Spectroscopic unit and spectroscopic module

Abstract

To provide a spectroscopic unit and a spectroscopic module which can improve the accuracy of spectroscopy by a Fabry-Perot interference filter.SOLUTION: A spectroscopic unit 100 comprises: a housing having a ceiling wall 6 in which an opening 2a is formed; a first aperture unit 71 in which a first aperture 80 is formed; and a second aperture unit 72 in which a second aperture 72a is formed. A length T2 of the second aperture 72a in a direction A is larger than a length T1 of the first aperture 80 in the direction A. When seen from the direction A, an outer edge 80d of the first aperture 80 is located inward of an outer edge of the opening 2a and an outer edge of the second aperture 72a. The first aperture 80 includes a first tapered portion 81 reaching a first surface 71a and expanding toward the first surface 71a and / or a second tapered portion 82 reaching a second surface 71b and expanding toward the second surface 71b.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a spectroscopic unit and a spectroscopic module.

Background Art

[0002] A spectroscopic module including a light source that emits light to irradiate an object, a spectroscopic unit that spectroscopically analyzes the light reflected by the object or the light transmitted through the object, and a photodetector that detects the light spectroscopically analyzed by the spectroscopic unit is known (see, for example, Patent Document 1). According to such a spectroscopic module, for example, the components of an object can be analyzed nondestructively.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the spectroscopic module as described above, a Fabry-Perot interference filter may be applied to the spectroscopic unit. In that case, improving the spectroscopic accuracy by the Fabry-Perot interference filter is extremely important, for example, in improving the analysis accuracy of the components of an object.

[0005] An object of the present invention is to provide a spectroscopic unit and a spectroscopic module capable of improving the spectroscopic accuracy by a Fabry-Perot interference filter.

Means for Solving the Problems

[0006] The spectroscopic unit of the present invention includes a Fabry-Perot interference filter having a first mirror part and a second mirror part with a variable distance therebetween, a housing having a wall part with an opening formed to face the Fabry-Perot interference filter in the facing direction and accommodating the Fabry-Perot interference filter, a first aperture part provided on the side opposite to the Fabry-Perot interference filter with respect to the wall part and having a first aperture formed to face the opening in the facing direction, and a second aperture part provided on the side opposite to the wall part with respect to the first aperture part and having a second aperture formed to face the first aperture in the facing direction. The length of the second aperture in the facing direction is larger than the length of the first aperture in the facing direction. When viewed from the facing direction, the outer edge of the first aperture is located inside each of the outer edge of the opening and the outer edge of the second aperture. The first aperture includes at least one of a first tapered portion reaching the first surface on the wall part side in the first aperture part and spreading toward the first surface, and a second tapered portion reaching the second surface on the second aperture part side in the first aperture part and spreading toward the second surface.

[0007] In this spectroscopic unit, the length of the second aperture in the opposing direction is greater than the length of the first aperture in the opposing direction. When viewed from the opposing direction, the outer edge of the first aperture is located inside each of the outer edge of the opening and the outer edge of the second aperture. Therefore, the light that has passed through the second aperture, the first aperture, and the opening enters the Fabry - Perot interference filter with the range of its incident angle narrowed. As a result, the Fabry - Perot interference filter can function properly. Also, in this spectroscopic unit, when viewed from the opposing direction, the outer edge of the first aperture is located inside the outer edge of the second aperture, and the first aperture includes at least one of a first tapered portion and a second tapered portion. Therefore, it is possible to suppress the light that has entered the second aperture at a large incident angle from becoming stray light by entering the housing while being reflected by the inner surface of the second aperture. As described above, according to this spectroscopic unit, it is possible to improve the resolution in the spectroscopic spectrum obtained by the Fabry - Perot interference filter and improve the spectroscopic accuracy by the Fabry - Perot interference filter.

[0008] In the spectroscopic unit of the present invention, the first aperture may include both a first tapered portion and a second tapered portion. Alternatively, in the spectroscopic unit of the present invention, the first aperture may include only the second tapered portion, and the second tapered portion may reach both the first surface and the second surface. In these cases, even if the light that has entered the second aperture at a large incident angle travels inside the second aperture while being reflected by the inner surface of the second aperture, the light is reflected by the inner surface of the second tapered portion to the side opposite to the housing. Therefore, according to these, it is possible to more reliably suppress the light that has entered the second aperture at a large incident angle from becoming stray light by entering the housing while being reflected by the inner surface of the second aperture.

[0009] In the spectroscopic unit of the present invention, when viewed from the opposite direction, the outer edge of the first aperture may be located inside the outer edge of the light transmission region of the Fabry - Perot interference filter. According to this, it is possible to increase the ratio of the light passing through the light transmission region of the Fabry - Perot interference filter among the light passing through the second aperture and the first aperture.

[0010] In the spectroscopic unit of the present invention, when viewed from the opposite direction, the outer edge of the opening may be located outside the outer edge of the second aperture. According to this, the first aperture and the second aperture can appropriately define the range of the incident angle of the light to be incident into the housing.

[0011] In the spectroscopic unit of the present invention, the first aperture may be an opening formed by etching. In this case, compared with the case where the first aperture is an opening formed by, for example, machining, it will have a high - precision shape. Therefore, according to this, the first aperture can function appropriately.

[0012] In the spectroscopic unit of the present invention, the first aperture portion may be a first aperture member formed separately from the wall portion and provided on the surface of the wall portion. According to this, the degree of freedom in the design of the first aperture portion, such as the selection of a suitable material, can be improved. Also, by forming a large light - incident opening in the housing, the positional accuracy of the Fabry - Perot interference filter in the housing can be relaxed while adjusting the positional relationship between the first aperture and the Fabry - Perot interference filter. Further, even if a gap is formed between the first aperture portion and the second aperture portion, it is possible to suppress the light incident through the gap from becoming stray light.

[0013] In the spectroscopic unit of the present invention, the first aperture portion may be fixed to the wall portion. According to this, it is possible to prevent the positional relationship between the first aperture and the Fabry - Perot interference filter from shifting due to vibration or the like.

[0014] In the spectroscopic unit of the present invention, the second aperture portion may be a second aperture member formed separately from the first aperture portion. According to this, the degree of freedom in designing the second aperture portion and the first aperture portion, such as the selection of a suitable material, can be improved. Further, by forming a large light incident opening in the housing, the positional accuracy of the Fabry-Perot interference filter in the housing can be relaxed, and the positional relationship between the second aperture and the Fabry-Perot interference filter can be adjusted. Also, the positional relationship between the second aperture and the first aperture can be adjusted.

[0015] In the spectroscopic unit of the present invention, the cross-sectional shape of the first aperture in a direction perpendicular to the opposing direction is circular, and the cross-sectional shape of the second aperture in a direction perpendicular to the opposing direction may be circular. According to this, an aperture having desired performance can be easily formed.

[0016] In the spectroscopic unit of the present invention, the region inside the first aperture is a space, and the region inside the second aperture may be a space. According to this, it is possible to prevent light loss due to passing through the first aperture and the second aperture.

[0017] The spectroscopic unit of the present invention may be further provided with a photodetector that is disposed in the housing and detects light transmitted through the Fabry-Perot interference filter. According to this, it is possible to accurately detect the spectroscopically separated light while suppressing the generation of noise caused by stray light. Also, since the photodetector is disposed in the housing, it is possible to reduce the size of the spectroscopic unit provided with the photodetector.

[0018] The spectroscopic unit of the present invention further includes a band-pass filter disposed between the first aperture and the Fabry-Perot interference filter, and the first aperture portion and the second aperture portion may be configured such that all of the light that has passed through the first aperture and the second aperture is incident on the band-pass filter. According to this, all of the light that has passed through the second aperture, the first aperture, and the opening is incident on the band-pass filter in a state where the range of its incident angle is narrowed. As a result, the band-pass filter functions properly, and the light in the desired wavelength range is incident on the Fabry-Perot interference filter in a state where the range of its incident angle is narrowed. Therefore, the resolution is improved in the spectroscopic spectrum obtained by the Fabry-Perot interference filter.

