support substrate 403 is preferably positioned with respect to the housing 1 by being fixed to the housing 1.

In the spectrum sensor 100, the first light receiving element 5 and the second light receiving element 7 are preferably arranged in a direction along the rotation direction of the movable portion 32. Thereby, when the MEMS mirror 30 is used by making incident light incident on the diffraction grating 35 along a plane orthogonal to the first direction D1, reflected light that is the 0th-order diffracted light DL0 from the diffraction grating 35 is The light can travel along the plane and enter the second light receiving element 7. In addition, the MEMS mirror 30 can cause the first-order diffracted light DL1 from the diffraction grating 35 to travel along the plane and enter the first light receiving element 5.

The shape of the second slit 81 in the second diaphragm 8 is preferably a linear shape, for example. The second diaphragm 8 is preferably arranged so that the longitudinal direction of the second slit 81 is in the direction along the first direction D1.

The distance between the second diaphragm 8 and the center of the diffraction grating 35 can be set to 5 mm, for example. In this case, the width of the second slit 81 can be set to 0.065 mm, for example. In the second diaphragm 8, the center of the second slit 81 is preferably on the optical axis 701 of the second light receiving element 7.

The second diaphragm 8 can be constituted by, for example, a second light shielding film arranged so as to cover the light receiving surface 71 of the second light receiving element 7. Thereby, the second diaphragm 8 can be formed integrally with the second light receiving element 7. The second light shielding film shields light. In the second diaphragm 8, the opening formed in the second light shielding film forms the second slit 81. As the material of the second light shielding film, for example, a metal or the like can be employed. The second light shielding film can be formed using, for example, a vapor deposition method, a sputtering method, a CVD method, a plating method, or the like. The second light-shielding film is preferably made of a material having a high light absorption rate from the viewpoint of reducing stray light due to multiple reflections of light, and may be formed of a material other than metal.

The storage unit 9 can be constituted by, for example, a semiconductor memory. As the semiconductor memory, for example, a nonvolatile memory is preferably employed. As the nonvolatile memory, for example, an EEPROM or the like can be adopted.

The storage unit 9 preferably stores a data table in which the deflection angle of the movable unit 32 and the wavelength of light incident on the first light receiving element 5 are associated with each other. Specifically, the data table includes various deflection angle values and various wavelengths (wavelength values) respectively associated with the various deflection angles. In this embodiment, the range of various deflection angles corresponds to the light receiving range of the first-order diffracted light DL1 by the first light receiving element 5, as shown in FIGS. In order to obtain in advance the relationship between the deflection angle of the movable portion 32 and the corresponding wavelength of the light received by the first light receiving element 5, for example, a spectrophotometer and a laser displacement meter may be used. In this case, a spectrophotometer is arranged in place of the first light receiving element 5, and the swing angle of the movable part 32 is changed by changing the magnitude of the voltage applied to the drive part 4 of the MEMS mirror 30, so that the spectrophotometer What is necessary is just to measure the wavelength of light with a meter. The deflection angle of the movable part 32 can be obtained, for example, by measuring the inclination of the movable part 32 with a laser displacement meter.

In the signal processing device 10, for example, the calculation unit 18 determines the deflection angle of the movable unit 32 based on the timing at which the 0th-order diffracted light DL 0 is detected by the second light receiving element 7 and the vibration frequency of the movable unit 32. Ask. The signal processing apparatus 10 includes a processing unit 19 that associates the wavelength read from the storage unit 9 based on the deflection angle obtained by the calculation unit 18 with the signal of the first light receiving element 5 on a one-to-one basis. . The signal processing apparatus 10 can be configured by, for example, mounting an appropriate program on a microcomputer.

In the MEMS mirror 30, when the movable part 32 swings with a resonance phenomenon, the swing angle of the movable part 32 changes according to a substantially sine curve as shown in FIG. In FIG. 9, the horizontal axis represents time elapsed from the start of driving of the movable unit 32 by the drive unit 4 (hereinafter also referred to as “elapsed time”). In FIG. 9, the vertical axis represents the deflection angle of the movable part 32. In FIG. 9, θm is the maximum deflection angle of the movable part 32. Further, in FIG. 9, tm ₀ and tm ₁ are times when the deflection angle of the movable part 32 becomes the maximum deflection angle θm. Here, the intermediate time point between tm ₀ and tm ₁ at which the negative maximum deflection angle θm− is reached corresponds to the timing at which the 0th-order diffracted light DL0 is detected by the second light receiving element 7. In FIG. 9, th ₁ , th ₂ , and th ₃ are times when the deflection angle becomes 0 degrees. Here, th ₁ , th ₂ , and th ₃ correspond to the timing at which the detection unit 36 detects that the deflection angle of the movable unit 32 is 0 degree.

