Wavelength variable interference filter

Abstract

The invention provides a wavelength variable interference filter which has high impact resistance of a diaphragm part and excellent reliability. A variable wavelength interference filter is provided with: a first substrate having a first reflective film; and a second substrate having a second reflective film facing the first reflective film, the second substrate having a diaphragm portion and a second electrode, the diaphragm portion including an annular trench surrounding the movable portion on which the second reflective film is disposed, the second electrode being an annular electrode surrounding the second reflective film, the first substrate having a first electrode, and the second substrate having a second reflective film facing the first electrode. The first electrode and the second electrode face each other, and the 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, thereby forming a multilayer film that forms the second reflective film so as to cover the diaphragm portion. The multilayer film includes a conduction structure for obtaining electrical conduction between the plurality of layers, the conduction structure including a conduction portion, and the conduction portion is disposed symmetrically with respect to the center of the second reflective film.

Description

Technical Field

[0001] The present invention relates to a wavelength-variable interference filter. Background Art

[0002] Conventionally, a variable-wavelength interference filter has been known. This filter comprises a pair of opposing mirrors and an electrostatic actuator. By varying the distance between the mirrors, the filter selects and emits light of a predetermined wavelength from the light being measured. While the mirrors can be made from a multilayer film composed of a low-refractive-index material and a high-refractive-index material, the high-refractive-index material is conductive, creating floating electrodes within the multilayer film. This leads to charge accumulation and can hinder the electrostatic actuator's operation.

[0003] In view of this, for example, Patent Document 1 discloses a technique for preventing charge accumulation by connecting an electrical wiring to an end face of a reflective mirror to achieve electrical conduction and thereby release the charge.

[0004] Furthermore, the distance between the pair of reflectors is adjusted by moving the reflector on the movable substrate side, which includes a diaphragm, forward and backward relative to the reflector on the fixed substrate side. This diaphragm is composed of a thin-walled portion formed by an annular groove surrounding the movable portion where the reflectors are located. However, this portion is relatively thin and structurally weak.

[0005] However, there is room for improvement in Patent Document 1. Specifically, Patent Document 1 does not contain any description or suggestion regarding improvement in the strength of the diaphragm portion.

[0006] That is, there is a demand for a wavelength-variable interference filter having a diaphragm portion with high impact resistance and excellent reliability.

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-212752 Summary of the Invention

[0008] A variable wavelength interference filter according to one embodiment of the present application includes: a first substrate having a first reflective film; and a second substrate having a second reflective film opposing the first reflective film. The second substrate includes a diaphragm portion and a second electrode, the diaphragm portion including an annular groove surrounding a movable portion on which the second reflective film is disposed. The second electrode is an annular electrode surrounding the second reflective film. The first substrate includes a first electrode, the first electrode and the second electrode facing each other, and a gap between the first and second reflective films is changed by applying a voltage between the first and second electrodes. In the variable wavelength interference filter, a multilayer film forming the second reflective film is formed so as to cover the diaphragm portion. The multilayer film includes a conductive structure for achieving electrical continuity between the multiple layers. The conductive structure includes conductive portions, and the conductive portions are symmetrically arranged about the center of the second reflective film. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a plan view of the optical device involved in embodiment 1.

[0010] Figure 2 A cross-sectional view of an optical device.

[0011] Figure 3 A plan view of a variable wavelength interference filter.

[0012] Figure 4 A cross-sectional view of a variable wavelength interference filter.

[0013] Figure 5 for Figure 4 Enlarged view of part b.

[0014] Figure 6 A plan view showing the planar morphology of a multilayer film.

[0015] Figure 7 for Figure 6 Cross-sectional view of the cc section.

[0016] Figure 8 Graph showing the amount of deformation of the diaphragm portion corresponding to the arrangement of the multilayer film.

[0017] Figure 9 It is a perspective view showing simulation results obtained using the multilayer film of this embodiment.

[0018] Figure 10 It is a perspective view showing the simulation results obtained using the multilayer film of the comparative example.

