Optical unit for hyperspectral camera and hyperspectral camera

Abstract

An optical unit includes a Fabry-Perot interference filter; a first aperture through which light toward the Fabry-Perot interference filter or the light passed through the Fabry-Perot interference filter passes; an imaging lens portion that images the light passed through the Fabry-Perot interference filter and the first aperture; and a housing that houses the Fabry-Perot interference filter, the first aperture, and the imaging lens portion and includes an incident portion for the light incident on the Fabry-Perot interference filter. Viewed in the optical axis direction, a width of an imaging area of ​​the light formed by the imaging lens portion is wider than a width of the first aperture.

Description

Technical field

[0001] The present disclosure relates to an optical unit for a hyperspectral camera and a hyperspectral camera. State of the art

[0002] For example, JP 2020-525 830 A describes a hyperspectral camera that spectrally separates light into wavelengths using a Fabry-Perot interference filter and captures the spectrally separated light as an image. In the hyperspectral camera described in JP 2020-525 830 A, the light passing through the Fabry-Perot interference filter is focused by a focusing lens and directed onto an image sensor. Summary of the invention; Technical task

[0003] The hyperspectral camera described above requires both an improvement in resolution and a suppression of the increase in manufacturing costs.

[0004] Therefore, one objective of the present disclosure is to provide an optical unit for a hyperspectral camera and a hyperspectral camera that enables an improvement in resolution and a suppression of the increase in manufacturing costs. Solution

[0005] An optical unit for a hyperspectral camera according to one aspect of the present disclosure is [1] “an optical unit for a hyperspectral camera comprising: a Fabry-Perot interference filter comprising a pair of mirror sections with a variable distance between them and which transmits incident light according to the distance between the pair of mirror sections; a first aperture through which the light traveling towards the Fabry-Perot interference filter or the light transmitted through the Fabry-Perot interference filter passes; an imaging lens section which images the light that has passed through the Fabry-Perot interference filter and the first aperture; and a housing which accommodates the Fabry-Perot interference filter, the first aperture and the imaging lens section and which has an incidence section for the light incident on the Fabry-Perot interference filter.Viewed in the direction of the optical axis, the width of an imaging area of ​​the light shaped / imaged by the imaging lens section is greater than the width of the first aperture.

[0006] In the optical unit of a hyperspectral camera, viewed along the optical axis, the width of the imaging area of ​​the light shaped by the imaging lens section is greater / wider than the width of the first aperture. In other words, the width of the first aperture is narrower than the width of the imaging area of ​​the light shaped by the imaging lens section. By reducing the width of the first aperture, the light can be extracted precisely for each wavelength, thus improving resolution. Furthermore, reducing the width of the first aperture allows for a smaller size of the Fabry-Perot interference filter, thereby ensuring the filter's productivity and preventing a reduction in resolution.For example, if the size of the Fabry-Perot interference filter is increased to approximately the same size as the imaging area of ​​the light formed by the lens section, there is a risk that the manufacturing of the Fabry-Perot interference filter will become difficult and the manufacturing costs will increase. Furthermore, there is a risk that it will become difficult to precisely control the distance between the pair of mirror sections in the Fabry-Perot interference filter, and that the resolution will decrease. In this respect, because the size of the Fabry-Perot interference filter can be reduced in the optical unit, the aforementioned increase in manufacturing costs and decrease in resolution can be mitigated. Moreover, since the width of the imaging area formed by the lens section is large, a large-area image-taking element, for example, can be used to capture the imaged light.In this way, according to the optical unit for a hyperspectral camera, the resolution can be improved and an increase in manufacturing costs suppressed.

[0007] An optical unit for a hyperspectral camera according to one aspect of the present disclosure can be [2] “the optical unit for a hyperspectral camera described in [1], in which the first aperture is integrally formed with the Fabry-Perot interference filter”. In this case, the size of the first aperture and the Fabry-Perot interference filter can be reduced together.

[0008] An optical unit for a hyperspectral camera according to one aspect of the present disclosure can be [3] “the optical unit for a hyperspectral camera described in [1] or [2] wherein the imaging lens section has a magnifying lens section which widens the width of the light and a focusing lens section which focuses the light from the magnifying lens section.” In this case, the light that has passed through the first aperture can be magnified and then focused and imaged.

