Patent Publication Number: US-2021191104-A1

Title: Optical Filter Device, Optical Module, Electronic Apparatus, And MEMS Device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/886,169, filed Feb. 12, 2018, which is a continuation of U.S. patent application Ser. No. 14/340,777, filed on Jul. 25, 2014, all of which claim priority to Japanese Patent Application No. 2013-155345, filed on Jul. 26, 2013. The disclosures of the above applications are incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present invention relates to an optical filter device, an optical module, an electronic apparatus, and a MEMS device. 
     2. Related Art 
     In the related art, various Micro Electro Mechanical System (MEMS) elements are known, such as an interference filter in which reflective films are respectively disposed on surfaces of a pair of substrates facing each other so that the reflective films face each other across a predetermined gap, a mirror element in which a reflective film is disposed on a substrate, or a piezoelectric vibration element in which a piezoelectric body such as a quartz crystal vibrator element is disposed on a substrate. In addition, a MEMS device is known in which a MEMS element is stored in a storage container (for example, refer to JP-A-2008-70163). 
     JP-A-2008-70163 discloses an infrared type gas detector (optical filter device) which includes a package (casing) provided with a plate-shaped pedestal and a cylindrical cap. In this casing, an outer circumferential part of a base substrate and one cylindrical end of the cap are connected to each other through welding or adhesion, and a space for storing a Fabry-Perot filter (interference filter) is provided between the base substrate and the cap. The interference filter is adhered and fixed to a lower surface side of a substrate forming the interference filter. 
     As described above, the interference filter disclosed in JP-A-2008-70163 is adhered and fixed to the lower surface side of the substrate, and is in close contact with an adhesive in a surface direction perpendicular to a thickness direction of the substrate. Since the adhesive typically contracts when cured, stress related to the contraction is applied to the substrate. For this reason, there is a concern that the lower surface of the substrate may receive the stress centering on the adhesion position in the surface direction, and thus the substrate may be deflected. If the substrate is deflected, there is a problem in that reflective films provided on the substrate are distorted, or a dimension of a gap between the reflective films changes, and thus the spectral accuracy of the interference filter deteriorates. 
     Also in the above-described various MEMS devices, if deflection occurs in a substrate forming the MEMS element, there is a problem in that a performance of the MEMS element deteriorates due to an influence of the deflection. 
     SUMMARY 
     An advantage of some aspects of the invention is to provide an optical filter device, an optical module, an electronic apparatus, and a MEMS device capable of minimizing performance deterioration. 
     An aspect of the invention is directed to an optical filter device including an interference filter that includes a first reflective film, a second reflective film facing the first reflective film, and a substrate provided with either of the first reflective film and the second reflective film; a casing that has an inner space for storing the interference filter therein; and a fixation portion that fixes the interference filter to the casing, in which the fixation portion is provided between a side surface of the substrate in a thickness direction of the substrate and the casing. 
     Various adhesives may be exemplified as the fixation portion. Here, typically, a dimension in the thickness direction of the substrate is considerably smaller than a dimension in a plane direction perpendicular to the thickness direction. Therefore, rigidity (resistance to deflection) in the thickness direction of the substrate is lower than rigidity in the plane direction. For this reason, as described above, if the fixation portion is provided on a substrate surface perpendicular to the side surface, such as a lower surface of the substrate, there is a concern that the substrate may be deflected by stress applied from the fixation portion. 
     In contrast, according to the aspect of the invention, the substrate of the interference filter is fixed to the casing by the fixation portion provided on the side surface. For this reason, the fixation portion is provided on the side surface having higher rigidity to deflection than that of the substrate surface, and thus there is almost no influence of stress. Therefore, it is possible to minimize deflection of the substrate due to a contraction stress of the fixation portion or a linear expansion coefficient difference between the substrate and the fixation portion. Accordingly, it is possible to minimize distortion of the reflective film provided on the substrate or a change in dimensions of a gap between reflective films, and thus to prevent a reduction in spectral accuracy of the interference filter. 
     In the optical filter device of the aspect of the invention, it is preferable that the interference filter includes a first substrate provided with the first reflective film and a second substrate facing the first substrate and provided with the second reflective film as the substrate, and the fixation portion is provided on the side surface of either of the first substrate and the second substrate. 
     According to this configuration, the interference filter includes the first substrate and the second substrate. The first substrate and the second substrate are disposed so as to face each other. In this configuration, if the fixation portion is provided on both side surfaces of the first substrate and the second substrate, there is a concern that parallelism between the first substrate and the second substrate may not be maintained, and a gap dimension between the reflective films may change since a stress from the fixation portion is applied in contact and separation directions of the first substrate and the second substrate. 
     In contrast, according to the configuration described above, since the fixation portion is provided on the side surface of either of the first substrate and the second substrate, it is possible to maintain parallelism between the substrates and also to prevent a change in dimensions of the gap between the reflective films, and thus to maintain spectral accuracy of the interference filter. 
     In the optical filter device of the aspect of the invention, it is preferable that one of the first substrate and the second substrate includes a projecting portion that projects more than the other substrate in a plan view in which the substrates are viewed from the thickness direction, and the fixation portion is provided at the projecting portion. 
     According to this configuration, one substrate has the projecting portion which projects more than the other substrate. In addition, the fixation portion is provided at the projecting portion. Accordingly, it is possible to prevent the fixation portion from being provided on both of the first substrate and the second substrate, and thus to more reliably provide the fixation portion only on the side surface of one substrate. Therefore, it is possible to more reliably maintain parallelism between the substrates as described above. 
     In the optical filter device of the aspect of the invention, it is preferable that the second substrate includes a movable portion provided with the second reflective film and a holding portion holding the movable portion in a displaceable manner in the thickness direction, and the fixation portion is provided on the side surface of the first substrate. 
     According to this configuration, the second substrate includes the holding unit which holds the movable portion in a displaceable manner in the thickness direction. This interference filter allows a dimension of a gap (hereinafter, also referred to as a gap dimension) formed between the first reflective film and the second reflective film to be changed by displacing the movable portion in the thickness direction by using the holding portion. Meanwhile, in the interference filter, since the holding unit is provided on the second substrate, rigidity of the first substrate in the substrate thickness direction is smaller than rigidity of the second substrate in the substrate thickness direction. Therefore, if the fixation portion is provided on the second substrate, there is a concern that the second substrate may be deflected due to a stress of the fixation portion. In contrast, in the configuration described above, since the fixation portion is provided on the first substrate having higher rigidity than that of the second substrate, it is possible to minimize the occurrence of deflection in the substrate and thus to prevent deterioration in spectral accuracy of the interference filter. 
     In the optical filter device of the aspect of the invention, it is preferable that a part of the side surface forms a planar first side surface, and the fixation portion is provided on the first side surface. 
     According to this configuration, the substrate has the planar first side surface at least at a part of the side surface, and the fixation portion is provided on the first side surface. In this configuration, after a member such as an adhesive for forming the fixation portion is disposed on the first side surface, the fixation portion is formed in a state in which the first side surface of the substrate is pressed against an inner wall or the like of the casing. At this time, the planar first side surface comes into contact with an inner surface of the casing at two or more locations or the entire surface, and thus a fixation position of the substrate for the casing is determined. Here, in a case where the entire side surface is curved, when a protrusion or the like for alignment is provided, a shape of the protrusion is determined in consideration of the curved shape of the side surface. In contrast, even in a case where the protrusion is provided on the planar first side surface, a dimension or the like of the protrusion is easily set. In addition, even in a case where the casing inner surface is formed to be planar, alignment is easily performed. From the above description, since the first side surface is provided, the substrate is easily aligned, and thus the substrate can be fixed to the casing while easily performing the alignment. Therefore, it is possible to easily design the optical filter device or to improve assembly efficiency. 
     In the optical filter device of the aspect of the invention, it is preferable that the substrate includes an electric component portion that is provided with a connection terminal which is electrically connected to a casing side terminal provided in the casing, at a part along an outer circumferential edge of the substrate, in a plan view in which the substrate is viewed from a substrate thickness direction, and the first side surface is a side surface of the electric component portion. 
     In this configuration, the side surface of the electric component portion becomes a first side surface on which the fixation portion is provided. Therefore, since the side surface of the electric component portion is fixed to the casing by the fixation portion, it is possible to minimize vibration of the electric component portion provided with the connection terminal even when the optical filter device is vibrated due to an impact being applied to the optical filter device or the optical filter device being driven. Therefore, it is possible to prevent a defect such as the connection terminal being disconnected from the casing side terminal. 
     In the optical filter device of the aspect of the invention, it is preferable that the fixation portion is provided at a single location of the first side surface. 
     According to this configuration, the fixation portion is provided at a single location on the first side surface. Accordingly, it is possible to reduce stress applied to the substrate from the fixation portion, and thus to more effectively minimize deflection of the substrate. 
     In the optical filter device of the aspect of the invention, it is preferable that the fixation portion is provided at a plurality of locations of the first side surface. 
     In this configuration, a plurality of fixation portions are provided. The plurality of fixation portions are provided in this way, and therefore it is possible to increase a fixation force of the substrate to the casing, and thus to more reliably fix the substrate to the casing. 
     In the optical filter device of the aspect of the invention, it is preferable that the side surface includes a planar first side surface and a second side surface parallel to the first side surface, and the fixation portion is provided on the first side surface and the second side surface. 
     According to this configuration, the fixation portion is provided on the first side surface and the second side surface which have a planar shape and are parallel to each other. Accordingly, since the substrate is fixed to the casing at each of a pair of side surfaces, it is possible to increase a fixation force of the substrate to the casing, and thus to more reliably fix the substrate to the casing. 
     In the optical filter device of the aspect of the invention, it is preferable that the fixation portion provided on the first side surface and the fixation portion provided on the second side surface are provided at positions which are symmetrical to each other with respect to a virtual plane which passes through a center of the substrate and is parallel to the first side surface and the second side surface. 
     In this configuration, the fixation portions are provided at positions which are symmetrical to each other (positions where the first side surface and the second side surface oppose each other) with respect to the virtual plane which passes through the center of the substrate. Therefore, stresses applied to the substrate from the respective fixation portions are balanced, and thus the stresses are canceled out. Accordingly, it is possible to more effectively reduce deflection of the substrate. 
     In the optical filter device of the aspect of the invention, it is preferable that the side surface includes a planar first side surface and a third side surface along a plane which is continued to the first side surface and intersects the first side surface, and the fixation portion is provided over the first side surface and the third side surface. 
     In this configuration, the fixation portion is provided over the first side surface and the third side surface which are connected to each other. 
     Accordingly, the substrate can be fixed to the casing by pressing the substrate against the inner wall or the like of the casing in a state in which a member such as an adhesive for forming the fixation portion is disposed from the first side surface to the third side surface through a corner at which the first side surface intersects the third side surface. Therefore, it is possible to fix the substrate to the casing with a simple operation. 