[0019] In the spectroscopic unit of the present invention, the first aperture portion and the second aperture portion may be configured such that all of the light that has passed through the first aperture and the second aperture and has passed through the band-pass filter is incident on the Fabry-Perot interference filter. According to this, it is possible to suppress the generation of stray light in the housing.

[0020] In the spectroscopic unit of the present invention, the band-pass filter may be separated from the first aperture portion via a wall portion. According to this, since the band-pass filter is disposed in the housing, the band-pass filter can be protected from physical interference and the like.

[0021] The spectroscopic module of the present invention includes the above-described spectroscopic unit, a light source, the housing of the spectroscopic unit, and a package that houses the light source, and the first aperture, the second aperture, and the light emitting portion of the light source are arranged along the outer surface of the package so as to be adjacent to each other.

[0022] According to this spectroscopic module, it is possible to realize a reflective spectroscopic module with improved spectroscopic accuracy by a Fabry-Perot interference filter.

Effects of the Invention

[0023] According to the present invention, it is possible to provide a spectroscopic unit and a spectroscopic module that can improve the spectroscopic accuracy by a Fabry-Perot interference filter.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0026] [Photodetector] Prior to the description of the spectroscopic module according to one embodiment, a photodetection device applied to the spectroscopic module will be described. As shown in FIG. 1, the photodetection device 1 includes a housing 2. In the present embodiment, the housing 2 is a CAN package having a stem 3 and a cap 4. The cap 4 has an integrally formed side wall 5 and a top wall (wall portion) 6. The materials of the stem 3 and the cap 4 are, for example, metal. The cap 4 has a cylindrical shape centered on the line L. The side wall 5 of the cap 4 extends along the line L. The top wall 6 of the cap 4 is provided on one end side of the side wall 5 in the direction along the line L. The top wall 6 extends along a plane intersecting the line L.

[0027] A wiring board 7 is fixed to the inner surface 3a of the stem 3. The substrate material of the wiring board 7 is, for example, silicon, ceramic, quartz, glass, plastic, or the like. A photodetector 8 and a temperature detector (not shown) such as a thermistor are mounted on the wiring board 7. The photodetector 8 is disposed in the housing 2 such that the center line of its light receiving portion coincides with the line L. The photodetector 8 detects light that has passed through a Fabry-Perot interference filter 10 described later. In the present embodiment, the photodetector 8 is an infrared detector and is constituted by a light receiving element such as an InGaAs photodiode, a thermopile, or a bolometer. When the photodetector 8 detects ultraviolet, visible, or near-infrared light, it may be constituted by a light receiving element such as a Si photodiode. Further, the photodetector 8 may be constituted by one light receiving element or may be constituted by a plurality of light receiving elements.

[0028] A plurality of spacers 9 are fixed on the wiring board 7. The material of the spacer 9 is, for example, silicon, ceramic, quartz, glass, plastic, or the like. A Fabry-Perot interference filter 10 is fixed on the plurality of spacers 9. The Fabry-Perot interference filter 10 is arranged in the housing 2 such that the center line of its light transmission region 10a coincides with the line L. That is, the housing 2 houses the Fabry-Perot interference filter 10. In this embodiment, the light transmission region 10a of the Fabry-Perot interference filter 10 has a circular shape when viewed from a direction parallel to the line L. Also, the plurality of spacers 9 may be formed integrally with the wiring board 7. Further, the Fabry-Perot interference filter 10 may be fixed on one spacer 9.

[0029] A plurality of lead pins 11 are fixed to the stem 3. Each lead pin 11 passes through the stem 3 while maintaining electrical insulation and airtightness with the stem 3. Each lead pin 11 is electrically connected to each of the electrode pads of the wiring board 7 and the terminals of the Fabry-Perot interference filter 10 via a wire 12. Thereby, input and output of electrical signals to and from each of the Fabry-Perot interference filter 10, the photodetector 8, and the temperature detector are enabled.

[0030] The housing 2 is formed with an opening 2a. The opening 2a is formed in the top wall 6 of the cap 4 such that its center line coincides with the line L. The opening 2a faces the light transmission region 10a of the Fabry - Perot interference filter 10 in a direction parallel to the line L. In the present embodiment, when viewed in a direction parallel to the line L, the opening 2a has a circular shape. A light transmission member 13 is joined to the inner surface 6a of the top wall 6 so as to close the opening 2a. The material of the light transmission member 13 is, for example, glass or the like. The light transmission member 13 has a light incident surface 13a, a light exit surface 13b, and side surfaces 13c that face each other in a direction parallel to the line L. The light incident surface 13a is substantially flush with the outer surface (surface) 6b of the top wall 6 of the cap 4 at the opening 2a. The side surface 13c is in contact with the inner surface 5a of the side wall 5 of the cap 4. Such a light transmission member 13 is formed by arranging glass pellets inside the cap 4 with the opening 2a facing downward and melting the glass pellets.

[0031] A band - pass filter 14 is fixed to the light exit surface 13b of the light transmission member 13 by an adhesive member 15 made of a light - transmissive material. The band - pass filter 14 selectively transmits light within the measurement wavelength range of the light detection device 1 (light within a predetermined wavelength range that should be incident on the light transmission region 10a of the Fabry - Perot interference filter 10) among the light that has passed through the light transmission member 13. In the present embodiment, the band - pass filter 14 has, for example, a rectangular plate shape. The band - pass filter 14 has a light incident surface 14a, a light exit surface 14b, and four side surfaces 14c that face each other in a direction parallel to the line L. The band - pass filter 14 is composed of, for example, a light - transmissive member made of silicon or glass or the like, and a dielectric multilayer film formed on the surface of the light - transmissive member. The dielectric multilayer film is composed of a film made of a high - refractive index material (for example, TiO2 or Ta2O5 or the like) and a film made of a low - refractive index material (for example, SiO2 or MgF2 or the like).

[0032] The bonding member 15 has a first portion 15a and a second portion 15b. The first portion 15a is the portion of the bonding member 15 that is disposed between the light emitting surface 13b of the light transmissive member 13 and the light incident surface 14a of the band pass filter 14. The second portion 15b is the portion of the bonding member 15 that is disposed between the side surface 14c of the band pass filter 14 and the inner surface 5a of the side wall 5 of the cap 4 at the light emitting surface 13b of the light transmissive member 13.

[0033] In the light detection device 1 configured as described above, when light enters the band pass filter 14 from outside the housing 2 through the opening 2a, the light transmissive member 13, and the bonding member 15, only light in a predetermined wavelength range passes through the band pass filter 14. The light that has passed through the band pass filter 14 enters the light transmission region 10a of the Fabry - Perot interference filter 10, and light having a wavelength corresponding to the distance between the first mirror portion 35 and the second mirror portion 36, which will be described later, passes through the light transmission region 10a. The light that has passed through the light transmission region 10a enters the light receiving portion of the photodetector 8 and is detected by the photodetector 8. Therefore, by changing the distance between the first mirror portion 35 and the second mirror portion 36 in the Fabry - Perot interference filter 10 and detecting the intensity of the light that has passed through the light transmission region 10a with the photodetector 8, a spectral spectrum can be obtained.

[0034] [Fabry - Perot interference filter] The Fabry - Perot interference filter 10 described above will be described in more detail. As shown in FIGS. 2 and 3, the Fabry - Perot interference filter 10 is provided with a light transmission region 10a that transmits light having a wavelength corresponding to the distance between the first mirror portion 35 and the second mirror portion 36. The light transmission region 10a is, for example, a cylindrical region centered on the line L.

[0035] The Fabry - Perot interference filter 10 includes a substrate 21. The substrate 21 has, for example, a rectangular plate shape. The material of the substrate 21 is, for example, silicon, quartz, or glass, etc. The substrate 21 has a first surface 21a and a second surface 21b that face each other in a direction parallel to the line L. The first surface 21a is the surface on the light incident side (the band - pass filter 14 side). The second surface 21b is the surface on the light emission side (the photodetector 8 side).

