Lens unit for hyperspectral camera and hyperspectral camera

Abstract

The lens unit (2) is provided with a housing (21) and an optical system (22) disposed in the housing. An optical system (22) is provided with: a Fabry-Perot interference filter (10); a first aperture (P1), which is formed integrally with the Fabry-Perot interference filter (10), and through which light directed toward the Fabry-Perot interference filter (10) or light transmitted through the Fabry-Perot interference filter (10) passes; a first lens unit (23) that focuses or parallelizes light from the incident unit toward the Fabry-Perot interference filter; and a second lens unit (24) that forms an image of the light that has passed through the Fabry-Perot interference filter and has been emitted from the emission unit. When viewed from the optical axis direction, the width of the light at the incident position of the first aperture (P1) is wider than the width of the first aperture (P1).

Description

Technical Field

[0001] The present invention relates to a lens unit for a hyperspectral camera and a hyperspectral camera. Background Art

[0002] As a hyperspectral camera, there is a hyperspectral camera that splits light by each wavelength using a Fabry - Perot interference filter and photographs the split light. As a related art, for example, Patent Document 1 discloses an imaging lens unit having an objective lens, an imaging lens, and a Fabry - Perot interference filter provided between them. The light guided by this imaging lens unit is photographed using an imaging unit provided in the camera body.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2016 - 11986 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] An object of one aspect of the present disclosure is to provide a lens unit for a hyperspectral camera that can perform good photography using a hyperspectral camera, and a hyperspectral camera that can perform good photography.

[0008] Technical Means for Solving the Problems

[0009] The lens unit for a hyperspectral camera according to one aspect of the present disclosure is [1] "a lens unit for a hyperspectral camera, comprising: a housing having an incident portion for light incidence, an emission portion for the light to be emitted, and a mounting portion for detachably mounting an optical device; and an optical system disposed within the housing, the optical system including: a Fabry - Perot interference filter having a pair of mirror portions with a variable distance therebetween, and causing the light from the incident portion to pass through according to the distance between the pair of mirror portions; a first aperture formed integrally with the Fabry - Perot interference filter, through which the light directed toward the Fabry - Perot interference filter or the light passing through the Fabry - Perot interference filter passes; a first lens portion that condenses or collimates the light from the incident portion toward the Fabry - Perot interference filter; and a second lens portion that forms an image of the light passing through the Fabry - Perot interference filter and emitted from the emission portion, and in a view from the optical axis direction, the width of the light at the incident position on the first aperture is wider than the width of the first aperture".

[0010] In the lens unit for a hyperspectral camera, when viewed from the optical axis direction of light, the width of the light at the incident position on the first aperture is wider than the width of the first aperture. Thus, for example, compared to the case where light reduced by the lens to a width narrower than the first aperture passes through the first aperture, the width of the first aperture can be utilized to the maximum extent, and the light quantity can be ensured. In addition, the light directed toward the Fabry - Perot interference filter or the light transmitted through the Fabry - Perot interference filter can be reduced by the first aperture, and the depth of field can be increased. Further, the first aperture is formed integrally with the Fabry - Perot interference filter. Thus, for example, compared to the case where the first aperture and the Fabry - Perot interference filter are formed separately, the occurrence of deviation from the design (for example, deviation in the distance or angle between a pair of mirror portions and the first aperture, or position deviation in the direction perpendicular to the optical axis, etc.) can be suppressed. As described above, according to this lens unit for a hyperspectral camera, the photographing by the hyperspectral camera can be performed well.

[0011] The lens unit for a hyperspectral camera according to one aspect of the present disclosure may also be [2] “The lens unit for a hyperspectral camera according to [1], wherein the Fabry - Perot interference filter is disposed at a position where the principal ray passing through the outer edge of the imaging region of the light based on the second lens unit intersects the optical axis of the light”. In this case, the size of the imaging region of the light based on the second lens can be made constant regardless of the size of the first aperture. In addition, since the incident angle of the light to the Fabry - Perot interference filter is constant, it is easy to correct the wavelength shift in the Fabry - Perot interference filter.

[0012] The lens unit for a hyperspectral camera according to one aspect of the present disclosure may also be [3] “The lens unit for a hyperspectral camera according to [1] or [2], wherein the first aperture is located on the incident portion side with respect to the pair of mirror portions”. In this case, before the light is incident on the pair of mirror portions, the stray light and the light with a large incident angle can be cut off by the first aperture, and the noise can be reduced.

[0013] The lens unit for a hyperspectral camera according to one aspect of the present disclosure may also be [4] “The lens unit for a hyperspectral camera according to any one of [1] to [3], wherein the optical system further includes a second aperture disposed between the Fabry - Perot interference filter and the first lens unit or between the Fabry - Perot interference filter and the second lens unit”. In this case, the light can be reduced within a desired angular range by the first aperture and the second aperture, and the resolution in the imaging for each wavelength can be improved.

[0014] The lens unit for a hyperspectral camera according to one aspect of the present disclosure may also be [5] "the lens unit for a hyperspectral camera according to [4], wherein the second aperture is constituted by an opening formed in the support body, and the Fabry - Perot interference filter is fixed to the support body". In this case, the Fabry - Perot interference filter (the first aperture) can be appropriately fixed near the second aperture.

[0015] The lens unit for a hyperspectral camera according to one aspect of the present disclosure may also be [6] "the lens unit for a hyperspectral camera according to [5], further comprising: a first lens holder that holds the first lens unit; and a second lens holder that holds the second lens unit, and the support body is fixed while being sandwiched between the first lens holder and the second lens holder". In this case, the support body can be appropriately fixed.

[0016] The lens unit for a hyperspectral camera according to one aspect of the present disclosure may also be [7] "the lens unit for a hyperspectral camera according to any one of [1] to [6], wherein, when viewed from the optical axis direction, the area of the incident region of the light at the incident position on the first aperture is 110% or less of the area of the first aperture". In this case, the utilization efficiency of light can be improved.

[0017] The lens unit for a hyperspectral camera according to one aspect of the present disclosure may also be [8] "the lens unit for a hyperspectral camera according to any one of [1] to [7], wherein the optical system further includes an additional optical system that is disposed between the Fabry - Perot interference filter and the first lens unit and reduces the width of the light". In this case, the utilization efficiency of light can be improved.

[0018] The lens unit for a hyperspectral camera according to one aspect of the present disclosure may also be [9] "the lens unit for a hyperspectral camera according to any one of [1] to [7], wherein the optical system further includes an additional optical system that is disposed between the Fabry - Perot interference filter and the first lens unit and parallelizes the light". In this case, by parallelizing the light before it enters the Fabry - Perot interference filter, the generation of wavelength shift can be suppressed.

[0019] The lens unit for a hyperspectral camera according to one aspect of the present disclosure may also be

[10] "the lens unit for a hyperspectral camera according to [9], wherein the additional optical system reduces the width of the light". In this case, the utilization efficiency of light can be improved.

[0020] The lens unit for a hyperspectral camera according to one aspect of the present disclosure may also be "

[11] The lens unit for a hyperspectral camera according to any one of [1] to

[10] , wherein the Fabry - Perot interference filter has: a substrate including a first surface and a second surface on the opposite side of the first surface; and a first stacked structure disposed on the first surface, the first stacked structure having: a first stacked body disposed on the first surface and having one of the pair of mirror portions; and a second stacked body disposed on the opposite side of the substrate with respect to the first stacked body and having the other of the pair of mirror portions". In this case, the shooting by the hyperspectral camera can also be performed well.

