WO2019009398A1 - Optical device - Google Patents

Abstract

An optical device that comprises: a base that has a main surface; a mobile part that has an optical function part; and an elastic support part that is connected between the base and the mobile part and supports the mobile part such that the mobile part can move along a first direction that is orthogonal to the main surface. The elastic support part has: a lever; a first torsional support part that extends along a second direction and is connected between the lever and the mobile part, the second direction being the orthogonal to the first direction; and a second torsional support part that extends along the second direction and is connected between the lever and the base. The torsional spring constant of the first torsional support part is greater than the torsional spring constant of the second torsional support part.

Description

Optical device

The present disclosure relates to an optical device configured as, for example, a MEMS (Micro Electro Mechanical Systems) device.

As a MEMS device, a base, a movable part having an optical function part, an elastic support part connected between the base and the movable part and supporting the movable part such that the movable part can move along the moving direction An optical device is known (see, for example, Patent Document 1). In such an optical device, the elastic support may be configured to include a twist support that is torsionally deformed when the movable part moves in the movement direction.

U.S. Patent Application Publication No. 2008/0284078

In the optical device as described above, it is conceivable to narrow the width of the torsion support portion so that the torsion support portion is easily twisted so that the movable portion can be moved largely along the moving direction. However, in such a configuration, when a displacement occurs in the shape of the torsion support portion due to a manufacturing error or the like, the movable portion tilts from the target posture when the movable portion moves in the movement direction, and as a result, optical There is a risk of deterioration of the characteristics.

An object of the present disclosure is to provide an optical device capable of suppressing a decrease in optical characteristics due to a variation in the shape of a torsional support.

An optical device according to one aspect of the present disclosure is connected between a base having a main surface, a movable portion having an optical function portion, and a base having a main surface and the movable portion, and the movable portion is perpendicular to the main surface. An elastic support portion for supporting the movable portion to be movable along a first direction, the elastic support portion extending along a second direction perpendicular to the first direction, the lever being a lever A first torsion support connected between the arm and the movable part, and a second torsion support extending along the second direction and connected between the lever and the base, The torsional spring constant of the torsional support is greater than the torsional spring constant of the second torsional support.

In this optical device, the torsion spring constant of the first torsion support connected between the lever and the movable part is larger than the torsion spring constant of the second torsion support connected between the lever and the base. As a result, even if the shape of at least one of the first torsion support portion and the second torsion support portion is deviated due to a manufacturing error or the like, the movable portion tilts from the target posture when the movable portion moves in the first direction. Can be suppressed. Therefore, according to this optical device, it is possible to suppress the deterioration of the optical characteristics caused by the variation in the shape of the torsion support portion.

In the optical device according to one aspect of the present disclosure, the width of the first torsion support may be wider than the width of the second torsion support when viewed from the first direction. In this case, the torsion spring constant of the first torsion support can be suitably made larger than the torsion spring constant of the second torsion support.

In the optical device according to one aspect of the present disclosure, the length of the first torsion support may be shorter than the length of the second torsion support when viewed from the first direction. In this case, the torsion spring constant of the first torsion support portion can be further preferably made larger than the torsion spring constant of the second torsion support portion.

In the optical device according to one aspect of the present disclosure, the base, the movable portion, and the elastic support may be configured by an SOI substrate. In this case, in the optical device formed by the MEMS technology, it is possible to suppress the deterioration of the optical characteristics due to the variation in the shape of the torsional support.

An optical device according to one aspect of the present disclosure is provided on a base and is provided on a fixed comb electrode having a plurality of fixed comb teeth, at least one of the movable portion and the elastic support portion, and the plurality of fixed comb teeth And a movable comb electrode having a plurality of movable comb teeth alternately arranged. In this case, the actuator unit for moving the movable unit can be simplified and power consumption can be reduced.

The optical device according to one aspect of the present disclosure may include only one pair of elastic support portions. In this case, the movement of the movable portion can be stabilized, for example, as compared with the case where only one elastic support portion is provided. In addition, the total number of torsion supports can be reduced, for example, as compared to the case where three or more elastic supports are provided. As a result, the spring constant of each torsion support can be secured, and the influence of the variation in the shape of the torsion support can be reduced.

According to one aspect of the present disclosure, it is possible to provide an optical device capable of suppressing a decrease in optical characteristics due to the variation in the shape of the torsional support.

FIG. 1 is a longitudinal sectional view of an optical module provided with an optical device according to an embodiment. FIG. 3 is a plan view of the optical device shown in FIGS. 2 and 1; FIG. 3 is a plan view showing a part of FIG. 2 in an enlarged manner. FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. FIG. 5 is a graph showing the tilt of the mirror surface at the time of movement in the example and the comparative example.

Hereinafter, an embodiment according to one aspect of the present disclosure will be described in detail with reference to the drawings. In the following description, the same or corresponding elements will be denoted by the same reference symbols, without redundant description.
[Optical module configuration]

As shown in FIG. 1, the optical module 1 includes a mirror unit 2 and a beam splitter unit 3. The mirror unit 2 has an optical device 10 and a fixed mirror 21. The optical device 10 includes a movable mirror (movable portion) 11. In the optical module 1, the beam splitter unit 3, the movable mirror 11 and the fixed mirror 21 form an interference optical system for the measurement light L 0. The interference optical system here is a Michelson interference optical system.

The optical device 10 includes, in addition to the movable mirror 11, a base 12, a drive unit 13, a first optical function unit 17, and a second optical function unit 18. The base 12 has a major surface 12 a. The movable mirror 11 has a mirror surface (optical function portion) 11a along a plane parallel to the major surface 12a. The movable mirror 11 is supported by the base 12 so as to be movable along a Z-axis direction (a direction parallel to the Z-axis, a first direction) perpendicular to the major surface 12 a. The drive unit 13 moves the movable mirror 11 along the Z-axis direction. The first optical function unit 17 is disposed on one side of the movable mirror 11 in the X-axis direction (a direction parallel to the X-axis, a third direction) perpendicular to the Z-axis direction when viewed from the Z-axis direction There is. The second optical function unit 18 is disposed on the other side of the movable mirror 11 in the X-axis direction when viewed from the Z-axis direction. Each of the first optical function unit 17 and the second optical function unit 18 is a light passing opening provided in the base 12 and is open on one side and the other side in the Z-axis direction. In the optical module 1, the second optical function unit 18 is not used as a light passing aperture. When the optical device 10 is applied to another apparatus, at least one of the first optical function unit 17 and the second optical function unit 18 may be used as an optical function unit, or the first optical function unit 17 and the second optical function unit 18 may be used. Both of the optical function units 18 may not be used as optical function units.