FIG. 10 schematically shows changes in the signal of the detection unit 36 and the signal of the second light receiving element 7 when the movable unit 32 vibrates. The time point t1 in FIG. 10 corresponds to the timing at which the movable part 32 becomes the negative maximum deflection angle θm− in the counterclockwise direction as shown in FIG. The time point t2 in FIG. 10 corresponds to the timing when the deflection angle of the movable part 32 becomes 0 as shown in FIG. A time point t3 in FIG. 10 corresponds to a timing at which the movable portion 32 reaches the (positive) maximum deflection angle θm in the clockwise direction.

It is preferable that the signal processing device 10 includes a time measuring unit 20 that measures elapsed time. The timing control unit 55 preferably controls the operation timing of the drive circuit 45 and the operation timing of the signal processing device 10 so that the operation timing of the drive circuit 45 and the operation timing of the timer unit 20 are synchronized. The timing control unit 55 can be configured using, for example, a PLD (programmable logic device).

The signal processing apparatus 10 stores the signal of the first light receiving element 5 and the elapsed time measured by the time measuring unit 20 in a one-to-one correspondence in the data storage unit 15 (for example, at predetermined time intervals). Preferably, it is configured. Accordingly, the calculation unit 18 can know the signal of the first light receiving element 5 at an arbitrary elapsed time from the stored contents of the data storage unit 15. Further, in the signal processing device 10, the signal of the second light receiving element 7 and the elapsed time measured by the time measuring unit 20 are associated with each other on a one-to-one basis and stored in the data storage unit 15 (for example, at predetermined time intervals). It is preferable to be configured as described above. Thereby, the calculation unit 18 can know the signal of the second light receiving element 7 at an arbitrary elapsed time from the stored contents of the data storage unit 15. Further, the signal processing apparatus 10 stores the signal (current) of the detection unit 36 and the elapsed time measured by the time measuring unit 20 in one-to-one correspondence in the data storage unit 15 (for example, at predetermined time intervals). It is preferable to be configured so that the

The signal processing device 10 converts the signal of the first light receiving element 5 from current to voltage and outputs the signal, and the signal converted by the first I / V converter 13 is converted from analog to digital. And a first A / D conversion unit 14 that outputs to the data storage unit 15.

Further, the signal processing device 10 converts the signal of the second light receiving element 7 from current to voltage and outputs it, and the signal converted by the second I / V converter 16 is converted from analog to digital. And a second A / D conversion unit 17 that outputs the data to the data storage unit 15.

In addition, the signal processing device 10 converts the signal of the detection unit 36 from current to voltage and outputs the signal, and the signal converted by the third I / V conversion unit 28 is converted from analog to digital. And a third A / D conversion unit 29 that outputs the data to the data storage unit 15.

The signal processing device 10 can be configured to obtain the deflection angle of the movable unit 32 at an arbitrary elapsed time, for example, by the following equation (1) in the calculation unit 18.

Here, θ is the deflection angle of the movable part 32. θm is the maximum deflection angle of the movable part 32 in the clockwise direction. For θm, for example, data measured in advance may be stored in the storage unit 9, and the calculation unit 18 may read out from the storage unit 9. T is an arbitrary elapsed time. Tm ₀ is the elapsed time up to the time tm ₀ when the deflection angle becomes the maximum deflection angle θm in the clockwise direction of the movable part 32 (see FIG. 9). Td is a delay time in the signal processing apparatus 10. The delay time Td is, for example, a delay time of a microcomputer circuit that constitutes the signal processing device 10. The delay time Td can be omitted in applications where the accuracy of the value (the deflection angle and the elapsed time value) obtained by the expression (1) or the expression (4) described later is not so much required. f is the vibration frequency of the movable part 32, and can be obtained by the following equation (2), for example.

Here, tm _i is the elapsed time up to the i-th time point when the swing angle becomes the maximum swing angle θm in the clockwise direction of the movable portion 32. tm _j is an elapsed time up to the j-th time point when the swing angle becomes the maximum swing angle θm in the clockwise direction of the movable portion 32. In equation (2), j = i + 1.