     In addition, since the substrate is fixed to the casing on the two intersecting side surfaces, it is possible to increase a fixation force of the substrate to the casing and thus to more reliably fix the substrate to the casing. 
     In the optical filter device of the aspect of the invention, it is preferable that the casing includes a support portion that supports the interference filter with respect to the casing, and the fixation portion is provided between the side surface and the support portion. 
     According to this configuration, the casing includes the support portion which supports the optical filter device, and the fixation portion is provided between the side surface and the support portion. Accordingly, it is possible to fix the interference filter to any casing on the side surface of the substrate regardless of a shape of the casing. 
     Another aspect of the invention is directed to an optical module including an optical filter device; and a detection unit that detects light extracted by the interference filter, in which the optical filter device includes an interference filter that has a first reflective film, a second reflective film facing the first reflective film, and a substrate provided with either of the first reflective film and the second reflective film; a casing that has an inner space for storing the interference filter therein; and a fixation portion that fixes the interference filter to the casing, in which the fixation portion is provided between a side surface of the substrate in a thickness direction of the substrate and the casing. 
     In this aspect of the invention, in the same manner as in the aspect described above, since the fixation portion is provided on the side surface of the substrate, as described above, it is possible to minimize the occurrence of deflection of the substrate due to a stress from the fixation portion, and thus to prevent deterioration in a performance of the interference filter. Accordingly, it is possible to more reliably provide an optical module having a desired performance. 
     Still another aspect of the invention is directed to an electronic apparatus including an optical filter device; and a controller that controls the interference filter, in which the optical filter device includes an interference filter that has a first reflective film, a second reflective film facing the first reflective film, and a substrate provided with either of the first reflective film and the second reflective film; a casing that has an inner space for storing the interference filter therein; and a fixation portion that adheres and fixes the interference filter to the casing, in which the fixation portion is provided between a side surface of the substrate in a thickness direction of the substrate and the casing. 
     In this aspect of the invention, in the same manner as in the aspects described above, since the fixation portion is provided on the side surface of the substrate, as described above, it is possible to minimize the occurrence of deflection of the substrate due to a stress from the fixation portion, and thus to prevent deterioration in a performance of the interference filter. Accordingly, it is possible to more reliably provide an electronic apparatus having a desired performance. 
     Yet another aspect of the invention is directed to a MEMS device including a MEMS element provided with a substrate; a casing that has an inner space for storing the MEMS element therein; and a fixation portion that fixes the MEMS element to the casing, in which the fixation portion is provided between a side surface of the substrate in a thickness direction of the substrate and the casing. 
     In this aspect of the invention, in the same manner as in the aspects described above, the substrate of the MEMS element is fixed to the casing by the fixation portion provided on the side surface. Accordingly, as described above, it is possible to minimize deflection of the substrate and thus to prevent deterioration in performance due to distortion occurring in the MEMS element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is a cross-sectional view illustrating a schematic configuration of an optical filter device of a first embodiment. 
         FIG. 2  is a plan view illustrating a schematic configuration of the optical filter device of the embodiment. 
         FIG. 3  is a cross-sectional view illustrating a schematic configuration of a wavelength variable interference filter of the embodiment. 
         FIG. 4  is a cross-sectional view schematically illustrating a fixation state of a substrate in a comparative example. 
         FIG. 5  is a cross-sectional view schematically illustrating a fixation state of a fixed substrate of the embodiment. 
         FIG. 6  is a plan view illustrating a schematic configuration of an optical filter device of a second embodiment. 
         FIG. 7  is a plan view illustrating a schematic configuration of an optical filter device of a third embodiment. 
         FIG. 8  is a plan view illustrating a schematic configuration of an optical filter device of a fourth embodiment. 
         FIG. 9  is a plan view illustrating a schematic configuration of an optical filter device of a fifth embodiment. 
         FIG. 10  is a plan view illustrating a schematic configuration of an optical filter device of a sixth embodiment. 
         FIG. 11  is a cross-sectional view illustrating a schematic configuration of an optical filter device of a seventh embodiment. 
         FIG. 12  is a plan view illustrating a schematic configuration of a wavelength variable interference filter of the embodiment. 
         FIG. 13  is a block diagram illustrating a schematic configuration of a colorimetry apparatus of an eighth embodiment. 
         FIG. 14  is a schematic diagram illustrating a gas detection apparatus which is an example of an electronic apparatus. 
         FIG. 15  is a block diagram illustrating a configuration of a control system of the gas detection apparatus of  FIG. 14 . 
         FIG. 16  is a diagram illustrating a schematic configuration of a food analysis apparatus which is an example of an electronic apparatus. 
         FIG. 17  is a diagram illustrating a schematic configuration of a spectroscopic camera which is an example of an electronic apparatus. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     First Embodiment 
     Hereinafter, a first embodiment will be described with reference to the drawings. 
     Configuration of Optical Filter Device 
       FIG. 1  is a cross-sectional view illustrating a schematic configuration of an optical filter device  600  which is an embodiment of an optical filter device. 
     The optical filter device  600  is a device which extracts targeted light with a predetermined wavelength from incident inspection target light and emits the targeted light, and includes a casing  610  and a wavelength variable interference filter  5  stored inside the casing  610 . The optical filter device  600  may be incorporated into, for example, an optical module such as a colorimetry sensor, or an electronic apparatus such as a colorimetry apparatus or a gas analysis apparatus. In addition, a configuration of the optical module or the electronic apparatus having the optical filter device  600  will be described later in detail. 
     Configuration of Wavelength Variable Interference Filter 
     A wavelength variable interference filter  5  corresponds to an interference filter.  FIG. 2  is a plan view illustrating a schematic configuration of the wavelength variable interference filter  5  stored inside the casing  610 , and  FIG. 3  is a cross-sectional view illustrating a schematic configuration of the wavelength variable interference filter  5 , taken along the line III-III in  FIG. 2 . 
     As illustrated in  FIG. 2 , the wavelength variable interference filter  5  is, for example, a rectangular plate-shaped optical member. The wavelength variable interference filter  5  includes a fixed substrate  51  and a movable substrate  52 . In addition, of the respective substrates  51  and  52 , the fixed substrate  51  corresponds to a first substrate, and the movable substrate  52  corresponds to a second substrate. Each of the fixed substrate  51  and the movable substrate  52  is made of, for example, a type of glass such as soda glass, crystalline glass, quartz glass, lead glass, potassium glass, borosilicate glass, and alkali-free glass, quartz crystal, or the like. In addition, the fixed substrate  51  and the movable substrate  52  are joined to each other via a joining film  53  (a first joining film  531  and a second joining film  532 ) and are thus integrally formed as illustrated in  FIG. 3 . Specifically, a first joining portion  513  of the fixed substrate  51  and a second joining portion  523  of the movable substrate  52  are joined to each other via the joining film  53  which is formed of, for example, a plasma polymerization film or the like having siloxane as a main component. 
     In addition, in the following description, a plan view in which the wavelength variable interference filter  5  is viewed from the substrate thickness direction of the fixed substrate  51  or the movable substrate  52 , that is, a plan view in which the wavelength variable interference filter  5  is viewed from a stacking direction of the fixed substrate  51 , the joining film  53 , and the movable substrate  52  is referred to as a filter plan view. 
     As illustrated in  FIG. 3 , a fixed reflective film  54  corresponding to a first reflective film is provided on the fixed substrate  51 . In addition, a movable reflective film  55  corresponding to a second reflective film is provided on the movable substrate  52 . The fixed reflective film  54  and the movable reflective film  55  are disposed so as to face each other with a gap G 1  between the reflective films. 
     The wavelength variable interference filter  5  is provided with an electrostatic actuator  56  which is used to adjust a distance (dimension) of the gap G 1  between the reflective films. The electrostatic actuator  56  includes a fixed electrode  561  provided on the fixed substrate  51  and a movable electrode  562  provided on the movable substrate  52 , and is formed by the electrodes  561  and  562  facing each other (a region indicated by the diagonal lines of  FIG. 2 ). The fixed electrode  561  faces the movable electrode  562  with a gap between the electrodes. Here, the electrodes  561  and  562  may be respectively directly provided on the substrate surfaces of the fixed substrate  51  and the movable substrate  52 , and may be provided via other film members. 
     In addition, in the present embodiment, a configuration is exemplified in which the gap G 1  between the reflective films is formed to be smaller than the gap between the electrodes, but the gap G 1  between the reflective films may be formed to be larger than the gap between the electrodes, for example, depending on a wavelength band which is desired to be transmitted by the wavelength variable interference filter  5 . 
     In the filter plan view, one side (for example, a side between vertexes C 3  and C 4  in  FIG. 2 ) of sides of the movable substrate  52  projects further outward than the fixed substrate  51 . A projecting part of the movable substrate  52  is an electric component portion  526  which is not joined to the fixed substrate  51 . In addition, the electric component portion  526  corresponds to a projecting portion in the movable substrate  52 . In the electric component portion  526  of the movable substrate  52 , an exposed surface when the wavelength variable interference filter  5  is viewed from the fixed substrate  51  side is an electric component surface  524 , and electrode pads  541 P,  551 P,  563 P and  564 P (corresponding to connection terminals) described later are provided thereon. 
     Configuration of Fixed Substrate 
     The fixed substrate  51  is formed by processing, for example, a glass base material which is formed to have a thickness of 500 μm. Specifically, as illustrated in  FIG. 3 , the fixed substrate  51  is provided with an electrode arrangement groove  511  and a reflective film installation portion  512  which are formed through etching. The fixed substrate  51  is formed to have a larger thickness dimension than that of the movable substrate  52 , and thus there is no deflection of the fixed substrate  51  due to an electrostatic attraction caused by application of a voltage between the fixed electrode  561  and the movable electrode  562  or an internal stress of the fixed electrode  561 . 
     The electrode arrangement groove  511  is formed in a ring shape centering on a plane central point O of the wavelength variable interference filter  5  in the filter plan view. The reflective film installation portion  512  is formed so as to protrude toward the movable substrate  52  side from the central part of the electrode arrangement groove  511  in the filter plan view as illustrated in  FIG. 3 . A groove bottom surface of the electrode arrangement groove  511  is an electrode installation surface  511 A on which a fixed electrode  561  is disposed. In addition, a protruding front end surface of the reflective film installation portion  512  is a reflective film installation surface  512 A. 
     Further, the fixed substrate  51  is provided with an electrode extraction groove  511 B which extends from the electrode arrangement groove  511  toward the electric component surface  524 . 
     The fixed electrode  561  is provided around the reflective film installation portion  512  on the electrode installation surface  511 A of the electrode arrangement groove  511 . The fixed electrode  561  is provided in a region facing the movable electrode  562  of a movable portion  521  described later on the electrode installation surface  511 A, and is formed in a substantially C shape having an opening on a side between vertexes C 1  and C 2  illustrated in  FIG. 2 . In addition, an insulating film for ensuring insulation between the fixed electrode  561  and the movable electrode  562  may be laminated on the fixed electrode  561 . 