The fixed mirror 21 has a mirror surface 21a extending along a plane parallel to the major surface 12a (a plane perpendicular to the Z-axis direction). The position of the fixed mirror 21 with respect to the base 12 is fixed. In the mirror unit 2, the mirror surface 11a of the movable mirror 11 and the mirror surface 21a of the fixed mirror 21 face one side (the beam splitter unit 3 side) in the Z-axis direction.

In addition to the optical device 10 and the fixed mirror 21, the mirror unit 2 has a support 22, a submount 23 and a package 24. The package 24 accommodates the optical device 10, the fixed mirror 21, the support 22 and the submount 23. The package 24 includes a bottom wall 241, side walls 242 and a top wall 243. The package 24 is formed in, for example, a rectangular box shape. The package 24 has, for example, a size of about 30 × 25 × 10 (thickness) mm. The bottom wall 241 and the side wall 242 are integrally formed with each other. The top wall 243 faces the bottom wall 241 in the Z-axis direction, and is fixed to the side wall 242. The top wall 243 is light transmissive to the measurement light L0. In the mirror unit 2, a space S is formed by the package 24. The space S is opened to the outside of the mirror unit 2 through, for example, a vent or a gap provided in the package 24. As described above, when the space S is not an airtight space, it is possible to suppress contamination, fogging, etc. of the mirror surface 11 a due to outgassing from the resin material present in the package 24 or moisture present in the package 24. . The space S may be an airtight space in which a high degree of vacuum is maintained, or an airtight space filled with an inert gas such as nitrogen.

The support 22 is fixed to the inner surface of the bottom wall 241 via the submount 23. The support 22 is formed, for example, in a rectangular plate shape. The support 22 is light transmissive to the measurement light L0. The base 12 of the optical device 10 is fixed to the surface 22 a of the support 22 opposite to the submount 23. That is, the base 12 is supported by the support 22. A recess 22 b is formed on the surface 22 a of the support 22, and a gap (a part of the space S) is formed between the optical device 10 and the top wall 243. Thereby, when the movable mirror 11 is moved along the Z-axis direction, the movable mirror 11 and the drive unit 13 are prevented from contacting the support 22 and the top wall 243.

An opening 23 a is formed in the submount 23. The fixed mirror 21 is disposed on the surface 22c of the support 22 on the submount 23 side so as to be located in the opening 23a. That is, the fixed mirror 21 is disposed on the surface 22 c of the support 22 opposite to the base 12. The fixed mirror 21 is disposed on one side of the movable mirror 11 in the X-axis direction when viewed from the Z-axis direction. The fixed mirror 21 overlaps the first optical function unit 17 of the optical device 10 when viewed in the Z-axis direction.

The mirror unit 2 further includes a plurality of lead pins 25 and a plurality of wires 26. Each lead pin 25 is fixed to the bottom wall 241 in a state of penetrating the bottom wall 241. Each lead pin 25 is electrically connected to the drive unit 13 via the wire 26. In the mirror unit 2, an electrical signal for moving the movable mirror 11 along the Z-axis direction is applied to the drive unit 13 via the plurality of lead pins 25 and the plurality of wires 26.

The beam splitter unit 3 is supported by the top wall 243 of the package 24. Specifically, the beam splitter unit 3 is fixed to the surface 243 a of the top wall 243 opposite to the optical device 10 by the optical resin 4. The optical resin 4 is light transmissive to the measurement light L0.

The beam splitter unit 3 has a half mirror surface 31, a total reflection mirror surface 32, and a plurality of optical surfaces 33a, 33b, 33c, and 33d. The beam splitter unit 3 is configured by bonding a plurality of optical blocks. The half mirror surface 31 is formed of, for example, a dielectric multilayer film. The total reflection mirror surface 32 is formed of, for example, a metal film.

The optical surface 33a is, for example, a surface perpendicular to the Z-axis direction, and overlaps the first optical function portion 17 of the optical device 10 and the mirror surface 21a of the fixed mirror 21 when viewed from the Z-axis direction. The optical surface 33a transmits the measurement light L0 incident along the Z-axis direction.

The half mirror surface 31 is, for example, a surface inclined 45 degrees with respect to the optical surface 33a, and overlaps the first optical function portion 17 of the optical device 10 and the mirror surface 21a of the fixed mirror 21 when viewed from the Z-axis direction. ing. The half mirror surface 31 reflects a part of the measurement light L0 incident on the optical surface 33a along the Z-axis direction along the X-axis direction, and the remaining part of the measurement light L0 along the Z-axis direction. Permeate to the side.

The total reflection mirror surface 32 is a surface parallel to the half mirror surface 31. The total reflection mirror surface 32 overlaps the mirror surface 11a of the movable mirror 11 when viewed from the Z axis direction and when viewed from the X axis direction. And overlap. The total reflection mirror surface 32 reflects a part of the measurement light L0 reflected by the half mirror surface 31 toward the movable mirror 11 along the Z-axis direction.

The optical surface 33 b is a surface parallel to the optical surface 33 a and overlaps the mirror surface 11 a of the movable mirror 11 when viewed in the Z-axis direction. The optical surface 33b transmits a part of the measurement light L0 reflected by the total reflection mirror surface 32 to the movable mirror 11 side along the Z-axis direction.

The optical surface 33c is a surface parallel to the optical surface 33a, and overlaps the mirror surface 21a of the fixed mirror 21 when viewed from the Z-axis direction. The optical surface 33 c transmits the remaining portion of the measurement light L 0 transmitted through the half mirror surface 31 to the fixed mirror 21 side along the Z-axis direction.

The optical surface 33 d is, for example, a surface perpendicular to the X-axis direction, and overlaps the half mirror surface 31 and the total reflection mirror surface 32 when viewed from the X-axis direction. The optical surface 33d transmits the measurement light L1 along the X-axis direction. The measurement light L1 is sequentially reflected by the mirror surface 11a of the movable mirror 11 and the total reflection mirror surface 32 and transmitted through the half mirror surface 31. A part of the measurement light L0 and the mirror surface 21a of the fixed mirror 21 and the half mirror surface This is interference light with the remaining part of the measurement light L0 sequentially reflected by 31.