As for the vibration frequency of the movable unit 32 used by the calculation unit 18 in the calculation of Expression (1), data measured in advance may be stored in the storage unit 9, and the calculation unit 18 may read out from the storage unit 9.

The wavelength read from the storage unit 9 based on the deflection angle obtained by the calculation unit 18 is the wavelength of light associated with the deflection angle in the storage unit 9 on a one-to-one basis. In short, the signal processing apparatus 10 can determine the wavelength of light by calculating the deflection angle of the movable unit 32 by the calculation unit 18.

The signal processing device 10 is configured to associate the wavelength read from the storage unit 9 based on the deflection angle obtained by the calculation unit 18 and the signal of the first light receiving element 5 on a one-to-one basis with the same elapsed time. Yes. Here, the signal of the first light receiving element 5 corresponds to the intensity of light incident on the first light receiving element 5 through the first slit 61. Therefore, the spectrum sensor 100 can obtain an intensity distribution for each wavelength of light.

The spectrum sensor 100 preferably includes a detection unit 36 that detects the timing at which the MEMS mirror 30 has a swing angle of the movable unit 32 of 0 degrees. In this case, the spectrum sensor 100 includes a timing at which the calculation unit 18 detects the 0th-order diffracted light DL0 by the second light receiving element 7, a vibration frequency of the movable unit 32, and a timing detected by the detection unit 36. It is preferable that the deflection angle of the movable part 32 is obtained based on the above. Thereby, the spectrum sensor 100 can further improve the measurement accuracy of the deflection angle of the movable part 32. Therefore, the spectrum sensor 100 can further improve the spectrum measurement accuracy.

More specifically, the signal processing device 10 obtains the deflection angle of the movable portion 32 by using the time difference between the elapsed times Th _i and Th _j until two timings when the deflection angle of the movable portion 32 becomes 0 degrees. . In the signal processing device 10, the swing angle of the movable part 32 is between the time point th _i corresponding to the fast timing and the time point th _j corresponding to the late timing of the two timings at which the swing angle of the movable part 32 becomes 0 degrees. The elapsed time Tmij until the time when the maximum deflection angle is _reached is obtained by the following equation (3).

Then, the signal processing device 10, the elapsed time _{Tm ij} obtained by Equation (3) determines the deflection angle of the movable portion 32 used in place of Tm ₀ of the formula (1). Therefore, the spectrum sensor 100 can accurately measure the deflection angle of the movable part 32 even when the vibration mode of the movable part 32 changes during driving of the movable part 32, for example.

The spectrum sensor 100 can be used for, for example, an illumination system as well as a spectroscopic device such as a fluorescence analyzer.

When the spectrum sensor 100 is used in a fluorescence analyzer, for example, the spectrum sensor 100 is arranged and used so that fluorescence emitted from the organic substance is incident on the collimating lens 2 when the organic substance is irradiated with excitation light from an excitation light source of the fluorescence analyzer. can do. In this case, the spectrum sensor 100 can measure the intensity distribution for each wavelength of light with respect to the fluorescence emitted by the organic substance. Thereby, in the fluorescence analyzer, it becomes possible to specify an organic substance, specify an amount, and the like based on the measurement result of the spectrum sensor 100.

As the illumination system, for example, a system that feedback-controls the illumination light source so as to adjust the circadian rhythm of the person in the illumination space by the illumination light source. Illumination spaces include, for example, rooms for residents in elderly welfare facilities and hospital rooms for hospital inpatients. The circadian rhythm means a rhythm with a cycle close to 24 hours that appears as behavior and physical function to people living on the earth. A cycle close to 24 hours means a cycle of 24 ± 4 hours. The spectrum in the illumination space varies depending on, for example, morning, noon, and night, and varies depending on the open / closed state of a window, weather, and the like. The illumination system can be configured to include a control device that controls an illumination light source or the like based on a spectrum measurement result in the illumination space by the spectrum sensor 100, for example.

Each figure explained in the above-mentioned embodiment etc. is a typical figure, and ratio of each size and thickness of each component does not necessarily reflect an actual size ratio. In addition, the materials, numerical values, and the like described in the embodiments and the like are merely preferred examples and are not intended to be limited thereto. Furthermore, the present invention can be appropriately modified in configuration without departing from the scope of its technical idea.