     Further, the fixed substrate  51  is provided with a fixed extraction electrode  563 A which extends from an outer circumferential edge around the opening of the C-shaped fixed electrode  561  toward the side between the vertexes C 3  and C 4  illustrated in  FIG. 2 . An extending front end (a part located at the side between the vertexes C 3  and C 4  of the fixed substrate  51 ) of the fixed extraction electrode  563 A is electrically connected to a fixed connection electrode  563 B which is provided on the movable substrate  52  side via a bump electrode  563 C. The fixed connection electrode  563 B extends up to the electric component surface  524  through an electrode extraction groove  511 B, and forms the fixed electrode pad  563 P corresponding to a connection terminal on the electric component surface  524 . The fixed electrode pad  563 P is connected to an internal terminal portion  624  which is provided inside the casing  610  and will be described later. 
     In addition, in the present embodiment, a configuration in which a single fixed electrode  561  is provided on the electrode installation surface  511 A is described, but, for example, a configuration (double electrode configuration) or the like in which two electrodes forming concentric circles centering on the plane central point O are provided may be employed. 
     As described above, the reflective film installation portion  512  is formed in a substantially columnar shape having a smaller diameter dimension than that of the electrode arrangement groove  511  on the same axis as the electrode arrangement groove  511 , and the reflective film installation portion  512  is provided with the reflective film installation surface  512 A facing the movable substrate  52 . 
     The reflective film installation portion  512  is provided with the fixed reflective film  54  as illustrated in  FIG. 3 . As the fixed reflective film  54 , for example, a metal film such as Ag, or an alloy film such as an Ag alloy may be used. In addition, for example, a dielectric multilayer film which has a high refractive index layer made of TiO 2  and a low refractive index layer made of SiO 2  may be used. Further, a reflective film in which a metal film (or an alloy film) is laminated on a dielectric multilayer film, a reflective film in which a dielectric multilayer film is laminated on a metal film (or an alloy film), a reflective film in which a single refractive layer (TiO 2  or SiO 2 ) and a metal film (or an alloy film) are laminated, or the like may be used. 
     Further, the fixed substrate  51  is provided with a fixed mirror electrode  541 A which is connected to the fixed reflective film  54 , extends toward the side between the vertexes C 1  and C 2  through the opening of the C-shape fixed electrode  561 , and then extends toward the side between the vertexes C 3  and C 4 . For example, in a case where the fixed reflective film  54  is formed of a metal film such as an Ag alloy, the fixed mirror electrode  541 A can be formed along with the fixed reflective film  54 . 
     A extending front end (a part located at the side between the vertexes C 3  and C 4  of the fixed substrate  51 ) of the fixed mirror electrode  541 A is electrically connected to a fixed mirror connection electrode  541 B provided on the movable substrate  52  side via a bump electrode  541 C. The fixed mirror connection electrode  541 B extends up to the electric component surface  524  through the electrode extraction groove  511 B, and forms the fixed mirror electrode pad  541 P corresponding to a connection terminal on the electric component surface  524 . In addition, the fixed mirror electrode pad  541 P is connected to an internal terminal portion  624  which is provided at a pedestal portion  621  and will be described later, and is also connected to a ground circuit (not illustrated). Accordingly, the fixed reflective film  54  is set to a ground potential (0 V). 
     Further, as illustrated in  FIG. 3 , a surface of the fixed substrate  51  on which the fixed reflective film  54  is not provided is a light incidence surface  516 . Further, an antireflective film may be formed at a position corresponding to the fixed reflective film  54  on the light incidence surface  516 . This antireflective film may be formed by alternately laminating a low refractive index film and a high refractive index film, and increases transmittance by reducing reflectance of visible light on the surface of the fixed substrate  51 . 
     Further, as illustrated in  FIG. 3 , a non-transmissive member  515  which is made of, for example, Cr, is provided on the light incidence surface  516  of the fixed substrate  51  (in  FIG. 2 , the non-transmissive member  515  is not illustrated). The non-transmissive member  515  is formed in a ring shape, and is preferably formed in a circular ring shape. In addition, an inner ring diameter of the non-transmissive member  515  is set to an effective diameter for optical interference using the fixed reflective film  54  and the movable reflective film  55 . Accordingly, the non-transmissive member  515  functions as an aperture which restricts incident light which is incident to the optical filter device  600 . 
     In addition, a part, in which the electrode arrangement groove  511 , the reflective film installation portion  512 , and the electrode extraction groove  511 B are not formed through etching on the surface of the fixed substrate  51  facing the movable substrate  52 , forms the first joining portion  513 . The first joining film  531  is provided at the first joining portion  513 , and the first joining film  531  is joined to the second joining film  532  provided on the movable substrate  52  so that the fixed substrate  51  and the movable substrate  52  are joined together as described above. The joined fixed substrate  51 , as illustrated in  FIG. 3 , has a projecting portion  514  so that one side (for example, the side between the vertexes C 1  and C 2  in  FIG. 2 ) of the sides of the fixed substrate  51  projects further outward than the movable substrate  52  in the filter plan view. The projecting portion  514  is a part which does not overlap the movable substrate  52  in the filter plan view. 
     Configuration of Movable Substrate 
     The movable substrate  52  is formed by processing, for example, a glass base material which is formed to have a thickness of 200 μm. 
     Specifically, in the filter plan view as illustrated in  FIG. 2 , the movable substrate  52  includes the movable portion  521  which has a circular shape centering on the plane central point O, a holding portion  522  which is provided outside the movable portion  521  and holds the movable portion  521 , and a substrate outer circumferential portion  525  which is provided outside the holding portion  522 . 
     The movable portion  521  is formed to have a larger thickness dimension than that of the holding portion  522 , and, for example, in the present embodiment, is formed in the same dimension as a thickness dimension of the movable substrate  52 . The movable portion  521  is formed to have a larger diameter dimension than at least a diameter dimension of the outer circumferential edge of the reflective film installation surface  512 A in the filter plan view. In addition, the movable electrode  562  and the movable reflective film  55  are provided at the movable portion  521 . 
     In the same manner as in the fixed substrate  51 , an antireflective film may be formed on a surface of the movable portion  521  on an opposite side to the fixed substrate  51 . This antireflective film may be formed by alternately laminating a low refractive index film and a high refractive index film, and increases transmittance by reducing reflectance of visible light on the surface of the movable substrate  52 . In addition, in the present embodiment, a surface of the movable portion  521  facing the fixed substrate  51  is a movable surface  521 A. 
     The movable electrode  562  faces the fixed electrode  561  with the gap between the electrodes, and is formed in a substantially C shape which has an opening on the side between the vertexes C 3  and C 4  illustrated in  FIG. 2  at a position facing the fixed electrode  561 . In addition, the movable substrate  52  is provided with a movable extraction electrode  564  which extends from the outer circumferential edge of the opening of the C-shaped movable electrode  562  toward the electric component surface  524 . An extending front end of the movable extraction electrode  564  forms the movable electrode pad  564 P corresponding to a connection terminal on the electric component surface  524 . The movable electrode pad  564 P is connected to the internal terminal portion  624  which is provided at the pedestal portion  621  and will be described later. 
     As illustrated in  FIG. 3 , the movable reflective film  55  is provided so as to face the fixed reflective film  54  with the gap G 1  between the reflective films at the center of the movable surface  521 A of the movable portion  521 . A reflective film having the same configuration as the above-described fixed reflective film  54  is used as the movable reflective film  55 . 
     In the same manner as in the fixed mirror electrode  541 A, the movable substrate  52  is provided with a movable mirror electrode  551  which is connected to the movable reflective film  55  and extends toward the electric component surface  524  through the opening of the C-shaped of the movable electrode  562 . An extending front end of the movable mirror electrode  551  forms the movable mirror electrode pad  551 P corresponding to a connection terminal on the electric component surface  524 . In addition, the movable mirror electrode pad  551 P is connected to the internal terminal portion  624  which is provided at the pedestal portion  621  and will be described later, and is connected to a ground circuit (not illustrated) in the same manner as the fixed mirror electrode pad  541 P. Accordingly, the movable reflective film  55  is set to a ground potential (0 V). 
     The holding portion  522  is a diaphragm which surrounds the periphery of the movable portion  521 , and is formed to have a smaller thickness dimension than that of the movable portion  521 . 
     The holding portion  522  is more easily deflected than the movable portion  521 , and can displace the movable portion  521  to the fixed substrate  51  side with a slight electrostatic attraction. At this time, the movable portion  521  has a larger thickness dimension than that of the holding portion  522 , and has an increasing rigidity. For this reason, the shape of the movable portion  521  is not changed even in a case where the holding portion  522  is pulled to the fixed substrate  51  side by an electrostatic attraction. Therefore, there is no occurrence of deflection of the movable reflective film  55  provided at the movable portion  521 , and it is possible to maintain the fixed reflective film  54  and the movable reflective film  55  in a parallel state at all times. 
     In addition, in the present embodiment, the holding portion  522  with a diaphragm shape is exemplified, but, the invention is not limited thereto and, for example, the holding portion may have a beam shape so as to be disposed at the same angle intervals centering on the plane central point O. 
     The substrate outer circumferential portion  525  is provided outside the holding portion  522  in the filter plan view as described above. A surface of the substrate outer circumferential portion  525  facing the fixed substrate  51  is provided with the second joining portion  523  facing the first joining portion  513 . In addition, the second joining film  532  is provided at the second joining portion  523 , and, as described above, the second joining film  532  is joined to the first joining film  531  so that the fixed substrate  51  and the movable substrate  52  are joined to each other. 
     Configuration of Casing 
     The casing  610  includes a base  620  and a lid  630  as illustrated in  FIG. 1 , and stores the wavelength variable interference filter  5  therein. 
     The base  620  is provided with a pedestal portion  621  and a sidewall portion  627 . 
     The pedestal portion  621  is a plate-shaped portion having a rectangular periphery in the filter plan view. The wavelength variable interference filter  5  is placed on a base inner surface  621 A of the pedestal portion  621  facing the lid  630 . The pedestal portion  621  has an opened light exit hole  622  which penetrates therethrough in the thickness direction at the center thereof. An exit side glass window  623  is joined over the light exit hole  622 . 
     In addition, the internal terminal portions  624  (corresponding to casing side terminals) which are connected to the electrode pads  541 P,  551 P,  563 P and  564 P of the wavelength variable interference filter  5  are provided on the base inner surface  621 A. The internal terminal portions  624  and the electrode pads  541 P,  551 P,  563 P and  564 P are connected to each other via wires  612  such as Au, for example, by wire bonding. In addition, in the present embodiment, the wire bonding is exemplified, but, for example, a flexible printed circuit (FPC) or the like may be used. 
     The pedestal portion  621  is provided with through-holes  625  which are formed at the positions where the internal terminal portions  624  are provided. The internal terminal portions  624  are connected to external terminal portions  626  which are provided on a base outer surface  621 B (a surface on an opposite side to the base inner surface  621 A) of the pedestal portion  621 , via the through-holes  625 . 