[0021] The lens unit for a hyperspectral camera according to one aspect of the present disclosure may also be "

[12] The lens unit for a hyperspectral camera according to

[11] , wherein the Fabry - Perot interference filter further has a second stacked structure disposed on the second surface of the substrate, a recess is formed on the surface of the second stacked structure on the opposite side of the substrate, and at least a part of the recess overlaps with the first aperture when viewed from the optical axis direction". In this case, by forming the recess, light can easily pass through the portion of the Fabry - Perot interference filter that overlaps with the first aperture, and the light utilization efficiency can be improved.

[0022] The lens unit for a hyperspectral camera according to one aspect of the present disclosure may also be "

[13] The lens unit for a hyperspectral camera according to any one of [1] to

[10] , wherein the Fabry - Perot interference filter has: a first substrate having a first surface; a second substrate having a second surface opposite to the first surface; one of the pair of mirror portions formed on the first surface; and the other of the pair of mirror portions formed on the second surface". In this case, the shooting by the hyperspectral camera can also be performed well.

[0023] The lens unit for a hyperspectral camera according to one aspect of the present disclosure may also be "

[14] The lens unit for a hyperspectral camera according to any one of [1] to

[13] , wherein the first aperture is formed by providing a light - shielding layer in a region other than the light - transmitting region in the Fabry - Perot interference filter and not providing the light - shielding layer in the light - transmitting region". In this case, the first aperture can be formed integrally with the Fabry - Perot interference filter.

[0024] The hyperspectral camera according to one aspect of the present disclosure may also be "

[15] A hyperspectral camera including: a lens unit for a hyperspectral camera according to any one of [1] to

[14] ; and a camera unit which is an optical device mounted on the mounting portion of the housing and has an imaging element for photographing the light emitted from the emission portion". According to this hyperspectral camera, for the above reasons, good photographing can be performed.

[0025] Effects of the Invention

[0026] According to one aspect of the present disclosure, there can be provided a lens unit for a hyperspectral camera capable of performing good photographing using the hyperspectral camera, and a hyperspectral camera capable of performing good photographing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural diagram of the hyperspectral camera according to the embodiment.

[0028] Figure 2 It is a perspective view of the filter unit.

[0029] Figure 3 It is along Figure 2 A cross-sectional view of the filter unit taken along line III-III.

[0030] Figure 4 It is a perspective view of the Fabry-Perot interference filter.

[0031] Figure 5 It is along Figure 4 A cross-sectional view of the Fabry-Perot interference filter taken along line V-V.

[0032] Figure 6 (a) and (b) are diagrams for explaining the control of the incident angle based on the first aperture and the second aperture.

[0033] Figure 7 It is a structural diagram of the first modification.

[0034] Figure 8 It is a structural diagram of the second modification.

[0035] Figure 9 It is a cross-sectional view of the Fabry-Perot interference filter of the third modification.

[0036] Figure 10 (a) and (b) are diagrams for explaining other modifications.

[0037] Figure 11 (a) and (b) are diagrams for explaining other modifications.

[0038] Figure 12Figs. (a) and (b) are diagrams for explaining other modified examples.

[0039] Figure 13 is a diagram for explaining other modified examples. Detailed Embodiment

[0040] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same or corresponding elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0041] As Figure 1 shown, the hyperspectral camera 1 includes: a lens unit 2 (a lens unit for a hyperspectral camera) and a camera unit 5 (an optical device). The lens unit 2 is an interchangeable lens device that is detachably mounted with respect to the camera unit 5. The hyperspectral camera 1 is a camera that can split light into dozens to hundreds of bands according to wavelength and acquire images for each band.

[0042] The lens unit 2 includes a housing 21 and an optical system 22 disposed within the housing 21. The optical system 22 includes a Fabry - Perot interference filter 10, a first lens unit 23, and a second lens unit 24. The Fabry - Perot interference filter 10 is fixed to a support 31 and together with the support 31 constitutes a filter unit 30. The camera unit 5 has a housing 51 and an imaging element 52 disposed within the housing 51. In the hyperspectral camera 1, the light L condensed by the first lens unit 23 passes through the Fabry - Perot interference filter 10 along the optical axis direction D. The light L that has passed through the Fabry - Perot interference filter 10 is imaged by the second lens unit 24 and captured by the imaging element 52. Hereinafter, first, with reference to Figure 4 and Figure 5 , the Fabry - Perot interference filter 10 will be described.

[0043] [Fabry - Perot Interference Filter]

[0044] As Figure 4 shown, the Fabry - Perot interference filter 10 has a light - transmitting region 10a. The Fabry - Perot interference filter 10 is a rectangular plate - shaped element. As will be described later, the Fabry - Perot interference filter 10 is arranged such that its thickness direction is parallel to the optical axis direction D. The light - transmitting region 10a is a cylindrical region having a center line parallel to the optical axis direction D. When viewed from the optical axis direction D, the center of the light - transmitting region 10a coincides with the center of the Fabry - Perot interference filter 10.

[0045] As Figure 5As shown, the Fabry - Perot interference filter 10 includes a substrate 11 with the optical axis direction D as the thickness direction. The material of the substrate 11 is, for example, silicon, quartz, or glass. The substrate 11 has a first surface 11a and a second surface 11b on the side opposite to the first surface 11a. The first surface 11a and the second surface 11b are, for example, flat surfaces perpendicular to the optical axis direction D. A first stacked structure 12 is stacked on the first surface 11a, and a second stacked structure 13 is stacked on the second surface 11b.

[0046] The first stacked structure 12 includes an antireflection layer 121, a first stacked body 122, an intermediate layer 123, and a second stacked body 124. The antireflection layer 121, the first stacked body 122, the intermediate layer 123, and the second stacked body 124 are stacked in sequence on the first surface 11a of the substrate 11. That is, the first stacked body 122 is disposed on the first surface 11a via the antireflection layer 121, and the second stacked body 124 is disposed on the side opposite to the first stacked body 122 with respect to the substrate ( Figure 5 the upper side in ). A gap (air gap) S is formed by the frame - shaped intermediate layer 123 between the first stacked body 122 and the second stacked body 124. When the material of the substrate 11 is silicon, the materials of the antireflection layer 121 and the intermediate layer 123 are, for example, silicon oxide. The thickness of the intermediate layer 123 is, for example, an integer multiple of 1 / 2 of the designed center wavelength. In addition, the thickness of the intermediate layer 123 can also be greater than an integer multiple of 1 / 2 of the designed center wavelength as needed.

[0047] The portion of the first stacked body 122 corresponding to the light - transmitting region 10a functions as a mirror portion 14. That is, the first stacked body 122 has a mirror portion 14. The mirror portion 14 is supported on the substrate 11 via the antireflection layer 121. As an example, the first stacked body 122 is formed by alternately stacking multiple polysilicon layers and multiple silicon nitride layers layer by layer. The optical thickness of each layer constituting the mirror portion 14 is, for example, an integer multiple of 1 / 4 of the designed center wavelength. In addition, a silicon oxide layer can also be used instead of the silicon nitride layer.

[0048] A portion of the second laminate 124 corresponding to the light-transmitting region 10a functions as a mirror portion 15. That is, the second laminate 124 has the mirror portion 15. The mirror portion 15 is supported on the substrate 11 via the antireflection layer 121, the first laminate 122, and the intermediate layer 123, and faces the mirror portion 14 via a gap S in the optical axis direction D. As an example, the second laminate 124 is formed by laminating multiple polysilicon layers and multiple silicon nitride layers alternately layer by layer. The optical thickness of each layer constituting the mirror portion 15 is, for example, an integer multiple of 1 / 4 of the design center wavelength. Additionally, a silicon oxide layer can be used instead of the silicon nitride layer. Furthermore, in a portion of the second laminate 124 corresponding to the gap S, a plurality of through holes are formed to such an extent that the function of the mirror portion 15 is not substantially affected. The plurality of through holes are used when forming the gap S by etching away a part of the intermediate layer 123.

