Spectroscopic device and spectroscopic camera

Abstract

To provide a spectroscopic device that can prevent deflection of a substrate of an interference filter regardless of the type of an adhesive for bonding the interference filter to a housing, ensure sufficient bond strength, and maintain the high resonance frequency of the interference filter, and provide a spectroscopic camera.SOLUTION: A spectroscopic device comprises: an interference filter that includes a first substrate, a first reflection coating provided on the first substrate, and a second reflection coating opposite to the first reflection coating; a housing that accommodates the interference filter; and a bonding part that fixes the interference filter to the housing. The housing has a base part opposite to the first substrate. An area where the first reflection coating and the second reflection coating overlap each other when seen from a first direction directed from the first reflection coating to the second reflection coating is defined an optical area. When seen from the first direction, the bonding part includes a first bonding part provided on a first virtual line along an outer peripheral edge of the first substrate, and a second bonding part provided on a second virtual line along an outer peripheral edge of the optical area.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a spectroscopic device and a spectroscopic camera. [Background technology]

[0002] Conventionally, some spectroscopic cameras that capture spectroscopic images and measuring instruments that perform spectroscopic measurements use Fabry-Perot etalons as spectroscopic devices. Such Fabry-Perot etalons are usually housed in a package housing and incorporated into devices in order to improve drive response when switching the wavelength of transmitted light, to suppress the inclusion of stray light, and to protect the Fabry-Perot etalon from external forces due to contact or the like (see, for example, Patent Document 1). The photodetector described in Patent Document 1 houses a Fabry-Perot etalon in a CAN package having a stem and a cap. Specifically, a wiring board is fixed to the stem, and the Fabry-Perot etalon is adhesively fixed via a pair of spacers arranged on the wiring board. The spacers are arranged to support a pair of opposing sides of the rectangular Fabry-Perot etalon. An adhesive member is arranged from the entire surface of the spacer facing the Fabry-Perot etalon to the side surface of the Fabry-Perot etalon, and fixes the Fabry-Perot etalon to the spacer. The photodetector of Patent Document 1 aims to improve temperature characteristics by having the adhesive member absorb the stress acting on the Fabry-Perot etalon due to the difference in thermal expansion coefficient between the Fabry-Perot etalon and the spacer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP2016-211860A Summary of the Invention [Problem to be solved by the invention]

[0004] However, a large Fabry-Perot etalon may be used when obtaining a spectroscopic image by capturing image light transmitted through the Fabry-Perot etalon. In this case, in a conventional photodetector such as that in Patent Document 1, the contact surface between the Fabry-Perot etalon and the adhesive member is also large. If an adhesive member with a large elastic modulus is used, there is a problem that stress acts on the substrate of the Fabry-Perot etalon due to the difference in thermal expansion coefficient between the adhesive member and the Fabry-Perot etalon, causing the substrate to bend. In other words, the material of the adhesive member is limited, reducing the degree of freedom in design. In response to this, it is possible to reduce the contact area between the adhesive member and the Fabry-Perot etalon by reducing the width of the spacer. However, in this case, the adhesive strength cannot be ensured, and there is a risk that the Fabry-Perot etalon will fall off due to an impact such as a drop impact. Furthermore, there is also the problem that reducing the adhesive member reduces the resonance frequency of the Fabry-Perot etalon, making it easier for the Fabry-Perot etalon to resonate with external vibrations, making it difficult to control the gap between the pair of mirrors that constitute the Fabry-Perot etalon. [Means for solving the problem]

[0005] A spectroscopy device according to a first aspect of the present disclosure includes a first substrate, an interference filter including a first reflective film provided on the first substrate and a second reflective film facing the first reflective film via a gap, a housing that houses the interference filter, and an adhesive portion that fixes the interference filter to the housing, wherein the housing has a base portion that faces the first substrate of the interference filter, a direction from the first reflective film toward the second reflective film is a first direction, a region where the first reflective film and the second reflective film overlap when viewed from the first direction is an optical region, and the adhesive portion includes: a first adhesive portion provided on a first virtual line along an outer circumferential edge of the first substrate when viewed from the first direction, and a second adhesive portion provided on a second virtual line along an outer circumferential edge of the optical region when viewed from the first direction.

[0006] In the spectroscopy device of this aspect, the first adhesive portion has a plurality of first partial adhesive portions spaced apart from each other on the first virtual line.

[0007] In the light-splitting device of this aspect, the first adhesive portion may be configured in a substantially annular shape that is continuous along the first virtual line.

[0008] In this case, it is preferable that the first adhesive portion has a first connecting portion that, when viewed from the first direction, connects an area within the substrate on the optical region side of the first virtual line with an area outside the substrate on the opposite side of the optical region from the first virtual line.

[0009] In the spectroscopy device of this aspect, the second adhesive portion has a plurality of second partial adhesive portions spaced apart from each other on the second virtual line.

[0010] In the light-splitting device of this aspect, the second adhesive portion may be formed in a substantially continuous ring shape along the second virtual line.

[0011] In this case, it is preferable that the second adhesive portion has a second connecting portion that connects the optical region side to the non-optical region between the first virtual line and the second virtual line when viewed from the first direction.

[0012] In the spectroscopy device of this aspect, the first adhesive portion has a uniform width in a direction perpendicular to the first virtual line when viewed from the first direction, and the second adhesive portion has a uniform width in a direction perpendicular to the second virtual line when viewed from the first direction.

[0013] In the spectroscopy device of this aspect, the first adhesive portion is provided from between the first substrate and the base portion to a side surface of the first substrate.

[0014] In the spectroscopic device of this aspect, the interference filter includes a second substrate facing the first substrate and bonded to the first substrate, and the second reflective film is provided on the second substrate.