[0019] Figure 11 This is a schematic structural diagram of a spectroscopic camera according to the second embodiment. DETAILED DESCRIPTION

[0020] Implementation Method 1

[0021] Structure of optical equipment

[0022] Figure 1 A plan view of the optical device. Figure 2 A cross-sectional view of an optical device.

[0023] The optical device 200 and the variable wavelength interference filter 100 according to this embodiment are configured using Figure 1 、 Figure 2 to illustrate. In each of the drawings, an X-axis, a Y-axis, and a Z-axis are shown as three axes that are orthogonal to each other. In this embodiment, the extension direction of the long side of the rectangular optical device 200 is set to the positive X direction. The direction along the X-axis is referred to as the "X direction", the direction along the Y-axis is referred to as the "Y direction", and the direction along the Z-axis is referred to as the "Z direction". For example, the Y direction refers to the direction of both the positive side of the Y direction and the negative side of the Y direction. In addition, the positive side of the Z direction is also referred to as "up", and the negative side of the Z direction is also referred to as "down". In addition, in the following drawings, in order to make the description easy to understand, it is sometimes recorded in a size or scale that is different from the actual size or scale.

[0024] Optical device 200 is a device that extracts light of a predetermined target wavelength from incident inspection target light and emits it. It is an optical filter device comprising a housing 60 and a variable wavelength interference filter 100 housed within housing 60. Optical device 200 is suitable for use in, for example, optical modules such as colorimetric sensors, and electronic devices such as colorimetric devices and gas analyzers.

[0025] like Figure 2 As shown, the housing 60 includes a base 61 and a cover 65 , and houses the variable wavelength interference filter 100 therein.

[0026] The base 61 is a ceramic substrate formed by stacking and firing ceramic thin layers. Figure 1 as well as Figure 2 As shown, the base 61 has a side wall portion 62 that forms a frame shape when the filter is viewed in plan view, on the surface facing the cover portion 65. Furthermore, the base 61 has a recess 63 formed by being surrounded by the side wall portion 62. Furthermore, the cover portion 65 is joined to a cover-joining surface 62a of the side wall portion 62 that faces the cover portion 65.

[0027] The wavelength variable interference filter 100 has a structure in which a first substrate 11 and a second substrate 12 are superimposed on each other. The first substrate 11 is also called a fixed substrate, and the second substrate 12 is also called a movable substrate.

[0028] In plan view, the variable wavelength interference filter 100 is in the shape of a rectangle that is slightly smaller than the frame 60 and includes an extension 13 and an extension 14 on its short sides. Figure 2 As shown, the extension portion 13 is a protrusion that extends the second substrate 12 from the short side of the first substrate 11 in the negative X direction. The extension portion 14 is a protrusion that extends the first substrate 11 from the short side of the second substrate 12 in the positive X direction.

[0029] The variable wavelength interference filter 100 is fixed to the X-positive side wall 62b of the recess 63 of the base 61 by the fixing member 64. Specifically, the end of the extension portion 14 of the variable wavelength interference filter 100 is bonded and fixed to the side wall 62b of the recess 63 by the fixing member 64. At this time, the second substrate 12 is separated from the bottom 63b of the recess 63.

[0030] A light passage hole 68 for passing light emitted from the variable wavelength interference filter 100 is provided on the bottom 63b of the recess 63. A light-transmitting member 66, such as a glass plate, serving as a cover is bonded to the light passage hole 68 using a bonding agent such as low-melting-point glass.

[0031] In addition, a sealing hole 67 is provided on the bottom 63b of the recessed portion 63, which penetrates the outside of the frame 60. The sealing hole 67 is a hole portion used, for example, to suck out the gas inside the frame 60 or replace it with an inert gas when manufacturing the optical device 200. When the inside of the frame 60 is in a vacuum or decompressed state, the sealing hole 67 can be filled with a sealing member 67b (e.g., Au) such as Au. Figure 2 ) for metal sealing.

[0032] The cover 65 has the same rectangular outer shape as the base 61 in plan view and is formed of light-transmitting glass. After the variable wavelength interference filter 100 is mounted on the base 61, the cover 65 is bonded to the cover bonding surface 62a.