For example, regarding the MEMS mirror 30, the outer peripheral shape of the movable portion 32 is not limited to a rectangular shape, and may be, for example, a circular shape. Further, the inner peripheral shape of the support portion 31 is not limited to a rectangular shape, and may be, for example, a circular shape. The microactuator constituting the drive unit 4 is not limited to an electrostatic actuator, but may be an electromagnetic actuator, a piezoelectric actuator, or the like. The electromagnetic actuator drives the movable part 32 by an electromagnetic force using a magnet or a coil provided integrally with the movable part 32. The piezoelectric actuator drives the movable part 32 by a piezoelectric element provided integrally with the movable part 32.

Further, the first light receiving element 5 can be constituted by, for example, a CMOS sensor, a photomultiplier tube, or the like. Moreover, the 2nd light receiving element 7 can be comprised by a CMOS sensor, a photomultiplier tube, etc., for example.

First, as various modifications, a first modification will be described. In the example of FIG. 1, a timer unit 20 configured to output a timing signal is provided, and timer data to be stored in the data storage unit 15 is obtained from the timing signal. For example, the timer data is data indicating an elapsed time such as an elapsed time from the start of driving of the movable portion 32 or an elapsed time from the time when the second light receiving element 7 receives the 0th-order diffracted light. In this case, as described above, the first input value (for example, light intensity value) obtained from the first light receiving element 5 through the first I / V conversion unit 13 and the first A / D conversion unit 14 is set together with the timer data for a predetermined time. It is stored in the data storage unit 15 at every interval. Hereinafter, a data set including various first input values and timer data associated with each of the various first input values is referred to as a first data set. Further, the second input value (for example, light intensity value) obtained from the second light receiving element 7 via the second I / V conversion unit 16 and the second A / D conversion unit 17 is stored together with the timer data at predetermined time intervals. Stored in the unit 15. Hereinafter, a data set including various second input values and timer data associated with each of the various second input values is referred to as a second data set.

As can be seen from the “signal of the second light receiving element” in FIG. 10, the signal processing device 10 (calculation unit 18) uses the second data set to obtain the timer data from which the movable unit 32 has the maximum deflection angle θm− in the counterclockwise direction. (T1) can be obtained. That is, the computing unit 18 can obtain an elapsed time corresponding to the time t1 by extracting timer data corresponding to the maximum value of various second input values from the second data set. Since the time t1 corresponds to the negative maximum deflection angle θm− in FIG. 9, the calculation unit 18 calculates from the first data set based on the extracted timer data (t1) and the vibration frequency f of the movable unit 32. 9, timer data corresponding to the positive maximum deflection angle θm (elapsed time corresponding to time tm ₀ or time tm ₁ ) can be extracted. As a result, the calculation unit 18 uses the above equation (1) based on at least the maximum shake angle θm, the vibration frequency f, and the timer data corresponding to the maximum shake angle θm. The angle θ can be obtained. When the calculation unit 18 obtains the deflection angle θ, the signal processing device 10 (processing unit 19) reads the wavelength (wavelength value) corresponding to the deflection angle θ from the storage unit 9, and also the first of the data storage unit 15 A first input value corresponding to the elapsed time T is read from the data set.

Subsequently, the signal processing device 10 (processing unit 19) outputs the read wavelength value and the first input value via the output unit 65 (to an external device). As another example, the signal processing apparatus 10 receives, via the output unit 65, a wavelength value in one cycle of the deflection angle θ (for example, see time 0 to th _{2 in} FIG. 9) and a first input corresponding to the wavelength value. The value may be output at predetermined time intervals (or predetermined deflection angles).

In short, the signal processing device 10 includes a timer unit 20 configured to output a timer signal and a data storage unit 15. The data storage unit 15 stores the first and second input values obtained from the first and second

light receiving elements

5 and 7 and timer data indicating the elapsed time obtained from the timing signal from the timing unit 20 at predetermined time intervals. Configured to store. The computing unit 18 extracts timer data (t1) corresponding to the maximum value of the second input value from the data storage unit 15, and based on the extracted timer data (t1) and the vibration frequency f, the data storage unit 15 Is extracted from the timer data (tm ₀ or tm ₁ ) corresponding to the maximum positive swing angle θm based on at least the maximum swing angle θm, the vibration frequency f, and the timer data corresponding to the maximum swing angle θm. The deflection angle θ corresponding to the elapsed time (T) is calculated. The signal processing device 10 (processing unit 19) reads the value of the wavelength corresponding to the calculated deflection angle θ from the storage unit 9, and the first input value corresponding to the elapsed time (T) from the data storage unit 15. The read wavelength value and the first input value are output via the output unit 65 (to an external device).

