Wavelength variable interference filter

Abstract

To provide a wavelength variable interference filter with which the impact resistance of a diaphragm part is high, and which excels in reliability.SOLUTION: The wavelength variable interference filter includes a first substrate having a first reflective film, and a second substrate having a second reflective film that faces the first reflective film. The second substrate comprises a diaphragm part including a toric groove enclosing a movable part where the second reflective film is located, and a toric second electrode enclosing the second reflective film. The first substrate has a first electrode facing the second electrode and changes a gap between the first reflective film and the second reflective film by applying a voltage between the first electrode and the second electrode. A multilayer film forming the second reflective film is formed by covering the diaphragm part, and the multiplayer film includes a conduction structure for establishing electrical continuity between the layers, the conductive structure including a conductive part located symmetrically about the center of the second reflective film.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a tunable interference filter. [Background technology]

[0002] A conventional tunable interference filter has a pair of opposing reflecting mirrors and an electrostatic actuator, and by varying the distance between the pair of reflecting mirrors, selects and emits light of a predetermined wavelength from the light to be measured. The reflecting mirrors used are multilayer mirrors made by stacking low-refractive index materials and high-refractive index materials. However, because the high-refractive index material is a conductive material, floating electrodes are formed within the multilayer film, and electric charges accumulate, which hinders the operation of the electrostatic actuator.

[0003] In view of this, for example, Patent Document 1 discloses that in order to prevent charge accumulation, electrical wiring is connected to the end face of the reflecting mirror to establish electrical continuity and allow charge to escape.

[0004] The distance between the pair of reflecting mirrors is adjusted by moving the reflecting mirror on the movable substrate, which is equipped with a diaphragm, toward or away from the reflecting mirror on the fixed substrate. This diaphragm is made up of a thin section formed by an annular groove that surrounds the movable section in which the reflecting mirror is located, but its thinness makes it a structurally weak section. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-212752 Summary of the Invention [Problem to be solved by the invention]

[0006] However, there is room for improvement in Patent Document 1. Specifically, Patent Document 1 does not contain any description or suggestion regarding improving the strength of the diaphragm portion. In other words, there was a demand for a tunable interference filter with a diaphragm that was highly impact resistant and highly reliable. [Means for solving the problem]

[0007] A tunable interference filter according to one aspect of the present application comprises a first substrate having a first reflective film and a second substrate having a second reflective film facing the first reflective film, wherein the second substrate has a diaphragm portion including an annular groove surrounding a movable portion on which the second reflective film is disposed, and a second annular electrode surrounding the second reflective film, the first substrate has a first electrode facing the second electrode, and a gap between the first reflective film and the second reflective film is changed by applying a voltage between the first electrode and the second electrode, a multilayer film forming the second reflective film is formed to cover the diaphragm portion, the multilayer film includes a conductive structure that ensures electrical conduction between the layers, and the conductive structure includes a conductive portion arranged symmetrically with respect to the center of the second reflective film. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a plan view of an optical device according to a first embodiment. [Figure 2] 1 is a cross-sectional view of an optical device. [Figure 3] FIG. 1 is a plan view of a tunable interference filter. [Figure 4] Cross-sectional view of a tunable interference filter. [Figure 5] Enlarged view of part b in Figure 4. [Figure 6] FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along the line cc in FIG. 6 . [Figure 8] FIG. 10 is a graph showing the amount of deformation of the diaphragm portion according to the arrangement of the multilayer film. [Figure 9] FIG. 10 is a perspective view showing a simulation result of the multilayer film of the present embodiment. [Figure 10] FIG. 10 is a perspective view showing a simulation result of a multilayer film of a comparative example. [Figure 11]FIG. 10 is a schematic configuration diagram of a spectroscopic camera according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiment 1 ***Optical Device Configuration*** 1 and 2 are plan and cross-sectional views of an optical device, respectively. The configurations of an optical device 200 and a tunable interference filter 100 according to this embodiment will be described with reference to FIGS. 1 and 2. Each figure illustrates three mutually orthogonal axes: an X axis, a Y axis, and a Z axis. In this embodiment, the direction in which the long side of the rectangular optical device 200 extends is the X-positive direction. The direction along the X-axis is referred to as the "X-direction," the direction along the Y-axis as the "Y-direction," and the direction along the Z-axis as the "Z-direction." For example, the Y-direction refers to both the positive and negative Y-directions. The positive Z-direction is also referred to as "up," and the negative Z-direction as "down." Furthermore, in the following figures, dimensions and scales may differ from the actual dimensions to facilitate understanding.