[0033] In addition, Figure 2 In FIG. 1 , an example is shown in which the wavelength variable interference filter 100 is fixed to the side wall 62 b on the X positive side of the recess 63 of the base 61 using the fixing member 64. However, the wavelength variable interference filter 100 may be fixed in another manner. For example, Figure 2 The fixing member 64 is bonded and fixed to the end of the extension portion 14 of the first substrate 11 and the side wall 62b of the recess 63. However, in another embodiment, the fixing member 64 may be bonded to the end of the extension portion 14 of the first substrate 11 and the side wall 62b of the recess 63. Figure 2 The Z negative side surface of the second substrate 12 and the bottom 63 b of the recess 63 are bonded and fixed at a position avoiding the light passage hole 68 .

[0034] Structure of the wavelength-tunable interference filter

[0035] Figure 3 It is a plan view showing the schematic structure of a variable wavelength interference filter. Figure 4 A cross-sectional view of the main parts of a variable wavelength interference filter.

[0036] The variable wavelength interference filter 100 has a structure in which a first substrate 11 and a second substrate 12 are superimposed. The first substrate 11 and the second substrate 12 are each formed of, for example, various types of glass or crystal, and in this embodiment, are made of quartz glass.

[0037] like Figure 4 As shown, the first substrate 11 and the second substrate 12 are integrally formed by being bonded together using a bonding film 53. 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, which is composed of, for example, a plasma polymerized film containing siloxane as a main component.

[0038] The surface on the positive Z side of the first substrate 11 is called the front surface, and the surface opposite to the front surface is called the inner surface. The surface on the positive Z side of the second substrate 12 is called the opposing surface, and the surface on the negative Z side of the second substrate 12 is called the back surface. The inner surface of the first substrate 11 and the opposing surface of the second substrate 12 face each other.

[0039] A first reflective film 21 is provided substantially 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 facing each other with a gap G therebetween.

[0040] In other words, the first reflective film 21 and the second reflective film 22 are formed to face each other with a gap G having a predetermined distance therebetween.

[0041] The first substrate 11 is provided with an annular electrode placement groove 81 so as to surround a cylindrical placement base portion 80 on which the first reflective film 21 is placed. In the electrode placement groove 81, an annular first electrode 56a is placed.

[0042] A second electrode 56b is provided on the second substrate 12, forming a pair with the first electrode 56a. The first and second electrodes 56a and 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 generating an electrostatic attraction corresponding to the drive voltage applied between the first and second electrodes 56a and 56b. The first substrate 11 is thicker than the second substrate 12 and has sufficient rigidity to resist deflection even under the electrostatic attraction generated by the electrostatic actuator 56.

[0043] An annular groove 90 is formed on the back surface of the second substrate 12 to surround the second reflective film 22. The annular portion thinned by the groove 90 is referred to as a support portion 91. The portion inside the support portion 91, including the second reflective film 22, is referred to as a movable portion 92.

[0044] The support portion 91 serves as an elastic, deformable diaphragm, and the electrostatic attraction of the electrostatic actuator 56 allows the movable portion 92 to advance and retract relative to the first substrate 11. Since the movable portion 92 has a greater thickness and, therefore, greater rigidity than the support portion 91, even if the support portion 91 is pulled toward the first substrate 11 by the electrostatic attraction, the movable portion 92 does not change shape, and thus the second reflective film 22 does not bend. Consequently, the first reflective film 21 and the second reflective film 22 can be maintained in a parallel state at all times.

[0045] In other words, the variable wavelength interference filter 100 includes: a first substrate 11 having a first reflective film 21; a second substrate 12 having a second reflective film 22 opposing 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 disposed; and a second electrode 56 b, which is an annular electrode surrounding the second reflective film 22; and the first substrate 11 having a first electrode 56 a facing the second electrode 56 b. A voltage is applied between the first electrode 56 a and the second electrode 56 b to change the gap G between the first reflective film 21 and the second reflective film 22.