In the optical module 1 configured as described above, when the measurement light L0 is incident on the beam splitter unit 3 from the outside of the optical module 1 via the optical surface 33a, a part of the measurement light L0 has the half mirror surface 31 and all The light is reflected sequentially by the reflection mirror surface 32 and travels toward the mirror surface 11 a of the movable mirror 11. Then, a part of the measurement light L0 is reflected by the mirror surface 11a of the movable mirror 11, travels in the opposite direction on the same optical path (optical path P1 described later), and passes through the half mirror surface 31 of the beam splitter unit 3. Do.

On the other hand, the remaining part of the measurement light L 0 passes through the half mirror surface 31 of the beam splitter unit 3, passes through the first optical function unit 17, passes through the support 22, and passes through the mirror surface 21 a of the fixed mirror 21. Progress towards The remaining portion of the measurement light L0 is reflected by the mirror surface 21a of the fixed mirror 21, travels in the opposite direction on the same optical path (optical path P2 described later), and is reflected by the half mirror surface 31 of the beam splitter unit 3. Ru.

Part of the measurement light L0 transmitted through the half mirror surface 31 of the beam splitter unit 3 and the remaining part of the measurement light L0 reflected by the half mirror surface 31 of the beam splitter unit 3 become measurement light L1 which is interference light, The measurement light L1 is emitted from the beam splitter unit 3 to the outside of the optical module 1 via the optical surface 33d. According to the optical module 1, since the movable mirror 11 can be reciprocated at high speed along the Z-axis direction, a compact and high-precision FTIR (Fourier transform infrared spectrometer) can be provided.

The support 22 corrects the optical path difference between the optical path P 1 between the beam splitter unit 3 and the movable mirror 11 and the optical path P 2 between the beam splitter unit 3 and the fixed mirror 21. Specifically, the optical path P1 is an optical path from the half mirror surface 31 to the mirror surface 11a of the movable mirror 11 located at the reference position through the total reflection mirror surface 32 and the optical surface 33b sequentially It is a light path along which a part of the light L0 travels. The optical path P2 is an optical path from the half mirror surface 31 to the mirror surface 21a of the fixed mirror 21 sequentially through the optical surface 33c and the first optical function unit 17, and is an optical path through which the remaining portion of the measurement light L0 travels. is there. The support 22 has an optical path length of the optical path P1 (optical path length considering the refractive index of each medium through which the optical path P1 passes) and an optical path length of the optical path P2 (optical path length considering the refractive index of each medium through which the optical path P2 passes). The optical path difference between the optical path P1 and the optical path P2 is corrected so that the difference becomes smaller (for example, eliminated). The support 22 can be made of, for example, the same light transmitting material as each optical block constituting the beam splitter unit 3. In that case, the thickness (length in the Z-axis direction) of the support 22 can be made equal to the distance between the half mirror surface 31 and the total reflection mirror surface 32 in the X-axis direction.
[Optical Device Configuration]

As shown in FIG. 2, FIG. 3 and FIG. 4, the movable mirror 11 other than the mirror surface 11 a, the base 12, the drive unit 13, the first optical function unit 17 and the second optical function unit 18 A silicon on insulator (substrate) 50 is formed. That is, the optical device 10 is configured of the SOI substrate 50. The optical device 10 is formed, for example, in a rectangular plate shape. The optical device 10 has, for example, a size of about 15 × 10 × 0.3 (thickness) mm. The SOI substrate 50 has a support layer 51, a device layer 52 and an intermediate layer 53. The support layer 51 is a first silicon layer. The device layer 52 is a second silicon layer. The intermediate layer 53 is an insulating layer disposed between the support layer 51 and the device layer 52.

The base 12 is formed by the support layer 51, the device layer 52 and part of the intermediate layer 53. The major surface 12 a of the base 12 is the surface of the device layer 52 opposite to the intermediate layer 53. The main surface 12 b of the base 12 opposite to the main surface 12 a is a surface of the support layer 51 opposite to the intermediate layer 53. In the optical module 1, the main surface 12a of the base 12 and the surface 22a of the support 22 are bonded to each other (see FIG. 1).

The movable mirror 11 is disposed with a point of intersection of the axis R1 and the axis R2 as a center position (center of gravity). The axis R1 is a straight line extending in the X-axis direction. The axis R2 is a straight line extending in a Y-axis direction (a direction parallel to the Y-axis, a second direction) perpendicular to the X-axis direction and the Z-axis direction. When viewed in the Z-axis direction, the optical device 10 exhibits a shape that is line-symmetrical about the axis R1 and line-symmetrical about the axis R2.

The movable mirror 11 has a main body portion 111, a frame portion 112, and a pair of connecting portions 113. The main body portion 111 has a circular shape when viewed from the Z-axis direction. The main body portion 111 has a central portion 114 and an outer edge portion 115. For example, a metal film is formed on the surface of the central portion 114 on the main surface 12 b side, and a circular mirror surface 11 a is provided. The central portion 114 is formed by a portion of the device layer 52. The outer edge portion 115 surrounds the central portion 114 when viewed in the Z-axis direction. The outer edge portion 115 has a first main body portion 115 a and a first beam portion 115 b. The first main body portion 115 a is formed of a part of the device layer 52.

The first beam portion 115 b is formed of a part of the support layer 51 and the intermediate layer 53. The first beam portion 115 b is provided on the surface of the first main portion 115 a on the main surface 12 b side. The first beam portion 115 b is formed such that the thickness of the outer edge portion 115 in the Z-axis direction is larger than the thickness of the central portion 114 in the Z-axis direction. When viewed in the Z-axis direction, the first beam portion 115b has an annular shape and surrounds the mirror surface 11a. The first beam portion 115 b extends along the outer edge of the main body portion 111 when viewed in the Z-axis direction. In the present embodiment, the outer edge of the first beam portion 115 b extends along the outer edge of the main body portion 111 at a predetermined distance from the outer edge of the main body portion 111 when viewed in the Z-axis direction. The inner edge of the first beam portion 115b extends along the outer edge of the mirror surface 11a at a predetermined distance from the outer edge of the mirror surface 11a when viewed in the Z-axis direction.