[0009] An optical unit for a hyperspectral camera according to one aspect of the present disclosure can be [4] “the optical unit for a hyperspectral camera described in one of the aspects [1] to [3], which additionally comprises a second aperture through which the light traveling towards the Fabry-Perot interference filter or the light passing through the Fabry-Perot interference filter passes. The imaging lens section images the light that has passed through the Fabry-Perot interference filter, the first aperture, and the second aperture.” In this case, the light that has passed through the first aperture and the second aperture can be imaged, and the resolution can be further improved.

[0010] An optical unit for a hyperspectral camera according to one aspect of the present disclosure can [5] be “the optical unit for a hyperspectral camera described in [4], wherein the second aperture is designed as an opening formed in a support, and wherein the Fabry-Perot interference filter is attached to the support.” In this case, the Fabry-Perot interference filter can be suitably attached near the second aperture.

[0011] An optical unit for a hyperspectral camera according to one aspect of the present disclosure may [6] “be the optical unit for a hyperspectral camera described in [4] or [5], wherein the second aperture is arranged between the incident section and the Fabry-Perot interference filter.” In this case, stray light or light with a large angle of incidence can be cut off by the second aperture before it strikes the pair of mirror sections, and noise can be reduced.

[0012] An optical unit for a hyperspectral camera according to one aspect of the present disclosure can [7] be “the optical unit for a hyperspectral camera described in one of the aspects [1] to [6], wherein, viewed in the optical axis direction, the width of the imaging area is at least 1.5 times greater than the width of the first aperture.” In this case, for example, an image-receiving element with a large area can be used as the image-receiving element that captures the imaged light.

[0013] An optical unit for a hyperspectral camera according to one aspect of the present disclosure can be [8] “the optical unit for a hyperspectral camera described in one of the aspects [1] to [7], which additionally includes an additional optical system arranged between the incident section and the Fabry-Perot interference filter and reduces the width of the light.” In this case, the light utilization efficiency can be improved by reducing the width of the light before it hits the Fabry-Perot interference filter.

[0014] An optical unit for a hyperspectral camera according to one aspect of the present disclosure can [9] “be the optical unit for a hyperspectral camera described in one of the aspects [1] to [7], which has an additional optical system arranged between the incident section and the Fabry-Perot interference filter and collimates / collects the light.” In this case, the occurrence of a wavelength shift in the Fabry-Perot interference filter can be suppressed by collimating the light before it hits the Fabry-Perot interference filter.

[0015] An optical unit for a hyperspectral camera according to one aspect of the present disclosure can be

[10] “the lens section for a hyperspectral camera described in [9], in which the additional optical system reduces a width of the light.” In this case, the light utilization efficiency can be improved.

[0016] An optical unit for a hyperspectral camera according to one aspect of the present disclosure can

[11] “be the optical unit for a hyperspectral camera described in one of the aspects [1] to

[10] , wherein the housing further comprises an emission section through which the light from the imaging lens section is emitted.” In this case, for example, the light spectrally separated into wavelengths can be imaged by taking pictures of the light emitted from the emission section.

[0017] An optical unit for a hyperspectral camera according to one aspect of the present disclosure can

[12] be “the optical unit for a hyperspectral camera described in

[11] , wherein the housing further comprises a first mounting section provided on a side where the incidence section is located in relation to the emission section, and to which a first optical device is detachably attached, and a second mounting section provided on a side where the emission section is located in relation to the incidence section, and to which a second optical device is detachably attached.” In this case, for example, the hyperspectral camera can be configured such that a lens section serving as a first optical device is attached to the first mounting section and a camera unit having an image-receiving element is attached to the second mounting section as a second optical device.

[0018] An optical unit for a hyperspectral camera according to one aspect of the present disclosure can

[13] “be the optical unit for a hyperspectral camera described in one of the aspects [1] to

[12] , which additionally includes an image acquisition element arranged inside the housing and (imaginally) receives the light from the imaging lens section.” In this case, the light, spectrally separated into wavelengths, can be image-captured by the image acquisition element inside the housing.