[0046] like Figure 3 As shown, the extension portion 13 is provided with terminals 8 a and 8 b.

[0047] The terminal 8a is a GND terminal, to which the wiring 1 is connected. The wiring 1 is electrically connected to the second electrode 56b and the second reflective film 22. In other words, the second reflective film 22 of the second substrate 12 and the second electrode 56b are at the same potential.

[0048] The wiring 2 is connected to the terminal 8b. The wiring 2 is electrically connected to the first electrode 56a. Specifically, the wiring 2 is electrically connected to the wiring 4 on the first substrate 11 side through the conductive bump 85 from the second substrate 12 side, and the wiring 4 is electrically connected to the first electrode 56a.

[0049] In addition, the extension portion 13 is also provided with terminals and the like for connection to wiring for detecting the capacitance between the first reflection film 21 and the second reflection film 22 , but these are omitted from the drawings.

[0050] Back to Figure 1 .

[0051] like Figure 1 As shown, a plurality of base terminals 19 corresponding to the plurality of terminals 8 of the extension portion 13 are provided on the bottom 63b of the recess 63 of the base 61. Figure 2 As shown, terminals 8 and corresponding base terminals 19 are electrically connected by bonding wires 82. Base terminals 19 are electrically connected to corresponding external terminals 83 formed on the outside of base 61 via wiring (not shown). External terminals 83 also serve as mounting terminals for optical device 200.

[0052] Multilayer film conductive structure

[0053] Figure 5 for Figure 4 Enlarged view of part b. Figure 6 A plan view showing the planar morphology of a multilayer film. Figure 7 for Figure 6 Cross-sectional view of the cc section.

[0054] like Figure 5 As shown, the second reflective film 22 is composed of a multilayer film 15 in which a plurality of high-refractive index layers and low-refractive index layers are stacked. Specifically, the multilayer film 15 has a three-layer structure, comprising 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. In a preferred embodiment, Si is used as the high-refractive index material for the first layer 5a and the third layer 5c. Si is also a conductive material. SiO2 is used as the low-refractive index material for the second layer 5b.

[0055] The multilayer film 15 is not limited to a three-layer structure, and may be a multilayer film in which high-refractive index layers and low-refractive index layers are alternately stacked.

[0056] Here, the end faces of the multilayer film 15 constituting the second reflective film 22 are covered by the topmost third layer 5c, thereby achieving electrical continuity between the three layers. Specifically, the end faces of the first layer 5a and the second layer 5b are covered by the third layer 5c, thereby achieving electrical continuity between the three layers. This conductive structure is referred to as a conductive structure 33. In other words, the multilayer film 15 includes a conductive structure 33 that achieves electrical continuity between the multiple layers. The conductive material is a layer of the optical film constituting the multilayer film 15. The end faces of the multilayer film 15 are covered by the third layer 5c, which is a conductive material for achieving electrical continuity. Furthermore, the method is not limited to covering with the third layer 5c; electrical continuity can be achieved through any conductive layer.

[0057] Furthermore, on the X-negative side of the conductive structure 33, a wiring 1 is provided using a multilayer film 15 as wiring, and a translucent conductive layer 17 is formed on the wiring 1. The translucent conductive layer 17 is an ITO layer, and a second electrode 56b is formed on the translucent conductive layer 17. Thus, the wiring 1 and the second electrode 56b are electrically connected.

[0058] like Figure 6 As shown, the multilayer film 15 of this embodiment is also formed extensively around the second reflective film 22. Specifically, the multilayer film 15 is formed in a concentric circle that is larger than the second reflective film 22 and is positioned slightly larger than the diaphragm portion, including the annular groove 90 surrounding the movable portion 92. In other words, the multilayer film 15 forming 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 outside the multilayer film 15.

[0059] The second reflective film 22 is formed by dividing the multilayer film 15 by an annular conductive structure 33. This annular pattern is referred to as an annular pattern 9. The annular pattern 9 is a conductive portion, thereby preventing charge accumulation in the multilayer film within the second reflective film 22.