[0015] A spectroscopic camera of a second aspect according to the present disclosure includes the spectroscopic device of the first aspect and an imaging unit that receives light that has passed through the optical region of the spectroscopic device. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a spectroscopic camera according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic configuration of a spectroscopic device according to the present embodiment. [Diagram 3] FIG. 11 is a diagram showing the position of the adhesive portion on the base in a plan view seen from the Z direction in the present embodiment. [Figure 4] 5A and 5B are diagrams illustrating a schematic view of a force acting on a substrate by an adhesive member provided on the substrate. [Diagram 5] 5A and 5B are diagrams illustrating the force that the first substrate receives from the adhesive portion in the embodiment. [Figure 6] 11A and 11B are diagrams for explaining the resonance frequency of an interference filter fixed by adhesive. [Figure 7] FIG. 2 is a diagram showing the adhesive joint of Comparative Example 1. [Figure 8] FIG. 13 is a diagram showing the adhesive joint of Comparative Example 2. [Figure 9] FIG. 4 is a graph showing temperature characteristics of Examples 1 and 2 and Comparative Examples 1 and 2. [Figure 10] FIG. 4 is a graph showing the resonance frequencies of the interference filters of Examples 1 and 2 and Comparative Examples 1 and 2. [Figure 11] FIG. 11 is a diagram showing the position of an adhesive portion in a second embodiment. [Figure 12] 10A and 10B are diagrams showing the positions and shapes of adhesive parts according to Modification 1. [Figure 13] 10A and 10B are diagrams showing other examples of the positions and shapes of the adhesive parts according to the first modification example. [Figure 14] 10A and 10B are diagrams showing other examples of the positions and shapes of the adhesive parts according to the first modification example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] [First embodiment] Hereinafter, a spectroscopic camera according to a first embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing a schematic configuration of a spectroscopic camera 1 according to this embodiment. The spectroscopic camera 1 of this embodiment can be mounted on, for example, a portable terminal device such as a smartphone, or a small flying object such as a drone. 1, the spectroscopic camera 1 includes a filter unit 2, an imaging unit 3, and a camera case 100 that houses the filter unit 2 and the imaging unit 3. A lens unit (not shown) is detachably attached to the camera case 100, and the spectroscopic camera 1 guides incident light that enters through the lens unit to a spectroscopic device 210 provided in the filter unit 2, and captures light of a predetermined wavelength dispersed by the spectroscopic device 210 with an imaging section 310 provided in the imaging unit 3. This allows the spectroscopic camera 1 to capture a spectroscopic image of the predetermined wavelength of the imaging target. Here, when the spectroscopic camera 1 captures an image of an object, the direction in which incident light from the object is incident is the first direction of the present invention, and hereinafter, the first direction will be described as the Z direction. Moreover, a direction perpendicular to the Z direction is the X direction, and a direction perpendicular to the Z direction and the X direction is the Y direction. Each component of the spectroscopic camera 1 will be described in detail below.

[0018] (Schematic configuration of filter unit 2) The filter unit 2 includes a spectroscopic device 210 and a filter substrate 220 in which the spectroscopic device 210 is incorporated. The spectroscopic device 210 is a filter having an optical region that separates light of a predetermined wavelength from the incident light that is incident along the Z direction.

[0019] (Schematic configuration of the spectroscopic device 210) FIG. 2 is a schematic cross-sectional view of a spectroscopic device 210 of this embodiment. As shown in FIG. 2, the spectroscopic device 210 includes an interference filter 230 and a package housing 240 that corresponds to the housing of the present disclosure. The interference filter 230 includes a first substrate 231 and a second substrate 232 . The first substrate 231 and the second substrate 232 are substrates that are translucent to the wavelength of the spectroscopic image captured by the spectroscopic camera 1, that is, the spectroscopic wavelengths dispersed by the spectroscopic device 210. For example, when a spectroscopic image of a predetermined wavelength in the visible light range is captured, the spectroscopic device 210 disperses the light of the predetermined wavelength in the visible light range from the incident light and transmits it. In this case, the first substrate 231 and the second substrate 232 may be made of a substrate that can transmit visible light, such as quartz glass. Also, for example, when a spectroscopic image of a predetermined wavelength in the near-infrared range is captured, the spectroscopic device 210 disperses the light of the predetermined wavelength in the near-infrared range from the incident light and transmits it. Therefore, the first substrate 231 and the second substrate 232 may be made of a substrate that can transmit near-infrared light, such as silicon. The first substrate 231 and the second substrate 232 are bonded via a bonding layer (not shown).

[0020] As shown in FIG. 2, a first reflection film 233A and a first electrode 234A constituting an electrostatic actuator 234 are provided on the surface of the first substrate 231 facing the second substrate 232. On the surface of the second substrate 232 facing the first substrate 231, a second reflective film 233B and a second electrode 234B constituting the electrostatic actuator 234 are provided. A recess is formed by, for example, etching on the surface of the first substrate 231 facing the second substrate 232. As a result, the first reflective film 233A and the second reflective film 233B face each other across a predetermined first gap G1, and the first electrode 234A and the second electrode 234B face each other across a predetermined second gap G2. 2, a circular recess is formed on the surface of the second substrate 232 opposite to the first substrate 231, thereby forming a movable portion 232A at the center of the substrate and a diaphragm portion 232B that holds the movable portion 232A. A second reflective film 233B is provided on the surface of the movable portion 232A facing the first substrate 231. The second electrode 234B may be provided on the movable portion 232A, on the diaphragm portion 232B, or from the movable portion 232A to the diaphragm portion 232B.

[0021] 2, the first substrate 231 has a first protruding portion 231C that protrudes outward from the outer periphery of the second substrate 232. Similarly, the second substrate 232 has a second protruding portion 232C that protrudes outward from the outer periphery of the first substrate 231. Although not shown in the drawings, the first protruding portion 231C is provided with an electrode terminal portion connected to the first electrode 234A, and the second protruding portion 232C is provided with an electrode terminal portion connected to the second electrode 234B. Note that the first protruding portion 231C may be configured to be provided with both an electrode terminal portion connected to the first electrode 234A and an electrode terminal portion connected to the second electrode 234B, and the second protruding portion 232C may be configured to be provided with both an electrode terminal portion connected to the first electrode 234A and an electrode terminal portion connected to the second electrode 234B. These electrode terminals are connected to wiring provided on the package housing 240 by, for example, wire bonding.

[0022] In the interference filter 230 configured as described above, the electrostatic actuator 234 functions as a gap changing unit, and when a voltage is applied, the electrostatic attraction force bends the diaphragm portion 232B, displacing the movable portion 232A in the Z direction. This changes the dimension of the first gap G1 between the first reflection film 233A and the second reflection film 233B, and changes the wavelength of the light transmitted through the interference filter 230. Note that since the thickness of the movable portion 232A is thicker than the thickness of the diaphragm portion 232B, bending of the movable portion 232A, that is, bending of the second reflection film 233B, is suppressed. When the spectroscopic device 210 of this embodiment is viewed along the Z direction, the region where the first reflecting film 233A and the second reflecting film 233B of the interference filter 230 overlap is the optical region A of the present invention.