[0036] On the first surface 21a of the substrate 21, a first - layer structure 30 is disposed. The first - layer structure 30 is composed of a first antireflection layer 31, a first laminate 32, a first intermediate layer 33, and a second laminate 34 laminated on the first surface 21a in this order. A gap (air - gap) S is formed by a frame - shaped first intermediate layer 33 between the first laminate 32 and the second laminate 34. When the material of the substrate 21 is silicon, the materials of the first antireflection layer 31 and the first intermediate layer 33 are, for example, silicon oxide. The thickness of the first intermediate layer 33 is, for example, several tens of nm to several tens of μm.

[0037] The portion of the first laminate 32 corresponding to the light - transmission region 10a functions as a first mirror portion 35. The first laminate 32 is composed of a plurality of polysilicon layers and a plurality of silicon nitride layers laminated alternately one by one. The optical thickness of each of the polysilicon layer and the silicon nitride layer constituting the first mirror portion 35 is preferably an integer multiple of 1 / 4 of the central transmission wavelength of the light transmitted through the light - transmission region 10a. Note that the first mirror portion 35 may be disposed on the first surface 21a of the substrate 21 without passing through the first antireflection layer 31.

[0038] The portion of the second laminate 34 corresponding to the light transmission region 10a functions as the second mirror portion 36. The second mirror portion 36 faces the first mirror portion 35 via the gap S in a direction parallel to the line L. The second laminate 34 is configured by alternately laminating a plurality of polysilicon layers and a plurality of silicon nitride layers one by one. The optical thickness of each of the polysilicon layer and the silicon nitride layer constituting the second mirror portion 36 is preferably an integer multiple of 1 / 4 of the central transmission wavelength of the light transmitted through the light transmission region 10a.

[0039] In the first laminate 32 and the second laminate 34, a silicon oxide layer may be disposed instead of the silicon nitride layer. Further, the material of each layer constituting the first laminate 32 and the second laminate 34 is not limited to the materials described above, and may be, for example, titanium oxide, tantalum oxide, zirconium oxide, magnesium fluoride, aluminum oxide, calcium fluoride, silicon, germanium, or zinc sulfide.

[0040] A plurality of through holes 34b are formed in the portion of the second laminate 34 corresponding to the gap S. Each through hole 34b extends from the surface 34a of the second laminate 34 on the side opposite to the first laminate 32 to the gap S. The plurality of through holes 34b are formed to such an extent that they do not substantially affect the function of the second mirror portion 36. The plurality of through holes 34b are used to form the gap S by removing a part of the first intermediate layer 33 by etching.

[0041] In the first laminate 32, a first electrode 22 is formed so as to surround the light transmission region 10a. In the first laminate 32, a second electrode 23 is formed so as to include the light transmission region 10a. The first electrode 22 and the second electrode 23 are formed by doping an impurity into the polysilicon layer closest to the gap S in the first laminate 32 to reduce the resistance. In the second laminate 34, a third electrode 24 is formed so as to face the first electrode 22 and the second electrode 23 with the gap S therebetween. The third electrode 24 is formed by doping an impurity into the polysilicon layer closest to the gap S in the second laminate 34 to reduce the resistance. Note that the second electrode 23 may have a size equal to or larger than that of the light transmission region 10a.

[0042] The first layer structure 30 is provided with a pair of first terminals 25 and a pair of second terminals 26. The pair of first terminals 25 face each other with the light transmission region 10a therebetween. Each first terminal 25 is disposed in a through hole extending from the surface 34a of the second laminate 34 to the first laminate 32. Each first terminal 25 is electrically connected to the first electrode 22 via a wiring 22a formed in the first laminate 32. The pair of second terminals 26 face each other with the light transmission region 10a therebetween in a direction perpendicular to the direction in which the pair of first terminals 25 face each other. Each second terminal 26 is disposed in a through hole extending from the surface 34a of the second laminate 34 to the inside of the first intermediate layer 33. Each second terminal 26 is electrically connected to the second electrode 23 via a wiring 23a formed in the first laminate 32 and is also electrically connected to the third electrode 24 via a wiring 24a formed in the second laminate 34.

[0043] On the surface 32a of the first laminate 32 on the side of the second laminate 34, trenches 27 and 28 are provided. The trench 27 extends annularly so as to surround the connection portion of the wiring 23a with the second terminal 26. The trench 27 electrically insulates the first electrode 22 and the wiring 23a. The trench 28 extends annularly along the inner edge of the first electrode 22. The trench 28 electrically insulates the first electrode 22 and the region inside the first electrode 22 (that is, the region where the second electrode 23 is present). On the surface 34a of the second laminate 34, a trench 29 is provided. The trench 29 extends annularly so as to surround the first terminal 25. The trench 29 electrically insulates the first terminal 25 and the third electrode 24. The region in each of the trenches 27, 28, and 29 may be an insulating material or may be a void.

[0044] On the second surface 21b of the substrate 21, a second layer structure 40 is disposed. The second layer structure 40 is configured by laminating a second antireflection layer 41, a third laminate 42, a second intermediate layer 43, and a fourth laminate 44 on the second surface 21b in this order. The second antireflection layer 41, the third laminate 42, the second intermediate layer 43, and the fourth laminate 44 each have the same configuration as the first antireflection layer 31, the first laminate 32, the first intermediate layer 33, and the second laminate 34, respectively. That is, the second layer structure 40 has a laminated structure symmetric to the first layer structure 30 with respect to the substrate 21. The second layer structure 40 is configured to correspond to the first layer structure 30, thereby suppressing warping of the Fabry - Perot interference filter 10.

[0045] In the third laminate 42, the second intermediate layer 43, and the fourth laminate 44, an opening 40a is formed so as to include the light transmission region 10a. The opening 40a has, for example, a columnar shape with the line L as the center line and has substantially the same diameter as the light transmission region 10a. The opening 40a opens to the light emission side, and the bottom surface of the opening 40a reaches the second antireflection layer 41. The opening 40a allows the light transmitted through the first mirror portion 35 and the second mirror portion 36 to pass through.

[0046] On the surface of the light-emitting side of the fourth laminate 44, a light-shielding layer 45 is formed. The material of the light-shielding layer 45 is, for example, aluminum or the like. On the surface of the light-shielding layer 45 and the inner surface of the opening 40a, a protective layer 46 is formed. The material of the protective layer 46 is, for example, aluminum oxide. Note that by setting the thickness of the protective layer 46 to 1 to 100 nm (preferably about 30 nm), the optical influence by the protective layer 46 can be ignored.

[0047] In the Fabry-Perot interference filter 10 configured as described above, when a voltage is applied between the first terminal 25 and the second terminal 26, a potential difference is generated between the first electrode 22 and the third electrode 24, and an electrostatic force corresponding to the potential difference is generated between the first electrode 22 and the third electrode 24. As a result, the second mirror portion 36 is attracted to the side of the first mirror portion 35 fixed to the substrate 21, and the distance between the first mirror portion 35 and the second mirror portion 36 changes. At this time, since no potential difference is generated between the second electrode 23 and the third electrode 24, the flatness of the second mirror portion 36 in the light transmission region 10a is ensured. Thus, in the Fabry-Perot interference filter 10, the distance between the first mirror portion 35 and the second mirror portion 36 is variable. Here, the wavelength of the light transmitted through the light transmission region 10a depends on the distance between the first mirror portion 35 and the second mirror portion 36. Therefore, by adjusting the voltage applied between the first terminal 25 and the second terminal 26, the wavelength of the light transmitted through the light transmission region 10a can be adjusted.

[0048] [Spectroscopy module] A spectroscopy module according to an embodiment to which the above-described light detection device 1 is applied will be described. In the following description, the direction in which the first mirror portion 35 and the second mirror portion 36 face each other (in this embodiment, the direction parallel to the line L) is referred to as direction A.