[0060] A plurality of linear wiring patterns 7a to 7h extend radially from the annular pattern 9. The wiring patterns 7a to 7h serve as conductive portions.

[0061] 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 extending beyond the groove 90. The wiring pattern 7b extends from the center o in the direction at an angle of 45° to a portion extending beyond the groove 90.

[0062] The wiring pattern 7c extends from the center o in the positive Y direction at an angle of 90° to a portion extending beyond the groove 90. The wiring pattern 7d extends from the center o in the direction at an angle of 135° to a portion extending beyond the groove 90.

[0063] The wiring pattern 7e extends from the center o in the negative X direction at an angle of 180 degrees to a portion beyond the groove 90. The wiring pattern 7f extends from the center o in the direction at an angle of 225 degrees to a portion beyond the groove 90.

[0064] The wiring pattern 7g extends from the center o in the Y negative 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.

[0065] In other words, the wiring patterns 7a to 7d and the wiring patterns 7e to 7h are in a point-symmetrical relationship with the center o of the second reflective film 22 as the object center. In other words, the conductive structure 33 includes the wiring patterns 7a to 7d and the wiring patterns 7e to 7h, which serve as the conductive portion, arranged symmetrically about the center o of the second reflective film 22. Furthermore, the conductive portion includes the wiring patterns 7a to 7h that radially extend from the movable portion 92 through the diaphragm portion. The conductive portion includes the annular ring pattern 9 that surrounds the second reflective film 22, and the radial wiring patterns 7a to 7h extend from the annular ring pattern 9. The number of wiring patterns is not limited to eight; any number of wiring patterns is sufficient.

[0066] like Figure 7 As shown in FIG, the cross section of the wiring pattern 7a forms a conductive structure 33. Specifically, by covering the end faces of the first layer 5a and the second layer 5b with the third layer 5c, the three layers are connected. Figure 7 In the embodiment, the light-transmitting conductive layer 17 ( Figure 5 ) are omitted in the illustration.

[0067] like Figure 6 As shown, the area of ​​the multilayer film 15 outside the annular pattern 9 is significantly larger than the area of ​​the second reflective film 22. Since the multilayer film 15 has a high resistivity, there is a concern that if the multilayer film 15 is too far away from the conductive structure 33, the charge may not be fully discharged.

[0068] In contrast, according to the present embodiment, the multilayer film 15 is electrically divided into eight trapezoidal regions by the wiring patterns 7 a to 7 h , thereby preventing charge accumulation in the multilayer film 15 in each trapezoidal region.

[0069] Furthermore, by covering the diaphragm portion including the annular groove 90 with the three-layer multilayer film 15, the thin support portion 91 is lined and reinforced, thereby increasing the strength of the thin and structurally weak diaphragm portion.

[0070] Back to Figure 4 .

[0071] like Figure 4 As shown, the first reflective film 21 of the first substrate 11 is also composed of a three-layer multilayer film 15. The end faces of the multilayer film 15 constituting the first reflective film 21 are covered by the topmost third layer 5c, thereby achieving electrical continuity between the three layers. Specifically, electrical continuity between the three layers is achieved through a conductive structure 33 in which the end faces of the first layer 5a and the second layer 5b are covered by the third layer 5c. This prevents the accumulation of charge within the multilayer film 15.

[0072] The functional film including the multilayer film 15 , the translucent conductive layer 17 , and the second electrode 56 b can be formed by forming the film using a known film forming method such as sputtering, vapor deposition, or CVD, and then patterning the film using photolithography.

[0073] Strength simulation results of the diaphragm

[0074] Figure 8 The graph shows the deformation amount of the diaphragm portion according to the arrangement of the multilayer film. The horizontal axis represents the distance (mm) from the center o of the second reflective film 22 , and the vertical axis represents the deformation amount (nm) of the diaphragm portion. Figure 9 It is a perspective view showing simulation results obtained using the multilayer film of this embodiment. Figure 10 is a perspective view showing the simulation results obtained by the multilayer film of the comparative example, and corresponds to Figure 9 .