Next, a second modification will be described. The signal processing device 10 includes a timer unit 20 configured to output a timer signal and a data storage unit 15. The data storage unit 15 stores the first and second input values obtained from the first and second

light receiving elements

5 and 7 and timer data indicating the elapsed time obtained from the timing signal from the timing unit 20 at predetermined time intervals. Configured to store. For example, the timer data is data indicating an elapsed time such as an elapsed time from the start of driving of the movable portion 32 or an elapsed time from the time when the second light receiving element 7 receives the 0th-order diffracted light. The computing unit 18 extracts timer data (t1) corresponding to the maximum value of the second input value from the data storage unit 15, and based on the extracted timer data (t1) and the vibration frequency f, the data storage unit 15 Is configured to extract timer data (tm ₀ or tm ₁ ) corresponding to the positive maximum deflection angle θm. Further, the calculation unit 18 calculates an elapsed time T corresponding to an arbitrary shake angle θ based on at least the maximum shake angle θm, the vibration frequency f, and timer data corresponding to the maximum shake angle θm. Configured. That is, the elapsed time T is given by equation (4) obtained from equation (1).

The signal processing device 10 (processing unit 19) is configured to read out a wavelength value corresponding to the deflection angle θ from the storage unit 9 and read out a first input value corresponding to the elapsed time T from the data storage unit 15. Is done.

The signal processing device 10 (processing unit 19) is configured to output the read wavelength value and the first input value via the output unit 65 (to an external device). In this case, if the spectrum sensor 100 further includes an input unit for inputting the deflection angle θ of the movable unit 32 from an external device, the wavelength value and the first input value corresponding to the desired deflection angle θ are obtained. be able to. The spectrum sensor includes an input unit for inputting a wavelength value instead of the input unit, and reads out the deflection angle θ corresponding to the input wavelength value from the storage unit 9 and performs the same processing. It may be configured as follows. As another example, the signal processing apparatus 10 uses the output unit 65 to output a wavelength value in one period of the deflection angle θ (for example, time 0 to th2 in FIG. 9) and a first input value corresponding to the wavelength value. May be output at predetermined time intervals (or at predetermined deflection angles or predetermined wavelength intervals).

A third modification will be described. The signal processing device 10 includes a timer unit 20 configured to output a timer signal and an arithmetic unit 18. In this alternative example, the timing signal is output to the calculation unit 18 and the processing unit 19. Based on the timing signal from the timing unit 20, the calculation unit 18 sets the time t1 when the second input value obtained from the second light receiving element 7 becomes the maximum value to the maximum deflection angle at which the movable unit 32 has a negative deflection angle. The time tm _{1 at} which the deflection angle of the movable part 32 becomes the positive maximum deflection angle θm is calculated based on the time when the negative deflection angle is detected and the vibration frequency f. Is done. That is, a time tm ₁ after the time t1 is calculated. The arithmetic unit 18, the maximum deflection angle .theta.m, the vibration frequency f, based on the time tm ₁ and comprising a maximum deflection angle .theta.m, equation (4) from a time corresponding to the deflection angle θ after the time t1 Is configured to compute The signal processing device 10 (processing unit 19) reads the value of the wavelength corresponding to the deflection angle θ from the storage unit 9, and calculates the first light receiving element 5 at the time calculated by the calculation unit 18 according to the timing signal from the timing unit 20. Is output together with the read wavelength via the output unit 65 (to an external device). Here, the time such as t1 and tm _1, means the time on the time axis shown in FIG.

In this case, if the spectrum sensor 100 further includes an input unit for inputting the deflection angle θ of the movable unit 32 from an external device, the wavelength value and the first input value corresponding to the desired deflection angle θ are obtained. be able to. The spectrum sensor includes an input unit for inputting a wavelength value instead of the input unit, and reads out the deflection angle θ corresponding to the input wavelength value from the storage unit 9 and performs the same processing. It may be configured as follows. As another example, the signal processing apparatus 10 uses the output unit 65 to output a wavelength value in one period of the deflection angle θ (for example, time 0 to th2 in FIG. 9) and a first input value corresponding to the wavelength value. May be output at predetermined time intervals (or at predetermined deflection angles or predetermined wavelength intervals).