[0010] The optical device 200 is an apparatus that extracts and emits light of a predetermined target wavelength from incident light to be inspected, and is an optical filter device that includes a housing 60 and a tunable interference filter 100 housed inside the housing 60. The optical device 200 can be suitably applied to, for example, optical modules such as colorimetric sensors, and electronic devices such as colorimetric devices and gas analyzers.

[0011] As shown in FIG. 2, the housing 60 includes a base 61 and a lid 65, and houses the tunable interference filter 100 inside. The base 61 is a ceramic substrate formed by stacking and firing thin ceramic layers. As shown in Figures 1 and 2, the base 61 has a sidewall 62 that is frame-shaped in a plan view of the filter on the surface facing the lid 65. The base 61 also has a recess 63 that is surrounded by the sidewall 62. The lid 65 is bonded to a lid bonding surface 62a, which is the surface of the sidewall 62 facing the lid 65.

[0012] The tunable interference filter 100 is configured by stacking a first substrate 11 and a second substrate 12. The first substrate 11 is also called a fixed substrate, and the second substrate 12 is also called a movable substrate. The tunable interference filter 100 has a rectangular shape that is slightly smaller than the housing 60 in plan view, and is provided with protruding portions 13 and 14 on its short sides. As shown in Fig. 2 , the protruding portion 13 is a protruding portion of the second substrate 12 that protrudes from the short side of the first substrate 11 in the negative X direction. The protruding portion 14 is a protruding portion of the first substrate 11 that protrudes from the short side of the second substrate 12 in the positive X direction. The tunable interference filter 100 is fixed to a side wall 62b on the X positive side of the recess 63 of the base 61 by a fixing member 64. More specifically, the end of the protruding portion 14 of the tunable interference filter 100 is adhesively fixed to the side wall 62b of the recess 63 by the fixing member 64. At this time, the second substrate 12 is spaced apart from the bottom 63b of the recess 63.

[0013] A light passing hole 68 is provided in the bottom 63b of the recess 63 to pass light emitted from the wavelength tunable interference filter 100. A light-transmitting member 66, such as a glass plate, which serves as a lid, is bonded to the light passing hole 68 with a bonding agent such as low-melting-point glass. Furthermore, a sealing hole 67 is provided in the bottom 63b of the recess 63, penetrating to the outside of the housing 60. This sealing hole 67 is a hole portion for, for example, sucking out gas from inside the housing 60 or replacing it with an inert gas when manufacturing the optical device 200, and can be metal-sealed with a sealing member 67b (FIG. 2) made of, for example, Au while the inside of the housing 60 is in a vacuum or reduced pressure state.

[0014] The lid 65 has a rectangular outer shape in plan view similar to that of the base 61, and is made of light-transmitting glass. After the tunable interference filter 100 is mounted on the base 61, the lid 65 is bonded to the lid bonding surface 62a. 2 shows an example in which the tunable interference filter 100 is fixed to the side wall 62b on the positive X side of the recess 63 of the base 61 by the fixing member 64, but the tunable interference filter 100 may be fixed in another manner. For example, in Fig. 2, the fixing member 64 adhesively fixes the end of the protruding portion 14 of the first substrate 11 to the side wall 62b of the recess 63, but in another manner, the fixing member 64 may adhesively fix the surface on the negative Z side of the second substrate 12 in Fig. 2 to a position on the bottom 63b of the recess 63 that avoids the light transmitting hole 68.