The frame portion 112 surrounds the main body portion 111 at a predetermined distance from the main body portion 111 when viewed from the Z-axis direction. The frame portion 112 has an annular shape when viewed from the Z-axis direction. The frame 112 has a second main body 112a and a second beam 112b. The second main body 112 a is formed by a part of the device layer 52.

The second beam portion 112 b is formed of a part of the support layer 51 and the intermediate layer 53. The second beam portion 112 b is provided on the surface of the second main portion 112 a on the main surface 12 b side. The second beam portion 112 b is formed such that the thickness of the frame portion 112 in the Z-axis direction is larger than the thickness of the central portion 114 in the Z-axis direction. The second beam portion 112 b has an annular shape when viewed in the Z-axis direction. The outer edge of the second beam 112 b extends along the outer edge of the frame 112 at a predetermined distance from the outer edge of the frame 112 when viewed in the Z-axis direction. The inner edge of the second beam portion 112 b extends along the inner edge of the frame portion 112 at a predetermined distance from the inner edge of the frame portion 112 when viewed in the Z-axis direction.

The thickness of the second beam portion 112b in the Z-axis direction is equal to the thickness of the first beam portion 115b in the Z-axis direction. When viewed in the Z-axis direction, the width of the second beam portion 112 b is wider than the width of the first beam portion 115 b. The width of the first beam portion 115b when viewed from the Z-axis direction is the length of the first beam portion 115b in the direction perpendicular to the extending direction of the first beam portion 115b, and in the present embodiment, the first beam portion 115b The length of the first beam portion 115b in the radial direction of the beam portion 115b. The same applies to the width of the second beam portion 112 b when viewed in the Z-axis direction.

Each of the pair of connecting portions 113 connects the main body portion 111 and the frame portion 112 to each other. The pair of connecting portions 113 is disposed on one side and the other side in the Y-axis direction with respect to the main body portion 111. Each connecting portion 113 has a third main portion 113a and a third beam portion 113b. The third main body portion 113 a is formed of a part of the device layer 52. The third main body portion 113a is connected to the first main body portion 115a and the second main body portion 112a.

The third beam portion 113 b is formed of a part of the support layer 51 and the intermediate layer 53. The third beam portion 113 b is connected to the first beam portion 115 b and the second beam portion 112 b. The third beam portion 113 b is provided on the surface of the third main portion 113 a on the main surface 12 b side. The third beam portion 113 b is formed such that the thickness of the connection portion 113 in the Z-axis direction is larger than the thickness of the central portion 114 in the Z-axis direction. The thickness of the third beam portion 113b in the Z-axis direction is equal to the thickness of each of the first beam portion 115b and the second beam portion 112b in the Z-axis direction. The width of the third beam portion 113b is larger than the width of each of the first beam portion 115b and the second beam portion 112b. The width of the third beam portion 113b is the length of the third beam portion 113b in the extending direction of the first beam portion 115b.

The movable mirror 11 further includes a pair of brackets 116 and a pair of brackets 117. Each bracket 116 and each bracket 117 are formed by a part of the device layer 52. Each bracket 116 extends along the Y-axis direction, and has a rectangular shape when viewed from the Z-axis direction. One bracket 116 protrudes from one side of the frame 112 toward one side in the Y-axis direction, and the other bracket 116 protrudes from the side of the frame 112 toward the other side in the Y-axis direction. There is. The pair of brackets 116 is disposed on the same center line parallel to the Y-axis direction. Each bracket 116 extends from an end of the frame portion 112 on the first optical function portion 17 side.

Each bracket 117 extends along the Y-axis direction, and has a rectangular shape when viewed from the Z-axis direction. One bracket 117 protrudes from one side of the frame 112 toward one side in the Y-axis direction, and the other bracket 117 protrudes from the side of the frame 112 toward the other side in the Y-axis direction. There is. The pair of brackets 117 is disposed on the same center line parallel to the Y-axis direction. Each bracket 117 extends from an end of the frame 112 on the second optical function portion 18 side (opposite to the first optical function portion 17).

The drive unit 13 has a first elastic support 14, a second elastic support 15, and an actuator 16. The first elastic support portion 14, the second elastic support portion 15 and the actuator portion 16 are formed by the device layer 52.

Each of the first elastic support portion 14 and the second elastic support portion 15 is connected between the base 12 and the movable mirror 11. The first elastic support portion 14 and the second elastic support portion 15 support the movable mirror 11 so that the movable mirror 11 can move along the Z-axis direction.

The first elastic support portion 14 includes a pair of levers 141, a link 142, a link 143, a pair of brackets 144, a pair of first torsion bars (first torsion support portions) 145, and a pair of second torsion bars (second torsion support). Part) 146 and a pair of electrode support parts 147. The pair of levers 141 is disposed on both sides of the first optical function portion 17 in the Y-axis direction. Each lever 141 has a plate shape extending along a plane perpendicular to the Z-axis direction. In the present embodiment, each lever 141 extends along the X-axis direction.

The link 142 is bridged between the ends 141 a of the pair of levers 141 on the movable mirror 11 side. The link 142 has a plate shape extending along a plane perpendicular to the Z-axis direction. The link 142 extends along the Y-axis direction. The link 143 is bridged between the end 141 b of the pair of levers 141 opposite to the movable mirror 11. The link 143 has a plate shape extending along a plane perpendicular to the Z-axis direction, and extends along the Y-axis direction. In the present embodiment, the first optical function portion 17 is an opening defined by the pair of levers 141, the link 142 and the link 143. The first optical function unit 17 has a rectangular shape when viewed from the Z-axis direction. The first optical function unit 17 is, for example, a cavity. Alternatively, a material having optical transparency to the measurement light L0 may be disposed in the opening forming the first optical function unit 17.

Each bracket 144 has a rectangular shape when viewed from the Z-axis direction. Each bracket 144 is provided on the surface of the link 142 on the movable mirror 11 side so as to protrude to the movable mirror 11 side. One bracket 144 is disposed in the vicinity of one end of the link 142, and the other bracket 144 is disposed in the vicinity of the other end of the link 142.

The pair of first torsion bars 145 is stretched between the end of one bracket 116 and one bracket 144 and between the end of the other bracket 116 and the other bracket 144, respectively. . That is, the pair of first torsion bars 145 is connected between the pair of levers 141 and the movable mirror 11 respectively. Each first torsion bar 145 extends along the Y-axis direction. The pair of first torsion bars 145 are disposed on the same center line parallel to the Y-axis direction.