[0049] As shown in FIGS. 4 and 5, the spectroscopic module 50 includes a light detection device 1, a light source 51, a wiring board 52, and a package 53. The light source 51 emits light to irradiate the object. The light source 51 is, for example, an infrared lamp that emits light in the wavelength range from near infrared to mid-infrared. A plurality of lead pins 11 of the light detection device 1 and a plurality of lead pins of the light source 51 are electrically connected to the wiring board 52. The package 53 houses the light detection device 1, the light source 51, the wiring board 52, the wiring board 56, etc. The package 53 has, for example, a rectangular parallelepiped shape. The package 53 has a package body 54 and a lid 55. The light detection device 1, the light source 51, the wiring board 52, the wiring board 56, etc. are arranged in the package body 54. The lid 55 has an outer surface 55a that is a plane. In the spectroscopic module 50, with the outer surface of the cover 20 (see FIG. 7) in contact with the object, it is possible to irradiate the object with light and detect the light reflected by the object. Note that the power supply to the spectroscopic module 50 is performed via a general-purpose connector such as a USB (Universal Serial Bus) socket. Further, the package 53 may house, for example, a wireless communication substrate or a battery case.

[0050] As shown in FIGS. 6 and 7, a recess 91 is formed in the inner surface 54b of the package body 54. The wiring board 52 is placed on the bottom surface 91a of the recess 91. The wiring board 52 is placed on the bottom surface 91a of the recess 91 such that the surface 52a of the wiring board 52 is flush with the inner surface 54b of the package body 54. The housing 2 is placed on the surface 52a of the wiring board 52. The housing 2 is fixed to the wiring board 52 by a plurality of lead pins 11 that penetrate the wiring board 52 and are fixed to the wiring board 52. The light source 51 is fixed to the wiring board 52. The light source 51 is adjacent to the housing 2 in a direction perpendicular to the direction A. The light source 51 is fixed to the wiring board 52 in a state of floating from the surface 52a of the wiring board 52 by a lead pin holding portion 51b that penetrates the wiring board 52 and is fixed to the wiring board 52.

[0051] On the outer surface 55a of the lid 55, a recess 61 is formed. On the bottom surface 61a of the recess 61, a cover (window glass) 20 made of, for example, glass or the like is provided. The outer surface of the cover 20 may be flush with the outer surface 55a of the lid 55, or may protrude slightly from the outer surface 55a. On the bottom surface 61a of the recess 61, a recess 62 that opens to the outside of the package 53 is formed. The recess 62 is composed of a first portion 63 and a second portion 64. The second portion 64 is deeper than the first portion 63. A concave curved surface 62b is formed between the bottom surface 64a of the second portion 64 and the side surface 62a of the recess 62. The concave curved surface 62b has a shape corresponding to a rounded chamfered surface applied to the corner formed by the bottom surface 64a and the side surface 62a.

[0052] On the inner surface 55b of the lid 55, a recess 65 is formed. On the bottom surface 65a of the recess 65, a recess 66 that opens to the inside of the package 53 is formed. When viewed from the direction A, the outer edge of the recess 66 is located outside the outer edge of the first portion 63 of the recess 62. The recess 66 communicates with the second portion 64 of the recess 62. Among the lid 55, the portion between the first portion 63 of the recess 62 and the recess 66 constitutes the second aperture portion 72. That is, the second aperture portion 72 is integrally formed with the lid 55. The second aperture portion 72 protrudes from the side surface 63b of the first portion 63 of the recess 62. A second aperture 72a is formed in the second aperture portion 72.

[0053] A hole 67 is formed in the bottom surface 64a of the second portion 64 of the recess 62. The hole 67 opens to the bottom surface 64a of the second portion 64 and the bottom surface 65a of the recess 65. When viewed from the direction A, the hole 67 has a size including the second aperture 72a. That is, when the shapes of the hole 67 and the second aperture 72a in a cross section perpendicular to the direction A are circular, the minimum diameter of the hole 67 in the cross section is larger than the maximum diameter of the second aperture 72a in the cross section.

[0054] The lid 55 is attached to the package body 54 such that the inner surface 55b contacts the inner surface 54b of the package body 54. In a state where the lid 55 is attached to the package body 54, the housing 2 of the photodetection device 1 is disposed in the recess 66 of the lid 55, and the light source 51 is disposed in the hole 67 of the lid 55. More specifically, with the opening 2a of the housing 2 facing the second aperture 72a, the cap 4 of the housing 2 is disposed in the recess 66. Further, with the light emitting portion 51a of the light source 51 disposed in the second portion 64 of the recess 62, the light source 51 is disposed in the hole 67. In a state where the lid 55 is attached to the package body 54, at least a part of the photodetection device 1 and the light source 51 are exposed in the recess 62 of the lid 55.

[0055] A gap is formed between the lid 55 and the housing 2. More specifically, in a state where the lid 55 is attached to the package body 54, a gap G1 is formed between the side surface 66b of the recess 66 of the lid 55 and the side wall 5 of the cap 4 of the housing 2. Further, in a state where the lid 55 is attached to the package body 54, a gap G2 is formed between the bottom surface 66a of the recess 66 of the lid 55 and the top wall 6 of the cap 4. The length of the gap G2 in the direction A is, for example, about 0.25 mm. A first aperture portion 71 is provided on the outer surface 6b of the top wall 6 of the housing 2. The first aperture portion 71 is disposed in the gap G2. A first aperture 80 is formed in the first aperture portion 71.

[0056] In the spectroscopic module 50 configured as described above, the light incident opening 72b of the second aperture 72a, the light incident opening 80b of the first aperture 80 (see FIG. 8), and the light emitting portion 51a of the light source 51 are located within the recess 62. The second aperture 72a, the first aperture 80, and the light emitting portion 51a of the light source 51 are arranged along the outer surface 55a of the lid 55 so as to be adjacent to each other.

[0057] The above-described first aperture 80 and second aperture 72a will be described in more detail. In the present embodiment, the band-pass filter 14 is separated from the first aperture portion 71 via the top wall 6 of the cap 4 which is a part of the housing 2. The band-pass filter 14 is disposed between the first aperture 80 and the Fabry-Perot interference filter 10. In the present embodiment, the housing 2, the first aperture portion 71, the second aperture portion 72, the band-pass filter 14, the Fabry-Perot interference filter 10, and the photodetector 8 constitute the spectroscopic unit 100.

[0058] As shown in FIG. 8, the first aperture portion 71 is provided on the side opposite to the Fabry-Perot interference filter 10 with respect to the top wall 6. The first aperture portion 71 has, for example, a quadrangular plate shape (see FIG. 5). The thickness of the first aperture portion 71 is, for example, about 0.1 mm to 0.2 mm. The first aperture portion 71 has a first surface 71a and a second surface 71b on the side opposite to the first surface 71a. The first aperture portion 71 is disposed between the top wall 6 and the second aperture portion 72 such that the first surface 71a faces the outer surface 6b of the top wall 6 and the second surface 71b faces the second aperture portion 72. The first surface 71a of the first aperture portion 71 is in contact with the outer surface 61b of the top wall 6. The first aperture portion 71 is fixed to the outer surface 6b of the top wall 6 by, for example, resin adhesion or the like. The first aperture portion 71 may be provided on the outer surface 61b of the top wall 6 via an adhesive member such as resin. The first aperture portion 71 may be provided on the outer surface 6b of the top wall 6 via a member such as a thin plate. Thus, the first aperture portion 71 is a first aperture member formed separately from the top wall 6. The material of the first aperture portion 71 is, for example, stainless steel or the like.

[0059] The first aperture 80 formed in the first aperture portion 71 is a through-hole that penetrates the first aperture portion 71. The first aperture 80 opens to the first surface 71a and the second surface 71b. The first aperture 80 is an opening formed by etching. The region inside the first aperture 80 is a space. The first aperture 80 faces the opening 2a in the direction A. The center line of the first aperture 80 coincides with the line L. The light incident aperture 80b of the first aperture 80 is the portion of the first aperture 80 that opens to the second surface 71b. The light exit aperture 80c of the first aperture 80 is the portion of the first aperture 80 that opens to the first surface 71a.

[0060] The first aperture 80 includes a first tapered portion 81 and a second tapered portion 82. The first tapered portion 81 reaches the first surface 71a on the top wall 6 side in the first aperture portion 71 and spreads toward the first surface 71a. The second tapered portion 82 reaches the second surface 71b on the second aperture portion 72 side in the first aperture portion 71 and spreads toward the second surface 71b.