[0023] The package housing 240 is a box-shaped housing whose internal space is maintained in a reduced pressure environment, and houses the interference filter 230 therein. As shown in FIG. 2, the package housing 240 includes, for example, a base 241 and a lid 242, and the base 241 and the lid 242 are joined together to form an accommodation space therein. The base 241 is made of, for example, ceramic, and includes a base portion 241A and a side wall portion 241B. The base portion 241A is configured in the shape of a flat plate having, for example, a rectangular outer shape in the XY plane perpendicular to the Z direction, and a cylindrical side wall portion 241B rises up toward the lid 242 from the outer periphery of the base portion 241A.

[0024] The base portion 241A has an opening 241C penetrating along the Z direction. This opening 241C overlaps with the optical region A in a plan view seen from the Z direction in a state in which the interference filter 230 is accommodated in the package housing 240. A glass substrate 241D that covers the opening 241C is bonded to the surface of the base portion 241A opposite to the lid 242.

[0025] Furthermore, a wiring section (not shown) connected to the first electrode 234A and the second electrode 234B of the interference filter 230 is provided on the inner surface of the base section 241A facing the lid 242. This wiring section is connected to an external terminal section (not shown) on the outer surface of the base section 241A by, for example, a through electrode, and is connected to a circuit section (not shown) provided on the filter substrate 220 via the external terminal.

[0026] The sidewall portion 241B is formed in a frame shape rising from the edge of the base portion 241A, and the end face opposite the base portion 241A is a flat face perpendicular to the Z direction, to which the lid 242 is joined. The lid 242 is, for example, a transparent member having a rectangular outer shape in a plan view, and is made of, for example, glass. The fixing of the interference filter 230 to the package housing 240 will be described in detail later.

[0027] (Schematic configuration of filter substrate 220) The filter substrate 220 is a substrate to which the package housing 240 is fixed. The filter substrate 220 has a through hole along the Z direction at a position overlapping the optical region A in a plan view from the Z direction. As a result, the light dispersed by the interference filter 230 passes through the through hole and is received by the imaging section 310 provided in the imaging unit 3, and a spectral image is captured.

[0028] Although not shown in the figure, the filter substrate 220 is provided with a circuit section that is connected to an external terminal section provided on the package housing 240. This circuit section is provided with various circuits that control the interference filter 230. Examples of the various circuits include a microcomputer that calculates the voltage to be applied to the electrostatic actuator 234 of the interference filter 230, and a voltage control circuit that applies a voltage to the electrostatic actuator 234 according to a command from the microcomputer.

[0029] Specifically, the microcomputer includes a storage unit such as a memory, and stores drive data for controlling the electrostatic actuator 234. Examples of the drive data include V-λ data that records a drive voltage for a spectral wavelength transmitted through the interference filter 230. In addition, in a case where the interference filter 230 is provided with a capacitance detection electrode that detects the capacitance of the first reflection film 233A and the second reflection film 233B, C-λ data that records the capacitance for the spectral wavelength may be stored. Then, the microcomputer outputs a drive voltage corresponding to a target spectral wavelength to a voltage control circuit based on a command from the imaging unit 3, for example. The voltage control circuit applies a drive voltage to the electrostatic actuator 234 based on a command input from the microcomputer. In addition, in the case where the interference filter 230 is provided with capacitance detection electrodes for detecting the electrostatic capacitance of the first reflection film 233A and the second reflection film 233B, the voltage applied to the electrostatic actuator 234 may be feedback-controlled based on the detected electrostatic capacitance.

[0030] (Configuration of imaging unit 3) The imaging unit 3 includes an imaging section 310 and an imaging board 320 to which the imaging section 310 is fixed. The imaging unit 310 includes an imaging element such as a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal-Oxide Semiconductor), receives incident light, and outputs a light reception signal for each pixel. Here, in this embodiment, when viewed from the Z direction, the light receiving surface of the imaging unit 310 overlaps with the optical region A, and the optical region A is included within the light receiving surface.

[0031] The imaging board 320 has a control circuit section electrically connected to the imaging section 310. The control circuit section has, for example, a storage circuit such as a memory and an arithmetic circuit such as a CPU, and controls the operation of the imaging section 310 to generate image information. The imaging board 320 is also communicably connected to the filter board 220, and issues a target spectral wavelength command to the filter board 220. As a result, a microcomputer provided on the filter board 220 controls the spectroscopic device 210, and light of the target wavelength passes through the spectroscopic device 210.

[0032] (Configuration of camera case 100) The camera case 100 is configured to include a bottomed cylindrical main body 110, a board base 120, and a lid 130. The main body 110 has a container shape that is open on the +Z side, for example, and the main body 110 and the lid 130 form a storage space for storing the filter unit 2, the board base 120, and the imaging unit 3. The main body 110 is a bottomed cylindrical member having a planar front portion 111 and a side portion 112 rising from the outer periphery of the front portion 111 toward the +Z side, and the opening on the opposite side to the front portion 111 is closed by the lid portion 130, forming a closed space inside.

[0033] The front surface 111 is provided with a lens mount portion 113 extending to the -Z side. The lens mount section 113 is a section to which a lens can be attached and detached, and is configured to a predetermined lens mount standard. For example, in this embodiment, the lens mount section 113 has a C-mount lens exchange standard, and is formed in a cylindrical shape into which a C-mount lens can be screwed. The cylindrical central axis of the lens mount section 113 becomes the optical axis of the lens attached to the lens mount section 113.

[0034] A wall 114 is provided on the +Z side of the lens mount 113. A cylindrical recess 114A is provided in the wall 114, which is coaxial with the lens mount 113, and an aperture 114B is provided on the bottom surface (the surface on the +Z side) of the recess 114A. The recess 114A is formed with a diameter dimension that ensures a viewing angle of the image light incident via a lens attached to the lens mount portion 113. Aperture 114B has an opening center that is coaxial with lens mount portion 113 and recess 114A. In this embodiment, the configuration in which the aperture 114B is provided in the wall 114 of the camera case 100 is illustrated, but a configuration in which a separate aperture is provided may also be used.