The pair of second torsion bars 146 is respectively disposed between the end portion 141 b of the one lever 141 opposite to the movable mirror 11 and the base 12 and the other end of the other lever 141 opposite to the movable mirror 11. It is bridged between the section 141 b and the base 12. That is, the pair of second torsion bars 146 is connected between the pair of levers 141 and the base 12 respectively. Each second torsion bar 146 extends along the Y-axis direction. The pair of second torsion bars 146 are disposed on the same center line parallel to the Y-axis direction. The end 141 b of each lever 141 is provided with a projecting portion 141 c that protrudes outward in the Y-axis direction, and the second torsion bar 146 is connected to the projecting portion 141 c.

Each electrode support portion 147 extends along the Y-axis direction, and has a rectangular shape when viewed from the Z-axis direction. One electrode support portion 147 extends from the middle portion of one lever 141 toward the opposite side to the first optical function portion 17. The other electrode support part 147 protrudes from the middle part of the other lever 141 to the opposite side to the first optical function part 17. The pair of electrode support portions 147 is disposed on the same center line parallel to the Y-axis direction when viewed from the Z-axis direction.

The second elastic support portion 15 includes a pair of levers 151, a link 152, a link 153, a pair of brackets 154, a pair of first torsion bars (a first torsion support portion) 155, and a pair of second torsion bars (a second torsion support). Part) 156 and a pair of electrode support parts 157. The pair of levers 151 is disposed on both sides of the second optical function portion 18 in the Y-axis direction. Each lever 151 has a plate shape extending along a plane perpendicular to the Z-axis direction. In the present embodiment, each lever 151 extends along the X-axis direction.

The link 152 is bridged between the ends 151 a of the pair of levers 151 on the movable mirror 11 side. The link 152 has a plate shape extending along a plane perpendicular to the Z-axis direction. The link 152 extends along the Y-axis direction. The link 153 is bridged between the end 151 b of the pair of levers 151 opposite to the movable mirror 11. The link 153 has a plate shape extending along a plane perpendicular to the Z-axis direction, and extends along the Y-axis direction. In the present embodiment, the second optical function portion 18 is an opening defined by the pair of levers 151, the link 152 and the link 153. The second optical function unit 18 has a rectangular shape when viewed from the Z-axis direction. The second optical function unit 18 is, for example, a cavity. Alternatively, a material having optical transparency to the measurement light L0 may be disposed in the opening forming the second optical function unit 18.

Each bracket 154 has a rectangular shape when viewed from the Z-axis direction. Each bracket 154 is provided on the surface of the link 152 on the movable mirror 11 side so as to protrude to the movable mirror 11 side. One bracket 154 is disposed in the vicinity of one end of the link 152, and the other bracket 154 is disposed in the vicinity of the other end of the link 152.

The pair of first torsion bars 155 is stretched between the end of one bracket 117 and one bracket 154 and between the end of the other bracket 117 and the other bracket 154, respectively. . That is, the pair of first torsion bars 155 is connected between the pair of levers 151 and the movable mirror 11 respectively. Each first torsion bar 155 extends along the Y-axis direction. The pair of first torsion bars 155 is disposed on the same center line parallel to the Y-axis direction.

The pair of second torsion bars 156 are respectively disposed between the end 151 b of the one lever 151 opposite to the movable mirror 11 and the base 12 and the other end of the other lever 151 opposite to the movable mirror 11. It is bridged between the unit 151 b and the base 12. That is, the pair of second torsion bars 156 are respectively connected between the pair of levers 151 and the base 12. Each second torsion bar 156 extends along the Y-axis direction. The pair of second torsion bars 156 is disposed on the same center line parallel to the Y-axis direction. The end 151b of each lever 151 is provided with a protrusion 151c that protrudes outward in the Y-axis direction, and the second torsion bar 156 is connected to the protrusion 151c.

Each electrode support portion 157 extends along the Y-axis direction, and has a rectangular shape when viewed from the Z-axis direction. One electrode support portion 157 extends from the middle portion of one lever 151 toward the opposite side to the second optical function portion 18. The other electrode support portion 157 protrudes from the middle portion of the other lever 151 to the opposite side to the second optical function portion 18. The pair of electrode support portions 157 is disposed on the same center line parallel to the Y-axis direction when viewed from the Z-axis direction.

The actuator unit 16 moves the movable mirror 11 along the Z-axis direction. The actuator unit 16 includes a pair of fixed comb electrodes 161, a pair of movable comb electrodes 162, a pair of fixed comb electrodes 163, and a pair of movable comb electrodes 164. The positions of the fixed comb electrodes 161 and 163 are fixed. The movable comb electrodes 162 and 164 move as the movable mirror 11 moves.

One fixed comb electrode 161 is provided on the surface of the device layer 52 of the base 12 facing the one electrode support portion 147. The other fixed comb electrode 161 is provided on the surface of the device layer 52 facing the other electrode support 147. Each fixed comb electrode 161 has a plurality of fixed comb teeth 161 a extending along a plane perpendicular to the Y-axis direction. These fixed comb teeth 161a are arranged side by side at a predetermined interval in the Y-axis direction.

One movable comb electrode 162 is provided on the surface on both sides in the X axis direction of one electrode support portion 147. The other movable comb electrode 162 is provided on the surface on both sides in the X-axis direction of the other electrode support portion 147. Each movable comb electrode 162 has a plurality of movable combs 162 a extending along a plane perpendicular to the Y-axis direction. These movable comb teeth 162a are arranged side by side at a predetermined interval in the Y-axis direction.

In one fixed comb electrode 161 and one movable comb electrode 162, a plurality of fixed comb teeth 161a and a plurality of movable comb teeth 162a are alternately arranged. That is, the fixed comb teeth 161 a of the one fixed comb electrode 161 are located between the movable comb teeth 162 a of the one movable comb electrode 162. In the other fixed comb electrode 161 and the other movable comb electrode 162, a plurality of fixed comb teeth 161a and a plurality of movable comb teeth 162a are alternately arranged. That is, the fixed comb teeth 161 a of the other fixed comb electrode 161 are located between the movable comb teeth 162 a of the other movable comb electrode 162. In the pair of fixed comb electrodes 161 and the pair of movable comb electrodes 162, adjacent fixed comb teeth 161a and movable comb teeth 162a face each other in the Y-axis direction. The distance between the adjacent fixed comb teeth 161a and the movable comb teeth 162a is, for example, about several μm.