[0075] like Figure 9 As shown, the multilayer film 15 of this embodiment is provided so as to completely cover the diaphragm portion as described above, and the outer peripheral edge of the multilayer film 15 is located outside the annular groove 90 .

[0076] In contrast, the multilayer film 25 of the modified example is as follows Figure 10 As shown, the outer peripheral edge thereof is located substantially in the middle of the annular groove 90. In other words, the outer peripheral edge of the multilayer film 25 is located substantially in the middle of the support portion 91.

[0077] Figure 8 Graph 71 is a simulation result when the diaphragm portion is in a stationary state, and is a result obtained by calculating a state in which only the film stress of the multilayer film 15 including the second reflective film 22 and the second electrode 56 b acts on the stationary flat second substrate 12 .

[0078] As shown in the graph 71 , the multilayer film 15 of the present embodiment has a substantially flat graph, no stress concentration is observed, and the deformation of the diaphragm portion is only about 230 nm.

[0079] In contrast, the multilayer film 25 of the modified example shown in graph 72 shows that stress concentrates approximately in the middle of the support portion 91, where the outer periphery of the multilayer film 25 is located, resulting in a deformation of approximately 1000 nm. This deformation is excessive given the need to control the gap G between the first reflective film 21 and the second reflective film 22 to a value of several nanometers in the variable wavelength interference filter 100. Thus, the multilayer film 15 of this embodiment can reinforce the diaphragm portion without generating a stress concentration area, thereby improving impact resistance. Furthermore, the conductive structure 33, including the wiring patterns 7a to 7h, can prevent charge accumulation within the multilayer film 15.

[0080] As described above, according to the variable wavelength interference filter 100 of this embodiment, the following effects can be obtained.

[0081] The variable wavelength 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 opposed to the first reflective film 21. The second substrate 12 includes a diaphragm portion including an annular groove 90 surrounding a movable portion 92 on which the second reflective film 22 is disposed, and a second electrode 56b, which is an annular electrode surrounding the second reflective film 22. The first substrate 11 includes a first electrode 56a facing the second electrode 56b. By applying a voltage between the first electrode 56a and the second electrode 56b, the gap G between the first reflective film 21 and the second reflective film 22 is changed, and a multilayer film 15 forming the second reflective film 22 is formed so as to cover the diaphragm portion. The multilayer film 15 includes a conductive structure 33 for achieving electrical continuity between the multiple layers. The conductive structure 33 includes wiring patterns 7a to 7d and wiring patterns 7e to 7h as conductive portions, which are symmetrically arranged about the center o of the second reflective film 22.

[0082] Thus, by reinforcing the thin support portion 91 with the multilayer film 15, the strength of the thin, and therefore structurally weak, diaphragm portion can be enhanced. Furthermore, the conductive portion, including the wiring patterns 7a to 7h arranged symmetrically about the center o of the second reflective film 22, can prevent the accumulation of charge within the multilayer film 15. Consequently, the driving reliability of the electrostatic actuator 56 can be improved.

[0083] Therefore, it is possible to provide the variable wavelength interference filter 100 having a high impact resistance of the diaphragm portion and excellent reliability.

[0084] Furthermore, the conductive portion includes wiring patterns 7a to 7h that radially extend through the diaphragm portion from the movable portion 92. Thus, by electrically dividing the multilayer film 15, which has a large area and a high resistivity, into eight trapezoidal regions using the wiring patterns 7a to 7h, the charge within the multilayer film 15 in each trapezoidal region can be efficiently released.

[0085] Furthermore, the second reflective film 22 of the second substrate 12 and the second electrode 56 b have the same potential.

[0086] Thus, the second substrate 12 is electrically stable.

[0087] Furthermore, the end faces of the multilayer film 15 are covered with the third layer 5 c , which is a conductive material for achieving electrical conduction, thereby preventing charge from being accumulated in the multilayer film 15 .

[0088] Furthermore, the conductive material is one layer of the optical films constituting the multilayer film 15 .