[0015] ***Configuration of tunable interference filter*** Fig. 3 is a plan view showing a schematic configuration of a wavelength tunable interference filter, and Fig. 4 is a cross-sectional view of a main part of the wavelength tunable interference filter. The tunable interference filter 100 is configured by stacking a first substrate 11 and a second substrate 12. The first substrate 11 and the second substrate 12 are each made of, for example, various types of glass or quartz, and in this embodiment, are made of quartz glass.

[0016] 4, the first substrate 11 and the second substrate 12 are integrally formed by being bonded together by a bonding film 53. More specifically, a first bonding portion 53a of the first substrate 11 and a second bonding portion 53b of the second substrate 12 are bonded together by the bonding film 53 made of, for example, a plasma polymerized film containing siloxane as a main component. The surface on the positive Z side of first substrate 11 is called the front surface, and the surface opposite the front surface is called the inner surface. The surface on the positive Z side of second substrate 12 is called the opposing surface, and the surface on the negative Z side of second substrate 12 is called the back surface. The inner surface of first substrate 11 and the opposing surface of second substrate 12 face each other.

[0017] A first reflective film 21 is provided approximately at the center of the inner surface of the first substrate 11. A second reflective film 22 is provided on the opposing surface of the second substrate 12 at a position overlapping the first reflective film 21. The first reflective film 21 and the second reflective film 22 are disposed opposite each other with a gap G therebetween. In other words, the first reflective film 21 and the second reflective film 22 are formed to face each other with a gap G therebetween of a predetermined distance.

[0018] The first substrate 11 is provided with a circular electrode placement groove 81 surrounding a cylindrical installation base 80 on which the first reflective film 21 is disposed. The electrode placement groove 81 is provided with a circular first electrode 56a. The second substrate 12 is provided with a second electrode 56b that pairs with the first electrode 56a, and the first electrode 56a and the second electrode 56b form an electrostatic actuator 56. The electrostatic actuator 56 adjusts the gap G between the first reflective film 21 and the second reflective film 22 by an electrostatic attractive force that corresponds to a drive voltage applied between the first electrode 56a and the second electrode 56b. The first substrate 11 is formed to be thicker than the second substrate 12, and has sufficient rigidity to prevent bending even when an electrostatic attractive force is generated by the electrostatic actuator 56.

[0019] An annular groove 90 is formed on the back surface of the second substrate 12 so as to surround the second reflective film 22. The annular portion whose thickness is reduced by the groove 90 is called a support portion 91. The portion inside the support portion 91 that includes the second reflective film 22 is called a movable portion 92. The support portion 91 is an elastic and deformable diaphragm, and the electrostatic attractive force of the electrostatic actuator 56 allows the movable portion 92 to move forward and backward relative to the first substrate 11. At this time, since the movable portion 92 is thicker and more rigid than the support portion 91, even if the support portion 91 is pulled toward the first substrate 11 by the electrostatic attractive force, the shape of the movable portion 92 does not change, and therefore the second reflective film 22 does not bend, and it is possible to always maintain the first reflective film 21 and the second reflective film 22 in a parallel state.

[0020] In other words, the tunable interference filter 100 comprises a first substrate 11 having a first reflective film 21 and a second substrate 12 having a second reflective film 22 facing the first reflective film 21, the second substrate 12 having a diaphragm portion including an annular groove 90 surrounding a movable portion 92 on which the second reflective film 22 is arranged, and a second annular electrode 56b surrounding the second reflective film 22, the first substrate 11 having a first electrode 56a facing the second electrode 56b, and the gap G between the first reflective film 21 and the second reflective film 22 is changed by applying a voltage between the first electrode 56a and the second electrode 56b.