One fixed comb electrode 163 is provided on the surface of the device layer 52 of the base 12 facing the one electrode support portion 157. The other fixed comb electrode 163 is provided on the surface of the device layer 52 facing the other electrode support portion 157. Each fixed comb electrode 163 has a plurality of fixed comb teeth 163 a extending along a plane perpendicular to the Y-axis direction. These fixed comb teeth 163a are arranged side by side at a predetermined interval in the Y-axis direction.

One movable comb electrode 164 is provided on the surface on both sides of one electrode support portion 157 in the X-axis direction. The other movable comb electrode 164 is provided on the surface on both sides of the other electrode support portion 157 in the X-axis direction. Each movable comb electrode 164 has a plurality of movable comb teeth 164 a extending along a plane perpendicular to the Y-axis direction. These movable comb teeth 164a are arranged side by side at a predetermined interval in the Y-axis direction.

In one fixed comb electrode 163 and one movable comb electrode 164, a plurality of fixed comb teeth 163a and a plurality of movable comb teeth 164a are alternately arranged. That is, the fixed comb teeth 163 a of one fixed comb electrode 163 are located between the movable comb teeth 164 a of one movable comb electrode 164. In the other fixed comb electrode 163 and the other movable comb electrode 164, a plurality of fixed comb teeth 163a and a plurality of movable comb teeth 164a are alternately arranged. That is, the fixed comb teeth 163 a of the other fixed comb electrode 163 are located between the movable comb teeth 164 a of the other movable comb electrode 164. In the pair of fixed comb electrodes 163 and the pair of movable comb electrodes 164, adjacent fixed comb teeth 163a and movable comb teeth 164a face each other in the Y-axis direction. The distance between the fixed comb teeth 163a and the movable comb teeth 164a adjacent to each other is, for example, about several μm.

The base 12 is provided with a plurality of electrode pads 121 and 122. Each of the electrode pads 121 and 122 is formed on the surface of the device layer 52 in an opening 12 c formed on the main surface 12 b of the base 12 so as to reach the device layer 52. Each electrode pad 121 is electrically connected to the fixed comb electrode 161 or the fixed comb electrode 163 via the device layer 52. Each electrode pad 122 is electrically connected to the movable comb electrode 162 or the movable comb electrode 164 via the first elastic support portion 14 or the second elastic support portion 15. The wires 26 are stretched between the electrode pads 121 and 122 and the lead pins 25.

In the optical device 10 configured as described above, when a voltage is applied between the plurality of electrode pads 121 and the plurality of electrode pads 122 via the plurality of lead pins 25 and the plurality of wires 26, for example, the Z axis Between the fixed comb electrode 161 and the movable comb electrode 162 opposed to each other, and the fixed comb electrode 163 and the movable comb electrode 164 opposed to each other, so as to move the movable mirror 11 to one side in the direction. Electrostatic force occurs during the At this time, the first torsion bars 145 and 155 and the second torsion bars 146 and 156 are twisted in the first elastic support 14 and the second elastic support 15, respectively, and the first elastic support 14 and the second elastic support An elastic force is generated at 15. In the optical device 10, the movable mirror 11 is reciprocated at the resonance frequency level along the Z-axis direction by applying a periodic electrical signal to the drive unit 13 via the plurality of lead pins 25 and the plurality of wires 26. be able to. Thus, the drive unit 13 functions as an electrostatic actuator.
[Detailed configuration of the torsion bar]

Each first torsion bar 145 and each second torsion bar 146 have a flat plate shape perpendicular to the X-axis direction. Each first torsion bar 145 has, for example, a length (length in the Y-axis direction) of 30 μm to 300 μm, a width (length in the X-axis direction) of 5 μm to 30 μm, and a thickness (length in the Z-axis direction) of 30 μm to 100 μm It is formed to a degree. Each second torsion bar 146 has, for example, a length (length in the Y-axis direction) of 30 μm to 300 μm, a width (length in the X-axis direction) of 5 μm to 30 μm, and a thickness (length in the Z-axis direction) of 30 μm to 100 μm It is formed to a degree.

In the present embodiment, the length of the first torsion bar 145 is equal to the length of the second torsion bar 146. The width of the first torsion bar 145 is wider than the width of the second torsion bar 146. The thickness of the first torsion bar 145 is equal to the thickness of the second torsion bar 146. In the case where at least one end on the bracket 116 side and the bracket 144 side of the first torsion bar 145 is provided with a widening portion whose width is widened toward the end, the length of the first torsion bar 145 is The length of the first torsion bar 145 not including the widening portion is meant, and the width of the first torsion bar 145 means the width of the first torsion bar 145 not including the widening portion. Further, the width of the first torsion bar 145 means the width (minimum width) at the narrowest position. These points also apply to the first torsion bar 155 and the second torsion bars 146 and 156.

The torsion spring constant of the first torsion bar 145 is larger than the torsion spring constant of the second torsion bar 146. The torsion spring constant of the first torsion bar 145 is, for example, about 0.00004 N · m / rad. The torsion spring constant of the second torsion bar 146 is, for example, about 0.00003 N · m / rad. The torsion spring constants of the first torsion bar 145 and the second torsion bar 146 are set, for example, in the range of about 0.000001 N · m / rad to 0.001 N · m / rad. In the present embodiment, the length and thickness of the first torsion bar 145 are equal to the length and thickness of the second torsion bar 146, and the width of the first torsion bar 145 is wider than the width of the second torsion bar 146. Thus, the torsion spring constant of the first torsion bar 145 is larger than the torsion spring constant of the second torsion bar 146.

Each first torsion bar 155 and each second torsion bar 156 have a flat plate shape perpendicular to the X-axis direction. The first torsion bar 155 is formed, for example, in the same shape as the first torsion bar 145. The second torsion bar 156 is formed, for example, in the same shape as the second torsion bar 146. In the present embodiment, the length of the first torsion bar 155 is equal to the length of the second torsion bar 156. The width of the first torsion bar 155 is wider than the width of the second torsion bar 156. The thickness of the first torsion bar 155 is equal to the thickness of the second torsion bar 156.