[0049] A first electrode 125 and a second electrode 126 are formed in the mirror portion 14. When viewed from the optical axis direction D, the first electrode 125 surrounds the light-transmitting region 10a. When viewed from the optical axis direction D, the second electrode 126 overlaps with the light-transmitting region 10a. The shape of the second electrode 126 when viewed from the optical axis direction D is substantially the same as the shape of the light-transmitting region 10a when viewed from the optical axis direction D. Each of the first electrode 125 and the second electrode 126 is formed by doping impurities in a part of the polysilicon layer and making that part have a low resistance.

[0050] A third electrode 127 is formed in the mirror portion 15. The third electrode 127 faces the first electrode 125 and the second electrode 126 via the gap S. The third electrode 127 is formed by doping impurities in a part of the polysilicon layer and making that part have a low resistance. As an example, the distance between the second electrode 126 and the third electrode 127 is substantially the same as the distance between the first electrode 125 and the third electrode 127.

[0051] In the first laminate structure 12, a pair of terminals 16 are provided so as to sandwich the light-transmitting region 10a (refer to Figure 4 ). Each terminal 16 is arranged in a through hole formed in the second laminate 124 and the intermediate layer 123 so as to open on the opposite side of the substrate 11 and reach the first laminate 122. Each terminal 16 is electrically connected to the first electrode 125 via a wiring 125a.

[0052] In the first laminate structure 12, a pair of terminals 17 are provided so as to sandwich the light-transmitting region 10a (refer to Figure 4)。Each terminal 17 is disposed in a through-hole formed in the second laminate 124 and the intermediate layer 123 so as to open on the opposite side of the substrate 11 and reach the intermediate layer 123. Each terminal 17 is electrically connected to the second electrode 126 via the wiring 126a and is also electrically connected to the third electrode 127 via the wiring 127a. In addition, the direction in which a pair of terminals 17 sandwich the light-transmitting region 10a is perpendicular to the direction in which a pair of terminals 16 sandwich the light-transmitting region 10a (see Figure 4 ).

[0053] A pair of grooves 122a are formed in the first laminate 122. Each groove 122a extends in a ring shape so as to surround a portion of the wiring 126a that extends in the optical axis direction D from each terminal 17. Each groove 122a electrically insulates the first electrode 125 from the wiring 126a. A groove 122b is formed in the first laminate 122. The groove 122b extends in a ring shape along the inner edge of the first electrode 125. The groove 122b electrically insulates the first electrode 125 from the second electrode 126. The regions within the respective grooves 122a and 122b may be filled with an insulating material or may be voids.

[0054] A pair of grooves 124a are formed in the second laminate 124. Each groove 124a extends in a ring shape so as to surround each terminal 16. Each groove 124a electrically insulates each terminal 16 from the third electrode 127. The regions within the respective grooves 124a may be filled with an insulating material or may be voids.

[0055] The second laminate structure 13 includes an antireflection layer 131, a third laminate 132, an intermediate layer 133, and a fourth laminate 134. The antireflection layer 131, the third laminate 132, the intermediate layer 133, and the fourth laminate 134 are sequentially laminated on the second surface 11b of the substrate 11. The antireflection layer 131 and the intermediate layer 133 respectively have the same structure as the antireflection layer 121 and the intermediate layer 123. The third laminate 132 and the fourth laminate 134 respectively have a laminated structure that is symmetric with respect to the first laminate 122 and the second laminate 124 with the substrate 11 as a reference. The antireflection layer 131, the third laminate 132, the intermediate layer 133, and the fourth laminate 134 have a function of suppressing warping of the substrate 11.

[0056] A recess 18 is formed in the surface 13a of the second laminate structure 13 on the side opposite to the substrate 11. The recess 18 opens on the side opposite to the substrate 11. When viewed from the optical axis direction D, the recess 18 overlaps with the light-transmitting region 10a. The shape of the recess 18 when viewed from the optical axis direction D is substantially the same as the shape of the light-transmitting region 10a when viewed from the optical axis direction D, and in this example, it is a circular shape. The center line of the recess 18 coincides with the center line of the light-transmitting region 10a. The recess 18 is formed in the third laminate 132, the intermediate layer 133, and the fourth laminate 134 and reaches the antireflection layer 131.

[0057] A light-shielding layer 135 is formed on the surface 13a of the second stacked structure 13. The light-shielding layer 135 is formed, for example, over the entire surface 13a. The material of the light-shielding layer 135 is, for example, aluminum or the like. The light-shielding layer 135 blocks the light L. In this example, the light-shielding layer 135 blocks the light L by reflecting the light L. On the other hand, in the region where the light-shielding layer 135 is not formed (in this example, the region where the recess 18 is formed), the light L passes through. That is, the light-transmitting region 10a corresponds to the region where the light-shielding layer 135 is not formed. In this way, in the Fabry - Perot interference filter 10, the first aperture P1 that defines the light-transmitting region 10a is formed by the light-shielding layer 135. That is, the first aperture P1 is formed by providing the light-shielding layer 135 in the region other than the light-transmitting region 10a in the Fabry - Perot interference filter 10 when viewed from the optical axis direction D, and not providing the light-shielding layer 135 in the light-transmitting region 10a. In addition, the first aperture P1 is formed integrally with the Fabry - Perot interference filter 10. The width of the first aperture P1 is fixed (does not change).

[0058] When viewed from the optical axis direction D, the first aperture P1 is formed in a circular shape. When viewed from the optical axis direction D, the entire recess 18 overlaps with the first aperture P1. In this example, the shape of the recess 18 when viewed from the optical axis direction D is substantially the same as the shape of the first aperture P1 when viewed from the optical axis direction D. The center line of the recess 18 coincides with the center line of the first aperture P1.

[0059] A protective layer 136 is formed on the light-shielding layer 135 and on the inner surface of the recess 18. The material of the protective layer 136 is, for example, alumina or the like. In addition, by making the thickness of the protective layer 136 100 nm or less (preferably about 30 nm), the optical influence caused by the protective layer 136 can be ignored.

[0060] In the Fabry - Perot interference filter 10 configured as described above, when a potential difference is generated between the first electrode 125 and the third electrode 127 by applying a voltage to the first electrode 125 and the third electrode 127 via a plurality of terminals 16, 17, an electrostatic force corresponding to the potential difference is generated between the first electrode 125 and the third electrode 127. By generating an electrostatic force between the first electrode 125 and the third electrode 127, the mirror part 15 is pulled toward the mirror part 14, thereby adjusting the distance between the mirror part 14 and the mirror part 15. At this time, the second electrode 126 having the same potential as the third electrode 127 functions as a compensation electrode, and the mirror part 15 is kept flat in the light-transmitting region 10a.

[0061] Thus, in the Fabry-Perot interference filter 10, a pair of mirror portions 14 and 15 that face each other in the optical axis direction D function as a pair of mirror portions with a variable distance therebetween. Here, the wavelength of the light transmitted through the Fabry-Perot interference filter 10 depends on the distance between the mirror portion 14 and the mirror portion 15. Therefore, by adjusting the voltages applied to the first electrode 125 and the third electrode 127 (the potential difference generated between the first electrode 125 and the third electrode 127), the wavelength of the light transmitted through the Fabry-Perot interference filter 10 can be selected. Thus, the Fabry-Perot interference filter 10 transmits the light of the wavelength corresponding to the distance between the mirror portions 14 and 15 in the incident light.