[0021] As shown in FIG. 3, the protruding portion 13 is provided with terminals 8a and 8b. Terminal 8a is a GND terminal, and is connected to wiring 1. Wiring 1 is electrically connected to second electrode 56b and second reflective film 22. In other words, second reflective film 22 of second substrate 12 and second electrode 56b are at the same potential. A wiring 2 is connected to the terminal 8b. The wiring 2 is electrically connected to the first electrode 56a. More specifically, the wiring 2 is electrically connected to the wiring 4 on the first substrate 11 side by a conductive bump 85 from the second substrate 12 side, and the wiring 4 is electrically connected to the first electrode 56a. The protruding portion 13 is also provided with terminals and the like for connecting to wiring for detecting the capacitance between the first reflective film 21 and the second reflective film 22, but these are not shown in the figure.

[0022] Return to Figure 1. 1, a plurality of base terminals 19 corresponding to the plurality of terminals 8 of the protruding portion 13 are provided on the bottom 63b of the recess 63 of the base 61. As shown in FIG. 2, the terminals 8 and the corresponding base terminals 19 are electrically connected by bonding wires 82. The base terminals 19 are electrically connected to corresponding external terminals 83 formed on the outside of the base 61 by wiring (not shown). The external terminals 83 also serve as mounting terminals for the optical device 200.

[0023] ***Multilayer film conductive structure*** Fig. 5 is an enlarged view of part b in Fig. 4. Fig. 6 is a plan view showing the planar aspect of the multilayer film. Fig. 7 is a cross-sectional view of the cc cross section in Fig. 6. As shown in FIG. 5, the second reflective film 22 is composed of a multilayer film 15 in which multiple high-refractive-index layers and multiple low-refractive-index layers are stacked. Specifically, the multilayer film 15 has a three-layer structure in which a first layer 5a made of a high-refractive-index material, a second layer 5b made of a low-refractive-index material, and a third layer 5c made of a high-refractive-index material are stacked. In a preferred example, the first layer 5a and the third layer 5c use Si as the high-refractive-index material. Si is also a conductive material. The second layer 5b uses SiO2 as the low-refractive-index material. The multilayer film 15 is not limited to a three-layer structure, but may be any multilayer film in which high refractive index layers and low refractive index layers are alternately stacked.

[0024] Here, the end faces of the multilayer film 15 constituting the second reflective film 22 are covered with the uppermost third layer 5c, thereby ensuring electrical continuity among the three layers. More specifically, the end faces of the first layer 5a and the second layer 5b are covered with the third layer 5c, thereby ensuring electrical continuity among the three layers. This conductive structure is referred to as a conductive structure 33. In other words, the multilayer film 15 includes the conductive structure 33 that ensures electrical continuity among the multiple layers. The conductive material is one layer of the optical film constituting the multilayer film 15. The end faces of the multilayer film 15 are covered with the third layer 5c, which serves as a conductive material for ensuring electrical continuity. However, the end faces are not limited to being covered with the third layer 5c, as long as electrical continuity is achieved by any one of the conductive layers. Furthermore, on the negative X side of the conductive structure 33, a wiring 1 using a multilayer film 15 as wiring is provided, and a light-transmitting conductive layer 17 is formed on the wiring 1. The light-transmitting conductive layer 17 is an ITO layer, and a second electrode 56b is formed on the light-transmitting conductive layer 17. This electrically connects the wiring 1 and the second electrode 56b.

[0025] As shown in Fig. 6, the multilayer film 15 of this embodiment is also widely formed around the second reflective film 22. More specifically, the multilayer film 15 is concentrically larger than the second reflective film 22 and is slightly larger than the diaphragm portion including the annular groove 90 surrounding the movable portion 92. In other words, the multilayer film 15 that forms the second reflective film 22 is formed to cover the diaphragm portion. The multilayer film 15 has the same GND potential as the second reflective film 22. A bonding film 53 is provided on the outside of the multilayer film 15. The second reflective film 22 is a portion of the multilayer film 15 partitioned by an annular conductive structure 33, and this annular pattern is called an annular pattern 9. The annular pattern 9 is a conductive portion, which can prevent charge accumulation in the multilayer film in the second reflective film 22.