In the example of FIG. 1, the light receiving range of the first-order diffracted light DL1 by the first light receiving element 5 is narrower than the swinging range of the movable portion 32. Therefore, in the various examples described above, the signal processing apparatus 10 The value and the first input value corresponding to the wavelength value may be sequentially output within the light receiving range.

In the various examples above, the first polarity and the second polarity are respectively the polarity of the clockwise swing angle and the polarity of the counterclockwise swing angle, respectively. The polarity of the swing angle may be used. In this case, the time (time point) tm ₀ and the time point tm ₁ in FIG. 9 are detected by the second light receiving element 7. Therefore, as in the first modification, the calculation unit 18 uses the timer data (tm) corresponding to the positive maximum deflection angle θm from the data storage unit 15 based on the extracted timer data (t1) and the vibration frequency f. _It is not necessary to extract ₀ or tm ₁ ). In this case, the calculation unit 18 is configured to calculate a deflection angle corresponding to the elapsed time based on at least the extracted timer data, the maximum deflection angle of the movable unit 32, and the vibration frequency f. It will be. Similarly, as in the second modification, the calculation unit 18 uses the timer data (tm) corresponding to the positive maximum deflection angle θm from the data storage unit 15 based on the extracted timer data (t1) and the vibration frequency f. _It is not necessary to extract ₀ or tm ₁ ). In this case, the calculation unit 18 is configured to calculate an elapsed time corresponding to the swing angle based on at least the extracted timer data, the maximum swing angle of the movable unit 32, and the vibration frequency f. It will be. Similarly, as in the third modification, the calculation unit 18 sets the time t1 when the second input value obtained from the second light receiving element 7 becomes the maximum value based on the time signal from the time measurement unit 20 to the movable unit. 32 is detected as a time when the deflection angle of 32 becomes the maximum negative deflection angle, and based on the time when the maximum deflection angle is negative and the vibration frequency f, the deflection angle of the movable portion 32 is the maximum positive deflection angle θm. There is no need to calculate the time tm ₁ to become. In this case, the calculation unit 18 detects the time t1 when the second input value obtained from the second light receiving element 7 becomes the maximum value based on the time signal from the time measuring unit 20, and the detected time and the movable unit Based on the maximum deflection angle of 32 and the vibration frequency f, the time corresponding to the deflection angle θ after the time t1 is calculated.