[0062] [Filter unit]

[0063] As Figures 1 to 3 shown, the filter unit 30 includes a support 31 (aperture plate), the above-mentioned Fabry-Perot interference filter 10, and a band-pass filter 32. As will be described later, the filter unit 30 is arranged such that the thickness direction of the Fabry-Perot interference filter 10 is parallel to the optical axis direction D. In Figure 2 , the Fabry-Perot interference filter 10 is indicated by a dashed line, and the band-pass filter 32 is indicated by a double-dot dash line.

[0064] The support 31 is formed of a metal material such as stainless steel into a substantially circular plate shape, for example. The support 31 has a first surface 31a and a second surface 32b on the side opposite to the first surface 31a. The first surface 31a and the second surface 31b are, for example, flat surfaces perpendicular to the optical axis direction D. A recess 33 for arranging the Fabry-Perot interference filter 10 and the band-pass filter 32 is formed in the support 31. The recess 33 is formed in the first surface 31a and opens on the first surface 31a.

[0065] The recess 32 has a first recess 34 and a second recess 35. The bottom surface 34a of the first recess 34 and the bottom surface 35a of the second recess 35 are located on the same plane perpendicular to the optical axis direction D. The first recess 34 and the second recess 35 are arranged in the X direction (a direction perpendicular to the optical axis direction D).

[0066] When viewed from the optical axis direction D, each of the first recess 34 and the second recess 35 is formed in a rectangular shape. In this example, when viewed from the Z-axis direction, each of the first recess 34 and the second recess 35 is formed in a rectangular shape with the X direction as the long side direction. When viewed from the optical axis direction D, the first recess 34 does not reach the outer edge of the support 31, but the second recess 35 reaches the outer edge of the support 31. That is, the second recess 35 opens on the side surface of the support 31.

[0067] The width of the second recess 35 in the Y direction (a direction perpendicular to both the optical axis direction D and the X direction) is wider than the width of the first recess 34 in the Y direction. An opening 36 and a through hole 37 are formed in the support 31. Each of the opening 36 and the through hole 37 opens at the bottom surface 34a of the first recess 34 and the second surface 31b of the support 31. The opening 36 and the through hole 37 are arranged in the X direction. When viewed from the optical axis direction D, each of the opening 36 and the through hole 37 is formed, for example, in a circular shape. The opening 36 constitutes a second aperture P2 through which the light L directed toward the Fabry - Perot interference filter 10 passes. In this example, the diameter (width) of the second aperture P2 is larger than the diameter (width) of the first aperture P1. The width of the second aperture P2 is fixed (does not change). The through hole 37 is used, for example, to release the gas generated from the adhesive material for fixing the Fabry - Perot interference filter 10 and the band - pass filter 32 during the manufacture of the filter unit 30.

[0068] Therefore, a widened portion 38 is formed in the support 31. The widened portion 38 widens relative to the opening of the first recess 34 toward the opposite side of the second recess 35 in the X direction and both sides in the Y direction. The widened portion 38 is a recess formed in the support 31 such that the optical axis direction D is the depth direction, opening at the first surface 31a and reaching the opening of the first recess 34. In the present embodiment, the width of the widened portion 38 in the Y direction is equal to the width of the second recess 35 in the Y direction.

[0069] The support 31 has a partition portion 39. The partition portion 39 is disposed between the first recess 34 and the second recess 35. In the present embodiment, the partition portion 39 is a wall portion extending in the Y direction between the bottom surface 34a of the first recess 34 and the bottom surface 35a of the second recess 35. When taking the plane where the bottom surface 34a and the bottom surface 35a are located as a reference, the height of the partition portion 39 in the optical axis direction D is lower than the height of the first surface 31a of the support 31 in the optical axis direction D and lower than the height of the bottom surface 38a of the widened portion 38 in the optical axis direction D.

[0070] The Fabry - Perot interference filter 10 is arranged on the support 31 in such a manner that it overlaps with the second aperture P2 (opening 36) when viewed from the optical axis direction D, and the thickness direction is parallel to the optical axis direction D. More specifically, the Fabry - Perot interference filter 10 is arranged in the first recess 34 in such a manner that it overlaps with the opening 36 when viewed from the optical axis direction D, and the thickness direction is parallel to the optical axis direction D. The Fabry - Perot interference filter 10 contacts the partition portion 39 within the first recess 34. Taking the bottom surface 34a of the first recess 34 as a reference, the height of the Fabry - Perot interference filter 10 in the optical axis direction D is lower than the height of the first surface 31a of the support 31 in the optical axis direction D, and is lower than the height of the bottom surface 38a of the widened portion 38 in the optical axis direction D. Taking the bottom surface 34a of the first recess 34 as a reference, the height of the partition portion 39 in the optical axis direction D is equal to or lower than the height of the Fabry - Perot interference filter 10 in the optical axis direction D.

[0071] As described above, the Fabry - Perot interference filter 10 is a rectangular plate - shaped element with the optical axis direction D as the thickness direction. The Fabry - Perot interference filter 10 is arranged on the bottom surface 34a of the first recess 34 in such a manner that when viewed from the optical axis direction D, each side of the rectangular outer edge is parallel to the X - direction or the Y - direction and the first aperture P1 faces the second aperture P2 (opening 36). The Fabry - Perot interference filter 10 is fixed to the bottom surface 34a by an adhesive material, for example. The center line of the first aperture P1 coincides with the center line of the second aperture P2.

[0072] The band - pass filter 32 is arranged on the support 31 in such a manner that it covers the opening of the first recess 34 and the thickness direction is parallel to the optical axis direction D. More specifically, the band - pass filter 32 is arranged in the widened portion 38 in such a manner that it covers the opening of the first recess 34 and the thickness direction is parallel to the optical axis direction D. The band - pass filter 32 is fixed to the bottom surface 38a of the widened portion 38 by an adhesive material, for example. In the present embodiment, the band - pass filter 32 covers the opening of the first recess 34 and also covers a part of the opening of the second recess 35. Taking the bottom surface 38a of the widened portion 38 as a reference, the height of the band - pass filter 32 in the optical axis direction D is lower than the height of the first surface 31a of the support 31 in the optical axis direction D.

[0073] The band - pass filter 32 is formed as a rectangular plate - shaped with the optical axis direction D as the thickness direction and the X - direction as the long - side direction. The band - pass filter 32 is arranged on the bottom surface 38a of the widened portion 38 in such a manner that when viewed from the optical axis direction D, each side of the rectangular outer edge is parallel to the X - direction or the Y - direction. The band - pass filter 32 transmits light in a specified wavelength range. In addition, although not shown in the figure, a wiring board or the like electrically connected to the Fabry - Perot interference filter 10 is arranged in the second recess 35, for example.

[0074] [Lens Unit and Camera Unit]

[0075] As Figure 1 shown, the lens unit 2 includes a housing 21 and an optical system 22 disposed within the housing 21. The optical system 22 includes the above-described Fabry - Perot interference filter 10, a first lens unit 23, and a second lens unit 24. In addition, the optical system 22 also includes the above-described first aperture P1 and second aperture P2.

[0076] The housing 21 is formed, for example, in a substantially cylindrical shape. The housing 21 has an incident portion 21a through which light L enters, an exit portion 21b through which light L exits, and a mounting portion 21c for detachably mounting the camera unit 5. In this example, the incident portion 21a is constituted by one end of the housing 21 in the optical axis direction D, and the exit portion 21b is constituted by the other end of the housing 21 in the optical axis direction D. In the lens unit 2, the light L incident from the incident portion 21a is guided along the optical axis direction D by the optical system 22 and exits from the exit portion 21b to the camera unit 5.

[0077] The mounting portion 21c is provided at the end portion (the other end in the optical axis direction D) on the exit portion 21b side of the housing 21. The mounting portion 21c is detachably engaged with the mounting portion 51b of the following camera unit 5. For example, when the lens unit 2 and the camera unit 5 are detachably mounted by screwing, one of a thread and a thread groove is provided in the mounting portion 21c, and the other of the thread and the thread groove that engages with the one is provided in the mounting portion 51b.