[0061] In the present embodiment, the first tapered portion 81 and the second tapered portion 82 each have a frustum shape. That is, the cross-sectional shapes of the first tapered portion 81 and the second tapered portion 82 in the direction perpendicular to the direction A are each circular. The cross-sectional shape of the first aperture 80 in the direction perpendicular to the direction A is circular. The diameter of the first tapered portion 81 gradually increases from the second surface 71b side toward the first surface 71a. The diameter of the second tapered portion 82 gradually increases from the first surface 71a side toward the second surface 71b. The rate of change of the diameter of the first tapered portion 81 is the same as the rate of change of the diameter of the second tapered portion 82. That is, the angle between the first tapered portion 81 and the first surface 71a is the same as the angle between the second tapered portion 82 and the second surface 71b.

[0062] The first tapered portion 81 and the second tapered portion 82 contact each other at the center of the first aperture portion 71 in the direction A. The outer edge 80d of the first aperture 80 is formed by an edge formed by the first tapered portion 81 and the second tapered portion 82 contacting each other. When viewed from the direction A, the outer edge 80d has a circular shape. The outer edge of the first aperture 80 is the innermost edge of the first aperture 80 when viewed from the direction A. The first tapered portion 81 and the second tapered portion 82 are symmetrical to each other with respect to a plane that divides the first aperture portion 71 in two in the direction A (a plane including the outer edge 80d).

[0063] The second aperture portion 72 is provided on the opposite side of the first aperture portion 71 from the top wall 6. The second aperture portion 72 is spaced apart from the second surface 71b of the first aperture portion 71. The second aperture portion 72 is a second aperture member formed separately from the first aperture portion 71. The second aperture 72a formed in the second aperture portion 72 is a through hole penetrating the second aperture portion 72. The second aperture 72a opens to a bottom surface 63a of a first portion 63 of a recess 62 formed in the lid 55 and a bottom surface 66a of a recess 66.

[0064] The region within the second aperture 72a is a space. The second aperture 72a faces the first aperture 80 in the direction A. The center line of the second aperture 72a coincides with the line L. The light entrance opening 72b of the second aperture 72a is a portion of the second aperture 72a that opens to the bottom surface 63a of the first portion 63 of the recess 62. The light exit opening 72c of the second aperture 72a is a portion of the second aperture 72a that opens to the bottom surface 66a of the recess 66. In this embodiment, the region within the second aperture 72a has a cylindrical shape. That is, the cross-sectional shape of the second aperture 72a in a direction perpendicular to the direction A has a circular shape.

[0065] The second aperture portion 72 is configured such that the value obtained by dividing the length T2 of the second aperture 72a in the direction A by the width of the second aperture 72a in the direction perpendicular to the direction A (the aspect ratio of the second aperture 72a) is 0.5 or more. The length of the second aperture 72a in the direction A is the distance between the light incident aperture 72b and the light emitting aperture 72c. The width of the second aperture 72a in the direction perpendicular to the direction A is a value that is half the sum of the effective diameter of the light incident aperture 72b and the effective diameter of the light emitting aperture 72c. The effective diameter of the light incident aperture 72b is the diameter when the shape of the light incident aperture 72b is circular, and is the diameter of a circle having the area of the light incident aperture 72b when the shape of the light incident aperture 72b is other than circular. Similarly, the effective diameter of the light emitting aperture 72c is the diameter when the shape of the light emitting aperture 72c is circular, and is the diameter of a circle having the area of the light emitting aperture 72c when the shape of the light emitting aperture 72c is other than circular.

[0066] The distance between the second aperture portion 72 and the first aperture portion 71 in the direction A (the distance between the bottom surface 66a and the second surface 71b) is smaller than the length T2 of the second aperture 72a in the direction A. The length T2 of the second aperture 72a is, for example, about 1 mm. The length T2 of the second aperture 72a in the direction A is larger than the length T1 of the first aperture 80 in the direction A. That is, the thickness of the second aperture portion 72 is larger than the thickness of the first aperture portion 71. The length of the first aperture 80 in the direction A is the distance between the light incident aperture 80b and the light emitting aperture 80c. The length T1 of the first aperture 80 is, for example, about 0.1 mm to 0.2 mm.

[0067] When viewed from direction A, the outer edge of the opening 2a formed in the ceiling wall 6 is located outside the outer edge of the second aperture 72a. That is, the diameter of the opening 2a is larger than the diameter of the second aperture 72a. When viewed from direction A, the outer edge of the second aperture 72a is located inside the outer edge of the light transmission region 10a of the Fabry - Perot interference filter 10. That is, the diameter of the second aperture 72a is smaller than the diameter of the light transmission region 10a. When viewed from direction A, the outer edge 80d of the first aperture 80 is located inside each of the outer edge of the opening 2a, the outer edge of the second aperture 72a, and the outer edge of the light transmission region 10a of the Fabry - Perot interference filter 10. That is, the diameter of the outer edge 80d is smaller than each of the diameter of the opening 2a, the diameter of the second aperture 72a, and the diameter of the light transmission region 10a. The distance between the second aperture portion 72 and the first aperture portion 71 in direction A is smaller than the diameter of the outer edge of the second aperture 72a. The diameter of the opening 2a is, for example, about 1.5 mm. The diameter of the outer edge 80d of the first aperture 80 is, for example, about 0.5 mm. The diameter of the outer edge of the second aperture 72a is, for example, about 1.0 mm.

[0068] The incident angle and the exit angle of the light passing through the second aperture 72a and the first aperture 80 (the light passing through the second aperture 72a and the first aperture 80 in an ideal state where reflections at the inner surfaces of the inner surface of the second aperture 72a, the first tapered portion 81 of the first aperture 80, and the second tapered portion 82 of the first aperture 80 are ignored) are defined by the light incident opening 72b of the second aperture 72a and the outer edge 80d of the first aperture 80. In other words, the light incident opening 72b and the outer edge 80d are the portions that define the incident angle and the exit angle of the light passing through the second aperture 72a and the first aperture 80 (the light passing through the second aperture 72a and the first aperture 80 in an ideal state where reflections at the inner surfaces of the inner surface of the second aperture 72a, the first tapered portion 81 of the first aperture 80, and the second tapered portion 82 of the first aperture 80 are ignored).

[0069] The first aperture unit 71 and the second aperture unit 72 are configured such that all of the light (in an ideal state where reflections at the inner surface of the second aperture 72a, the inner surface of the first tapered portion 81 of the first aperture 80, and the inner surface of the second tapered portion 82 are ignored) that has passed through the second aperture 72a and the first aperture 80 is incident on the band-pass filter 14. Further, the first aperture unit 71 and the second aperture unit 72 are configured such that all of the light that has passed through the second aperture 72a and the first aperture 80 and has transmitted through the band-pass filter 14 is incident on the Fabry-Perot interference filter 10.

[0070] [Operation and Effect] As described above, in the spectroscopic unit 100, the length T2 of the second aperture 72a in the direction A is larger than the length T1 of the first aperture 80 in the direction A, and when viewed from the direction A, the outer edge 80d of the first aperture 80 is located inside the outer edges of the aperture 2a and the second aperture 72a, respectively. Therefore, the light that has passed through the second aperture 72a, the first aperture 80, and the aperture 2a is incident on the Fabry-Perot interference filter 10 in a state where the range of its incident angle is narrowed. As a result, the Fabry-Perot interference filter 10 can function properly. Further, in the spectroscopic unit 100, when viewed from the direction A, the outer edge 80d of the first aperture 80 is located inside the outer edge of the second aperture 72a, and the first aperture 80 includes the first tapered portion 81 and the second tapered portion 82. Therefore, it is possible to suppress the light that has entered the second aperture 72a at a large incident angle from becoming stray light by being reflected by the inner surface of the second aperture 72a and entering the housing 2. As described above, according to the spectroscopic unit 100, the resolution can be improved in the spectroscopic spectrum obtained by the Fabry-Perot interference filter 10, and the spectroscopic accuracy by the Fabry-Perot interference filter 10 can be improved.