     The sidewall portion  627  rises from the edge of the rectangular pedestal portion  621  and covers the periphery of the wavelength variable interference filter  5  placed on the base inner surface  621 A. A surface (hereinafter, also referred to as an end surface  627 A) of the sidewall portion  627  facing the lid  630  is formed as a planarized surface which is parallel to the base inner surface  621 A. 
     The lid  630  has a rectangular periphery in the same manner as the pedestal portion  621  in the filter plan view, and is made of glass through which light can be transmitted. The lid  630  is joined to the end surface  627 A in a state in which the wavelength variable interference filter  5  is disposed on the base inner surface  621 A. A space surrounded by an inner surface  627 B of the sidewall portion  627 , the base inner surface  621 A, and the lid  630  is an inner space  611  of the casing  610 , and is sealed when the lid  630  is joined. 
     In the optical filter device  600  configured in this way, light which is incident from the lid  630  side is incident to the wavelength variable interference filter  5 . In addition, light spectrally diffracted by the wavelength variable interference filter  5  exits from the light exit hole  622 . 
     Configuration of Fixation Portion 
     The wavelength variable interference filter  5  is fixed to the casing  610  by a fixation portion  7  as illustrated in  FIGS. 1 and 2 . Specifically, the fixation portion  7  is formed by using, for example, an epoxy based or silicone based adhesive. The fixation portion  7  is provided on a side surface  517  (corresponding to a first side surface) of the fixed substrate  51  which is connected to the side between the vertexes C 1  and C 2  on an opposite side to the location where the electrode pads  541 P,  551 P,  563 P and  564 P are formed in the wavelength variable interference filter  5 . Particularly, in the illustrated example, the fixation portion  7  is provided at a single location of a central part of the side surface  517  in a direction along the side between the vertexes C 1  and C 2 . In addition, the fixation portion  7  is provided at the projecting portion  514  of the fixed substrate  51 . The fixation portion  7  configured in this way joins the side surface  517  to the inner surface  627 B of the sidewall portion  627  of the casing  610  facing the side surface  517 . 
     Manufacturing of Optical Filter Device 
     First, an adhesive for forming the fixation portion  7  is coated on the side surface  517  of the wavelength variable interference filter  5  which is created in advance. In addition, the side surface  517  is pressed against the inner surface  627 B of the sidewall portion  627  while bringing the movable substrate  52  into contact with the base inner surface  621 A. Further, the side surface  517  is joined to the inner surface  627 B by the fixation portion  7  which is formed by the cured adhesive. As mentioned above, the wavelength variable interference filter  5  is fixed to the base  620  by the fixation portion  7 . 
     Next, the electrode pads  541 P,  551 P,  563 P and  564 P of the wavelength variable interference filter  5  are connected to the internal terminal portions  624  of the base  620  via the wires  612  by wire bonding. Specifically, wires are inserted into a capillary, and balls (free air balls: FAB) are formed at front ends of the wires  612 . The capillary is moved in this state so as to bring the balls into contact with the fixed electrode pad  563 P, thereby allowing a bond to be formed. In addition, the capillary is moved so that the wires are also connected to the internal terminal portions  624 , and then the wires are cut. The same connection step is also performed on the other electrode pads  541 P,  551 P and  564 P. 
     Although a description has been made of an example in which the connection is performed by using ball bonding as the wire bonding, wedge bonding or the like may be used. In addition, connection is not limited to using the wire bonding, and, an FPC may be used, and joining may be performed by using Ag paste, an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP) or the like. 
     Then, the base  620  is joined to the lid  630 . The joining between the base  620  and the lid  630  is performed, for example, by using a low melting glass under an environment which is set to a vacuum atmosphere by a vacuum chamber device. 
     Due to the above-described steps, the optical filter device  600  is manufactured. 
     Operations and Effects of First Embodiment 
     In the present embodiment, the wavelength variable interference filter  5  is fixed to the casing  610  by the fixation portion  7  which is provided on the side surface  517  of the fixed substrate  51 . In this configuration, it is possible to minimize the occurrence of deflection of the fixed substrate  51  as compared with in a case where the fixation portion  7  is provided on the lower surface of the substrate (for example, the movable substrate  52 ) and the wavelength variable interference filter  5  is fixed to the casing, and thus to prevent a reduction in spectral accuracy of the wavelength variable interference filter  5 . 
     Hereinafter, a description will be made of a principle in which the occurrence of deflection of the fixed substrate  51  is minimized by the optical filter device  600  of the present embodiment. 
       FIG. 4  is a cross-sectional view schematically illustrating a state in which a lower surface of a substrate is fixed to a casing by a fixation portion as a comparative example. In addition,  FIG. 5  is a cross-sectional view schematically illustrating a configuration of the present embodiment. Further, in  FIG. 5 , only the fixed substrate  51  of the wavelength variable interference filter  5  is illustrated, and other members such as the movable substrate  52  are not illustrated. 
     In a case where the fixation portion  7  is provided on a lower surface  8 A of a substrate  8  as in the comparative example illustrated in  FIG. 4 , the substrate  8  receives stresses f 1  directed to a position C 5  centering on the position C 5  where the fixation portion  7  is provided. As a result, the substrate  8  is deflected in a substrate thickness direction centering on the position C 5 . 
     In contrast, as illustrated in  FIG. 5 , in a case where the fixation portion  7  is provided on the side surface  517  of the fixed substrate  51 , the fixed substrate  51  receives stresses f 2  directed to a position C 6  where the fixation portion  7  is provided from the fixation portion  7  in a direction along the side surface  517 . The stresses are forces which cause deflection of the fixed substrate  51  in a direction perpendicular to the side surface  517  centering on the position C 6 . Here, the fixed substrate  51  is a plate-shaped member, in which a dimension in the plane direction is much larger than a thickness dimension, and rigidity in the plane direction is larger than rigidity in the thickness direction. Therefore, the fixation portion  7  is provided on the side surface  517 , and thus it is possible to minimize deflection of the fixed substrate  51 . 
     As mentioned above, since deflection of the fixed substrate  51  is minimized, deflection of the movable substrate  52  joined to the fixed substrate  51  can be also minimized, and thus deterioration in an optical characteristic of the wavelength variable interference filter  5 , that is, spectral accuracy can be prevented. 
     In addition,  FIGS. 4 and 5  exemplify a case where the fixed substrate  51  receives a compression stress caused by curing of an adhesive forming the fixation portion  7 , but this is also the same for a case where the fixed substrate  51  receives a stress caused by a difference between linear expansion coefficients of the fixed substrate  51  and the fixation portion  7 . In addition, the stress caused by a difference between linear expansion coefficients may occur as a decompression stress in an opposite direction to the stress for compressing the fixed substrate  51 . For example, an expansion coefficient of the fixation portion  7  is larger than that of the fixed substrate  51 . The decompression stress is a stress which causes the substrate to be deflected in an opposite direction to the compression stress. 
     In addition, in the present embodiment, the wavelength variable interference filter  5  includes the fixed substrate  51  and the movable substrate  52 . The fixed substrate  51  and the movable substrate  52  are disposed so as to face each other, and are joined together via the joining film  53 . In this configuration, if the fixation portion  7  is provided on both side surfaces of the fixed substrate  51  and the movable substrate  52 , there is a concern that parallelism between the fixed substrate  51  and the movable substrate  52  or a gap dimension between the reflective films  54  and  55  may be changed by a stress of the fixation portion  7 . 
     In contrast, in the present embodiment, the fixation portion  7  is provided on the side surface  517  of the fixed substrate  51 , and thus a stress for displacing the fixed substrate  51  and the movable substrate  52  in contact and separation directions is not applied from the fixation portion as described above. Therefore, there is not the above-described problem, and deterioration in spectral accuracy of the wavelength variable interference filter  5  does not occur. 
     In the wavelength variable interference filter  5  of the present embodiment, the fixation portion  7  is provided at the projecting portion  514  of the fixed substrate  51  which does not overlap the movable substrate  52  in the filter plan view. In this configuration, the side surface  517  of the fixed substrate  51  provided with the fixation portion  7  can be separated from the movable substrate  52 . For this reason, an adhesive can be prevented from being spread from the side surface  517  of the fixed substrate  51  to the side surface of the movable substrate  52 , and thus it is possible to prevent simultaneous fixation of the fixed substrate  51  and the movable substrate  52  from being performed by the fixation portion  7 . Therefore, as described above, it is possible to more reliably maintain parallelism between the substrates  51  and  52 . 
     The wavelength variable interference filter  5  of the present embodiment has a configuration in which the movable portion  521  and the holding portion  522  are provided on the movable substrate  52  so as to change a dimension of the gap between the reflective films. In the wavelength variable interference filter  5 , rigidity of the fixed substrate  51  is larger than rigidity of the movable substrate  52  and has high resistance to a stress. Therefore, the fixation portion  7  is provided on the fixed substrate  51 , and therefore it is possible to more reliably minimize the occurrence of deflection and thus to prevent deterioration in spectral accuracy. 
     In the present embodiment, each of the substrates  51  and  52  has a rectangular periphery in the filter plan view, and the fixation portion  7  is provided on the side surface  517  corresponding to the side between the vertexes C 1  and C 2 . Accordingly, the fixed substrate  51  is made to close to or to be pressed against the inner surface of the casing  610  in a state in which an adhesive is coated on the side surface  517 , and thus the fixed substrate  51  can be fixed to the casing  610 . Therefore, it is possible to fix the wavelength variable interference filter  5  to the casing  610  with a simple operation. 
     Since the fixed substrate  51  is fixed to the casing at a single location, a stress applied to the fixed substrate  51  is smaller than, for example, in a case where the fixation portion  7  is provided at a plurality of locations, and it is possible to further minimize deflection of the fixed substrate  51 . 
     In addition, since the side surface  517  is planar, the fixed substrate  51  is pressed against the planar inner surface of the casing  610  after an adhesive is coated on the side surface  517 , and thus it is possible to easily align the fixed substrate  51  with the casing  610 . Also in a case where a protrusion or the like for alignment is provided on the inner surface of the casing  610 , the side surface  517  of the fixed substrate  51  is planar, and thus it is possible to easily determine a dimension of the protrusion or the like. From the above description, it becomes easier to align the fixed substrate  51 , and thus it is possible to fix the fixed substrate  51  to the casing  610  while easily performing the alignment. Therefore, it is possible to easily design the optical filter device  600  and to improve assembly efficiency. 
     Second Embodiment 
     Next, a second embodiment will be described with reference to the drawings. 
     In the present embodiment, the fixation portion  7  is provided on the side surface of the movable substrate  52  on the side (the side between the vertexes C 3  and C 4 ) where the electric component portion  526  is formed in the wavelength variable interference filter  5 . 
       FIG. 6  is a plan view illustrating a schematic configuration of an optical filter device  600 A of the second embodiment. In  FIG. 6 , the lid  630  is not illustrated. In addition, in the following description, constituent elements which have already been described are given the same reference numerals, and description thereof will not be repeated or will be made briefly. 
