JP2017215372A - Diffraction grating, spectroscope, spectroscopic device, and analyzing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diffraction grating so structured that the diffraction grating and a drive mechanism are integrated and made compact, and characterized in that a voltage in driving is a low voltage and a power consumption is reducible.SOLUTION: A diffraction grating comprises: a coupling member 20 which has a plurality of grating units 21 arrayed on the same plane at substantially equal intervals and varies intervals between adjacent grating units 21; a casing 11 to which both ends of the coupling member 20 are fixed; and driving means 30 for driving and displacing the coupling member 20. The coupling member 20 consists of an elastic coupling body 12 and a moving body 15 driven by the driving means 30, the driving means 30 comprises a piezoelectric element 13 and a vibration body 14 where a plurality of projection parts 14a capable of abutting on an edge part of the moving body 15 are formed. The moving body 15 is displaced by transmitting vibration that the piezoelectric element 13 generates through the vibration body 14, and the elastic coupling body 12 expands and contracts as the moving body 15 is displaced.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a diffraction grating, a spectroscope, a spectroscopic device, and an analysis device.

The diffraction grating is a spectroscopic element that has a periodically arranged grating and applies diffraction interference of incident light. It is known that the spectral characteristics depend on the incident angle of light and the grating period.
The diffraction grating is applied to a spectroscope, a wavelength filter, an optical modulator, a photodetector, and the like.

  As a technique for changing the wavelength characteristics of the diffraction grating, there is a method of changing the incident angle of light by changing the direction of the diffraction grating. In this method, the mainstream method is to change the incident angle of light by rotating the diffraction grating itself and control the emission angle. However, since a mechanical rotation mechanism (a space for rotation), a drive control component, and the like are required, there is a problem that the apparatus is increased in size.

  On the other hand, in the method of changing the wavelength characteristics of the diffraction grating by changing the period of the diffraction grating, for example, a fine mechanism can be produced by using MEMS (Micro-electro-mechanical system) technology, The apparatus can be miniaturized.

  Specifically, in a structure in which ribbon-shaped diffractive elements are arranged in a line on a silicon substrate, fixed diffractive elements and diffractive elements that can be bent downward by drawing in electrostatic force are alternately provided, and a bias is applied. A diffraction grating having a mechanism of generating diffracted light by bending a movable diffraction element downward and forming an uneven surface is known.

According to the diffraction grating structure using such MEMS technology, a large optical modulation can be obtained with a small mechanical displacement. In addition, high-speed response is possible, and mechanical reliability is high.
However, in the above-described example, there is room for improvement in terms of the complexity of the structure and the difficulty in manufacturing due to the downward bending of the ribbon-shaped diffraction element, and the limitation of the optical degree of freedom. . Therefore, a technique for improving this has been proposed (see, for example, Patent Document 1).

  Patent Document 1 includes a plurality of beam bodies arranged side by side in the first direction on the same plane, and the interval between the beam bodies viewed in the first direction is variable, A first state in which the arrangement of the beam bodies has a first period; and a second state in which the arrangement of the beam bodies in the first direction has a second period different from the first period; A diffraction grating is disclosed that can be selectively formed.

  However, since the operation of the diffraction grating described in Patent Document 1 is high voltage (electrostatic) driving, there is a problem that power consumption increases. Further, since the structure is still complicated, there is a possibility that problems such as an increase in cost and a decrease in yield may not be solved.

  Accordingly, an object of the present invention is to provide a diffraction grating that has a structure in which a diffraction grating and a driving mechanism are integrated and miniaturized, and that can be driven at a low voltage and can reduce power consumption.

  In order to achieve this object, a diffraction grating according to the present invention has a plurality of grating units arranged on the same plane, and a coupling member that can vary the interval between adjacent grating units, and the grating of the coupling member A housing that fixes both ends in the unit arrangement direction, and a driving unit that drives the coupling member to displace it in the lattice unit arrangement direction, and the coupling member is driven by an elastic coupling body and the driving unit. The driving means includes a piezoelectric element and a vibrating body formed with a plurality of convex portions that can come into contact with an edge of the moving body, and the piezoelectric element is interposed via the vibrating body. The moving body is displaced by transmitting the vibration generated by the movement, and the elastic coupling body expands and contracts with the displacement of the moving body.