[0071] The above effects will be described in more detail. As shown in FIG. 8, for example, when light L1 is incident on the second aperture 72a at a large incident angle, the light L1 travels toward the housing 2 while being reflected by the inner surface of the second aperture 72a. Here, for example, when the outer edge 80d of the first aperture 80 is located outside the outer edge of the second aperture 72a, or when the first aperture portion 71 does not exist, the light L1 is reflected by the inner surface of the opening 2a (or after directly passing through the opening 2a) and then enters the housing 2 (see the light L1a shown by the dotted line). On the other hand, in the spectroscopic unit 100, since the outer edge 80d of the first aperture 80 is located inside the outer edge of the second aperture 72a, the light L1 is reflected by the second surface 71b of the first aperture portion 71 and does not enter the housing 2 (see the light L1b shown by the solid line).

[0072] Also, for example, when light L2 is incident on the second aperture 72a at a large incident angle, the light L2 travels toward the housing 2 while being reflected by the inner surface of the second aperture 72a. Here, for example, when the first aperture 80 does not have the first tapered portion 81 and the second tapered portion 82 and the region inside the first aperture 80 has a cylindrical shape (see the portion shown by the two-dot chain line), the light L2 is reflected by the inner surface 80e of the first aperture 80 and then enters the housing 2 (see the light L2a shown by the dotted line). On the other hand, in the spectroscopic unit 100, since the first aperture 80 includes the first tapered portion 81 and the second tapered portion 82, the light L2 is reflected to the side opposite to the inside of the housing 2 by the inner surface of the second tapered portion 82 and does not enter the housing 2 (see the light L2b shown by the solid line).

[0073] By the way, in a spectroscopic module such as the spectroscopic module 50, even when there are dimensional variations in each component, it is required to securely assemble each component. As a result, gaps such as a gap G1 and a gap G2 may be formed in the spectroscopic module 50 after assembling each component. If a gap G2 is formed between the second aperture portion 72 and the top wall 6, there is a possibility that light incident through the gap G2 (for example, light not reflected by the target portion) enters the housing 2 and becomes stray light. In the spectroscopic module 50, the first aperture portion 71 is provided on the outer surface 6b of the top wall 6. According to this, as described above, not only the light incident on the second aperture 72a at a large incident angle but also the light incident through the gap G2 can be suppressed from becoming stray light by entering the housing 2. In other words, even when it is difficult to make the gap G2 zero, by arranging the first aperture portion 71 in the gap G2, the entry of stray light into the housing 2 can be reduced. As a result, it is possible to obtain an effect of suppressing the entry of stray light equivalent to the case where the gap G2 is zero.

[0074] In the spectroscopic unit 100, the first aperture 80 includes both the first tapered portion 81 and the second tapered portion 82. According to this, even if the light incident on the second aperture 72a at a large incident angle travels inside the second aperture 72a while being reflected by the inner surface of the second aperture 72a, the light is reflected by the inner surface of the second tapered portion 82 to the side opposite to the inside of the housing 2. Therefore, it is possible to more reliably suppress the light incident on the second aperture 72a at a large incident angle from becoming stray light by being incident into the housing 2 while being reflected by the inner surface of the second aperture 72a. Further, even if the first aperture portion 71 is provided (misassembled) in the opposite direction, the above-described effects can be achieved. That is, even if the first aperture portion 71 is provided such that the first surface 71a faces the second aperture portion 72 and the second surface 71b faces the outer surface 6b of the top wall 6, the first tapered portion 81 can reflect the light L2 as the light L2b as described above instead of the second tapered portion 82. Furthermore, the first tapered portion 81 and the second tapered portion 82 are symmetric with respect to the plane that bisects the first aperture portion 71 in the direction A. According to this, as described above, even if the first aperture portion 71 is provided in the opposite direction, the first tapered portion 81 can exhibit the same function as the second tapered portion 82.

[0075] In the spectroscopic unit 100, when viewed from the direction A, the outer edge 80d of the first aperture 80 is located inside the outer edge of the light transmission region 10a of the Fabry - Perot interference filter 10. According to this, it is possible to increase the ratio of the light that passes through the light transmission region 10a of the Fabry - Perot interference filter 10 among the light that has passed through the second aperture 72a and the first aperture 80.

[0076] In the spectroscopic unit 100, when viewed from the direction A, the outer edge of the opening 2a is located outside the outer edge of the second aperture 72a. According to this, the first aperture 80 and the second aperture 72a can appropriately define the range of the incident angle of the light to be incident into the housing 2.

[0077] In the spectroscopic unit 100, the first aperture 80 is an opening formed by etching. According to this, the first aperture 80 will have a highly accurate shape as compared with the case where the first aperture 80 is an opening formed by, for example, machining. Therefore, according to this, the first aperture 80 can function properly.

[0078] In the spectroscopic unit 100, the first aperture portion 71 is a first aperture member formed separately from the top wall 6 and is provided on the outer surface 6b of the top wall 6. According to this, the degree of freedom in designing the first aperture portion 71, such as the selection of a suitable material, can be improved. Also, by forming a large light incident opening in the housing 2, while relaxing the positional accuracy of the Fabry - Perot interference filter 10 in the housing 2, the positional relationship between the first aperture 80 and the Fabry - Perot interference filter 10 can be adjusted. Further, even if a gap G2 is formed between the first aperture portion 71 and the second aperture portion 72, as described above, it is possible to suppress the light from becoming stray light by entering the housing 2 through the gap G2.

[0079] In the spectroscopic unit 100, the first aperture portion 71 is fixed to the top wall 6. According to this, it is possible to prevent a shift in the positional relationship between the first aperture 80 and the Fabry - Perot interference filter 10 due to vibration or the like.

[0080] In the spectroscopic unit 100, the second aperture portion 72 is a second aperture member formed separately from the first aperture portion 71. According to this, the degree of freedom in designing the second aperture portion 72 and the first aperture portion 71, such as the selection of a suitable material, can be improved. Also, by forming a large light incident opening in the housing 2, while relaxing the positional accuracy of the Fabry - Perot interference filter 10 in the housing 2, the positional relationship between the second aperture 72a and the Fabry - Perot interference filter 10 can be adjusted. Also, the positional relationship between the second aperture 72a and the first aperture 80 can be adjusted.

[0081] In the spectroscopic unit 100, the cross-sectional shape of the first aperture 80 in the direction perpendicular to direction A is circular, and the cross-sectional shape of the second aperture 72a in the direction perpendicular to direction A is circular. According to this, an aperture having desired performance can be easily formed.

[0082] In the spectroscopic unit 100, the region inside the first aperture 80 is a space, and the region inside the second aperture 72a is a space. According to this, it is possible to prevent light loss caused by passing through the first aperture 80 and the second aperture 72a.

[0083] The spectroscopic unit 100 is disposed in the housing 2 and includes a photodetector 8 that detects light transmitted through the Fabry-Perot interference filter 10. According to this, it is possible to accurately detect the spectroscopically separated light while suppressing the generation of noise caused by stray light. Further, since the photodetector 8 is disposed inside the housing 2, it is possible to reduce the size of the spectroscopic unit 100 including the photodetector 8.

[0084] The spectroscopic unit 100 includes a band-pass filter 14 disposed between the first aperture 80 and the Fabry-Perot interference filter 10. The first aperture portion 71 and the second aperture portion 72 are configured such that all of the light that has passed through the first aperture 80 and the second aperture 72a is incident on the band-pass filter 14. According to this, all of the light that has passed through the second aperture 72a, the first aperture 80, and the opening 2a is incident on the band-pass filter 14 in a state where the range of its incident angle is narrowed. As a result, the band-pass filter 14 functions appropriately, and light in a desired wavelength range is incident on the Fabry-Perot interference filter 10 in a state where the range of its incident angle is narrowed. Therefore, the resolution is improved in the spectroscopic spectrum obtained by the Fabry-Perot interference filter 10.

[0085] In the spectroscopic unit 100, the first aperture section 71 and the second aperture section 72 are configured such that all of the light that has passed through the first aperture 80 and the second aperture 72a and transmitted through the band-pass filter 14 is incident on the Fabry-Perot interference filter 10. According to this, it is possible to suppress the generation of stray light inside the housing 2.