[0035] A filter storage section 115 is provided on the +Z side of wall section 114. For example, in this embodiment, a step portion 110A capable of holding the board base 120 is provided on the inner circumferential surface of the main body portion 110, and the board base 120 is fixed to the step portion 110A. As a result, a filter storage portion 115 is formed by a space surrounded by the front portion 111, the side portion 112, the wall portion 114, and the board base 120. The board base 120 is formed in a flat plate shape, and the filter unit 2 incorporating the spectroscopic device 210 is fixed to the surface on the -Z side. The board base 120 is also formed with a passing hole 121 through which the light transmitted through the optical region A passes. The opening size of the passing hole 121 may be formed to be larger than the outer diameter of the optical region A. The filter unit 2 is stored in the filter storage section 115 by placing the board base 120 on the step section 110A. The outer shape of the board base 120 in the XY plane perpendicular to the Z direction is smaller than the shape of the inner peripheral surface of the side section 112. Therefore, the board base 120 is movable within a predetermined allowable distance range in the XY directions on the step section 110A. This allows fine adjustment of the position of the spectroscopic device 210 to a position where the optical region A overlaps with the aperture 114B. Furthermore, by fixing the board base 120 to the step portion 110A, the lid 242 of the light-splitting device 210 comes into contact with the wall portion 114. This makes it possible to suppress incidence of stray light into the light-splitting device 210.

[0036] The side surface portion 112 on the +Z side of the main body portion 110, the board base 120, and the lid portion 130 form an imaging storage portion 116. The imaging unit 3 is stored in the imaging storage portion 116. Specifically, the imaging board 320 is fixed to the board base 120 at a position where the light receiving surface of the imaging portion 310 overlaps with the optical region A, thereby storing the imaging unit 3 in the imaging storage portion 116.

[0037] Although not shown, other optical components may be disposed on the optical path of the incident light. For example, a bandpass filter may be provided on the opening surface of aperture 114B on the lens mount unit 113 side, between aperture 114B and spectroscopic device 210, or between spectroscopic device 210 and image capture unit 310.

[0038] (Fixing of interference filter 230 to package housing 240) Next, the structure for fixing the interference filter 230 to the package housing 240 will be described. In this embodiment, the first substrate 231 is adhered and fixed to the base portion 241A by the adhesive portion 250, whereby the interference filter 230 is fixed to the package housing 240.

[0039] FIG. 3 is a diagram showing the position of the adhesive portion 250 on the base 241 in a plan view seen from the Z direction. Here, in a plan view seen from the Z direction, a line along the outer periphery of the first substrate 231 is defined as a first virtual line N1, and a line along the outer periphery of the optical region A is defined as a second virtual line N2. The first virtual line N1 along the outer periphery of the first substrate 231 may coincide with the outer periphery of the first substrate 231 in a plan view seen from the Z direction, or may coincide with the outer periphery of the region where the first substrate 231 and the second substrate 232 overlap. In this embodiment, an example is shown in which the first virtual line N1 coincides with the outer periphery of the region where the first substrate 231 and the second substrate 232 overlap. Moreover, the second virtual line N2 may coincide with the outer periphery of the optical region A, or may be located a predetermined distance outside the outer periphery of the optical region A. That is, in this embodiment, the second adhesive portion 252 constituting a part of the adhesive portion 250 is provided on the second virtual line N2, but when the second adhesive portion 252 overlaps with the optical region A, the region that transmits light of the desired wavelength in the interference filter 230 is narrowed. Therefore, in this embodiment, the second virtual line N2 is a line located slightly outside the optical region A.

[0040] In this embodiment, the outer periphery of the area where the first substrate 231 and the second substrate 232 overlap is rectangular in plan view from the Z direction, so the first virtual line N1 also has a rectangular frame shape, but is not limited thereto. For example, when the outer periphery of the area where the first substrate 231 and the second substrate 232 overlap, or the outer periphery of the first substrate 231, is circular or elliptical in plan view, the first virtual line N1 also has a circular ring shape or an elliptical ring shape. In addition, when the outer periphery of the area where the first substrate 231 and the second substrate 232 overlap, or the outer periphery of the first substrate 231, is polygonal, such as triangular or pentagonal, in plan view, the first virtual line N1 also has an approximate polygonal frame shape that follows the outer shape. The same is true for the second virtual line N2, and in this embodiment, since the first reflective film 233A and the second reflective film 233B are circular, the second virtual line N2, which is the outer edge of the optical region A, is a ring. In contrast, if the optical region A is polygonal, the second virtual line N2 will be a polygonal frame shape that follows the outer edge.

[0041] The adhesive portion 250 includes a first adhesive portion 251 provided along the first imaginary line N1 and a second adhesive portion 252 provided along the second imaginary line N2. For the first adhesive portion 251 and the second adhesive portion 252, a general adhesive such as an epoxy resin can be used.

[0042] The first adhesive portion 251 includes a plurality of first partial adhesive portions 251A along the first virtual line N1. Each first partial adhesive portion 251A is formed longitudinally along the first virtual line N1 and with a predetermined width inward from the first virtual line N1. The length (width) of the first partial adhesive portion 251A in the direction perpendicular to the first virtual line N1 is uniformly formed, and the width is, for example, 1.0 mm or less. In addition, as shown in FIG. 2, a part of the first partial adhesive portion 251A is provided from between the first substrate 231 and the base portion 241A to the side surface of the first substrate 231, forming a fillet 251B. These first partial adhesive portions 251A are disposed spaced apart from each other on the first virtual line N1. For example, in this embodiment, as shown in FIG. 3, the adjacent first partial adhesive portions 251A are spaced apart from each other at the rectangular corners of the first virtual line N1. In this configuration, the intra-substrate region S1, which is closer to the optical region A than the first virtual line N1, and the extra-substrate region S2, which is farther from the optical region A than the first virtual line N1, communicate with each other in a region where the first partial adhesive portion 251A is not provided at the rectangular corner of the first virtual line N1. This allows air in the intra-substrate region S1 and gas generated when the adhesive portion 250 solidifies to escape to the extra-substrate region S2.