  According to the present invention, it is possible to provide a diffraction grating that has a structure in which the diffraction grating and the drive mechanism are integrated and miniaturized, and that the voltage at the time of driving is low and power consumption can be reduced.

It is a top view of the diffraction grating concerning one Embodiment of this invention. It is a perspective view of the elastic coupling body (diffraction grating part) which comprises a diffraction grating. It is explanatory drawing which shows an example of the manufacturing process of a diffraction grating part. It is explanatory drawing which shows typically the displacement of the moving body by a drive means. It is sectional drawing of the spectrometer concerning one Embodiment of this invention. It is sectional drawing of the spectrometer concerning one Embodiment of this invention. 1 is a structural diagram of an analyzer according to an embodiment of the present invention.

  Hereinafter, a diffraction grating, a spectroscope, a spectroscopic device, and an analysis device according to the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and other embodiments, additions, modifications, deletions, and the like can be changed within a range that can be conceived by those skilled in the art, and any aspect is possible. As long as the functions and effects of the present invention are exhibited, the scope of the present invention is included.

The diffraction grating of this embodiment is demonstrated based on FIG.1 and FIG.2.
FIG. 1 is a top view showing an embodiment of the diffraction grating of the present invention, and FIG. 2 is a perspective view of an elastic coupling body (diffraction grating portion) constituting the diffraction grating.

The diffraction grating according to the present embodiment includes a plurality of grating units 21 arranged at substantially equal intervals on the same plane, and a coupling member 20 in which the interval between adjacent grating units 21 is variable, and a grating unit arrangement of the coupling members 20. And a driving means 30 for driving the coupling member 20 to displace it in the lattice unit arrangement direction.
The coupling member 20 includes a movable body 15 driven by the elastic coupling body 12 and the driving means 30.
The driving unit 30 includes the piezoelectric element 13 and the vibrating body 14 formed with a plurality of convex portions 14 a that can come into contact with the edge of the moving body 15, and is generated by the piezoelectric element 13 via the vibrating body 14. The moving body 15 is displaced by transmitting the vibration.
The elastic coupling body 12 expands and contracts with the displacement of the moving body 15.
The elastic coupling body 12 has a periodic structure with a rectangular uneven shape in cross section, and the interval of the lattice units 21 changes as the moving body 15 is displaced.

  In FIG. 1A, the interval (diffraction grating period) of the grating units 21 formed by the elastic coupling body 12a on the left side of the drawing through the movable body 15 is d1, and the elastic coupling body 12b on the right side of the drawing forms. In FIG. 1B, which shows a state in which the moving body 15 is displaced, d1 becomes larger and d2 becomes smaller if the distance between the grating units 21 (diffraction grating period) is d2. Since the direction of the diffracted light is changed by changing the period of the diffraction grating, it can be adjusted to obtain a desired wavelength characteristic by changing the interval of the grating units 21.

  As shown in FIG. 2, the elastic coupling body 12 has a periodic structure with a rectangular concave and convex section, and functions as an elastic body that expands and contracts in the arrangement direction of the lattice units. Depending on the pattern shape on the back surface, the expanding and contracting strength (spring strength) can be adjusted to a desired strength.

  Since both ends of the coupling member 20 in the lattice unit arrangement direction are connected and fixed to the housing 11, the period of the folded lattice changes due to the displacement in the lattice unit arrangement direction. On the other hand, since the moving body 15 is in contact with the convex portion 14a of the vibrating body 14, displacement in a direction perpendicular to the lattice unit arrangement direction is restricted.

The casing 11 and the coupling member 20 are preferably formed of a material having elasticity, and specifically, are preferably formed of silicon.
A plurality of wiring pads 16 are formed in an area in the short side direction of the housing 11.
The casing 11 and the coupling member 20 are integrated together with the driving unit 30 by the MEMS technology.