[0089] This allows the conductive optical film constituting the multilayer film 15 to be utilized as a conductive material.

[0090] Furthermore, the conductive portion includes a circular ring pattern 9 that is a circular ring-shaped pattern surrounding the second reflective film 22 , and the radial wiring patterns 7 a to 7 h are led out from the circular ring pattern 9 .

[0091] This can prevent charges from being accumulated in the multilayer film 15 .

[0092] Implementation Method 2

[0093] Spectroscopic Camera

[0094] Figure 11 This is a schematic structural diagram of a spectroscopic camera according to the second embodiment.

[0095] Figure 11 The spectroscopic camera 300 of the present embodiment shown includes an optical device 200 equipped with the wavelength-variable interference filter 100 of the above-described embodiment. Components identical to those of the above-described embodiment are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0096] The spectroscopic camera 300 is an infrared camera including an optical device 200 equipped with a variable wavelength interference filter 100 , and includes a camera body 310 , an imaging lens unit 320 , and an imaging section 330 .

[0097] The camera body 310 is a portion that is grasped and operated by a user.

[0098] The imaging lens unit 320 is provided on the camera body 310 to guide the incident image light to the imaging unit 330. Figure 11 As shown, the optical device 200 includes an objective lens 321 , an imaging lens 322 , and the optical device 200 provided between these lenses.

[0099] The imaging unit 330 is composed of a light receiving element, and captures image light guided by the imaging lens unit 320 .

[0100] According to such a spectroscopic camera 300 , by transmitting light of a wavelength to be imaged using the optical device 200 having relatively high reliability, it is possible to capture a spectroscopic image of light of a desired wavelength.

[0101] Explanation of symbols

[0102] 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…circular pattern; 11…first substrate; 12…second substrate; 13…extending portion; 14…extending portion; 15…multilayer film; 17…light-transmitting 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…frame; 61…base; 62…side wall 62a…cover joint surface; 62b…side wall; 63…recess; 63b…bottom; 64…fixing component; 65…cover; 66…translucent component; 67…sealing hole; 67b…sealing component; 68…light passage hole; 71…curve graph; 72…curve graph; 80…base portion; 81…electrode configuration groove; 82…bonding wire; 83…external terminal; 85…conductive bump; 90…groove; 91…support portion; 92…movable portion; 100…variable wavelength interference filter; 200…optical device; 300…spectrographic camera; 310…camera body; 320…imaging lens unit; 321…objective lens; 322…imaging lens; 330…imaging portion.

Claims

1. A variable wavelength interference filter comprising: a first substrate having a first reflective film; a second substrate having a second reflective film opposite to the first reflective film; The second substrate includes a diaphragm portion and a second electrode. The diaphragm portion includes an annular groove surrounding a movable portion on which the second reflective film is disposed. The second electrode is an annular electrode surrounding the second reflective film. The first substrate has a first electrode, and the first electrode faces the second electrode. By applying a voltage between the first electrode and the second electrode, the gap between the first reflective film and the second reflective film is changed. In the variable wavelength interference filter, a multilayer film forming the second reflective film is formed so as to cover the diaphragm portion. The multilayer film includes a conductive structure for achieving electrical conduction between the multiple layers. The conductive structure includes a conductive portion, and the conductive portion is symmetrically arranged with respect to a center of the second reflective film.

2. The wavelength variable interference filter according to claim 1, wherein: The conductive portion includes a wiring pattern that radially passes through the diaphragm portion from the movable portion.

3. The wavelength variable interference filter according to claim 1, wherein: The second reflective film of the second substrate and the second electrode have the same potential.

4. The wavelength variable interference filter according to claim 1, wherein: The end faces of the multilayer film are covered with a conductive material for achieving electrical conduction.

5. The wavelength variable interference filter according to claim 4, wherein: The conductive material is a layer of the optical film constituting the multilayer film.

6. The wavelength variable interference filter according to claim 2, wherein: The conductive portion includes a circular pattern, and the circular pattern is a circular pattern surrounding the second reflective film. The radial wiring pattern is drawn out from the annular pattern.

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