[0043] The second adhesive portion 252 includes a plurality of second partial adhesive portions 252A along the second imaginary line N2. Each of the second partial adhesive portions 252A is formed longitudinally along the second imaginary line N2 and with a predetermined width from the second imaginary line N2. The width of the second adhesive portions 252 is uniform and is, for example, 1.0 mm or less. In addition, these second partial adhesive portions 252A are disposed spaced apart from each other on the second virtual line N2. For example, in this embodiment, the second adhesive portion 252 is configured with two semicircular second partial adhesive portions 252A, and the adjacent second partial adhesive portions 252A are spaced apart from each other at positions spaced 180 degrees apart from each other with respect to the center of the optical region A. In this configuration, the optical region A inside the second virtual line N2 and the non-optical region B outside the second virtual line N2 in the intra-substrate region S1 communicate with each other through the gaps between the second partial adhesive parts 252A. This allows air in the optical region A and gas generated when the adhesive part 250 solidifies to escape to the non-optical region B.

[0044] (Optical characteristics of the spectroscopic device 210) Next, the optical characteristics of the interference filter 230 fixed to the package housing 240 by the adhesive part 250 as described above will be described. FIG. 4 is a diagram showing a schematic view of a force acting on the substrate K by an adhesive member R provided on the substrate K. In FIG. When the adhesive member R is formed on the substrate K, the deformation amount of the substrate K and the deformation amount of the adhesive member R when the temperature changes will differ due to the difference in thermal expansion coefficient between the substrate K and the adhesive member R. For example, in the interference filter 230, the first substrate 231 is formed of a Si or glass substrate, and its thermal expansion coefficient is 1×10 ―6 / K~10×10 ―6 / K. In contrast, the thermal expansion coefficient of the adhesive portion 250 made of a resin such as epoxy resin is about 1×10 ―5 / K~20×10 ―5 / K. For this reason, the amount of deformation of the adhesive member R becomes larger than the amount of deformation of the substrate K, and a tensile stress P acts on the adhesive member R, as shown in the upper diagram of Fig. 4. In this case, as shown in the lower diagram of Fig. 4, a bending moment M that tries to bend the substrate K acts on the outer edge of the adhesive member R. When such a bending moment acts on the first substrate 231, the first reflective film 233A provided in the optical region A bends, and the central wavelength of the light transmitted through the interference filter 230 changes depending on the environmental temperature.

[0045] FIG. 5 is a diagram illustrating the force that first substrate 231 receives from adhesive portion 250 in this embodiment. In this embodiment, the first adhesive portion 251 is provided with a uniform width along the first virtual line N1, and the second adhesive portion 252 is provided with a uniform width along the second virtual line N2. That is, in the direction generally toward the optical region A, the distance between the ends of the first adhesive portion 251 and the second adhesive portion 252 becomes shorter. In this case, as shown in FIG. 5, the bending moments M acting on the ends of the first adhesive portion 251 and the second adhesive portion 252 cancel each other out, making it possible to suppress bending of the first substrate 231. Therefore, in this embodiment, it is possible to suppress changes in the optical characteristics of the interference filter 230 due to temperature changes.

[0046] Incidentally, in this embodiment, the first substrate 231 is adhered and fixed to the base portion 241A in a double adhesion region centered on the optical region A by the first adhesion portion 251 along the first virtual line N1 and the second adhesion portion 252 along the second virtual line N2. With this configuration, the resonance frequency of the interference filter 230 can be maintained high, and it becomes difficult for the interference filter 230 to resonate with external vibrations. FIG. 6 is a diagram for explaining the resonance frequency of the interference filter 230 fixed by adhesive. When the interference filter 230 is fixed to the base portion 241A, the optical region A cannot be adhered. Therefore, the portion of the first substrate 231 other than the optical region A is adhered to the base portion 241A. Here, in the interference filter 230 of this embodiment, as shown in FIG. 6, the resonant frequency of the interference filter 230 changes depending on the distance L of the adhesive portion 250 in the radial direction of the center O of the optical region A, that is, in the diameter direction of the optical region A. Specifically, the resonance frequency of the interference filter 230 is 1 / L, where L is the distance between the adhesive portions 250 in the diameter direction of the optical region A. 2 is proportional to. In this embodiment, the optical region A is a circular region, but when the optical region A is a rectangular region, the distance between the adhesive parts 250 in the short side direction is dominant over the resonance frequency of the interference filter 230. When the optical region A is an ellipse, the distance between the adhesive parts 250 in the short axis direction is dominant over the resonance frequency of the interference filter 230.

[0047] In order to suppress the resonance of the interference filter 230 due to external vibration, it is necessary to increase the resonance frequency. In particular, when the spectroscopic camera 1 is mounted on a small flying object such as a drone, it is necessary to suppress the resonance of the interference filter 230 with respect to the frequency of a motor that drives a propeller. In addition, when the spectroscopic camera 1 is mounted on a portable terminal device such as a smartphone, it is necessary to suppress the resonance of the interference filter 230 with respect to various vibrations caused in daily life, such as vibrations when riding in a vehicle. In order to suppress such resonance, it is usually preferable to set the resonance frequency of the interference filter 230 to at least 30 kHz or more. In order to increase the resonant frequency, the adhesive area of ​​the adhesive part 250 can be increased, and the distance between the adhesive parts 250 sandwiching the optical region A can be decreased. Here, when the adhesive area is increased, as described above, the optical characteristics of the interference filter 230 with respect to temperature changes deteriorate. In contrast, in this embodiment, in addition to the first adhesive part 251, a second adhesive part 252 is further provided to form a double adhesive region with respect to the optical region A, so that the resonant frequency can be increased while suppressing deterioration of the temperature characteristics.

[0048] Next, the temperature characteristics and the resonant frequency of the light separating device 210 of this embodiment will be described in comparison with a comparative example. Here, in the spectroscopy device 210 of this embodiment, the width of the first adhesive portion 251 and the second adhesive portion 252 is 0.5 mm, which is taken as Example 1, and the width of the first adhesive portion 251 and the second adhesive portion 252 is 0.9 mm, which is taken as Example 2. 7 and 8 are diagrams showing adhesive parts of comparative examples. Fig. 7 is a diagram showing Comparative Example 1 in which the first adhesive part 251 and the second adhesive part 252 are not provided in the spectroscopy device 210 of this embodiment, and instead, the adhesive part 259 is provided on the entire part other than the optical region A. Fig. 8 is a diagram showing Comparative Example 2 in this embodiment in which the second adhesive part 252 is not provided, and only the first adhesive part 251 having a width of 0.5 mm is provided.