  As for the size of the case of the diffraction grating of this embodiment, the long side is 10 mm and the short side is 5 mm. Note that the size of the housing 11 is not limited to the present embodiment, but may be in an appropriate range to be created by the MEMS technology.

The coupling member 20 is formed with a reflective layer 17 made of a material having a high light reflectance. By providing the reflective layer 17, the effect of improving the intensity of diffracted light by the reflection effect can be obtained.
The reflective layer 17 can be formed of a metal thin film such as Ag, Al, or Au, for example. In this embodiment, a reflective layer made of Al is provided.

FIG. 3 is a schematic cross-sectional view showing an example of the manufacturing process of the diffraction grating part constituting the diffraction grating of this embodiment.
FIG. 3A is a cross-sectional view of a substrate having a structure in which an Al thin film 17a serving as a reflective layer is stacked on a silicon substrate 10. FIG. Hereinafter, the surface on which the Al thin film is formed is referred to as a front surface (reference numeral 10a), and the other surface is referred to as a rear surface (reference numeral 10b).
FIG. 3B shows a state where the Al thin film 17a is etched to form the reflective layer 17 (mirror shape).

FIG. 3C shows a state in which the surface 10a of the silicon substrate exposed by removing the Al thin film 17a is etched.
FIG. 3D shows a state in which the back surface 10b of the silicon substrate is etched to form a structure with a rectangular concavo-convex cross section. As described above, the spring strength of the elastic coupling body 12 can be adjusted by controlling the etching of the back surface.

As described above, the diffraction grating portion shown in FIG. 3E is obtained by etching the front and back surfaces of the silicon substrate.
3 shows only the diffraction grating portion on one side of the coupling member 20, the diffraction grating portion on the other side via the movable body 15 is formed in the same manner.

Next, driving of the moving body 15 by the driving means 30 will be described with reference to FIG.
In the periodic array type diffraction grating of the present embodiment, the vibration generated by the piezoelectric element 13 is ultrasonic vibration.
As shown in FIG. 4, the drive unit 30 includes the piezoelectric element 13 and the vibrating body 14 formed with a plurality of convex portions 14 a that can come into contact with the edge of the moving body 15. A voltage waveform having a phase difference is applied to the adjacent piezoelectric element 13.

  When traveling waves propagate through the vibrating body 14, the particles of the convex bodies 14a near the surface move along an elliptical locus. Using this motion, ultrasonic vibration is converted into motion in one direction via frictional force. That is, ultrasonic vibration is generated in the vibrating body (stator) 14 by the piezoelectric element 13, and the moving body (slider) 15 is driven and displaced by the frictional force. The moving body 15 is frictionally driven by a deflection traveling wave generated in the vibrating body 14.

  In order to transmit the bending traveling wave of the vibrating body 14 to the moving body 15, the convex portion 14a and the moving body 15 need to be in pressure contact with a certain level of pressure, and the accuracy of the contact surface needs to be increased. If the flexural traveling wave of the vibrating body 14 is not transmitted well to the moving body 15, there is a risk that heat generation will increase due to frictional heat.

  As described above, the diffraction grating of the present embodiment has a structure in which the diffraction grating and the drive mechanism are integrated and miniaturized by the MEMS technology, and the period is changed by the ultrasonic actuator. Low voltage and power consumption can be reduced.

[Spectrometer]
FIG. 5 is a cross-sectional view showing an embodiment of the spectrometer of the present invention.
The spectroscope 40 of this embodiment includes a light incident part 3, concave light reflecting parts 6 and 7, and a diffraction grating 4, and the diffraction grating is the above-described diffraction grating of the present invention. Due to the miniaturization of the diffraction grating, the spectroscope 40 of the present embodiment is also miniaturized.