[0078] In this example, the housing 21 is divided in the optical axis direction D and has a first part 211 disposed on one side in the optical axis direction D and a second part 212 disposed on the other side in the optical axis direction D. The first part 211 constitutes a first lens holder that holds the first lens unit 23, and the second part 212 constitutes a second lens holder that holds the second lens unit 24. In the present embodiment, the support 31 of the filter unit 30 is fixed while being sandwiched between the first part 211 and the second part 212. For example, the first part 211 contacts the first surface 31a of the support 31, and the second part 212 contacts the second surface 31b of the support 31.

[0079] Thereby, the Fabry - Perot interference filter 10 is fixed on the optical axis A between the first lens unit 23 and the second lens unit 24. The filter unit 30 is fixed on the optical axis A such that the center line of the light transmission region 10a of the Fabry - Perot interference filter 10, the center line of the first aperture P1, and the center line of the second aperture P2 are located on the optical axis A (refer to Figures 1 to 5)。In this fixed state, the second surface 31b of the support 31 faces the incident portion 21a side, and the first aperture P1 is located on the incident portion 21a side with respect to the mirror portions 14 and 15 of the Fabry - Perot interference filter 10. The second aperture P2 is located between the first lens portion 23 and the Fabry - Perot interference filter 10. That is, the second aperture P2 is located on the incident portion 21a side with respect to the first aperture P1.

[0080] The first lens portion 23 is a condensing optical system that condenses the light L from the incident portion 21a toward the Fabry - Perot interference filter 10. The first lens portion 23 is configured to include at least one lens, and in this example, it has three lenses 23a, 23b, and 23c (lens group) arranged along the optical axis direction D (direction parallel to the optical axis A). The first lens portion 23 is fixed by being embedded in the first part 211 of the housing 21 on the outer peripheral portion. Alternatively, the first lens portion 23 can be fixed relative to the housing 21 by fixing a fixing ring mounted on the outer peripheral portion of the first lens portion 23 to the first part 211 of the housing 21 using screws or the like.

[0081] The second lens portion 24 is an imaging optical system that forms an image of the light L that passes through the Fabry - Perot interference filter 10 and exits from the emission portion 21b. The second lens portion 24 is configured to include at least one lens, and in this example, it has three lenses 24a, 24b, and 24c (lens group) arranged along the optical axis direction D. The second lens portion 24 is fixed by being embedded in the second part 212 of the housing 21 on the outer peripheral portion. Alternatively, the second lens portion 24 can be fixed relative to the housing 21 by fixing a fixing ring mounted on the outer peripheral portion of the second lens portion 24 to the second part 212 of the housing 21 using screws or the like.

[0082] The camera unit 5 has a housing 51 and an imaging element 52 disposed within the housing 51. The housing 51 has: a main body portion 51a having a bottom surface, and a mounting portion 51b. The mounting portion 51b is formed in a cylindrical shape that is one size smaller than the main body portion 51a. The mounting portion 51a is detachably engaged with the mounting portion 21c of the above - mentioned lens unit 2.

[0083] The imaging element 52 is disposed within the main body portion 51a of the housing 51. The imaging element 52 is, for example, an InGaAs image sensor. The imaging element 52 has a light - receiving surface 52a disposed on the imaging surface of the light L based on the second lens portion 24, and captures the light L emitted from the emission portion 21b. In addition, a control circuit for controlling the imaging element 52, an image - processing circuit for processing the image obtained by the imaging element 52, and a cooling mechanism for cooling the imaging element 52 are also disposed within the main body portion 51a. In Figure 1 this case, they are denoted by reference numeral 53.

[0084] In the hyperspectral camera 1, the light L incident from the incident portion 21a is condensed by the first lens unit 23 and travels toward the filter unit 30 (see Figure 1 , Figure 3 ). The light L traveling toward the filter unit 30 sequentially passes through or transmits through the second aperture P2, the first aperture P1, the mirror units 14, 15, and the band-pass filter 32 (see Figure 1 , Figure 3 , Figure 5 ). The light L is split according to the wavelength when passing through the Fabry-Perot interference filter 10 (mirror units 14, 15). The light L emitted from the filter unit 30 (band-pass filter 32) is imaged on the light-receiving surface 52a of the imaging element 52 by the second lens unit 24 and is captured by the imaging element 52.

[0085] In the hyperspectral camera 1, the Fabry-Perot interference filter 10 (first aperture P1) is disposed at the position where the principal ray passing through the outer edge Ra of the imaging region R of the light L by the second lens unit 24 intersects the optical axis A. That is, the Fabry-Perot interference filter 10 is disposed at the position of the aperture in the optical system 22 and functions as an aperture. In this example, the optical system 22 is configured as a non-telecentric optical system on both sides, and the Fabry-Perot interference filter 10 is disposed by separating only the focal length of the first lens unit 23 from the first lens unit 23 and by separating only the focal length of the second lens unit 24 from the second lens unit 24. The Fabry-Perot interference filter 10 is disposed such that the incident position of the light L on the first aperture P1 coincides with the position where the principal ray passing through the outer edge Ra of the imaging region R intersects the optical axis A. In addition, the principal ray is the ray passing through the center of the aperture (first aperture P1).

[0086] In the hyperspectral camera 1, when viewed from the optical axis direction D, the width (spot width) of the light L at the incident position on the first aperture P1 is larger than the width of the first aperture P1. Thus, the light L toward the Fabry-Perot interference filter 10 (mirror units 14, 15) can be reduced by the first aperture P1. In this example, at the incident position on the first aperture P1, the light L is in a circular shape with a diameter of 1.6 mm, and the first aperture P1 is in a circular shape with a diameter of 1.5 mm. When viewed from the optical axis direction D, the area of the incident region of the light L at the incident position on the first aperture P1 may also be 110% or less of the area of the first aperture P1. Further, in the present embodiment, in all directions perpendicular to the optical axis direction D, the width of the light L at the incident position on the first aperture P1 is wider than the width of the first aperture P1, but it is sufficient that the width of the light L at the incident position on the first aperture P1 is wider than the width of the first aperture P1 in at least one direction perpendicular to the optical axis direction D.

[0087] Figure 6This is a diagram for explaining the control of the incident angle based on the first aperture P1 and the second aperture P2. In Figure 6 , each element is schematically shown. As described above, in the hyperspectral camera 1, the second aperture P2 is located on the incident portion 21a side with respect to the first aperture P1 ( Figure 6 the upper side in ), and the diameter (width) of the second aperture P2 is larger than the diameter (width) of the first aperture P1. Therefore, the light L from the incident portion 21a passes through the first aperture P1 after passing through the second aperture P2. When the width of the light L at the incident position on the second aperture P2 is wider than the width of the second aperture P2 when viewed from the optical axis direction D, the light L from the incident portion 21a passes through the second aperture P2 and is reduced and then passes through the first aperture P1 and is reduced. In this way, by adopting a double aperture structure provided with the first aperture P1 and the second aperture P2, not only can the light L be reduced by the first aperture P1, but also the incident angle of the light L with respect to the Fabry - Perot interference filter 10 can be controlled by the second aperture P2.

[0088] For example, as shown in (a) of Figure 6 , if the thickness (depth) of the second aperture P2 is made thinner, light L with a relatively large incident angle is allowed to be incident on the Fabry - Perot interference filter 10. On the other hand, as shown in (b) of Figure 6 , if the thickness of the second aperture P2 is increased, compared with the case of (a) of Figure 6 , the incidence of light L with a relatively large incident angle on the Fabry - Perot interference filter 10 is restricted. In this way, by adjusting the thickness of the second aperture P2, the incident angle of the light L with respect to the Fabry - Perot interference filter 10 can be controlled.