[0019] An optical unit for a hyperspectral camera according to one aspect of the present disclosure can be

[14] “the optical unit for a hyperspectral camera described in one of the aspects [1] to

[13] , wherein the Fabry-Perot interference filter comprises a substrate having a first surface and a second surface opposite the first surface, and has a first laminated structure arranged on / at the first surface. The first laminated structure comprises a first laminate arranged on the first surface and comprising one of the pair of mirror sections, and a second laminate arranged on one side opposite the substrate with respect to the first laminate and comprising the other of the pair of mirror sections.” In this case as well, the resolution can be improved and an increase in manufacturing costs suppressed.

[0020] An optical unit for a hyperspectral camera according to one aspect of the present disclosure can be

[15] “the optical unit for a hyperspectral camera described in

[14] , wherein the Fabry-Perot interference filter further comprises a second laminated structure arranged on the second surface of the substrate. A depression is formed on a surface of the second laminated structure opposite the substrate. At least part of the depression overlaps the first aperture when viewed in the optical axis direction.” In this case, due to the depression formed, the light can easily pass through a section of the Fabry-Perot interference filter that overlaps the first aperture, and the light utilization efficiency can be improved.

[0021] An optical unit for a hyperspectral camera according to one aspect of the present disclosure can be

[16] “the optical unit for a hyperspectral camera described in one of the aspects [1] to

[13] , wherein the Fabry-Perot interference filter has a first substrate with a first surface, a second substrate with a second surface opposite the first surface, one of the pair of mirror sections being formed on the first surface and the other of the pair of mirror sections being formed on the second surface.” In this case as well, the resolution can be improved and an increase in manufacturing costs suppressed.

[0022] An optical unit for a hyperspectral camera according to one aspect of the present disclosure can

[17] “be the optical unit for a hyperspectral camera described in one of the aspects [1] to

[16] , wherein the first aperture is formed by providing a light-shielding layer in a region of the Fabry-Perot interference filter that is not the light transmission region, while the light-shielding layer is not provided in the light transmission region.” In this case, the first aperture can be formed integrally with the Fabry-Perot interference filter.

[0023] A hyperspectral camera according to one aspect of the present disclosure is

[18] “a hyperspectral camera comprising the optical unit for a hyperspectral camera described in one of the aspects [1] to

[17] and a camera unit which includes an image acquisition element which receives the light emitted from the housing and which is attached to the housing.” According to the hyperspectral camera, for the reasons described above, the resolution can be improved and an increase in manufacturing costs suppressed. Advantageous effects of the invention

[0024] According to one aspect of the present disclosure, it is possible to provide the optical unit for a hyperspectral camera and the hyperspectral camera itself, which are capable of improving the resolution and suppressing an increase in manufacturing costs. Brief description of the drawings Fig. Figure 1 is a configuration view of a hyperspectral camera according to one embodiment. Fig. Figure 2 is a perspective view of a filter unit. Fig. Figure 3 is a cross-sectional view of the filter unit along line III-III in Fig. 2. Fig. Figure 4 is a perspective view of a Fabry-Perot interference filter. Fig. Figure 5 is a cross-sectional view of the Fabry-Perot interference filter along line VV in Fig. 4. Fig. Figure 6 is a configuration view of a first modification example. Fig. Figure 7 is a configuration view of a second modification example. Fig. 8 (a) and (b) are configuration views of other modification examples. Fig. Figure 9 is a cross-sectional view of a Fabry-Perot interference filter of a third modification example. Description of the embodiments

[0025] An embodiment of the present disclosure is described in detail below with reference to the drawings. In the following description, the same reference numerals are used for identical or corresponding elements, and duplicate descriptions are omitted.

[0026] As in Fig. As shown in Figure 1, a hyperspectral camera 1 comprises an optical unit 2 (optical unit for a hyperspectral camera), a lens section 4 (first optical device), and a camera unit 5 (second optical device). The hyperspectral camera 1 is a camera that can spectrally separate light into several tens to several hundred bands according to its wavelength and capture an image for each band.