     In the present embodiment, as illustrated in  FIG. 6 , a base  620 A of a casing  610 A is provided with a casing side projection  628  for fixing the wavelength variable interference filter  5 . The casing side projection  628  is integrally formed with the sidewall portion  627  (a corner on the vertex C 4  side of the wavelength variable interference filter  5  in  FIG. 6 ) on the side where the internal terminal portions  624  is provided. In addition, the casing side projection  628  has a planarized surface facing the side between the vertexes C 3  and C 4  of the electric component portion  526  of the wavelength variable interference filter  5 , and the planarized surface is parallel to the arrangement direction of the internal terminal portions  624 . 
     As illustrated in  FIG. 6 , the fixation portion  7  is provided between a side surface  528  of the movable substrate  52  connected to the side between the vertexes C 3  and C 4  of the electric component portion  526  and the casing side projection  628 , and fixes the wavelength variable interference filter  5  to the casing side projection  628 . In other words, in the present embodiment, the side surface  528  corresponding to the side between the vertexes C 3  and C 4  of the movable substrate  52  corresponds to a first side surface. 
     Operations and Effects of Second Embodiment 
     In the present embodiment, the fixation portion  7  fixes the side surface  528  corresponding to the side between the vertexes C 3  and C 4  of the electric component portion  526  where the electrode pads  541 P,  551 P,  563 P and  564 P are provided, to the casing  610 A. 
     For this reason, it is possible to minimize vibration of the electric component portion  526  when an impact is applied to the wavelength variable interference filter  5  or when the electrostatic actuator  56  is driven. Therefore, it is possible to prevent a defect such as the wires  612  connected to the electrode pads  541 P,  551 P,  563 P and  564 P on the electric component portion  526  being disconnected due to the vibration. 
     Third Embodiment 
     Next, a third embodiment will be described with reference to the drawings. 
     In the second embodiment, a description has been made of an example in which the casing side projection  628  is provided only at the corner corresponding to the vertex C 4  of the wavelength variable interference filter. In contrast, the present embodiment is different from the second embodiment in that two casing side projections are provided at a base  620 B of a casing  610 B, and the fixation portions  7  are respectively provided at positions corresponding to the casing side projections. 
       FIG. 7  is a plan view illustrating a schematic configuration of an optical filter device  600 B of the third embodiment. In addition, in  FIG. 7 , the lid  630  is not illustrated. 
     In the present embodiment, as illustrated in  FIG. 7 , the base  620 B is provided with two casing side projections  628  and  629 . 
     The casing side projection  629  is formed in the same manner as the casing side projection  628 , is provided at a corner of the base  620 B corresponding to the vertex C 3  of the wavelength variable interference filter  5 , and projects toward an inner space  611  in a direction which is spaced apart from the sidewall portion  627 . In addition, the casing side projection  629  has a planarized surface facing the side between the vertexes C 3  and C 4  of the wavelength variable interference filter  5 , and the planarized surface is parallel to the arrangement direction of the internal terminal portions  624 . 
     The fixation portions  7  are respectively provided between the side surface  528  of the movable substrate  52  continued to the side between the vertexes C 3  and C 4  and the casing side projections  628  and  629 , and the wavelength variable interference filter  5  is fixed to the base  620 B by the two fixation portions  7 . 
     Operation and Effects of Third Embodiment 
     In the present embodiment, a plurality of fixation portions  7  are provided on the side surface  528 . Accordingly, it is possible to increase a fixation force to the casing  610 B and thus to more reliably fix the substrate to the casing  610 B. 
     Here, in a case where the plurality of fixation portions  7  are provided, the substrate receives stresses from the fixation portions  7 , respectively, but, as described above, it is possible to sufficiently minimize influences of the stresses by providing the fixation portions  7  on the side surface  528 . Accordingly, in the present embodiment, it is possible to improve a fixation force while minimizing defection of the substrate. 
     In addition, in the present embodiment, the plurality of fixation portions  7  are provided on a single side surface  528 . For this reason, it is possible to easily fix the wavelength variable interference filter  5  to the casing by providing the fixation portions  7  such as adhesives on at least either of the casing side projections  628  and  629  of the casing  610 B and the side surface  528  and then by pressing the wavelength variable interference filter  5  against the casing side projections  628  and  629 . 
     In the present embodiment, the movable substrate  52  is fixed to the casing  610 B at two locations on the side surface  528  with the electrode pads  541 P,  551 P,  563 P and  564 P interposed therebetween in the filter plan view. Accordingly, it is possible to more effectively minimize the above-described vibration of the electric component portion  526  side of the movable substrate  52 , and thus to more effectively prevent a defect such as disconnection of the wires  612 . 
     Fourth Embodiment 
     Next, a fourth embodiment will be described with reference to the drawings. 
     In the second and third embodiments, a description has been made of an example in which the fixation portion  7  is provided on the side surface  528  corresponding to the side between the vertexes C 3  and C 4  of the electric component portion  526 . In contrast, the present embodiment is different from the above-described embodiments in that the fixation portion  7  is provided at a part of the side between the vertexes C 1  and C 4  corresponding to the electric component portion  526 . 
       FIG. 8  is a plan view illustrating a schematic configuration of an optical filter device  600 C of the fourth embodiment. 
     As illustrated in  FIG. 8 , the fixation portion  7  is provided on a side surface  529  (a side surface connected to the side between the vertexes C 1  and C 4 ) of the electric component portion  526  intersecting the side surface  528  corresponding to the side between the vertexes C 3  and C 4 . In addition, the fixation portion  7  joins the side surface  529  to the inner surface  627 B of the sidewall portion  627  facing the side surface  529 . In other words, in the present embodiment, the side surface  529  of the movable substrate  52  corresponding to the side between the vertexes C 1  and C 4  corresponds to a first side surface. 
     Operations and Effects of Fourth Embodiment 
     In the present embodiment, the fixation portion  7  is provided at a single location of the side surface  529  of the movable substrate  52 . Accordingly, in the same manner as in the first embodiment, it is possible to perform fixation to the casing  610 , and thus to minimize deflection of the respective substrates  51  and  52  with a simple operation. 
     In the present embodiment, the fixation portion  7  is provided near the vertex C 4  of the side between the vertexes C 3  and C 4  of the electric component portion  526  on the side surface  529 . Accordingly, in the same manner as in the second embodiment, it is possible to minimize the above-described vibration of the side surface  528  side of the movable substrate  52  and thus to prevent the wires  612  from deviating. 
     Fifth Embodiment 
     Next, a fifth embodiment will be described with reference to the drawings. 
     The present embodiment is different from the fourth embodiment in that a pair of fixation portions  7  is provided at opposing positions. 
       FIG. 9  is a plan view illustrating a schematic configuration of an optical filter device  600 D of the fifth embodiment. 
     As illustrated in  FIG. 9 , the pair of fixation portions  7  are provided at mutually opposing positions of a pair of side surfaces  529 A and  529 B intersecting the side surface  528  corresponding to the side between the vertexes C 3  and C 4  in the electric component portion  526 . In other words, in the present embodiment, the side surfaces  529 A and  529 B are parallel to each other, and the side surface  529 A corresponds to a first side surface, and the side surface  529 B corresponds to a second side surface. In addition, the fixation portions  7  are formed with the electric component portion  526  interposed therebetween at positions which are symmetrical to each other with respect to a virtual plane P which passes through the plane central point O of the wavelength variable interference filter  5 . 
     Operations and Effects of Fifth Embodiment 
     In the present embodiment, the fixation portions  7  are respectively provided so as to oppose each other at the pair of side surfaces  529 A and  529 B of the movable substrate  52 . In this configuration, the plurality of fixation portions  7  are provided, and the substrate is fixed to the casing  610  at a plurality of positions. Accordingly, it is possible to increase a fixation force to the casing  610  and thus to more reliably fix the substrate to the casing  610 . 
     In addition, since the fixation portions  7  are provided at mutually opposing positions, a stress applied to the movable substrate  52  from one fixation portion  7  can be canceled out by a stress from the other fixation portion  7 , and thus to more effectively minimize deflection of the movable substrate  52 . 
     Sixth Embodiment 
     Next, a sixth embodiment will be described with reference to the drawings. 
     The present embodiment is different from the above-described embodiments in that the fixation portion is provided between the corner (vertex) of the wavelength variable interference filter and the corner of the sidewall portion of the base. 
       FIG. 10  is a plan view illustrating a schematic configuration of an optical filter device  600 E of the sixth embodiment. 
     In the present embodiment, as illustrated in  FIG. 10 , the fixation portion  7  includes a corner  519  at which a vertex (for example, the vertex C 2 ) of the fixed substrate  51  is located, and is provided over the side surfaces  517  and  518  adjacent to the corner  519 . In addition, the fixation portion  7  joins the side surfaces  517  and  518  to the inner surface  627 B of the sidewall portion  627  at the corner  519 . In other words, in the present embodiment, the side surface  517  corresponds to a first side surface. Further, the side surface  518  corresponds to a third side surface, and intersects the side surface  517  along the plane intersecting the side surface  517  so as to form the corner  519 . The fixation portion  7  is provided over the side surface  517  (first side surface) and the side surface  518  (third side surface). 
     Operations and Effects of Sixth Embodiment 
     In the present embodiment, the fixation portion  7  is provided across the corner  519  of the fixed substrate  51  over the two adjacent side surfaces  517  and  518 . In this configuration, in the same manner as in the first, second and fourth embodiments in which the fixation portion is provided only on a single side surface of the substrate, it is possible to perform fixation of the wavelength variable interference filter  5  with a simple operation in which the fixed substrate  51  coated with an adhesive is pressed against the inner surface  627 B. 
     In addition, since the fixed substrate  51  is fixed to the casing  610  at a plurality of positions of the two side surfaces  517  and  518 , it is possible to increase a fixation force to the casing  610  and thus to more reliably fix the wavelength variable interference filter  5  to the casing  610 . 
     The wavelength variable interference filter  5  is provided with main members which have influence on spectral accuracy of the wavelength variable interference filter  5 , such as the respective reflective films  54  and  55  or the movable portion  521  and the holding portion  522  forming the electrostatic actuator, centering on the plane central point O. 
     In addition, since the fixation portion  7  is disposed at the corner  519  which is spaced apart from the central position (plane central point O) of the fixed substrate  51  in the filter plan view, it is possible to minimize delivery of a stress of the fixation portion  7  to the main members provided around the plane central point O and thus to more effectively prevent a reduction in spectral accuracy. 
     Seventh Embodiment 
     Next, a seventh embodiment will be described with reference to the drawings. 
     In the above-described respective embodiments, the casing has the sidewall portion  627  to which the wavelength variable interference filter  5  can be fixed, and the wavelength variable interference filter  5  is fixed to the inner surface  627 B of the sidewall portion  627  by the fixation portion  7 . In an optical filter device of the present embodiment, the casing does not have the sidewall portion to which the wavelength variable interference filter  5  can be fixed, and, alternatively, has a support portion which supports the wavelength variable interference filter  5 . 