[0026] A plurality of linear wiring patterns 7a to 7h extend radially from the circular pattern 9. The wiring patterns 7a to 7h are conductive parts. The wiring pattern 7a extends from the center o of the second reflective film 22 in the positive X direction at an angle of 0° to a portion beyond the groove 90. The wiring pattern 7b extends from the center o in the direction at an angle of 45° to a portion beyond the groove 90. The wiring pattern 7c extends from the center o in the positive Y direction at an angle of 90° to a portion beyond the groove 90. The wiring pattern 7d extends from the center o in the direction at an angle of 135° to a portion beyond the groove 90. The wiring pattern 7e extends from the center o in the negative X direction at an angle of 180° to a portion beyond the groove 90. The wiring pattern 7f extends from the center o in the direction at an angle of 225° to a portion beyond the groove 90.

[0027] The wiring pattern 7g extends from the center o in the negative Y direction at an angle of 270° to a portion beyond the groove 90. The wiring pattern 7h extends from the center o in the direction at an angle of 315° to a portion beyond the groove 90. That is, the wiring patterns 7a to 7d and the wiring patterns 7e to 7h are in a point-symmetric relationship with respect to the center o of the second reflective film 22. In other words, the conductive structure 33 includes the wiring patterns 7a to 7d and the wiring patterns 7e to 7h as conductive parts that are arranged symmetrically with respect to the center o of the second reflective film 22. The conductive parts include the wiring patterns 7a to 7h that extend radially from the movable part 92 to the diaphragm part. The conductive part includes an annular pattern 9 that is circular and surrounds the second reflective film 22, and the radial wiring patterns 7a to 7h are drawn out from the annular pattern 9. The number of wiring patterns is not limited to eight, and may be any plural number.

[0028] As shown in Fig. 7, the cross section of the wiring pattern 7a has a conductive structure 33. More specifically, the end faces of the first layer 5a and the second layer 5b are covered with the third layer 5c, thereby ensuring electrical continuity among the three layers. Note that the translucent conductive layer 17 (Fig. 5) is not shown in Fig. 7.

[0029] 6, the area of ​​the multilayer film 15 outside the annular pattern 9 is significantly larger than the area of ​​the second reflective film 22. Because the multilayer film 15 has high resistivity, there was a concern that the charge would not be able to escape if the distance from the conductive structure 33 was too great. In contrast, according to this embodiment, the multilayer film 15 is electrically divided into eight trapezoidal regions by the wiring patterns 7a to 7h, thereby making it possible to prevent charge accumulation in the multilayer film 15 in each trapezoidal region. Furthermore, the three-layered multilayer film 15 covers the diaphragm portion including the annular groove 90, thereby lining and reinforcing the thin support portion 91. This increases the strength of the diaphragm portion, which is thin and structurally weak.

[0030] Return to Figure 4. As shown in Figure 4, the first reflective film 21 of the first substrate 11 is also composed of a multilayer film 15 with a three-layer structure. The end faces of the multilayer film 15 constituting the first reflective film 21 are covered with the uppermost third layer 5c, thereby ensuring electrical continuity among the three layers. More specifically, the end faces of the first layer 5a and the second layer 5b are covered with the third layer 5c to form a conductive structure 33, ensuring electrical continuity among the three layers. This prevents electric charges from accumulating within the multilayer film 15. The functional film including the multilayer film 15, the transparent conductive layer 17, and the second electrode 56b can be formed by depositing the film using a known film-forming method such as sputtering, vapor deposition, or CVD, and then patterning the film using photolithography.

[0031] ***Diaphragm strength simulation results*** Fig. 8 is a graph showing the amount of deformation of the diaphragm portion according to the arrangement of the multilayer film, with the horizontal axis representing the distance (mm) from the center o of the second reflective film 22 and the vertical axis representing the amount of deformation (nm) of the diaphragm portion. Fig. 9 is a perspective view showing the results of a simulation using the multilayer film of this embodiment. Fig. 10 is a perspective view showing the results of a simulation using a multilayer film of a comparative example, corresponding to Fig. 9.