The torsion spring constant of the first torsion bar 155 is larger than the torsion spring constant of the second torsion bar 156. The torsion spring constant of the first torsion bar 155 is, for example, equal to the torsion spring constant of the first torsion bar 145. The torsion spring constant of the second torsion bar 156 is, for example, equal to the torsion spring constant of the second torsion bar 146. In the present embodiment, the length and thickness of the first torsion bar 155 are equal to the length and thickness of the second torsion bar 156, and the width of the first torsion bar 155 is wider than the width of the second torsion bar 156. Thus, the torsion spring constant of the first torsion bar 155 is larger than the torsion spring constant of the second torsion bar 156.
[Action and effect]

The effects of the optical device 10 will be described with reference to FIG. FIG. 5 is a graph showing the inclination of the mirror surface 11a at the time of movement in the example and the comparative example. The example corresponds to the optical device 10 of the above embodiment. In the embodiment, the width of the first torsion bar 145 is 18 μm, the width of the second torsion bar 146 is 15 μm, the width of the first torsion bar 155 is 18 μm, and the width of the second torsion bar 156 is 16 μm. The length of each of the first torsion bars 145 and 155 and the second torsion bars 146 and 156 is 100 μm, and the thickness is 70 μm.

In the comparative example, the width of the first torsion bar 145 is 16 μm, the width of the second torsion bar 146 is 17 μm, the width of the first torsion bar 155 is 16 μm, and the width of the second torsion bar 156 is 18 μm. The length of each of the first torsion bars 145 and 155 and the second torsion bars 146 and 156 is 100 μm, and the thickness is 70 μm. The other configuration of the comparative example is the same as that of the example.

The embodiment corresponds to the case where the width of the second torsion bar 146 is narrowed by 1 μm in the configuration in which the width of the first torsion bars 145 and 155 is 18 μm and the width of the second torsion bars 146 and 156 is 16 μm. . The comparative example corresponds to the case where the width of the second torsion bar 146 is narrowed by 1 μm in the configuration in which the width of the first torsion bars 145 and 155 is 16 μm and the width of the second torsion bars 146 and 156 is 18 μm. .

In the configuration before the width of the second torsion bar 146 is narrowed in the embodiment, the torsion spring constant of the first torsion bar 145 is larger than the torsion spring constant of the second torsion bar 146, and the first torsion bar 155 The torsion spring constant is larger than the torsion spring constant of the second torsion bar 156. In the configuration before the width of the second torsion bar 146 is narrowed in the comparative example, the torsion spring constant of the first torsion bar 145 is smaller than the torsion spring constant of the second torsion bar 146 and the first torsion bar 155 The torsion spring constant is smaller than the torsion spring constant of the second torsion bar 156.

Deviation of the shape of the second torsion bar 146 as described above may occur due to the following reasons. The optical device 10 is formed on the SOI substrate 50 using MEMS technology (patterning and etching) or the like. In the second torsion bar 146, the processing in the longitudinal direction is performed by patterning, while the processing in the width direction is performed by etching. Therefore, while the shift of the length of the second torsion bar 146 is unlikely to occur, the shift of the width of the second torsion bar 146 may occur due to a manufacturing error or the like. Since the processing in the thickness direction of the second torsion bar 146 is performed by etching using the intermediate layer 53 as an etching stop layer, the thickness of the second torsion bar 146 hardly deviates.

As shown in FIG. 5, when the width of the second torsion bar 146 is narrowed as in the embodiment and the comparative example, the mirror surface 11a (movable mirror 11) is moved when the movable mirror 11 moves in the Z-axis direction. Tilt from the target attitude. In the embodiment and the comparative example, the target posture is a posture in which the mirror surface 11 a is perpendicular to the Z-axis direction.

As shown in FIG. 5, in the example, the inclination from the target posture of the mirror surface 11a was smaller than in the comparative example. As described above, by making the torsion spring constants of the first torsion bars 145 and 155 larger than the torsion spring constants of the second torsion bars 146 and 156, it is possible to suppress the inclination from the target posture of the mirror surface 11a. This is because, in the example, although the rate of change (the ratio of the amount of deformation to the original length) of the second torsion bar 146 is larger than the rate of change in the comparative example, compared to the comparative example. This is also apparent from the fact that the inclination of the mirror surface 11a from the target posture is small.

As described above, in the optical device 10, the torsion spring constant of the first torsion bar 145 connected between the lever 141 and the movable mirror 11 is the second torsion connected between the lever 141 and the base 12. It is larger than the torsion spring constant of the bar 146. As a result, even when a displacement occurs in at least one of the first torsion bar 145 and the second torsion bar 146 due to a manufacturing error or the like, the movable mirror 11 is moved from the target posture when the movable mirror 11 moves in the Z-axis direction. It is possible to suppress tilting. Further, the torsion spring constant of the first torsion bar 155 connected between the lever 151 and the movable mirror 11 is larger than the torsion spring constant of the second torsion bar 156 connected between the lever 151 and the base 12 . As a result, even when a displacement occurs in at least one of the first torsion bar 155 and the second torsion bar 156 due to a manufacturing error or the like, the movable mirror 11 is moved from the target posture when the movable mirror 11 moves in the Z-axis direction. It is possible to suppress tilting. Therefore, according to the optical device 10, it is possible to suppress a decrease in optical characteristics caused by the variation in the shapes of the first torsion bars 145 and 155 and the second torsion bars 146 and 156. In the optical device 10, the movable mirror 11 is prevented from tilting from the target posture not only when the width of the second torsion bar 146 becomes narrow but also when the width of the second torsion bar 146 becomes wide. be able to. In addition, even when a deviation occurs in at least one of the length and the thickness of the second torsion bar 146, the movable mirror 11 can be prevented from tilting from the target posture. Similarly, not only when the shape of the second torsion bar 146 deviates, but also when the shape of at least one of the first torsion bars 145 and 155 and the second torsion bar 156 deviates, the movable mirror 11 Can be prevented from tilting from the target attitude.

Further, in the optical device 10, the width of the first torsion bars 145, 155 is wider than the width of the second torsion bars 146, 156 when viewed in the Z-axis direction. Thereby, the torsion spring constant of the first torsion bars 145 and 155 can be suitably made larger than the torsion spring constant of the second torsion bars 146 and 156.