       FIG. 11  is a cross-sectional view illustrating a schematic configuration of an optical filter device  600 F of the seventh embodiment. 
     As illustrated in  FIG. 11 , the optical filter device  600 F includes the wavelength variable interference filter  5  and a casing  640  which stores the wavelength variable interference filter  5  therein. 
     The casing  640  is provided with abase substrate  650 , a lid  660 , abase side glass substrate  670 , and a lid side glass substrate  680 . 
     The base substrate  650  is provided with the movable substrate  52  of the wavelength variable interference filter  5 , and is formed of, for example, a single layer ceramic substrate. In addition, a light passing hole  651  is opened and formed on the base substrate  650  in a region opposing an effective region Ar 0 . In addition, the base side glass substrate  670  is joined so as to cover the light passing hole  651 . A joining method of the base side glass substrate  670  may use, for example, glass frit joining using a glass frit which is a piece of glass obtained by melting a glass raw material at a high temperature and then rapidly cooling the material, joining using an epoxy resin, or the like. 
       FIG. 12  is a plan view illustrating the base substrate  650  and the wavelength variable interference filter  5  disposed on the base substrate  650 . 
     As illustrated in  FIG. 12 , internal terminal portions  654  are provided so as to respectively correspond to the electrode pads  541 P,  551 P,  563 P and  564 P of the wavelength variable interference filter  5  on a base inner surface  652  of the base substrate  650  facing the lid  660 . In addition, connection between respective extraction electrodes  563  and  564  and the internal terminal portions  654  are performed by using wire bonding. Further, connection is not limited to using the wire bonding, and, for example, an FPC or the like may be used. 
     In addition, the base substrate  650  is provided with through-holes (not illustrated) so as to respectively correspond to the internal terminal portions  654 . The internal terminal portions  654  are connected to external terminal portions  655  (refer to  FIG. 11 ) which are provided on a base outer surface  653  on an opposite side to the base inner surface  652  of the base substrate  650  via conductive members which fill the through-holes. 
     Further, a base joining portion  656  which is joined to the lid  660  is provided at the outer circumference of the base substrate  650 . 
     As illustrated in  FIG. 12 , the base substrate  650  is provided with a support portion  690  which supports the wavelength variable interference filter  5  and fixes the wavelength variable interference filter  5  to the casing  640 . The support portion  690  has, for example, a rectangular parallelepiped shape, and is provided at a position adjacent to the internal terminal portions  654  in the filter plan view. The support portion  690  has a side surface  691  facing the wavelength variable interference filter  5  as a planarized surface, and the planarized surface is provided so as to be parallel to the arrangement direction of the plurality of internal terminal portions  654 . The side surface  528  of the movable substrate  52  of the wavelength variable interference filter  5  is fixed to the side surface  691  by the fixation portion  7 , and is fixed to the casing  640  via the support portion  690 . The support portion  690  may be formed of, for example, a ceramic and may be provided separately from the base substrate  650 , and a part of the base substrate  650  may be made to protrude so as to be used as the support portion  690 . 
     As illustrated in  FIG. 11 , the lid  660  includes a lid joining portion  662  which is joined to the base joining portion  656 , a sidewall portion  663  which rises from the lid joining portion  662 , and a ceiling portion  664  which is continued to the sidewall portion  663  and covers the wavelength variable interference filter  5 . The lid  660  is made of, for example, an alloy such as Kovar, or a metal. 
     The lid  660  is closely joined to the base substrate  650  through joining between the lid joining portion  662  and the base joining portion  656  of the base substrate  650 . 
     A joining method thereof may use, for example, not only laser welding, but also soldering using silver solder, sealing using a eutectic alloy layer, welding using a low melting point glass, glass attachment, glass frit joining, adhesion using an epoxy resin, and the like. These joining methods may be selected as appropriate depending on materials of the base substrate  650  and the lid  660 , joining circumstances, and the like. 
     The ceiling portion  664  of the lid  660  is parallel to the base substrate  650 . A light passing hole  661  is opened and formed in a region facing the effective region Ar 0  of the wavelength variable interference filter  5  at the ceiling portion  664 . In addition, the lid side glass substrate  680  is joined so as to cover the light passing hole  661 . A joining method of the lid side glass substrate  680  may use, for example, glass frit joining, adhesion using an epoxy resin or the like, and the like in the same manner as the joining of the base side glass substrate  670 . 
     Operations and Effects of Seventh Embodiment 
     In the present embodiment, the casing  640  includes the support portion  690  which supports the wavelength variable interference filter  5 , and the wavelength variable interference filter  5  is fixed to the support portion  690  by the fixation portion  7 . Accordingly, even in a configuration of the casing  640  in which the base substrate  650  on which the wavelength variable interference filter  5  is disposed does not have a sidewall portion, fixation of the side surface of the movable substrate  52  of the wavelength variable interference filter  5  can be performed by the fixation portion  7 . 
     Eighth Embodiment 
     Next an eighth embodiment will be described with reference to the drawings. 
     In the eighth embodiment, a description will be made of a colorimetry sensor  3  which is an optical module into which the optical filter device  600  of the first embodiment is incorporated, and a colorimetry apparatus  1  into which the optical filter device  600  is incorporated. 
     Schematic Configuration of Colorimetry Apparatus 
       FIG. 13  is a block diagram illustrating a schematic configuration of the colorimetry apparatus  1 . 
     The colorimetry apparatus  1  is an example of an electronic apparatus. The colorimetry apparatus  1 , as illustrated in  FIG. 13 , includes a light source device  2  which emits light to an inspection target X, a colorimetry sensor  3 , and a control device  4  which controls an entire operation of the colorimetry apparatus  1 . In addition, the colorimetry apparatus  1  is an apparatus in which light emitted from the light source device  2  is reflected by the inspection target X, and reflected inspection target light is received by the colorimetry sensor  3 . Further, the colorimetry apparatus  1  analyzes and measures a chromaticity of the inspection target light, that is, a color of the inspection target X on the basis of a detection signal output from the colorimetry sensor  3  which has received the light. 
     Configuration of Light Source Device 
     The light source device  2  includes a light source  21  and a plurality of lenses  22  (only one lens is illustrated in  FIG. 13 ), and emits, for example, white light to the inspection target X. In addition, the plurality of lenses  22  may include a collimator lens, and, in this case, the light source device  2  converts the white light emitted from the light source  21  into parallel light by using the collimator lens, and emits the parallel light toward the inspection target X from a projection lens (not illustrated). Further, in the present embodiment, the colorimetry apparatus  1  including the light source device  2  is exemplified, but, for example, in a case where the inspection target X is a light emitting member such as a liquid crystal panel, the light source device  2  may not be provided. 
     Configuration of Colorimetry Sensor 
     The colorimetry sensor  3  constitutes an optical module, and includes the optical filter device  600  of the first embodiment. The colorimetry sensor  3 , as illustrated in  FIG. 13 , includes the optical filter device  600 , a detection unit  31  which receives light transmitted through the optical filter device  600 , and a voltage control unit  32  which changes a wavelength of light transmitted through the wavelength variable interference filter  5 . 
     In addition, the colorimetry sensor  3  includes an incidence optical lens (not illustrated) which guides light (inspection target light) reflected by the inspection target X to inside thereof at a position opposing the wavelength variable interference filter  5 . Further, in the colorimetry sensor  3 , light of a predetermined wavelength among inspection target light beams which are incident from the incidence optical lens is spectrally diffracted by the wavelength variable interference filter  5  of the optical filter device  600 , and the spectrally diffracted light is received by using the detection unit  31 . 
     The detection unit  31  is formed by a plurality of photoelectric conversion elements, and generates an electrical signal corresponding to a light reception amount. Here, the detection unit  31  is connected to the control device  4 , for example, via a circuit board  311 , and outputs the generated electrical signal to the control device  4  as a light reception signal. 
     In addition, the external terminal portions  626  formed on the base outer surface  621 B of the casing  610  is connected to the circuit board  311 , and is connected to the voltage control unit  32  via circuits formed on the circuit board  311 . 
     In this configuration, the optical filter device  600  and the detection unit  31  can be integrally formed via the circuit board  311 , and thus it is possible to simplify a configuration of the colorimetry sensor  3 . 
     The voltage control unit  32  is connected to the external terminal portions  626  of the optical filter device  600  via the circuit board  311 . In addition, the voltage control unit  32  applies a predetermined step voltage between the fixed electrode pad  563 P and the movable electrode pad  564 P on the basis of a control signal input from the control device  4 , so as to drive the electrostatic actuator  56 . Accordingly, an electrostatic attraction occurs in the gap between the electrodes so as to deflect the holding portion  522 , and thus the movable portion  521  is displaced to the fixed substrate  51  side, thereby allowing the gap G 1  between the reflective films to be set to a desired dimension. 
     Configuration of Control Device 
     The control device  4  is controls an entire operation of the colorimetry apparatus  1 . 
     As the control device  4 , for example, a general purpose personal computer, a portable information terminal, a colorimetry-dedicated computer, or the like may be used. 
     In addition, the control device  4 , as illustrated in  FIG. 13 , includes a light source control unit  41 , a colorimetry control unit  42 , a colorimetry processing unit  43 , and the like. 
     The light source control unit  41  is connected to the light source device  2 . In addition, the light source control unit  41  outputs a predetermined control signal to the light source device  2  on the basis of, for example, an input set by a user, so as to allow white light with predetermined brightness to be emitted from the light source device  2 . 
     The colorimetry control unit  42  is connected to the colorimetry sensor  3 . In addition, the colorimetry control unit  42  sets a wavelength of light which is to be received by the colorimetry sensor  3  on the basis of, for example, an input set by a user, and outputs a control signal for detecting a light reception amount of the light with the wavelength to the colorimetry sensor  3 . Accordingly, the voltage control unit  32  of the colorimetry sensor  3  sets a voltage applied to the electrostatic actuator  56  so that only the wavelength of light desired by the user is transmitted, on the basis of the control signal. 
     The colorimetry processing unit  43  analyzes a chromaticity of the inspection target X on the basis of the light reception amount detected by the detection unit  31 . 
     Operations and Effects of Eighth Embodiment 
     The colorimetry apparatus  1  of the present embodiment includes the optical filter device  600  which is the same as that of the first embodiment. As described above, according to the optical filter device  600 , since the fixation portion  7  is provided on the side surface  517  of the fixed substrate  51  of the wavelength variable interference filter  5  so that the wavelength variable interference filter  5  is fixed to the casing  610 , it is possible to minimize deflection of the fixed substrate  51  and the movable substrate  52 . For this reason, it is possible to prevent deterioration in spectral accuracy of the wavelength variable interference filter  5 . In addition, since the optical filter device  600  has high air-tightness of the inner space, and has no permeation of a foreign substance such as a water particle, it is also possible to prevent optical characteristics of the wavelength variable interference filter  5  from being changed by such a foreign substance. Therefore, also in the colorimetry sensor  3 , it is possible to detect light with a desired wavelength extracted with a high resolution by using the detection unit  31  and thus to detect an accurate light amount for the light with the desired wavelength. Accordingly, the colorimetry apparatus  1  can perform accurate color analysis of the inspection target X. 