[0049] Fig. 9 is a diagram showing the temperature characteristics of Examples 1 and 2 and Comparative Examples 1 and 2, and shows the fluctuation in the central wavelength of light transmitted through the interference filter 230 when the environmental temperature is changed from 25° C. to 45° C. in each case where an adhesive having an elastic modulus of 10 MPa, 100 MPa, or 1000 MPa is used as the adhesive part. Fig. 10 shows the resonance frequencies of the interference filters of Examples 1 and 2 and Comparative Examples 1 and 2. When the interference filter 230 and the base portion 241A are bonded and fixed with the adhesive portion 259 as in Comparative Example 1, the resonant frequency is very high as shown in Fig. 10, and the interference filter is unlikely to resonate with external vibrations. However, as shown in Fig. 9, the central wavelength of the light passing through the spectroscopic device varies greatly depending on the elastic modulus of the adhesive used as the adhesive portion 259. That is, in Comparative Example 1, in order to obtain appropriate temperature characteristics, the adhesive used in the adhesive portion is limited to one with a small elastic modulus, which reduces the degree of freedom in design.

[0050] On the other hand, in the case of Comparative Example 2 in which the first adhesive portion 251 is provided and the second adhesive portion 252 is not provided, the change in the central wavelength of the light transmitted through the interference filter 230 due to the temperature change can be suppressed as shown in Fig. 9. However, as shown in Fig. 10, the resonance frequency tends to be lower. For this reason, in Comparative Example 2, in order to increase the resonance frequency, the adhesive is limited to one with a large elastic modulus, which reduces the degree of freedom in design. Furthermore, when the interference filter 230 is fixed to the base portion 241A only by the narrow first adhesive portion 251 as in Comparative Example 2, the adhesive strength is low and there is a risk that the interference filter 230 may fall off due to an impact such as being dropped. Although not listed as a comparative example, in the case where the first adhesive portion 251 is not provided, and only the second adhesive portion 252 is provided, the fluctuation in characteristics of the interference filter 230 due to temperature changes is suppressed regardless of the elastic modulus of the adhesive used, and an increase in the resonance frequency can be expected. However, as in comparative example 2, the adhesive strength is low, and there is a risk that the interference filter 230 may fall off due to an impact.

[0051] In contrast to this, in both Examples 1 and 2, regardless of the adhesive used, it is possible to suppress the characteristic fluctuation of the interference filter 230 due to temperature changes and to increase the resonance frequency of the interference filter 230. Furthermore, by providing a double adhesive region by the first adhesive portion 251 and the second adhesive portion 252, it is possible to ensure sufficient adhesive strength and to suppress the detachment of the interference filter 230 due to impact.

[0052] [Effects of this embodiment] The spectroscopic device 210 of this embodiment includes an interference filter 230, a package housing 240 that is a housing, and an adhesive part 250 that fixes the interference filter 230 to the package housing 240. The interference filter 230 includes a first substrate 231, a first reflection film 233A provided on the first substrate 231, and a second reflection film 233B that faces the first reflection film 233A across a first gap G1. The package housing 240 has a base part 241A that faces the first substrate 231 of the interference filter 230. When viewed from the Z direction, the adhesive portion 250 is configured to include a first adhesive portion 251 provided on a first virtual line N1 along the outer peripheral edge of the first substrate 231, and a second adhesive portion 252 provided on a second virtual line N2 along the outer peripheral edge of the optical region A.

[0053] In such a light-splitting device 210, the width of the first adhesive portion 251 perpendicular to the first virtual line N1 and the width of the second adhesive portion 252 perpendicular to the second virtual line N2 are reduced. That is, the widths of the first adhesive portion 251 and the second adhesive portion 252 approximately along the radial direction centered on the center of gravity of the optical region A are reduced. As a result, the bending moment generated at the end of the first adhesive portion 251 on the optical region A side and the bending moment generated at the end opposite the optical region A cancel each other out, and the bending of the first substrate 231 due to the stress generated due to the difference in thermal expansion coefficient between the first substrate 231 and the first adhesive portion 251 can be suppressed. Similarly, the bending moment generated at the end of the second adhesive portion 252 on the optical region A side and the bending moment generated at the end opposite the optical region A cancel each other out, and the bending of the first substrate 231 due to the stress generated due to the difference in thermal expansion coefficient between the first substrate 231 and the second adhesive portion 252 can be suppressed. In other words, regardless of the elastic modulus of adhesive used for the first adhesive portion 251 and the second adhesive portion 252, the temperature characteristics of the interference filter 230 can be kept approximately constant, and fluctuations in the central wavelength of the light passing through the interference filter 230 due to temperature changes can be suppressed. Furthermore, since the adhesive strength between the first substrate 231 and the base portion 241A can be increased compared to when only the first adhesive portion 251 is provided or when only the second adhesive portion 252 is provided, the inconvenience of the interference filter 230 falling off from the package housing 240 can be suppressed even when an impact or the like is applied. Furthermore, since the second adhesive portion 252 is provided on the second virtual line N2 along the outer periphery of the optical region A, the resonance frequency of the interference filter 230 can be maintained high, and the inconvenience of the interference filter 230 resonating due to external vibration can be suppressed. In particular, even when the spectroscopic camera 1 is mounted on a small flying object such as a drone, the inconvenience of the interference filter 230 resonating due to vibration of a motor mounted on the drone can be suppressed, and a highly accurate spectroscopic image can be captured.

[0054] In the light-splitting device 210 of the present embodiment, the first adhesive portion 251 has a plurality of first partial adhesive portions 251A that are spaced apart from each other on the first virtual line N1. In this configuration, a gap through which air can pass is formed between adjacent first partial adhesive portions 251A. In other words, in the case where a closed frame-shaped first adhesive portion is provided on the first virtual line N1, the pressure in the intra-substrate region S1 may change due to temperature change, and the first substrate 231 may be warped. In contrast, by configuring the intra-substrate region S1 and the extra-substrate region S2 to communicate with each other as in this embodiment, it is possible to suppress warping of the first substrate 231 due to pressure fluctuations in the intra-substrate region S1.