Further, in the optical device 10, the base 12, the movable mirror 11, the first elastic support portion 14, and the second elastic support portion 15 are configured by the SOI substrate 50. Thereby, in the optical device 10 formed by the MEMS technology, it is possible to suppress the deterioration of the optical characteristics due to the variation in the shapes of the first torsion bars 145 and 155 and the second torsion bars 146 and 156.

Further, the optical device 10 is provided on the base 12 and provided on the fixed comb electrodes 161 and 163 having a plurality of fixed comb teeth 161 a and 163 a, and on the first elastic support portion 14 and the second elastic support portion 15. And a movable comb electrode 162, 164 having a plurality of movable comb teeth 162a, 164a alternately arranged. Thus, the actuator unit 16 for moving the movable mirror 11 can be simplified and the power consumption can be reduced.

The optical device 10 also includes a first elastic support 14 and a second elastic support 15. Thereby, the movement of the movable mirror 11 can be stabilized as compared with, for example, the case where only one elastic support portion is provided. In addition, the total number of torsion bars can be reduced, for example, as compared to the case where three or more elastic supports are provided. As a result, the spring constant of each torsion bar can be secured, and the influence of variations in the shape of the torsion bar can be reduced.

As mentioned above, although one embodiment of this indication was described, this indication is not limited to the above-mentioned embodiment. The material and shape of each configuration are not limited to the above-described materials and shapes, and various materials and shapes can be adopted.

In the above embodiment, the width of the first torsion bar 145 is equal to the width of the second torsion bar 146, and the length of the first torsion bar 145 is shorter than the length of the second torsion bar 146. The torsion spring constant of 145 may be larger than the torsion spring constant of the second torsion bar 146. Similarly, the width of the first torsion bar 155 is equal to the width of the second torsion bar 156, and the length of the first torsion bar 155 is shorter than the length of the second torsion bar 156. The torsion spring constant may be larger than the torsion spring constant of the second torsion bar 156.

Also in this case, it is possible to suppress the deterioration of the optical characteristics caused by the variation in the shapes of the first torsion bars 145 and 155 and the second torsion bars 146 and 156 as in the above embodiment. That is, the torsion spring constant of the first torsion bar 145 may be larger than the torsion spring constant of the second torsion bar 146, and the length, width and thickness of each of the first torsion bar 145 and the second torsion bar 146 The relationship may be arbitrarily selected. The same applies to the first torsion bar 155 and the second torsion bar 156.

In the above embodiment, each of the main body 111 and the mirror surface 11a may have an arbitrary shape such as a rectangular shape or an octagonal shape when viewed from the Z-axis direction. The frame portion 112 may have an arbitrary ring shape such as a rectangular ring shape or an octagonal ring shape when viewed from the Z-axis direction. The frame portion 112 and the connecting portion 113 may be omitted. Each of the 1st beam part 115b, the 2nd beam part 112b, and the 3rd beam part 113b may be formed in arbitrary shapes, and may be omitted. In the said embodiment, although the 1st torsion support part was comprised by the plate-shaped 1st torsion bar 145, the structure of a 1st torsion support part is not restricted to this. The first torsion bar 145 may have any shape such as a bar shape. The first torsion support may be configured by connecting a plurality of (for example, two) torsion bars in series via the connection. The same applies to the first torsion bar 155 and the second torsion bars 146 and 156 (second torsion support portion). For example, the second torsion support may be configured by connecting a plurality of (for example, three) torsion bars in series via the connection.

In the above embodiment, the links 143 and 153 may be omitted. In this case, each of the first optical function unit 17 and the second optical function unit 18 may be configured by an opening formed in the SOI substrate 50. Each of the first optical function unit 17 and the second optical function unit 18 may have an arbitrary cross-sectional shape such as a circular shape or an octagonal shape. The movable comb electrodes 162 and 164 may be provided on the movable mirror 11, and may be disposed, for example, along the outer edge of the frame portion 112. The optical device 10 may include a movable portion provided with another optical function portion other than the mirror surface 11 a instead of the movable mirror 11. As another optical function part, a lens etc. are mentioned, for example. The actuator unit 16 is not limited to the electrostatic actuator, and may be, for example, a piezoelectric actuator, an electromagnetic actuator, or the like. The optical module 1 is not limited to that which comprises FTIR, but may comprise another optical system. The optical device 10 may be configured by something other than the SOI substrate 50, and may be configured by, for example, a substrate made of only silicon.

DESCRIPTION OF SYMBOLS 10 ... Optical device, 11 ... Movable mirror (movable part), 11a ... Mirror surface (optical function part), 12a ... Principal surface, 12 ... Base, 14 ... 1st elastic support part, 15 ... 2nd elastic support part, 141 , 151 ... lever, 145, 155 ... first torsion bar (first torsion support), 146, 156 ... second torsion bar (second torsion support), 161, 163 ... fixed comb electrode 161a, 163a ... Fixed comb teeth, 162, 164 ... movable comb electrodes, 162a, 164a ... movable combs.

Claims (6)

1. A base having a main surface,
   A movable part having an optical function part,
   An elastic support portion connected between the base and the movable portion and supporting the movable portion such that the movable portion can move along a first direction perpendicular to the main surface;
   The elastic support portion includes a lever, a first torsion support portion extending along a second direction perpendicular to the first direction, and connected between the lever and the movable portion, and the second direction. And a second torsion support connected between the lever and the base.
   The optical device, wherein a torsion spring constant of the first torsion support portion is larger than a torsion spring constant of the second torsion support portion.
2. The optical device according to claim 1, wherein a width of the first torsion support portion is wider than a width of the second torsion support portion when viewed from the first direction.
3. The optical device according to claim 1, wherein a length of the first torsion support portion is shorter than a length of the second torsion support portion when viewed from the first direction.
4. The optical device according to any one of claims 1 to 3, wherein the base, the movable portion, and the elastic support portion are formed of an SOI substrate.
5. A fixed comb electrode provided on the base and having a plurality of fixed comb teeth;
   5. The movable comb electrode according to claim 1, further comprising: a movable comb electrode provided on at least one of the movable portion and the elastic support portion and having a plurality of movable comb teeth alternately arranged with the plurality of fixed comb teeth. An optical device according to any one of the preceding claims.
6. The optical device according to any one of claims 1 to 5, comprising only one pair of elastic support portions.

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