[0027] The optical unit 2 comprises a housing 21 and an optical system 22 arranged within the housing 21. The optical system 22 includes a Fabry-Perot interference filter 10 and an imaging lens section 23. The Fabry-Perot interference filter 10 is attached to a support 31 and, together with the support 31, forms a filter unit 30. The camera unit 5 comprises a housing 51 and an image acquisition element 52 arranged within the housing 51. In the hyperspectral camera 1, the light L focused by the lens section 4 is transmitted along an optical axis direction D through the Fabry-Perot interference filter 10. The light L transmitted through the Fabry-Perot interference filter 10 is imaged by the imaging lens section 23 and captured as an image by the image acquisition element 52. The Fabry-Perot interference filter 10 will first be described with reference to the Fig. 4 and Fig. 5 described. [Fabry-Perot interference filter]

[0028] As in Fig. As shown in Figure 4, the Fabry-Perot interference filter 10 has a light transmission 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 one thickness direction runs parallel to the optical axis direction D. The light transmission region 10a is a column-shaped region with a center line that is parallel to the optical axis direction D. When viewed along the optical axis direction D, the center point of the light transmission region 10a coincides with the center point of the Fabry-Perot interference filter 10.

[0029] As in Fig. As shown in Figure 5, the Fabry-Perot interference filter 10 comprises a substrate 11 whose thickness direction runs along the optical axis D. The substrate 11 is made of, for example, silicon, quartz, glass, or the like. The substrate 11 has a first surface 11a and a second surface 11b opposite the first surface 11a. The first surface 11a and the second surface 11b are, for example, flat surfaces perpendicular to the optical axis D. A first laminated structure 12 is laminated onto the first surface 11a, and a second laminated structure 13 is laminated onto the second surface 11b.

[0030] The first laminated structure 12 comprises an antireflective layer 121, a first laminate 122, an intermediate layer 123, and a second laminate 124. The antireflective layer 121, the first laminate 122, the intermediate layer 123, and the second laminate 124 are laminated in this order onto the first surface 11a of the substrate 11. Specifically, the first laminate 122 is arranged over the antireflective layer 121 on the first surface 11a, and the second laminate 124 is positioned on one side opposite the substrate with respect to the first laminate 122 (in Fig. 5 a top side). An air gap S is formed between the first laminate 122 and the second laminate 124 by the frame-shaped intermediate layer 123. If the substrate 11 material is silicon, the antireflection layer 121 and the intermediate layer 123 are, for example, silicon oxide or the like. The thickness of the intermediate layer 123 is, for example, an integer multiple of 1 / 2 a design center wavelength. It should be noted that the thickness of the intermediate layer 123 can be greater than an integer multiple of 1 / 2 the design center wavelength if required.

[0031] A section of the first laminate 122, corresponding to the light transmission region 10a, functions as a mirror section 14. Specifically, the first laminate 122 comprises the mirror section 14. The mirror section 14 is supported by the substrate 11 via the antireflection layer 121. As an example, the first laminate 122 is configured by alternately laminating multiple polysilicon layers and multiple silicon nitride layers. The optical thickness of each layer that (together) forms the mirror section 14 is, for example, an integer multiple of 1 / 4 of the design center wavelength. It should be noted that a silicon oxide layer can be used instead of the silicon nitride layer.

[0032] A section of the second laminate 124, corresponding to the light transmission region 10a, functions as a mirror section 15. Specifically, the second laminate 124 comprises the mirror section 15. The mirror section 15 is supported by the antireflection layer 121, the first laminate 122, and the intermediate layer 123 on the substrate 11 and is oriented in the optical axis direction D towards the mirror section 14 with the air gap S between them. As an example, the second laminate 124 is configured by having a plurality of polysilicon layers and a plurality of silicon nitride layers laminated alternately one after the other. The optical thickness of each layer that (together) forms the mirror section 15 is, for example, an integer multiple of 1 / 4 of the design center wavelength. It should be noted that a silicon oxide layer can be used instead of the silicon nitride layer.It should be noted that a multitude of through-holes in a section of the second laminate 124, corresponding to the air gap S, are formed to such an extent that the function of the mirror section 15 is not significantly impaired. The multitude of through-holes is used when the air gap S is formed by removing part of the intermediate layer 123 by etching.