[0055] Similarly, the second adhesive portion 252 has a plurality of second partial adhesive portions 252A spaced apart from each other on the second imaginary line N2. This creates a gap between adjacent second partial adhesive portions 252A through which air can pass, and the optical region A and non-optical region B communicate with each other, so that bending of the first substrate 231 due to pressure fluctuations in the optical region A can be suppressed.

[0056] In this embodiment, the first adhesive portion 251 is formed with a uniform width in a direction perpendicular to the first virtual line N1, and the second adhesive portion 252 is formed with a uniform width in a direction perpendicular to the second virtual line N2. That is, the first adhesive portion 251 and the second adhesive portion 252 are formed with a narrow width in the direction toward the optical region A (radial direction) at any position, and the bending moment acting between the ends of the width can be suitably cancelled out. This makes it possible to more suitably suppress the bending of the first substrate 231, and to suppress the deterioration of spectroscopic accuracy due to temperature change.

[0057] In this embodiment, the first adhesive portion 251 is provided from between the first substrate 231 and the base portion 241A to the side surface of the first substrate 231, that is, a fillet is formed. This can further increase the adhesive strength between the first substrate 231 and the base portion 241A.

[0058] The interference filter 230 of this embodiment has a second substrate 232 opposed to a first substrate 231 and bonded to the first substrate 231, a first reflective film 233A is provided on the first substrate 231, and a second reflective film 233B is provided on the second substrate 232. Such an interference filter 230 having two substrates can be made thinner than a filter using three or more substrates, which can facilitate miniaturization of the spectroscopic device 210. In addition, the first reflection film 233A is supported by the first substrate 231, and the second reflection film 233B is supported by the second substrate 232. In such a configuration, for example, bending of the first reflection film 233A and the second reflection film 233B can be suppressed compared to a configuration in which the first reflection film and the second reflection film are not supported independently by a substrate or the like, and breakage of the first reflection film 233A and the second reflection film 233B due to impact or the like can also be suppressed.

[0059] The spectroscopic camera 1 of this embodiment includes the above-described spectroscopic device 210 and an imaging section 310. As described above, the spectroscopic device 210 of the present embodiment can suppress the fluctuation of the central wavelength of light passing through the interference filter 230 due to temperature changes, can increase the resonance frequency of the interference filter 230, and can suppress the interference filter 230 from falling off due to impact, etc. In other words, it is possible to provide a highly versatile spectroscopic camera 1 that can be used regardless of the usage environment, and can be suitably incorporated into, for example, flying objects such as drones and portable terminal devices.

[0060] [Second embodiment] In the first embodiment, an example was shown in which the first adhesive portion 251 is composed of a plurality of first partial adhesive portions 251A, and the second adhesive portion 252 is composed of a plurality of second partial adhesive portions 252A. In contrast, the second embodiment differs from the first embodiment in that a single first adhesive portion 251 is provided along the first virtual line N1, and a single second adhesive portion 252 is provided along the second virtual line N2.

[0061] FIG. 11 is a diagram showing the position of the adhesive portion 250 in the second embodiment. In this embodiment, the first adhesive portion 251 is formed in a substantially annular shape that continues along the first virtual line N1. In this disclosure, the substantially annular shape includes a polygonal frame shape in addition to a circular ring shape, and is not limited to a closed ring, but also includes a shape in which a part of the ring is cut out, such as a substantially C-shape. For example, in this embodiment, an unadhesive portion where the first substrate 231 and the base portion 241A are not adhered by the first adhesive portion 251 is provided at one location on the first virtual line N1. The unadhesive portion becomes a first communicating portion 253 that communicates between the intra-substrate region S1 and the extra-substrate region S2.

[0062] Similarly, the second adhesive portion 252 is formed in a continuous, generally annular shape along the second virtual line N2. In this embodiment, an unadhesive portion is provided in a portion of the second virtual line N2 where the first substrate 231 and the base portion 241A are not joined, that is, where the second adhesive portion 252 is not provided. This unadhesive portion becomes a second communicating portion 254 that communicates between the optical region A and the non-optical region B in the intra-substrate region S1.

[0063] In the second embodiment as described above, the same effects as those of the first embodiment can be achieved. Furthermore, in this embodiment, the first adhesive portion 251 is configured in a substantially annular shape that continues along the first virtual line N1. Therefore, the adhesive area of ​​the first adhesive portion 251 is larger than that of the first embodiment, and the bonding strength between the first substrate 231 and the base portion 241A can be further increased. Similarly, the second adhesive portion 252 is configured in a generally annular shape that continues along the second virtual line N2. Therefore, the adhesive area of ​​the second adhesive portion 252 is larger than that of the first embodiment, and the bonding strength between the first substrate 231 and the base portion 241A can be further increased.

[0064] In this embodiment, the first adhesive portion 251 includes a first communicating portion 253 that communicates the intra-substrate region S1 with the extra-substrate region S2. Similarly, the second adhesive portion 252 includes a second communicating portion 254 that communicates the optical region A with the non-optical region B. Therefore, even if the first adhesive portion 251 and the second adhesive portion 252 are formed in an approximately annular shape, the optical region A between the first substrate 231 and the base portion 241A and the region S1 within the substrate are not sealed, and air can be released to the outside.

[0065] [Variations] The present invention is not limited to the above-described embodiment, and modifications and improvements within the scope of the present invention that can achieve the object of the present invention are included in the present invention.

[0066] (Variation 1) For example, in the above first embodiment, the first adhesive portion 251 is composed of a plurality of first partial adhesive portions 251A, and each first partial adhesive portion 251A is formed longitudinally along the first virtual line N1, but this is not limited to this example. 12 to 14 are diagrams showing the position and shape of the adhesive portion 250 according to the first modification. 12, the first partial adhesive portion 251A may be, for example, dot-shaped. That is, the first partial adhesive portion 251A may be formed so that the length in the direction perpendicular to the first virtual line N1 and the length in the direction along the first virtual line N1 are approximately the same. Similarly, the second partial adhesive portion 252A may be formed in a dot shape as shown in Fig. 12. That is, the second partial adhesive portion 252A may be formed so that the length in the direction perpendicular to the second virtual line N2 and the length in the direction along the second virtual line N2 are approximately the same.