[0089] [Function and Effect]

[0090] In the lens unit 2, when viewed from the optical axis direction D, the width of the light L at the incident position on the first aperture P1 is wider than the width of the first aperture P1. Thus, for example, compared with the case where the light L reduced by the lens to a width narrower than the first aperture P1 passes through the first aperture P1, the width of the first aperture P1 can be utilized to the maximum extent, and the light quantity can be ensured. In addition, the light directed toward the Fabry - Perot interference filter 10 can be reduced by the first aperture P1, and the depth of field can be increased. By increasing the depth of field, the influence caused by focus shift can be suppressed. In addition, the first aperture P1 is integrally formed with the Fabry - Perot interference filter 10. Thus, for example, compared with the case where the first aperture P1 and the Fabry - Perot interference filter 10 are formed separately, the occurrence of deviation from the design (for example, the deviation of the distance or angle between the pair of mirror parts 14 and 15 and the first aperture P1, or the position deviation in the direction perpendicular to the optical axis A, etc.) can be suppressed. As described above, according to the lens unit 2, the photographing performed by the hyperspectral camera 1 can be carried out well. In addition, since the Fabry - Perot interference filter 10 constitutes the lens unit 2 and the lens unit 2 is detachable from the camera unit 5, the degree of freedom in selecting the camera unit 5 can be increased. In addition, since the Fabry - Perot interference filter 10 is disposed between the first lens part 23 and the second lens part 24, the overall length along the optical axis direction D can be shortened compared with, for example, the case where the Fabry - Perot interference filter 10 is disposed between the second lens part 24 and the camera unit 5.

[0091] The Fabry - Perot interference filter 10 is disposed at the position where the principal ray passing through the outer edge Ra of the imaging region R of the light L by the second lens part 24 intersects the optical axis A. Thus, the size of the imaging region R of the light L by the second lens part 24 can be made constant regardless of the size of the first aperture P1. Therefore, an imaging element 52 of the same size can be used regardless of the size of the first aperture P1. In addition, since the incident angle of the light L to the Fabry - Perot interference filter 10 is constant, it is easy to correct the wavelength shift in the Fabry - Perot interference filter 10.

[0092] The first aperture P1 is located on the incident part 21a side with respect to the mirror parts 14 and 15. Thus, before the light is incident on the mirror parts 14 and 15, the first aperture P1 can cut off stray light and light with a large incident angle, and the noise can be reduced.

[0093] The optical system 22 includes a second aperture P2 disposed between the Fabry - Perot interference filter 10 and the first lens unit 23. Thus, the light L can be narrowed within a desired angular range by the first aperture P1 and the second aperture P2, and the resolution in imaging for each wavelength can be improved. Since the first aperture P1 is integrally formed with the Fabry - Perot interference filter 10, it is difficult to increase the thickness (depth) of the first aperture P1. In this regard, the adjustment of the thickness of the second aperture P2 is easier than that of the first aperture P1. Therefore, it is effective to provide the second aperture P2 in addition to the first aperture P1.

[0094] The second aperture P2 is constituted by an opening 36 formed in the support 31, and the Fabry - Perot interference filter 10 is fixed to the support 31. Thus, the Fabry - Perot interference filter 10 (the first aperture P1) can be appropriately fixed near the second aperture P2.

[0095] The support 31 is sandwiched and fixed by a first part 211 of the housing 21 (the first lens holder that holds the first lens unit 23) and a second part 212 of the housing 21 (the second lens holder that holds the second lens unit 24). Thus, the support 31 can be appropriately fixed.

[0096] When viewed from the optical axis direction D, the area of the incident region of the light L at the incident position on the first aperture P1 may also be 110% or less of the area of the first aperture P1. In this case, the utilization efficiency of the light can be improved.

[0097] The Fabry - Perot interference filter 10 has a substrate 11 including a first surface 11a and a second surface 11b, and a first stacked structure 12 disposed on the first surface 11a. The first stacked structure 12 has: a first stacked body 122 disposed on the first surface 11a and having a mirror portion 14; and a second stacked body 124 disposed on the opposite side of the substrate 11 with respect to the first stacked body 122 and having a mirror portion 15. In this case, the imaging by the hyperspectral camera 1 can also be performed well.

[0098] The Fabry - Perot interference filter 10 has a second stacked structure 13 disposed on the second surface 11b of the substrate 11, and a concave portion 18 is formed on the surface 13a of the second stacked structure 13 on the side opposite to the substrate 11. When viewed from the optical axis direction D, the concave portion 18 overlaps with the first aperture P1. Thus, by forming the concave portion 18, the light L can be made to easily pass through the portion of the Fabry - Perot interference filter 10 that overlaps with the first aperture P1, and the utilization efficiency of the light can be improved.

[0099] The first aperture P1 is formed by providing a light-shielding layer 135 in a region outside the light-transmitting region 10a in the Fabry-Perot interference filter 10, and not providing the light-shielding layer 135 in the light-transmitting region 10a. Thus, the first aperture P1 can be formed integrally with the Fabry-Perot interference filter 10.

[0100] [Modification Example]

[0101] As Figure 7 shown in the first modification example, the optical system 22 may further include a reduction optical system 26 (additional optical system) disposed between the Fabry-Perot interference filter 10 and the first lens unit 23 and reducing the width of the light L. In this example, the reduction optical system 26 is disposed between the first lens unit 23 and the second aperture P2. The reduction optical system 26 is configured to include, for example, a plurality of lenses. Even with such a first modification example, it is possible to perform shooting by the hyperspectral camera 1 well in the same manner as in the above-described embodiment. In addition, by reducing the width of the light L before the light is incident on the Fabry-Perot interference filter 10 using the reduction optical system 26, the utilization efficiency of the light can be improved.

[0102] In Figure 8 the second modification example shown, the reduction optical system 26 is an optical system that reduces the width of the light L and collimates the light L (reduces the incident angle with respect to the Fabry-Perot interference filter 10, that is, the angle with respect to the optical axis direction D). That is, the reduction optical system 26 makes the incident angle of the light L with respect to the Fabry-Perot interference filter 10 smaller than the angle of the light L that travels from the first lens unit 23 toward the Fabry-Perot interference filter 10 (reduction optical system 26). In addition, the optical system 22 further includes an optical system 7 disposed between the Fabry-Perot interference filter 10 and the second lens unit 24 that returns the angle of the light L to the angle before collimation (returns the angle with respect to the optical axis direction D to the original angle). Even with such a second modification example, it is possible to perform shooting by the hyperspectral camera 1 well in the same manner as in the above-described embodiment. In addition, by reducing the width of the light before the light is incident on the Fabry-Perot interference filter 10, the utilization efficiency of the light can be improved. In addition, by collimating (making parallel) the light L before the light is incident on the Fabry-Perot interference filter, the generation of wavelength shift can be suppressed. In addition, in the second modification example, the optical system 22 may have an additional optical system that collimates the light L without reducing the width of the light L instead of the reduction optical system 26. In this case, the generation of wavelength shift can also be suppressed.

[0103] Figure 9The Fabry - Perot interference filter 400 of the third modified example shown can also be used in place of the Fabry - Perot interference filter 10. The Fabry - Perot interference filter 400 includes a substrate layer 411 (first substrate), a mirror portion 412, and a drive electrode 413. The substrate layer 411 has surfaces 411a and 411b that face each other. The substrate layer 411 is formed of a light - transmissive material. The mirror portion 412 is, for example, a metal film, a dielectric multilayer film, or a composite film thereof. The drive electrode 413 is formed of a metal material, for example.