Claims

A housing having an opening;
A collimating lens arranged to close the opening of the housing;
A spectral separation unit that is housed in the housing, includes a diffraction grating, and includes a MEMS mirror that separates light emitted from the collimating lens into a plurality of spectra;
A first light receiving element housed in the housing;
A spectrum sensor comprising: a first diaphragm having a first slit that is disposed on the light-receiving surface side of the first light-receiving element and is housed in the housing and transmits light of a predetermined wavelength band;
The spectrum sensor
A second light receiving element disposed so as to be capable of receiving zero-order diffracted light out of the light diffracted by the diffraction grating provided in the movable part of the MEMS mirror and housed in the housing;
A second diaphragm having a second slit that is disposed on the light receiving surface side of the second light receiving element and is housed in the housing, and transmits light of the predetermined wavelength band;
A signal processing device;
A drive unit housed in the housing;
The first light receiving element is disposed so as to be able to receive a diffracted light of a specified order other than the 0th order among the lights diffracted by the diffraction grating,
The signal processing device corresponds to a swing angle of the movable part or a swing angle thereof based on at least the timing when the second-order diffracted light is detected by the second light receiving element and the vibration frequency of the movable part. A calculation unit for obtaining a time to perform, and a configuration in which the prestored wavelength corresponding to the deflection angle of the movable unit and the signal of the first light receiving element obtained by the deflection angle are associated one-to-one And
The MEMS mirror includes a frame-shaped support part, the movable part arranged inside the support part, and a pair of twists arranged so as to sandwich the movable part and connecting the support part and the movable part. A spring part, and a mirror part formed on the surface side of the movable part,
The diffraction grating is formed on the surface of the mirror part,
The spectrum sensor according to claim 1, wherein the driving unit is provided integrally with the MEMS mirror and configured to drive the movable unit.
A storage unit that stores in advance a relationship between a swing angle of the movable unit and a wavelength of light incident on the first light receiving element;
The calculation unit is configured to obtain a deflection angle of the movable part based on at least the timing when the second-order diffracted light is detected by the second light receiving element and the vibration frequency of the movable part,
The signal processing device has a one-to-one correspondence between the wavelength read from the storage unit based on the deflection angle obtained by the computing unit and the signal of the first light receiving element obtained by the deflection angle obtained by the computing unit. The spectrum sensor according to claim 1, wherein the spectrum sensor is associated with each other.
The second light receiving element is disposed at a position for receiving 0th-order diffracted light when a swing angle of the movable part in a predetermined rotation direction of the movable part is maximized.
The spectrum sensor according to claim 1 or 2, wherein
The MEMS mirror includes a detection unit that detects a timing at which the swing angle of the movable unit becomes 0 degrees,
The calculation unit is configured to detect a deflection angle of the movable unit based on a timing when the second-order diffracted light is detected by the second light receiving element, a vibration frequency of the movable unit, and a timing detected by the detection unit. Configured to ask for,
The spectrum sensor according to any one of claims 1 to 3, wherein:
The detection unit includes a pair of movable electrodes formed on both sides in a second direction perpendicular to the first direction in which the pair of torsion springs are arranged in the movable unit, and the pair of movable electrodes formed on the support unit. A capacitive sensor comprising a pair of fixed electrodes facing each of the electrodes,
The spectrum sensor according to claim 4.
The movable part is rotatable about the pair of torsion spring parts arranged in the first direction as a rotation axis,
The drive unit has a pair of movable electrodes formed on both sides of the movable unit in a second direction orthogonal to the first direction, and a pair of movable electrodes formed on the support unit and is opposed to the pair of movable electrodes on a one-to-one basis. The spectrum sensor according to claim 1, further comprising: a pair of fixed electrodes.
A storage unit for storing a table including values of various deflection angles and values of various wavelengths respectively associated with the various deflection angles;
A timing unit configured to output a timing signal;
Data configured to store first and second input values obtained from the first and second light receiving elements and timer data indicating elapsed time obtained from a time signal from the time measuring unit at predetermined time intervals. A storage unit;
Timer data corresponding to the maximum value of the second input value is extracted from the data storage unit, and at least based on the extracted timer data, the maximum deflection angle of the movable unit, and the vibration frequency An arithmetic unit configured to calculate a deflection angle corresponding to time;
A signal processing device comprising:
An output section;
Further comprising
The signal processing device reads a wavelength value corresponding to the calculated deflection angle from the storage unit, reads a first input value corresponding to the elapsed time from the data storage unit, and reads the read wavelength value. The spectrum sensor according to claim 1, wherein the first input value and the first input value are output via the output unit.
A storage unit for storing a table including values of various deflection angles and values of various wavelengths respectively associated with the various deflection angles;
A timing unit configured to output a timing signal;
Data configured to store first and second input values obtained from the first and second light receiving elements and timer data indicating elapsed time obtained from a time signal from the time measuring unit at predetermined time intervals. A storage unit;
Timer data corresponding to the maximum value of the second input value is extracted from the data storage unit, and at least based on the extracted timer data, the maximum deflection angle of the movable unit, and the vibration frequency A computing unit configured to calculate an elapsed time corresponding to the corner;
A signal processing device comprising:
An output section;
Further comprising
The signal processing device reads a wavelength value corresponding to the deflection angle from the storage unit, and reads a first input value corresponding to the elapsed time from the data storage unit. The spectrum sensor according to claim 1, wherein one input value is configured to be output via the output unit.
8. The data according to claim 7, wherein the elapsed time is data indicating an elapsed time from a driving start time of the movable part or an elapsed time from a light receiving time of the 0th-order diffracted light by the second light receiving element. 8. The spectrum sensor according to 8.
A storage unit for storing a table including values of various deflection angles and values of various wavelengths respectively associated with the various deflection angles;
A timing unit configured to output a timing signal;
Based on the time signal from the time measuring unit, the time when the second input value obtained from the second light receiving element becomes the maximum value is detected, the detected time, the maximum deflection angle of the movable unit, and the vibration A computing unit configured to compute a time corresponding to the deflection angle based on the frequency;
A signal processing device comprising:
An output section;
Further comprising
The signal processing device reads a wavelength value corresponding to the deflection angle from the storage unit, and obtains a first value obtained from the first light receiving element at a time calculated by the calculation unit according to a timing signal from the timing unit. The spectrum sensor according to claim 1, wherein an input value is output via the output unit together with the read wavelength.