The spectroscope 40 is formed of a first substrate 1 and a second substrate 2. A light incident part 3, a diffraction grating 4 and a light emitting part 5 are formed on the first substrate 1, and a first concave light reflecting part 6 and a second concave light reflecting part are formed on the second substrate 2. 7 is formed.
The first substrate 1 and the second substrate 2 are aligned so as to be in a desired position when being fixed via the spacer 8.
The diffraction grating 4 is the above-described diffraction grating of the present invention. Due to the miniaturization of the diffraction grating, the spectroscope 40 of the present embodiment is also miniaturized.

  An arrow in FIG. 5 indicates an optical path of light having a certain wavelength. As indicated by the arrow, the incident light incident from the light incident part 3 of the spectroscope 40 is reflected by the first concave light reflecting part 6 and guided to the diffraction grating 4. Incident light is wavelength-dispersed by the diffraction grating 4, reflected by the second concave light reflecting portion 7, and imaged by the light emitting portion 5.

  Here, the diffraction grating 4 has a function of wavelength dispersion and a function of image formation at the position of the light emitting part 5, and the second concave light reflecting part 7 emits light dispersed by the diffraction grating 4. It has a function of enabling scanning at the position of the emitting portion 5.

An example of a method for manufacturing the spectroscope 40 will be described below.
When a silicon substrate is used as the first substrate 1, the diffraction grating 4 is formed on the first substrate 1 using a dry etching technique using a nanoimprint or a gray scale mask.
On the other hand, the light incident part 3 and the light emitting part 5 are formed on the first substrate 1 by anisotropic etching of a wet process or a dry process.

  On the second substrate 2, the reflecting surfaces of the first concave light reflecting portion 6 and the second concave light reflecting portion 7 are formed of a metal thin film such as Ag, Al, Au.

  The first substrate 1 and the second substrate 2 can be fixed by direct bonding or via a spacer 8. For fixing, a fixing member can also be used. When fixing via the spacer 8, the thickness of the spacer 8 is adjusted so that the first light reflecting portion 6 and the second concave light reflecting portion 7 and the diffraction grating 4 have a desired positional relationship and distance. Can be aligned.

  In addition, the material of each member which comprises a spectrometer, the formation method and manufacturing process of a spectrometer are not limited to the above-mentioned method.

[Spectroscope]
FIG. 6 is a cross-sectional view showing an embodiment of the spectroscopic device of the present invention.
The spectroscopic device 50 according to the present embodiment includes the spectroscope 40 described above and a detection unit 9 that receives a light beam split by the spectroscope 40. Specifically, the light incident portion 3, the concave light reflecting portions 6 and 7, the diffraction grating 4, and the detection portion 9 are provided, and the diffraction grating is the above-described diffraction grating of the present invention. Due to the miniaturization of the diffraction grating, the spectroscopic device 50 of the present embodiment is also miniaturized.

The spectroscopic device 50 has a detection unit 9 formed at the position of the light emitting unit 5 of the spectroscope 40 described above. It can be formed in the same manner as the above-described spectroscope 40 except for the formation of the detection unit 9.
By forming the detection unit 9 on the first substrate 1, it is possible to integrate light detection means installed outside as a separate device in the past, and to achieve further miniaturization.
The light detection means installed outside requires alignment adjustment for receiving the light emitted from the spectroscope 40, which may increase the final product cost. According to this, this problem is also solved.

When receiving light with a photodiode, it is necessary to select a material corresponding to the wavelength to be measured, and for example, Si, Ge, InGaAs, or the like can be used.
In the case of a Si detector, a Si photodiode can be formed on a Si substrate or an SOI (Silicon On Insulator) substrate by a CMOS process. In the case of a detector such as Ge or InGaAs, a photodiode chip such as Ge or InGaAs can be mounted on the Si substrate.

In addition, the material of each member which comprises a spectroscopic device, the formation method and manufacturing process of a spectroscopic device are not limited to the above-mentioned method.
The spectroscope and the spectroscopic device created at the wafer level as shown in FIGS. 5 and 6 are not limited as long as the structure includes the above-described periodic variable diffraction grating.
Further, although the light incident part 3 and the light emitting part 5 are provided on the first substrate 1, the light incident part 3 and the light emitting part 5 may be separately provided as slits separate from the first substrate 1. .