[0067] Also, as shown in FIG. 13, the first adhesive portion 251 may be formed in the same manner as in the first embodiment, and the second adhesive portion 252 may be formed in a dot shape, or as shown in FIG. 14, the second adhesive portion 252 may be formed in the same manner as in the first embodiment, and the first adhesive portion 251 may be formed in a dot shape. Furthermore, as the first adhesive portion 251, as in the second embodiment, a single, approximately annular first adhesive portion 251 that is continuous along the first virtual line N1 may be used, and as the second adhesive portion 252, as in the first embodiment and Figures 12 and 13, a plurality of second partial adhesive portions 252A may be used. Alternatively, as the second adhesive portion 252, as in the second embodiment, a single, approximately annular second adhesive portion 252 that is continuous along the second virtual line N2 may be used, and as the first adhesive portion 251, as in the first embodiment and Figures 12 and 14, a plurality of first partial adhesive portions 251A may be used.

[0068] The widths of the first adhesive portion 251 and the second adhesive portion 252 may be different from each other. For example, the width of the first adhesive portion 251 perpendicular to the first virtual line N1 may be 0.9 mm, and the width of the second adhesive portion 252 perpendicular to the second virtual line N2 may be 0.5 mm. In this case, it is preferable to make the width of the second adhesive portion 252 arranged at a position close to the optical region A smaller than that of the first adhesive portion 251. As a result, the narrow width of the second adhesive portion 252 can further suppress the bending of the first substrate 231 due to temperature changes.

[0069] (Variation 2) In the above embodiment, an example was shown in which the second substrate 232 has a movable portion 232A and a diaphragm portion 232B, and the movable portion 232A is displaced toward the first substrate 231 by applying a voltage to the electrostatic actuator 234, but this is not limited to this. For example, a surface of first substrate 231 opposite to second substrate 232 may be processed by etching or the like, so that first substrate 231 is provided with a movable portion and a diaphragm portion. That is, a movable portion provided on first substrate 231 joined to base portion 241A of package housing 240 may be configured to be displaceable toward second substrate 232.

[0070] (Variation 3) In the above embodiment, a Fabry-Perot etalon in which the first reflecting film 233A and the second reflecting film 233B face each other via the first gap G1 has been exemplified as the spectroscopic device 210, but other spectroscopic devices may be used. For example, an AOTF (Acousto-Optic Tunable Filter) or an LCTF (Liquid crystal tunable filter) may be used as the spectroscopic device.

[0071] Furthermore, in the present embodiment, the electrostatic actuator 234 including the first electrode 234A provided on the first substrate 231 and the second electrode 234B provided on the second substrate 232 is exemplified as the gap changer that changes the first gap G1, but is not limited thereto. For example, the gap changer may be an actuator that displaces the movable part 232A by magnetic force using a magnetic body provided on the first substrate 231 and a coil electrode provided on the second substrate 232, or the movable part 232A may be displaced by other driving forces. In addition, although the above embodiment is an example in which the movable part 232A is displaced toward the first substrate 231, a configuration in which the movable part 232A is displaced in a direction away from the first substrate 231 may also be used. [Explanation of symbols]

[0072] 1...spectroscopic camera, 2...filter unit, 3...imaging unit, 210...spectroscopic device, 220...filter substrate, 230...interference filter, 231...first substrate, 231C...first protruding portion, 232...second substrate, 232A...movable portion, 232B...diaphragm portion, 232C...second protruding portion, 232C...second protruding portion, 233A...first reflective film, 233B...second reflective film, 234...electrostatic actuator, 234A...first electrode, 234B...second electrode, 240...package housing (housing), 241...base, 2 41A...base portion, 241B...side wall portion, 241C...opening, 241D...glass substrate, 242...lid, 250...adhesive portion, 251...first adhesive portion, 251A...first partial adhesive portion, 251B...fillet, 252...second adhesive portion, 252A...second partial adhesive portion, 253...first connecting portion, 254...second connecting portion, 310...imaging portion, 320...imaging substrate, A...optical region, B...non-optical region, G1...first gap, G2...second gap, N1...first virtual line, N2...second virtual line, S1...region within substrate, S2...region outside substrate.

Claims

1. an interference filter including a first substrate, a first reflective film provided on the first substrate, and a second reflective film facing the first reflective film across a gap; A housing that houses the interference filter; an adhesive portion that fixes the interference filter to the housing; the housing has a base portion facing the first substrate of the interference filter, A direction from the first reflective film toward the second reflective film is defined as a first direction, and a region where the first reflective film and the second reflective film overlap when viewed from the first direction is defined as an optical region, The adhesive portion is A first adhesive portion provided on a first virtual line along an outer circumferential edge of the first substrate when viewed from the first direction; A second adhesive portion provided on a second virtual line along an outer periphery of the optical region when viewed from the first direction; A spectroscopic device comprising:

2. The first adhesive portion has a plurality of first partial adhesive portions spaced apart from each other on the first virtual line. The spectroscopic device according to claim 1 .

3. The first adhesive portion is configured in a substantially annular shape that is continuous along the first virtual line. The spectroscopic device according to claim 1 .

4. The first adhesive portion includes a first communicating portion that communicates, when viewed from the first direction, an area within the substrate that is closer to the optical region than the first virtual line and an area outside the substrate that is on the opposite side to the optical region than the first virtual line. The spectroscopic device according to claim 3 .

5. The second adhesive portion has a plurality of second partial adhesive portions spaced apart from each other on the second virtual line. The spectroscopic device according to claim 1 .

6. The second adhesive portion is formed in a substantially annular shape that is continuous along the second virtual line. The spectroscopic device according to claim 1 .

7. the second adhesive portion includes a second communicating portion that communicates the optical region side with a non-optical region between the first virtual line and the second virtual line when viewed from the first direction; The spectroscopic device according to claim 6 .

8. When viewed from the first direction, the first adhesive portion has a uniform width in a direction perpendicular to the first virtual line, When viewed from the first direction, the second adhesive portion has a uniform width in a direction perpendicular to the second virtual line. The spectroscopic device according to claim 1 .

9. The first adhesive portion is provided from between the first substrate and the base portion to a side surface of the first substrate. The spectroscopic device according to claim 1 .

10. the interference filter includes a second substrate facing the first substrate and bonded to the first substrate; The second reflective film is provided on the second substrate. The spectroscopic device according to claim 1 .

11. The spectroscopic device according to any one of claims 1 to 10, an imaging unit that receives light transmitted through the optical region of the spectroscopic device; A spectroscopic camera equipped with

Images