[0086] Also, in the spectroscopic unit 100, the band-pass filter 14 is separated from the first aperture section 71 via the top wall 6. According to this, since the band-pass filter 14 is to be disposed inside the housing 2, the band-pass filter 14 can be protected from physical interference and the like.

[0087] The spectroscopic module 50 includes a spectroscopic unit 100, a light source 51, the housing 2 of the spectroscopic unit 100, and a package 53 that houses the light source 51. The first aperture 80 and the light-emitting section 51a of the light source 51 of the second aperture 72a are arranged along the outer surface 55a of the package 53 so as to be adjacent to each other. According to this, it is possible to realize a reflective spectroscopic module 50 with improved spectroscopic accuracy by the Fabry-Perot interference filter 10.

[0088] Also, in the spectroscopic module 50, the light-incident aperture 72b of the second aperture 72a and the light-emitting section 51a of the light source 51 are located inside the recess 62. Thereby, even in a state where the outer surface 55a of the lid 55 is in contact with the object, since the region inside the recess 62 is secured as an optical path, it is possible to perform irradiation of light onto the object and detection of the light reflected by the object.

[0089] Also, in the spectroscopic module 50, the second aperture 72a is formed on the bottom surface 63a of the first portion 63 of the recess 62. Thereby, even in a state where the outer surface 55a of the lid 55 is in contact with the object, the light reflected by the object can be surely incident on the second aperture 72a.

[0090] In the spectroscopic module 50, a hole 67 in which the light source 51 is disposed is formed in the bottom surface 64a of the second portion 64 that is deeper than the first portion 63 of the concave portion 62. Thereby, even in a state where the outer surface 55a of the lid 55 is in contact with the object, the light emitted from the light source 51 can sufficiently irradiate the object.

[0091] In the spectroscopic module 50, a concave curved surface 62b is formed between the bottom surface 64a of the second portion 64 and the side surface 62a of the concave portion 62. Thereby, since the light reflected by the concave curved surface 62b is also irradiated onto the object, the light emitted from the light source 51 can more sufficiently irradiate the object.

[0092] In the spectroscopic module 50, when viewed from the direction A, the hole 67 has a size including the second aperture 72a. Thereby, the light emitted from the light source 51 can irradiate the object over a wide range.

[0093] [Modification Example] The present invention is not limited to the above-described embodiment. For example, although an example in which the first tapered portion 81 and the second tapered portion 82 are in contact with each other has been shown, the first tapered portion 81 and the second tapered portion 82 may be separated from each other. The first tapered portion 81 and the second tapered portion 82 may reach, for example, an intermediate portion formed between the first tapered portion 81 and the second tapered portion 82 in the direction A. The region within the intermediate portion may have, for example, a columnar shape extending in the direction A. Further, although an example in which the rate of change of the diameter of the first tapered portion 81 is the same as the rate of change of the diameter of the second tapered portion 82 has been shown, the rate of change of the diameter of the first tapered portion 81 may be different from the rate of change of the diameter of the second tapered portion 82.

[0094] Also, as shown in FIG. 9(a), the first aperture 80 may include only the second tapered portion 82. The second tapered portion 82 may reach both the first surface 71a and the second surface 71b. In this case, the outer edge of the first aperture 80 is the edge of the light emission opening 80c. According to this, even if the light incident on the second aperture 72a at a large incident angle travels inside the second aperture 72a while being reflected by the inner surface of the second aperture 72a, the light is reflected by the inner surface of the second tapered portion 82 to the side opposite to the inside of the housing 2. Therefore, according to this, it is possible to more reliably suppress the light incident on the second aperture 72a at a large incident angle from becoming stray light by entering the housing 2 while being reflected by the inner surface of the second aperture 72a. Further, as shown in FIG. 9(b), the first aperture 80 may include only the first tapered portion 81. The first tapered portion 81 may reach both the first surface 71a and the second surface 71b. In this case, the outer edge of the first aperture 80 is the edge of the light incident opening 80b. Thus, the first aperture 80 only needs to include at least one of the first tapered portion 81 and the second tapered portion 82. When the first aperture 80 includes at least one of the first tapered portion 81 and the second tapered portion 82, at least one of the first tapered portion 81 and the second tapered portion 82 can be easily formed by etching. Also, the weight of the first aperture 80 can be reduced.

[0095] Further, when the first aperture 80 includes at least one of the first tapered portion 81 and the second tapered portion 82, even if the first aperture portion 71 is arranged in a state inclined with respect to the direction A (line L) (a state where the center line of the first aperture 80 intersects the line L), the traveling direction of the light incident on the first aperture 80 along the direction A can be maintained. Specifically, as shown in FIG. 10(a), when the aperture 720 formed in the aperture portion 710 does not include a tapered portion, that is, when the inner surface of the aperture 720 has a cylindrical shape, for example, if the aperture portion 710 is arranged in a state inclined with respect to the direction A, the light L3 incident on the aperture 720 along the direction A is reflected by the inner surface of the aperture 720. As a result, the light L3 incident along the direction A travels inside the aperture 720 while being reflected by the inner surface of the aperture 720, and then exits from the aperture 720 along a direction intersecting the direction A.

[0096] In contrast, as shown in FIG. 10(b), when the first aperture 80 includes the first tapered portion 81 and the second tapered portion 82, even if the first aperture portion 71 is arranged in a state inclined with respect to the direction A, the light L3 incident on the first aperture 80 along the direction A travels inside the first aperture 80 along the direction A without being reflected by the inner surface of the first tapered portion 81 or the second tapered portion 82, and then exits from the first aperture 80 along the direction A. Similarly, as shown in FIG. 10(c), when the first aperture 80 includes only the first tapered portion 81, even if the first aperture portion 71 is arranged in a state inclined with respect to the direction A, the light L3 incident on the first aperture 80 along the direction A travels inside the first aperture 80 along the direction A without being reflected by the inner surface of the first tapered portion 81, and then exits from the first aperture 80 along the direction A. Similarly, as shown in FIG. 10(d), when the first aperture 80 includes only the second tapered portion 82, even if the first aperture portion 71 is arranged in a state inclined with respect to the direction A, the light L3 incident on the first aperture 80 along the direction A travels inside the first aperture 80 along the direction A without being reflected by the inner surface of the second tapered portion 82, and then exits from the first aperture 80 along the direction A. According to these, by relaxing the positional accuracy of the first aperture portion 71 and causing the light L3 incident on the first aperture 80 along the direction A to exit along the direction A, the bandpass filter 14 or the Fabry-Perot interference filter 10 can function properly.

[0097] In such cases, this is particularly important when the width (e.g., diameter) of the outer edge of the aperture is small. That is, when the width of the outer edge of the aperture is small, the amount of light passing through the aperture (here, the light traveling along direction A) tends to decrease. Therefore, in order to ensure the amount of light passing through the aperture, it is important not to reduce the amount of light traveling along direction A. Also, the smaller the width of the outer edge of the aperture, the more likely the light incident on the aperture along direction A is to be reflected by the inner surface of the aperture when the aperture portion is tilted slightly with respect to direction A (see, for example, Fig. 10(a)). According to the first aperture portion 71, as described above, even if the first aperture portion 71 is arranged in a tilted state with respect to direction A, the traveling direction of the light incident on the first aperture 80 along direction A can be maintained. Therefore, a decrease in the amount of light passing through the aperture along direction A can be suppressed. Note that in the first aperture portion 71 and the Fabry-Perot interference filter 10 shown in Figs. 10(b) to (d) and the first aperture portion 71 and the Fabry-Perot interference filter 10 shown in other figures, for the sake of illustration, the dimensional ratios and the like are different.

[0098] Also, when viewed from direction A, the outer edge of the second aperture 72a may be located outside the outer edge of the light transmission region 10a of the Fabry-Perot interference filter 10 or the outer edge of the opening 2a. In that case, a sufficient amount of light entering the housing 2 can be ensured.