〔Analysis equipment〕
FIG. 7 is a structural diagram showing a mobile analysis device 60 as an embodiment of the analysis device of the present invention.
The analysis device 60 of the present embodiment is a device that includes a light source that irradiates light to the object to be measured and the above-described spectroscopic device 50, and spectrally reflects the reflected light from the object to be measured by the spectroscopic device 50. . Note that the spectroscope 40 described above can also be used as the spectroscopic device 50. In that case, the light detection unit 9 is provided on the outgoing light side of the spectroscope 40.

The mobile analysis device 60 of this embodiment is equipped with a light source 101, a spectroscopic device 50, a drive circuit 104, a processing circuit 105, a battery 106 that is a power source of these, and the like. The spectroscopic device 50 is the spectroscopic device according to the present invention described above.
The drive circuit 104 drives the light source 101 and the spectroscopic device 50. The processing circuit 105 performs amplification, A / D conversion, communication, and the like of the detected signal.

  In the analyzer 60 of the present embodiment, the emitted light 221 emitted from the light source 101 is applied to the object 230 to be measured and diffusely reflected while colliding with molecules in the object 230 to be measured. The diffusely reflected light 222 enters the spectroscopic device 50 and is detected by the light detection unit 9 provided in the spectroscopic device 50. In this manner, a wavelength spectrum characteristic of the molecular structure of the object to be measured 230 can be obtained.

  The analyzer 60 of the present embodiment can be reduced in size and cost by using the spectroscopic device 50 or the spectroscope 40 according to the present invention, and can improve mobility.

DESCRIPTION OF SYMBOLS 3 Light incident part 4 Diffraction grating 5 Light emitting part 6 1st concave light reflection part 7 2nd concave light reflection part 8 Spacer 9 Light detection part 10 Silicon substrate 11 Case 12 Elastic coupling body (diffraction grating part)
13 Piezoelectric element 14 Vibrating body 15 Moving body 16 Wiring pad 17 Reflective layer 20 Coupling member 21 Lattice unit 30 Driving means 40 Spectroscope 50 Spectrometer 60 Analyzer

Japanese Patent No. 4957441

Claims (9)

A coupling member having a plurality of lattice units arranged on the same plane, and a variable interval between adjacent lattice units;
A housing that fixes both ends of the coupling member in the lattice unit arrangement direction;
Driving means for driving the coupling member to displace it in the lattice unit arrangement direction, and
The coupling member comprises an elastic coupling body and a moving body driven by the driving means,
The driving means includes a piezoelectric element and a vibrating body formed with a plurality of convex portions capable of coming into contact with an edge of the moving body, and transmits vibration generated by the piezoelectric element through the vibrating body. To displace the moving body,
The diffraction grating, wherein the elastic coupling body expands and contracts with the displacement of the moving body.   The diffraction grating according to claim 1, wherein the elastic coupling body has a periodic structure having a rectangular uneven shape in cross section.   The diffraction grating according to claim 1, wherein the vibration generated by the piezoelectric element is an ultrasonic vibration.   The diffraction grating according to claim 1, wherein the movable body is frictionally driven by a deflection traveling wave generated in the vibrating body.   5. The diffraction grating according to claim 1, wherein the casing and the coupling member are made of an elastic material.   6. The diffraction grating according to claim 1, wherein the casing and the coupling member are made of silicon.   A spectroscope comprising: a light incident part; a light reflecting part; and a diffraction grating, wherein the diffraction grating is the diffraction grating according to claim 1.   7. A spectroscopic device comprising: the spectroscope according to claim 6; and a detection unit that receives a light beam split by the spectroscope. A light source for irradiating light to the object to be measured; and the spectroscopic device according to claim 8,
An analyzer characterized in that reflected light from the object to be measured is dispersed by the spectroscopic device to obtain a wavelength spectrum.