[0104] The Fabry - Perot interference filter 400 further includes a substrate layer 421 (second substrate), a mirror portion 422, and a drive electrode 423. The substrate layer 421 has surfaces 421a and 421b that face each other. The substrate layer 421 is formed of a light - transmissive material. The mirror portion 422 is, for example, a metal film, a dielectric multilayer film, or a composite film thereof. The drive electrode 423 is formed of a metal material, for example.

[0105] A recess 414 is formed in the surface 411a of the substrate layer 411. A protrusion 415 is provided on the bottom surface 414a of the recess 414. When taking the bottom surface 414a as a reference, the height of the end surface 415a of the protrusion 415 is lower than the height of the surface 411a of the substrate layer 411. The mirror portion 412 is provided on the end surface 415a (first surface) of the protrusion 415. The drive electrode 413 is provided on the bottom surface 414a of the recess 414 so as to surround the protrusion 415. The drive electrode 413 is electrically connected to an electrode pad (not shown) via a wiring (not shown) provided in the substrate layer 411. This electrode pad is provided, for example, in an area of the substrate layer 411 that can be accessed from the outside.

[0106] The surface 421b of the substrate layer 421 is joined to the surface 411a of the substrate layer 411 by plasma bonding or the like, for example. A mirror portion 422 and a drive electrode 423 are provided on the surface 421b (second surface) of the substrate layer 421. The surface 421b of the substrate layer 421 faces the end surface 415a of the substrate layer 411 in the optical axis direction D. The mirror portion 422 faces the mirror portion 412 via a gap S in the optical axis direction D. The drive electrode 423 is provided on the surface 421b of the substrate layer 421 so as to surround the mirror portion 422 and faces the drive electrode 413 via the gap S. The drive electrode 423 is electrically connected to an electrode pad (not shown) via a wiring (not shown) provided in the substrate layer 421. This electrode pad is provided, for example, in an area of the substrate layer 421 that can be accessed from the outside.

[0107] When viewed from the optical axis direction D, on the surface 421a of the substrate layer 421, a groove 424 is formed so as to surround the mirror portion 422 and the drive electrode 423. The groove 424 extends in an annular shape. The portion of the substrate layer 421 surrounded by the groove 424 forms a diaphragm-shaped holding portion 425 with the portion where the groove 424 is formed, and can move in the direction in which the pair of mirror portions 412 and 422 face each other.

[0108] In addition, the diaphragm-shaped holding portion 425 may be constituted by a groove that surrounds the mirror portion 422 and the drive electrode 423 when viewed from the optical axis direction D and is formed on at least one of the surface 421a and the surface 421b of the substrate layer 421. The diaphragm-shaped holding portion may also be constituted in the substrate layer 411 by a groove that surrounds the mirror portion 412 and the drive electrode 413 when viewed from the optical axis direction D. Instead of the diaphragm-shaped holding portion, the holding portion may be constituted by a plurality of beams arranged radially.

[0109] In the Fabry - Perot interference filter 400, if a potential difference is generated between the drive electrode 413 and the drive electrode 423 by applying a voltage to the drive electrode 413 and the drive electrode 423, an electrostatic force corresponding to the potential difference is generated between the drive electrode 413 and the drive electrode 423. By generating an electrostatic force between the drive electrode 413 and the drive electrode 423, the portion of the substrate layer 421 surrounded by the groove 424 is pulled toward the substrate layer 411 side, and the distance between the mirror portion 412 and the mirror portion 422 can be adjusted. Thereby, light having a wavelength corresponding to the distance between the mirror portion 412 and the mirror portion 422 passes through.

[0110] When using such a Fabry - Perot interference filter 400 of the third modification instead of the Fabry - Perot interference filter 10, similarly to the above-described embodiment, the hyperspectral camera 1 can be photographed well. In addition, in the Fabry - Perot interference filter 400, for example, a light-shielding layer may be formed on the surface 411b of the substrate layer 411 opposite to the substrate layer 421, and the first aperture P1 may be integrally formed with the Fabry - Perot interference filter 400. Such a first aperture P1, similarly to the above-described embodiment, may be formed by providing a light-shielding layer in a region other than the light-transmitting region in the Fabry - Perot interference filter 400 and not providing a light-shielding layer in the light-transmitting region. Alternatively, the first aperture P1 may be integrally formed with the Fabry - Perot interference filter 400 by forming a light-shielding layer on the surface 421a of the substrate layer 421 opposite to the substrate layer 411. In this case, the first aperture P1 is located on the opposite side (the light-emitting portion 21b side) of the incident portion 21a with respect to the mirror portions 412 and 422 of the Fabry - Perot interference filter 1400.

[0111] As another modification, in the above-described embodiment, the Fabry-Perot interference filter 10 is in contact with the support 31. However, as shown in (a) of Figure 10 , the Fabry-Perot interference filter 10 may be arranged away from the support 31. For example, a gap may be formed between the Fabry-Perot interference filter 10 and the support 31, or a glass member may be arranged between the Fabry-Perot interference filter 10 and the support 31. When the Fabry-Perot interference filter 10 is arranged away from the support 31, the effect of suppressing the incident angle obtained by the above-described double aperture structure is significantly exhibited.

[0112] As shown in (b) of Figure 10 , the first aperture P1 may also be located on the opposite side (the emission portion 21b side) of the incident portion 21a with respect to the mirror portions 14 and 15 of the Fabry-Perot interference filter 10. In this case, the light L transmitted through the Fabry-Perot interference filter 10 passes through the first aperture P1. For example, in the above-described embodiment, such an arrangement can be achieved by fixing the Fabry-Perot interference filter 10 to the support 31 in the opposite orientation in the optical axis direction D. Alternatively, instead of forming the light-shielding layer 135 on the incident portion 21a side with respect to the mirror portions 14 and 15 in the above-described embodiment and providing the first aperture P1, the light-shielding layer 135 is formed on the opposite side of the incident portion 21a (for example, the surface of the Fabry-Perot interference filter 10 opposite to the incident portion 21a) with respect to the mirror portions 14 and 15, and the first aperture P1 is provided, and this arrangement can also be achieved.

[0113] As shown in (a) of Figure 11 , the second aperture P2 may also be located on the opposite side (the emission portion 21b side) of the incident portion 21a with respect to the mirror portions 14 and 15 of the Fabry-Perot interference filter 10. That is, the second aperture P2 may be arranged between the Fabry-Perot interference filter 10 and the second lens portion 24.

[0114] As shown in (b) of Figure 11 , both the first aperture P1 and the second aperture P2 may be located on the opposite side (the emission portion 21b side) of the incident portion 21a with respect to the mirror portions 14 and 15 of the Fabry-Perot interference filter 10.

[0115] As shown in (a) of Figure 12 and (b) of Figure 12 , when the second aperture P2 is located on the opposite side of the incident portion 21a with respect to the mirror portions 14 and 15 of the Fabry-Perot interference filter 10, the diameter (width) of the second aperture P2 may be smaller than the diameter (width) of the second aperture P1. Even with the modification examples shown in Figures 10 to 12 described above, the high-spectral camera 1 can perform shooting as well as in the above-described embodiment.

[0116] In Figure 13 In the hyperspectral camera 1 shown, the first lens unit 23 does not condense the light L from the incident unit 21a onto the Fabry - Perot interference filter 10, but parallelizes it. In this example, the first lens unit 23 has four lenses 23a, 23b, 23c, 23d arranged along the optical axis direction D. The second lens unit 24 has six lenses 24a, 24b, 24c, 24d, 24e, 24f arranged along the optical axis direction D. Even with such a modification example, similar to the above - described embodiment, the hyperspectral camera 1 can perform shooting well.