     Modifications of Embodiments 
     In addition, the invention is not limited to the above-described embodiments, and modifications, alterations, and the like in the scope in which the object of the invention can be achieved are included in the invention. 
     For example, in the above-described respective embodiments, fixation of either of the fixed substrate  51  and the movable substrate  52  is performed by the fixation portion  7 , but the invention is not limited thereto, and fixation of both of the fixed substrate  51  and the movable substrate  52  may be performed by the fixation portion  7 . However, in this case, if a material having a linear expansion coefficient which is considerably different from that of the fixed substrate  51  or the movable substrate  52  is used, or an adhesive having a greater compression force in the thickness direction than rigidity of the joining film  53  is used as the fixation portion  7 , this causes the fixed substrate  51  and the movable substrate  52  to be tilted or a gap dimension to be changed. Therefore, as in the above-described respective embodiments, the fixation portion  7  is preferably provided on either of the fixed substrate  51  and the movable substrate  52 . 
     In the respective embodiments excluding the sixth embodiment, one or two fixation portions  7  are provided on any one of the side surfaces  517  and  518  of the fixed substrate  51  and the side surfaces  528  and  529  of the movable substrate  52 , but the invention is not limited thereto. For example, three or more fixation portions  7  may be provided on any one of the side surfaces of the respective substrates  51  and  52 . In addition, one entire side surface may be covered with a single fixation portion  7 , and any area of a single fixation portion  7  may be set. It is possible to improve a fixation force by increasing the number of fixation portions  7  or an area of a single fixation portion  7 . However, from the viewpoint of minimizing application of a stress to the substrates  51  and  52  from the fixation portion  7 , a joining area of the fixation portion  7  is preferably reduced by reducing the number of fixation portions  7  and reducing an area of a single fixation portion  7 . In addition, in the configuration of the seventh embodiment, a plurality of support portions  690  may be provided in accordance with fixation positions. 
     In the fifth embodiment, the fixation portions  7  are respectively provided near the vertexes C 3  and C 4  adjacent to each other of the rectangular movable substrate  52 , but the invention is not limited thereto, and a plurality of fixation portions may be provided so that a plurality of sets each of which includes a pair of mutually opposing fixation portions are formed. 
     For example, the fixation portions  7  may be respectively provided near the vertexes C 1  and C 2  adjacent to each other of the fixed substrate  51 . 
     In the sixth embodiment, the fixation portion  7  is provided at a single corner, but the invention is not limited thereto, and the fixation portions  7  may be provided at a plurality of corners. In addition, the fixation portions  7  may be provided not only at the corners but also on the side surfaces. 
     For example, the fixation portions  7  may be provided at positions of the vertexes C 2  and C 3  of the fixed substrate  51 . In addition, as described in the second embodiment, there may be a configuration in which the casing side projection  628  and the fixation portion  7  is provided at a position of the vertex C 3  of the movable substrate  52 , a configuration in which the casing side projections  628  and  629  are provided and the fixation portions  7  are provided at the vertexes C 3  and C 4  of the movable substrate  52 , or the like. 
     In the above-described respective embodiments, a configuration has been exemplified in which the wavelength variable interference filter  5  is provided in the casing so that the movable substrate  52  is in contact with the pedestal portion  621  of the base  620 , but the invention is not limited thereto. For example, the wavelength variable interference filter  5  may be provided in the casing so that the fixed substrate  51  is in contact with the pedestal portion  621 . 
     In addition, as in the above-described respective embodiments, an opening edge of the light exit hole  622  may be disposed at a position of the movable substrate  52  opposing the holding portion  522  by disposing the movable substrate  52  at the pedestal portion  621 . In this case, for example, even in a case where protrusions occur such as burrs along the opening edge when the base  620  is formed, the protrusions can be released to an etching space of the holding portion  522 , and thus it is possible to minimizing tilting or the like of the movable substrate  52 . 
     In the above-described respective embodiments, a configuration has been exemplified in which a voltage is applied to the fixed electrode  561  and the movable electrode  562  of the wavelength variable interference filter  5  so that a size of the gap G 1  between the reflective films is changed by an electrostatic attraction, but the invention is not limited thereto. For example, a dielectric actuator, in which a first dielectric coil is disposed instead of the fixed electrode  561 , and a second dielectric coil or a permanent magnet is disposed instead of the movable electrode  562 , may be used as an actuator which changes the gap G 1  between the reflective films. 
     In addition, a piezoelectric actuator may be used instead of the electrostatic actuator  56 . In this case, for example, a lower electrode layer, a piezoelectric film, and an upper electrode layer may laminated and disposed at the holding portion  522 , and a voltage applied between the lower electrode layer and the upper electrode layer is varied as an input value so as to expand and contract the piezoelectric film, thereby deflecting the holding portion  522 . 
     In the above-described respective embodiments, the wavelength variable interference filter  5  which allows a size of the gap G 1  between the reflective films to be changed has been exemplified, but the invention is not limited thereto, and an interference filter in which a size of the gap G 1  between the reflective films is not changed may be used. 
     In addition, in the above-described respective embodiments, the wavelength variable interference filter  5  provided with the rectangular substrates  51  and  52  has been exemplified, but the invention is not limited thereto. For example, a shape of each of the substrates  51  and  52  in the filter plan view may be not only a rectangular shape but also various polygonal shapes, and may be a circular shape or an elliptical shape. Further, the substrates  51  and  52  may have a curved side surface. 
     Furthermore, in the above-described respective embodiments, the wavelength variable interference filter  5  has been exemplified which includes the pair of substrates  51  and and the pair of reflective films  54  and  55  which are respectively provided on the substrates  51  and  52 , but the invention is not limited thereto. For example, the movable substrate  52  may not be provided, and the fixed substrate  51  may be fixed to the casing  610 . In this case, for example, a first reflective film, a gap spacer, and a second reflective film are laminated and formed on one surface of a substrate (for example, the fixed substrate), and the first reflective film and the second reflective film oppose each other with a gap. The configuration is formed by using a single substrate, and thus it is possible to further thin a spectroscopic element. 
     In addition, in the above-described respective embodiments, the optical filter device has been exemplified in which the wavelength variable interference filter or the interference filter is stored in the casing, but the invention is not limited thereto. 
     For example, the invention is also suitably applicable to a MEMS device in which a MEMS element is stored in a casing. 
     The MEMS element may exemplify an optical element such as, for example, a mirror device which can minutely change a light reflection direction. Also in this configuration, it is possible to minimize deflection of a substrate included in the optical element, and thus to prevent a stress from being applied to an optical member included in the optical element. Therefore, it is possible to prevent deterioration optical characteristics of the optical element. 
     Further, the MEMS element may exemplify various MEMS elements which are stored in a casing for the purpose of performance improvement, deterioration prevention, or the like, such as a piezoelectric vibration element (for example, a quartz crystal vibrator, a ceramic vibrator, or a silicon vibrator), a pressure sensor element, an acceleration sensor element, or a gyro sensor element. 
     In the piezoelectric vibration element, it is possible to minimize deflection of a substrate so as to minimize application of a stress to a vibrator, and thus to prevent a vibration characteristic from being changed. In the pressure sensor element, it is possible to minimize application of a stress to a diaphragm, and thus it is possible to prevent a reduction in detection accuracy due to deformation of the diaphragm. Also in the acceleration sensor element or the gyro sensor element, similarly, it is possible to minimize application of a stress to a detection unit which is provided on the substrate so as to detect acceleration or angular velocity, and thus it is possible to prevent a reduction in detection accuracy. 
     In addition, the colorimetry apparatus  1  has been exemplified as the electronic apparatus in the eighth embodiment, but the optical filter device, the optical module, and the electronic apparatus may be used in various fields. 
     Hereinafter, modification examples of the electronic apparatus using the optical filter device will be described. In addition, the electronic apparatuses exemplified below include the optical filter device  600 , and the wavelength variable interference filter  5  is fixed to the casing  610  by the fixation portion  7 . 
     The electronic apparatus may be used as an optical base system for detecting presence of a specific substance. Such a system may exemplify an in-vehicle gas leakage detector which employs a spectrometry method using, for example, the wavelength variable interference filter included in the optical filter device, and detects a specific gas with high sensitivity, or a gas detection apparatus such as a photoacoustic rare gas detector for testing expiration. 
     An example of such a gas detection apparatus will be described below with reference to the drawings. 
       FIG. 14  is a schematic diagram illustrating an example of a gas detection apparatus having the wavelength variable interference filter. 
       FIG. 15  is a block diagram illustrating a configuration of a control system of the gas detection apparatus of  FIG. 14 . 
     The gas detection apparatus  100 , as illustrated in  FIG. 14 , includes a sensor chip  110 , a flow channel  120  having a suction port  120 A, a suction flow channel  120 B, a discharge flow channel  120 C, and a discharge port  120 D, and a main body  130 . 
     The main body  130  is constituted by a detection device including a sensor unit cover  131  having an opening which allows the flow channel  120  to be attachable and detachable, a discharge unit  133 , a casing  134 , an optical unit  135 , a filter  136 , the optical filter device  600 , a light reception element  137  (detection unit), and the like; a controller  138  which controls the detection unit; a power supply unit  139  which supplies power; and the like. In addition, the optical unit  135  includes a light source  135 A which emits light; a beam splitter  135 B which reflects light incident from the light source  135 A to the sensor chip  110  side and transmits light incident from the sensor chip side through the light reception element  137  side; and lenses  135 C,  135 D and  135 E. 
     In addition, as illustrated in  FIG. 14 , an operation panel  140 , a display unit  141 , a connection unit  142  for interfacing with external devices, and the power supply unit  139  are provided on a surface of the gas detection apparatus  100 . In a case where the power supply unit  139  is a secondary battery, a connection unit  143  for charging may be provided. 
     Further, the controller  138  of the gas detection apparatus  100 , as illustrated in  FIG. 15 , includes a signal processing unit  144  constituted by a CPU and the like; a light source driver circuit  145  which controls the light source  135 A; a voltage control unit  146  which controls the wavelength variable interference filter  5  of the optical filter device  600 ; a light reception circuit  147  which receives a signal from the light reception element  137 ; a sensor chip detection circuit  149  receiving a signal from a sensor chip detector  148  which reads a code of the sensor chip  110  and detects presence or absence of the sensor chip  110 ; a discharge driver circuit  150  which controls the discharge unit  133 ; and the like. 
     Next, an operation of the above-described gas detection apparatus  100  will be described below. 