[0032] As shown in FIG. 9, the multilayer film 15 of this embodiment is provided so as to completely cover the diaphragm portion as described above, and its outer periphery is positioned outside the annular groove 90. 10, the outer periphery of the multilayer film 25 of the modified example is located in the middle of the annular groove 90. In other words, the outer periphery of the multilayer film 25 is located in the middle of the support portion 91.

[0033] Graph 71 in Figure 8 is the simulation result when the diaphragm portion is in a stationary state, and is a calculation of a state in which only film stresses including the multilayer film 15 including the second reflective film 22 and the second electrode 56b act on the stationary, flat second substrate 12. As shown in graph 71, in the multilayer film 15 of this embodiment, the graph is substantially flat, no stress concentration is observed, and it is understood that the deformation of the diaphragm portion is slight, with a range of approximately 230 nm. In contrast, in the multilayer film 25 of the modified example shown in graph 72, stress is concentrated in the middle of the support portion 91 where the outer periphery of the multilayer film 25 is located, and it can be seen that the amount of deformation reaches approximately 1000 nm. Considering that the wavelength tunable interference filter 100 requires that the gap G between the first reflective film 21 and the second reflective film 22 be controlled to within the order of several nanometers, this amount of deformation is too large. As described above, the multilayer film 15 of this embodiment can reinforce the diaphragm portion without generating stress concentration areas, thereby improving impact resistance, and the conductive structure 33 including the wiring patterns 7a to 7h can prevent charge accumulation within the multilayer film 15.

[0034] As described above, the wavelength tunable interference filter 100 of this embodiment can provide the following effects. The wavelength tunable interference filter 100 includes a first substrate 11 having a first reflective film 21 and a second substrate 12 having a second reflective film 22 facing the first reflective film 21. The second substrate 12 has a diaphragm portion including an annular groove 90 surrounding a movable portion 92 on which the second reflective film 22 is disposed, and an annular second electrode 56b surrounding the second reflective film 22. The first substrate 11 has a first electrode 56a facing the second electrode 56b, and By applying a voltage between the first electrode 56b and the second electrode 56b, the gap G between the first reflective film 21 and the second reflective film 22 is changed, and the multilayer film 15 that forms the second reflective film 22 is formed to cover the diaphragm portion, and the multilayer film 15 includes a conductive structure 33 that ensures electrical conduction between the layers, and the conductive structure 33 includes wiring patterns 7a to 7d and wiring patterns 7e to 7h as conductive portions that are arranged symmetrically with respect to the center o of the second reflective film 22.

[0035] This increases the strength of the thin and structurally weak diaphragm portion due to the multilayer film 15 backing the thin support portion 91. Furthermore, the conductive portion including the wiring patterns 7a to 7h arranged symmetrically about the center o of the second reflective film 22 prevents electric charges from accumulating in the multilayer film 15. This improves the driving reliability of the electrostatic actuator 56. Therefore, it is possible to provide a tunable interference filter 100 in which the diaphragm portion has high impact resistance and excellent reliability.

[0036] The conductive portion also includes wiring patterns 7a-7h that extend radially from the movable portion 92 to the diaphragm portion. By electrically dividing the multilayer film 15, which has a large area and high resistivity, into eight trapezoidal regions by the wiring patterns 7a-7h, the charge in the multilayer film 15 in each trapezoidal region can be efficiently released.

[0037] The second reflective film 22 and the second electrode 56b of the second substrate 12 are at the same potential. This makes the second substrate 12 electrically stable.

[0038] Furthermore, the end faces of the multilayer film 15 are covered with a third layer 5c, which is a conductive material for electrical conduction, thereby preventing charges from accumulating in the multilayer film 15.

[0039] The conductive material is one layer of the optical film that constitutes the multilayer film 15. This allows the conductive optical film that constitutes the multilayer film 15 to be used as a conductive material.