[0117] The present invention is not limited to the above - described embodiment and modification example. For example, the materials and shapes of each structure are not limited to the above - described materials and shapes, and various materials and shapes can be adopted.

[0118] The Fabry - Perot interference filter 10 may not be fixed to the support 31, or may be fixed to a component different from the component in which the second aperture P2 is formed. The second aperture P2 may not be constituted by the opening 36 formed in the support 31. For example, an aperture component having an opening constituting the second aperture P2 may be provided separately from the support 31. The second aperture P2 may also be omitted.

[0119] The fixing method of the support 31 is not limited to the above example, and it may not be fixed while being sandwiched between the first part 211 of the housing 21 and the second part 212 of the housing 21. In the above - described embodiment, the first lens holder that holds the first lens unit 23 is constituted by the first part 211 of the housing 21, and the second lens holder that holds the second lens unit 24 is constituted by the second part 212 of the housing 21. However, the first lens holder and the second lens holder may also be provided separately from the housing 21. In this case, the support 31 may also be fixed while being sandwiched between the first lens holder and the second lens holder. The housing 21 may not be divided in the optical axis direction D, and may be constituted by a single component. In this case, the support 31 may also be fixed to the housing 21.

[0120] When viewed from the optical axis direction D, the area of the incident region of the light L at the incident position of the first aperture P1 may also be greater than 110% of the area of the first aperture P1. When viewed from the optical axis direction D, the width of the light L at the incident position of the second aperture P2 may also be narrower than the width of the second aperture P2. That is, the light L may not necessarily be reduced by the second aperture P2.

[0121] In the case of observing from the optical axis direction D, at least a part of the concave portion 18 may overlap with the first aperture P1. In the case of observing from the optical axis direction D, the outer edge of the concave portion 18 may also be located outside the outer edge of the first aperture P1, or the outer edge of the first aperture P1 may also be located at a position more outside than the outer edge of the concave portion 18. In the above-described embodiment, the light-shielding layer 135 may not be formed on the entire surface 13a of the second laminated structure 13. In the case of observing from the Z direction, the outer edge of the first aperture P1 may also be located at a position more outside than the outer edge of the concave portion 18. The concave portion 18 may not be provided. An optical device other than the camera unit 5 may be installed in the mounting portion 21c of the housing 21. The hyperspectral camera 1 may further include an annular illumination for assisting the light quantity, and the annular illumination is arranged to face the incident portion 21a in the lens unit 2.

[0122] Description of Reference Numerals

[0123] 1... Hyperspectral camera, 2... Lens unit (lens unit for hyperspectral camera), 5... Camera unit (optical device), 10... Fabry - Perot interference filter, 10a... Translucent region, 11... Substrate, 11a... First surface, 11b... Second surface, 12... First laminated structure, 122... First laminate, 124... Second laminate, 13... Second laminated structure, 13a... Surface, 135... Light-shielding layer, 14, 15... Mirror portions, 18... Concave portion, 21... Housing, 21a... Incident portion, 21b... Ejection portion, 21c... Mounting portion, 22... Optical system, 23... First lens portion, 24... Second lens portion, 26... Reduction optical system (additional optical system), 31... Support, 36... Opening, 52... Imaging element, 400... Fabry - Perot interference filter, 411... Substrate layer (first substrate), 412, 422... Mirror portions, 415a... End face (first surface), 421... Substrate layer (second substrate), 421b... Surface (second surface), P1... First aperture, P2... Second aperture, A... Optical axis, D... Optical axis direction, L... Light, R... Imaging region, Ra... Outer edge.

Claims

1. A lens unit for a hyperspectral camera, wherein: Comprising: A housing having an incident portion for light incident, an emission portion for the light to be emitted, and a mounting portion for detachably mounting an optical device; and An optical system disposed within the housing, The optical system includes: A Fabry - Perot interference filter having a pair of mirror portions with a variable distance therebetween, and causing the light from the incident portion to pass through according to the distance between the pair of mirror portions; A first aperture formed integrally with the Fabry - Perot interference filter and allowing the light directed towards the Fabry - Perot interference filter or the light passing through the Fabry - Perot interference filter to pass through; A first lens portion that condenses or collimates the light from the incident portion towards the Fabry - Perot interference filter; and A second lens portion that images the light passing through the Fabry - Perot interference filter and emitted from the emission portion, When viewed from the optical axis direction, the width of the light at the incident position on the first aperture is wider than the width of the first aperture.

2. The lens unit for a hyperspectral camera according to claim 1, wherein: The Fabry - Perot interference filter is disposed at a position where the principal ray passing through the outer edge of the imaging region of the light by the second lens portion intersects the optical axis of the light.

3. The lens unit for a hyperspectral camera according to claim 1 or 2, wherein: The first aperture is located on the incident portion side with respect to the pair of mirror portions.

4. The lens unit for a hyperspectral camera according to any one of claims 1 to 3, wherein: The optical system further includes: a second aperture disposed between the Fabry - Perot interference filter and the first lens portion, or between the Fabry - Perot interference filter and the second lens portion.

5. The lens unit for a hyperspectral camera according to claim 4, wherein: The second aperture is formed by an opening in a support body, The Fabry - Perot interference filter is fixed to the support body.

6. The lens unit for a hyperspectral camera according to claim 5, wherein: Further comprising: A first lens holder for holding the first lens portion; and A second lens holder for holding the second lens portion, The support body is fixed while being sandwiched between the first lens holder and the second lens holder.

7. The lens unit for a hyperspectral camera according to any one of claims 1 to 6, wherein: When viewed from the optical axis direction, the area of the incident region of the light at the incident position on the first aperture is 110% or less of the area of the first aperture.

8. The lens unit for a hyperspectral camera according to any one of claims 1 to 7, wherein: The optical system further includes: an additional optical system disposed between the Fabry - Perot interference filter and the first lens portion and reducing the width of the light.

9. The lens unit for a hyperspectral camera according to any one of claims 1 to 7, wherein: The optical system further includes: an additional optical system, which is disposed between the Fabry-Perot interference filter and the first lens unit and parallelizes the light.

10. The lens unit for a hyperspectral camera according to claim 9, wherein, the additional optical system reduces the width of the light.

11. The lens unit for a hyperspectral camera according to any one of claims 1 to 10, wherein, the Fabry-Perot interference filter has: a substrate, which includes a first surface and a second surface on the opposite side of the first surface; and a first stacked structure, which is disposed on the first surface, the first stacked structure has: a first stacked body, which is disposed on the first surface and has one of the pair of mirror parts; and a second stacked body, which is disposed on the opposite side of the substrate with respect to the first stacked body and has the other of the pair of mirror parts.

12. The lens unit for a hyperspectral camera according to claim 11, wherein, the Fabry-Perot interference filter further has a second stacked structure disposed on the second surface of the substrate, a concave portion is formed on the surface on the opposite side of the substrate in the second stacked structure, when viewed from the optical axis direction, at least a part of the concave portion overlaps with the first aperture.

13. The lens unit for a hyperspectral camera according to any one of claims 1 to 10, wherein, the Fabry-Perot interference filter has: a first substrate, which has a first surface; a second substrate, which has a second surface opposite to the first surface; one of the pair of mirror parts, which is formed on the first surface; and the other of the pair of mirror parts, which is formed on the second surface.

14. The lens unit for a hyperspectral camera according to any one of claims 1 to 13, wherein, the first aperture is formed by providing a light-shielding layer in a region other than the light-transmitting region in the Fabry-Perot interference filter and not providing the light-shielding layer in the light-transmitting region.

15. A hyperspectral camera, wherein, it includes: the lens unit for a hyperspectral camera according to any one of claims 1 to 14; and a camera unit, which is an optical device mounted on the mounting portion of the housing and has an imaging element for imaging the light emitted from the emitting portion.

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