     The sensor chip detector  148  is provided inside the sensor unit cover  131  on the upper part of the main body  130 , and detects presence or absence of the sensor chip  110 . When a detection signal from the sensor chip detector  148  is detected, the signal processing unit  144  determines that the sensor chip  110  is installed, and outputs a display signal for displaying that a detection operation can be performed on the display unit  141 . 
     In addition, for example, when the operation panel  140  is operated by a user, and an instruction signal indicating that a detection process starts is output from the operation panel  140  to the signal processing unit  144 , first, the signal processing unit  144  outputs a signal for starting the light source to the light source driver circuit  145  so as to start the light source  135 A. When the light source  135 A starts to be driven, laser light having a single wavelength and stable linear polarization is emitted from the light source  135 A. In addition, the light source  135 A has a built-in temperature sensor or a light amount sensor, and outputs information thereon to the signal processing unit  144 . Further, the signal processing unit  144  controls the discharge driver circuit  150  so as to start the discharge unit  133  when it is determined that the light source  135 A is stably operated on the basis of a temperature or a light amount input from the light source  135 A. Accordingly, a gas sample including a target substance (gas molecules) to be detected is guided from the suction port  120 A to the suction flow channel  120 B, the inside of the sensor chip  110 , the discharge flow channel  120 C, and the discharge port  120 D. Furthermore, the suction port  120 A is provided with a dust removing filter  120 A 1 , and relatively large dust, some water vapor, or the like is removed. 
     The sensor chip  110  is a sensor into which a plurality of metal nano-structure bodies are incorporated, and which uses localized surface plasmon resonance. In this sensor chip  110 , if an enhanced electric field is formed between the metal nano-structure bodies by laser light, and gas molecules enter the enhanced electric field, Raman scattering light and Rayleigh scattering light including molecular vibration information are generated. 
     The Raman scattering light and Rayleigh scattering light are incident to the filter  136  through the optical unit  135  so that the Rayleigh scattering light is separated by the filter  136 , and the Raman scattering light is incident to the optical filter device  600 . In addition, the signal processing unit  144  controls the voltage control unit  146  so as to adjust a voltage applied to the wavelength variable interference filter  5  of the optical filter device  600 , and thus the Raman scattering light corresponding to the gas molecule which is a detection target is spectrally diffracted by the wavelength variable interference filter  5  of the optical filter device  600 . Next, when the spectrally diffracted light is received by the light reception element  137 , a light reception signal corresponding to the light reception amount is output to the signal processing unit  144  via the light reception circuit  147 . 
     The signal processing unit  144  compares spectral data on the Raman scattering light corresponding to the gas molecule which is a detection target, obtained in this way, with data stored in a ROM, and determines whether or not the gas molecule is a target gas molecule so as to specify a substance. In addition, the signal processing unit  144  displays result information on the display unit  141 , or outputs the result information from the connection unit  142  to an external device. 
     In addition, in  FIGS. 14 and 15 , the gas detection apparatus  100  has been exemplified in which Raman scattering light is spectrally diffracted by the wavelength variable interference filter  5  of the optical filter device  600 , and a gas is detected from the spectrally diffracted Raman scattering light. In addition, a gas detection apparatus may be used which specifies the kind of gas by detecting absorbance unique to a gas. In this case, a gas sensor, which allows a gas to flow into the sensor and detects light which is absorbed by the gas among incident light beams, is used as the optical module. In addition, a gas detection apparatus which analyzes and discriminates the gas which is made to flow into the sensor by the gas sensor is used as the electronic apparatus. Also with this configuration, it is possible to detect a component of a gas by using the wavelength variable interference filter. 
     In addition, a system for detecting presence of a specific substance is not limited to the above-described gas detection apparatus, and may exemplify a substance component analysis apparatus such as an apparatus for noninvasive measurement of a saccharide using near-infrared spectroscopy, or an apparatus for noninvasive measurement of information on food, a living body, a mineral, or the like. 
     Hereinafter, a food analysis apparatus will be described as an example of the substance component analysis apparatus. 
       FIG. 16  is a diagram illustrating a schematic configuration of a food analysis apparatus which is an example of the electronic apparatus using the optical filter device  600 . 
     The food analysis apparatus  200 , as illustrated in  FIG. 16 , includes a detector  210  (optical module), a controller  220 , and a display unit  230 . The detector  210  includes alight source  211  which emits light; an imaging lens  212  into which light from a measurement target object is introduced; the optical filter device  600  which spectrally diffracts the light introduced from the imaging lens  212 ; and an imaging unit  213  (detection unit) which detects the spectrally diffracted light. 
     In addition, the controller  220  includes a light source control unit  221  which controls turning on and off the light source  211  and controls brightness during turning-on of the light source; a voltage control unit  222  which controls the wavelength variable interference filter  5  of the optical filter device  600 ; a detection control unit  223  which controls the imaging unit  213  so as to acquire a spectroscopic image captured by the imaging unit  213 ; a signal processing unit  224 ; and a storage unit  225 . 
     When the system of the food analysis apparatus  200  is driven, the light source  211  is controlled by the light source control unit  221 , and thus a measurement target object is irradiated with light by the light source  211 . In addition, light reflected by the measurement target object is incident to the optical filter device  600  through the imaging lens  212 . A voltage which allows a desired wavelength to be spectrally diffracted is applied to the wavelength variable interference filter  5  of the optical filter device  600  under the control of the voltage control unit  222 , and the spectrally diffracted light is imaged by the imaging unit  213  formed by, for example, a CCD camera or the like. Further, the imaged light is accumulated in the storage unit  225  as a spectroscopic image. The signal processing unit  224  controls the voltage control unit  222  so as to change a value of a voltage applied to the wavelength variable interference filter  5 , thereby acquiring a spectroscopic image for each wavelength. 
     The signal processing unit  224  performs a calculation process on pixel data of each image accumulated in the storage unit  225  so as to obtain a spectrum of each pixel. In addition, the storage unit  225  stores, for example, information regarding a component of food for a spectrum, and the signal processing unit  224  analyzes data on the obtained spectrum on the basis of the information regarding food stored in the storage unit  225  so as to obtain a food component included in a detection target and a content thereof. Further, food calorie, freshness, and the like can be calculated from the obtained food component and the content thereof. Furthermore, it is possible to perform extraction or the like of a part whose freshness is reduced in food which is an inspection target by analyzing a spectral distribution in an image, and it is also possible to detect a foreign substance included in the food. 
     In addition, the signal processing unit  224  performs a process of displaying information such as the component of the food which is an inspection target, the content, the calorie, and the freshness obtained in the above-described way on the display unit  230 . 
     In addition, in  FIG. 16 , the food analysis apparatus  200  is exemplified, but may also be used as an apparatus for noninvasive measurement of the above-described other information by using the substantially same configuration. For example, the food analysis apparatus may be used as a living body analysis apparatus which performs analysis of a living body component, such as analysis and measurement of a component of a body fluid such as blood. If such a living body analysis apparatus is used as an apparatus which measures a component of a body fluid such as blood so as to detect ethyl alcohol therein, the apparatus may be used as an intoxicated driving prevention apparatus which detects a drunken state of a driver. Further, the food analysis apparatus may also be used as an electronic endoscope system including such a living body analysis apparatus. 
     In addition, the food analysis apparatus may also be used as a mineral analysis apparatus which performs a mineral component analysis. 
     Further, the wavelength variable interference filter, the optical module, and the electronic apparatus are applicable to the following apparatuses. 
     For example, data can be transferred by light with each wavelength by changing an intensity of the light of each wavelength over time. In this case, light with a specific wavelength is spectrally diffracted by the wavelength variable interference filter provided in an optical module and is received by a light reception unit, and thus data transferred by the light with a specific wavelength can be extracted. Therefore, data of light with each wavelength is processed by an electronic apparatus having the data extraction optical module, thereby allowing optical communication to be performed. 
     In addition, the electronic apparatus is applicable to a spectroscopic camera, a spectroscopic analyzer, and the like which capture a spectroscopic image by spectrally diffracting light with the wavelength variable interference filter included in the optical filter device. An example of the spectroscopic camera may include an infrared camera which has the built-in wavelength variable interference filter. 
       FIG. 17  is a diagram illustrating a schematic configuration of a spectroscopic camera. The spectroscopic camera  300 , as illustrated in  FIG. 17 , includes a camera main body  310 , an imaging lens unit  320 , and an imaging unit  330  (detection unit). 
     The camera main body  310  is a part held and operated by a user. 
     The imaging lens unit  320  is provided in the camera main body  310 , and guides incident image light to the imaging unit  330 . In addition, the imaging lens unit  320 , as illustrated in  FIG. 17 , includes an objective lens  321 , an image forming lens  322 , and the optical filter device  600  provided between the lenses. 
     The imaging unit  330  is formed by a light reception element, and images the image light guided by the imaging lens unit  320 . 
     In the spectroscopic camera  300 , the wavelength variable interference filter  5  of the optical filter device  600  transmits light with a wavelength which is an imaging target therethrough, and thus it is possible to capture a spectroscopic image of light with a desired wavelength. 
     In addition, the wavelength variable interference filter included in the optical filter device may be used as a band-pass filter, and may be used in, for example, an optical laser apparatus in which, among light beams in a predetermined wavelength band emitted by a light emitting element, only light in a narrow band centering on a predetermined wavelength is spectrally diffracted and transmitted by the wavelength variable interference filter. 
     Further, the wavelength variable interference filter included in the optical filter device may be used in a living body authentication apparatus, and is also applicable to, for example, authentication apparatuses of a blood vessel, a fingerprint, retina, iris, and the like, using light in a near-infrared region or a visible region. 
     Furthermore, the optical module and the electronic apparatus may be used as a concentration detection apparatus. In this case, infrared energy (infrared light) emitted from a substance is spectrally diffracted and analyzed by the wavelength variable interference filter, and thus a subject concentration in a sample is measured. 
     As described above, the optical filter device and the electronic apparatus which are examples of the MEMS device are applicable to any apparatus which spectrally diffracts predetermined light from incident light. In addition, the optical filter device can spectrally diffract a plurality of wavelengths with a single device as described above, and thus it is possible to measure spectra of a plurality of wavelengths and detect a plurality of components with high accuracy. Therefore, miniaturization of an optical module or an electronic apparatus can be promoted as compared with an apparatus of the related art which extracts a desired wavelength by using a plurality of devices, and thus the optical filter device or the electronic apparatus can be suitably used as, for example, a portable or in-vehicle electronic apparatus. 
     In the above description of the colorimetry apparatus  1 , the gas detection apparatus  100 , the food analysis apparatus  200 , and the spectroscopic camera  300 , an example in which the optical filter device  600  of the first embodiment is applied thereto has been described, and the invention is not limited thereto. Of course, the optical filter devices of the other embodiments may be applied to the colorimetry apparatus  1  and the like as described above. 
     In addition, a specific structure at the time of implementing the invention may be configured by combining the respective embodiments and modification examples as appropriate within the scope in which the object of the invention can be achieved, and may be changed to other structures as appropriate.