[0040] The conductive portion also includes a circular ring pattern 9 that surrounds the second reflective film 22, and the radial wiring patterns 7a to 7h are drawn out from the circular ring pattern 9. This makes it possible to prevent charges from accumulating in the multilayer film 15.

[0041] Embodiment 2 ***Spectroscopic camera*** FIG. 11 is a schematic diagram of the spectroscopic camera according to the second embodiment. 11, a spectroscopic camera 300 of this embodiment includes an optical device 200 equipped with the tunable interference filter 100 of the above embodiment. Hereinafter, the same parts as those in the above embodiment will be assigned the same numbers, and duplicated explanations will be omitted.

[0042] The spectroscopic camera 300 is an infrared camera equipped with an optical device 200 equipped with a tunable interference filter 100 , and includes a camera body 310 , an imaging lens unit 320 , and an imaging section 330 . The camera body 310 is the part that is held and operated by the user. The imaging lens unit 320 is provided in the camera body 310, and guides incident image light to the imaging section 330. As shown in Fig. 11, the imaging lens unit 320 is configured to include an objective lens 321, an imaging lens 322, and an optical device 200 provided between these lenses.

[0043] The imaging section 330 is configured with a light receiving element, and captures an image of the image light guided by the imaging lens unit 320 . According to the spectroscopic camera 300, the optical device 200 having excellent reliability transmits light of a wavelength to be imaged, so that a spectroscopic image of light of a desired wavelength can be captured. [Explanation of symbols]

[0044] 1...wiring, 2...wiring, 4...wiring, 5a...first layer, 5b...second layer, 5c...third layer, 7a to 7h...wiring pattern, 8...terminal, 8a...terminal, 8b...terminal, 9...annular pattern, 11...first substrate, 12...second substrate, 13...extending portion, 14...extending portion, 15...multilayer film, 17...transparent conductive layer, 19...base terminal, 21...first reflective film, 22...second reflective film, 25...multilayer film, 33...conductive structure, 53...bonding film, 53a...first bonding portion, 53b...second bonding portion, 56...electrostatic actuator, 56a...first electrode, 56b...second electrode, 60...casing, 61...base, 62...side wall portion, 62 a...lid bonding surface, 62b...side wall, 63...recess, 63b...bottom, 64...fixing member, 65...lid, 66...light-transmitting member, 67...sealing hole, 67b...sealing member, 68...light passage hole, 71...graph, 72...graph, 80...mounting base, 81...electrode placement groove, 82...bonding wire, 83...external terminal, 85...conductive bump, 90...groove, 91...supporting portion, 92...movable portion, 100...tunable interference filter, 200...optical device, 300...spectroscopic camera, 310...camera body, 320...imaging lens unit, 321...objective lens, 322...imaging lens, 330...imaging unit.

Claims

1. a first substrate having a first reflective film; a second substrate having a second reflective film facing the first reflective film, the second substrate has a diaphragm portion including an annular groove surrounding a movable portion on which the second reflective film is disposed, and a second annular electrode surrounding the second reflective film; the first substrate has a first electrode facing the second electrode; a tunable interference filter that changes a gap between the first reflective film and the second reflective film by applying a voltage between the first electrode and the second electrode, a multilayer film forming the second reflective film is formed to cover the diaphragm portion, the multilayer film includes a conductive structure for achieving electrical conduction between the layers, the conductive structure includes conductive portions arranged symmetrically with respect to the center of the second reflective film; Tunable interference filters.

2. the conductive portion includes a wiring pattern that extends radially from the movable portion to the diaphragm portion; The tunable interference filter according to claim 1 .

3. the second reflective film and the second electrode of the second substrate are at the same potential; The tunable interference filter according to claim 1 .

4. The end faces of the multilayer film are covered with a conductive material for electrical conduction. The tunable interference filter according to claim 1 .

5. the conductive material is one layer of an optical film constituting the multilayer film; The tunable interference filter according to claim 4 .

6. the conductive portion includes an annular pattern surrounding the second reflective film, The radial wiring pattern is drawn out from the circular pattern. The tunable interference filter according to claim 2 .

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