[0099] Also, the first aperture portion 71 may be formed integrally with the housing 2. In this case, a part of the top wall 6 of the cap 4 functions as the first aperture portion 71, and the first aperture 80 is formed in the top wall 6 so as to communicate with the opening 2a. When the first aperture portion 71 is formed integrally with the housing 2, a shift in the positional relationship between the first aperture 80 and the Fabry-Perot interference filter 10 due to vibration or the like can be prevented with a simple configuration.

[0100] In addition, although an example where the first aperture portion 71 is in contact with the top wall 6 has been shown, the first aperture portion 71 may be separated from the top wall 6. Further, the first aperture portion 71 may be in contact with the second aperture portion 72. Further, the first aperture portion 71 may be integrally formed with the second aperture portion 72. In this case, a part of the lid 55 functions as the first aperture portion 71, and the first aperture 80 is formed in the lid 55 so as to communicate with the second aperture 72a. When the first aperture portion 71 is integrally formed with the second aperture portion 72, it is possible to prevent a deviation in the positional relationship between the first aperture 80 and the second aperture 72a due to vibration or the like with a simple configuration.

[0101] Further, the second aperture portion 72 may be a second aperture member formed separately from the lid 55. In this case, the degree of freedom in the design of the second aperture portion 72, such as the selection of a suitable material, can be improved. Further, the positional relationship between the second aperture 72a and the first aperture 80 or the Fabry - Perot interference filter 10 can be adjusted more easily.

[0102] In addition, the above - described reflection - type spectroscopic module 50 can perform irradiation of light to the object and detection of the light reflected by the object even when the outer surface 55a of the lid 55 is separated from the object without contacting the outer surface 55a of the lid 55 with the object. Further, the spectroscopic unit 100 may be applied to a transmission - type spectroscopic module 50 that detects light emitted from the light source 51 and transmitted through the object. Further, even when the spectroscopic unit 100 does not include the photodetector 8 and the light transmitted through the Fabry - Perot interference filter 10 is detected by the photodetector 8 disposed outside the housing 2.

Explanation of Reference Numerals

[0103] 1... Photodetection device, 2... Housing, 2a... Opening, 6... Top wall (wall portion), 8... Photodetector, 10... Fabry - Perot interference filter, 10a... Light transmission region, 35... First mirror portion, 36... Second mirror portion, 50... Spectroscopic module, 51... Light source, 51a... Light emitting portion, 53... Package, 55a... Outer surface, 71... First aperture portion, 71a... First surface, 71b... Second surface, 72... Second aperture portion, 72a... Second aperture, 80... First aperture, 80d... Outer edge, 81... First tapered portion, 82... Second tapered portion, 100... Spectroscopic unit, A... Direction (opposing direction), T1, T2... Lengths.

Claims

1. A Fabry - Perot interference filter having a first mirror part and a second mirror part with a variable distance therebetween, a housing that has a wall part in which an opening facing the Fabry - Perot interference filter is formed in the facing direction of the first mirror part and the second mirror part, and that houses the Fabry - Perot interference filter, a first aperture part that is fixed to the housing and in which a first aperture facing the opening is formed in the facing direction, a second aperture part that is provided on the side opposite to the Fabry - Perot interference filter with respect to the wall part and in which a second aperture facing the first aperture is formed in the facing direction, and the length of the second aperture in the facing direction is larger than the length of the first aperture in the facing direction, when viewed from the facing direction, the outer edge of the first aperture is located inside each of the outer edge of the opening and the outer edge of the second aperture, the first aperture includes both a first tapered portion that reaches and spreads toward a first surface on the Fabry - Perot interference filter side in the first aperture part and a second tapered portion that reaches and spreads toward a second surface on the side opposite to the Fabry - Perot interference filter in the first aperture part, a spectroscopic unit.

2. A Fabry - Perot interference filter having a first mirror part and a second mirror part with a variable distance therebetween, a housing that has a wall part in which an opening facing the Fabry - Perot interference filter is formed in the facing direction of the first mirror part and the second mirror part, and that houses the Fabry - Perot interference filter, a first aperture part that is fixed to the housing and in which a first aperture facing the opening is formed in the facing direction, a second aperture part that is provided on the side opposite to the Fabry - Perot interference filter with respect to the wall part and in which a second aperture facing the first aperture is formed in the facing direction, and the length of the second aperture in the facing direction is larger than the length of the first aperture in the facing direction, when viewed from the facing direction, the outer edge of the first aperture is located inside each of the outer edge of the opening and the outer edge of the second aperture, The first aperture includes only the second tapered portion that reaches the second surface on the side opposite to the Fabry - Perot interference filter in the first aperture portion and spreads toward the second surface, reaching the first surface on the Fabry - Perot interference filter side in the first aperture portion and spreading toward the first surface. The second tapered portion reaches both the first surface and the second surface, and is a spectroscopic unit.

3. A Fabry - Perot interference filter having a first mirror portion and a second mirror portion with a variable distance therebetween, A housing that has a wall portion in which an opening facing the Fabry - Perot interference filter is formed in the facing direction of the first mirror portion and the second mirror portion, and houses the Fabry - Perot interference filter, A first aperture portion that is fixed to the housing and in which a first aperture facing the opening is formed in the facing direction, A second aperture portion that is provided on the side opposite to the Fabry - Perot interference filter with respect to the wall portion and in which a second aperture facing the first aperture is formed in the facing direction, The length of the second aperture in the facing direction is greater than the length of the first aperture in the facing direction. When viewed from the facing direction, the outer edge of the first aperture is located inside the outer edges of the opening and the second aperture, respectively. The first aperture includes at least one of a first tapered portion that reaches the first surface on the Fabry - Perot interference filter side in the first aperture portion and spreads toward the first surface, and a second tapered portion that reaches the second surface on the side opposite to the Fabry - Perot interference filter in the first aperture portion and spreads toward the second surface. When viewed from the facing direction, the outer edge of the opening is located outside the outer edge of the second aperture, and is a spectroscopic unit.

4. The spectroscopic unit according to any one of claims 1 to 3, wherein when viewed from the facing direction, the outer edge of the first aperture is located inside the outer edge of the light transmission region of the Fabry - Perot interference filter.

5. The spectroscopic unit according to any one of claims 1 to 4, wherein the first aperture is an opening formed by etching.

6. The first aperture part is a first aperture member formed separately from the wall part and is provided on the surface of the wall part. The spectroscopic unit according to any one of claims 1 to 5.

7. The first aperture part is fixed to the wall part. The spectroscopic unit according to claim 6.

8. The second aperture part is a second aperture member formed separately from the first aperture part. The spectroscopic unit according to any one of claims 1 to 7.

9. The cross-sectional shape of the first aperture in the direction perpendicular to the facing direction is circular. The cross-sectional shape of the second aperture in the direction perpendicular to the facing direction is circular. The spectroscopic unit according to any one of claims 1 to 8.

10. The region inside the first aperture is a space. The region inside the second aperture is a space. The spectroscopic unit according to any one of claims 1 to 9.

11. The spectroscopic unit according to any one of claims 1 to 10, further comprising a photodetector disposed inside the housing for detecting light that has passed through the Fabry-Perot interference filter.

12. The spectroscopic unit further comprises a band-pass filter disposed between the first aperture and the Fabry-Perot interference filter. The first aperture part and the second aperture part are configured such that all of the light that has passed through the first aperture and the second aperture is incident on the band-pass filter. The spectroscopic unit according to any one of claims 1 to 11.

13. The first aperture part and the second aperture part are configured such that all of the light that has passed through the first aperture and the second aperture and has passed through the band-pass filter is incident on the Fabry-Perot interference filter. The spectroscopic unit according to claim 12.

14. The first aperture part is provided on the side of the wall part opposite to the Fabry-Perot interference filter. The band-pass filter is separated from the first aperture part via the wall part. The spectroscopic unit according to claim 12 or 13.

15. The spectroscopic unit according to any one of claims 1 to 14, a light source, and a package that houses the housing of the spectroscopic unit and the light source. A spectroscopic module in which the first aperture, the second aperture, and the light emitting portion of the light source are arranged along the outer surface of the package so as to be adjacent to each other.

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