[0033] A first electrode 125 and a second electrode 126 are formed in the mirror section 14. The first electrode 125 surrounds the light transmission area 10a in the optical axis direction D. The second electrode 126 overlaps the light transmission area 10a in the optical axis direction D. The shape of the second electrode 126 in the optical axis direction D essentially corresponds to the shape of the light transmission area 10a in the optical axis direction D. The first electrode 125 and the second electrode 126 are each formed by doping a portion of a polysilicon layer with an impurity to reduce the resistance of that portion.

[0034] A third electrode 127 is formed in the mirror section 15. The third electrode 127 faces the first electrode 125 and the second electrode 126 with the air gap S between them. The third electrode 127 is formed by doping a section of a polysilicon layer with an impurity to reduce the resistance of this section. For example, the distance between the second electrode 126 and the third electrode 127 is essentially the same as the distance between the first electrode 125 and the third electrode 127.

[0035] A pair of terminals 16 is provided on the first laminated structure 12, so that they enclose the light transmission area 10a in between (see Fig. 4) Each of the terminals 16 is arranged in a through-hole formed in the second laminate 124 and the intermediate layer 123, opening towards the side opposite the substrate 11 and reaching the first laminate 122. Each of the terminals 16 is electrically connected to the first electrode 125 via a cable 125a.

[0036] A pair of terminals 17 is provided on the first laminated structure 12 such that they enclose the light transmission area 10a between them (see Fig. 4) Each of the terminals 17 is arranged in a through-hole formed in the second laminate 124 and the intermediate layer 123 such that it opens towards the side opposite the substrate 11 and reaches the intermediate layer 123. Each of the terminals 17 is electrically connected to the second electrode 126 via a cable 126a and electrically connected to the third electrode 127 via a cable 127a. It should be noted that a direction in which the pair of terminals 17 encloses the light transmission area 10a between them is perpendicular to a direction in which the pair of terminals 16 enclose the light transmission area 10a between them (see Fig. 4).

[0037] A pair of grooves 122a is formed in the first laminate 122. Each groove 122a extends in a ring shape, surrounding a section of the wiring 126a, with the section extending from each of the terminals 17 in the optical axis direction D. Each groove 122a electrically insulates the first electrode 125 from the wiring 126a. A groove 122b is formed in the first laminate layer 122. The groove 122b extends in a ring shape along an inner edge of the first electrode 125. The groove 122b electrically insulates the first electrode 125 from the second electrode 126. A region in each of the grooves 122a and 122b can be filled with an insulating material or form an air gap.

[0038] A pair of grooves 124a is formed in the second laminate 124. Each of the grooves 124a extends in a ring shape, so that it surrounds each of the terminals 16. Each of the grooves 124a electrically insulates each of the terminals 16 from the third electrode 127. A region in each of the grooves 124a can be filled with an insulating material or form an air gap.

[0039] The second laminated structure 13 comprises an antireflective layer 131, a third laminate 132, an intermediate layer 133, and a fourth laminate 134. The antireflective layer 131, the third laminate 132, the intermediate layer 133, and the fourth laminate 134 are laminated in this order onto the second surface 11b of the substrate 11. The antireflective layer 131 and the intermediate layer 133 have the same configurations as the antireflective layer 121 and the intermediate layer 123, respectively. The third laminate 132 and the fourth laminate 134 have laminated structures that are symmetrical with respect to the first laminate 122 and the second laminate 124, respectively, with the substrate 11 as the reference point. The anti-reflective layer 131, the third laminate 132, the intermediate layer 133 and the fourth laminate 134 have the function of suppressing warping of the substrate 11.

[0040] A depression 18 is formed on a surface 13a of the second laminated structure 13, opposite the substrate 11. The depression 18 opens towards a side opposite the substrate 11. The depression 18 overlaps the light transmission area 10a when viewed in the optical axis direction D. The shape of the depression 18, when viewed in the optical axis direction D, is essentially the same as the shape of the light transmission area 10a when viewed in the optical axis direction D, and in this example is circular. A centerline of the depression 18 coincides with a centerline of the light transmission area 10a. The depression 18 is formed in the third laminate 132, the intermediate layer 133, and the fourth laminate 134, and extends to the antireflection layer 131.

[0041] A light-shielding layer 135 is formed on the surface 13a of the second laminated structure 13. The light-shielding layer 135 extends, 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, the light L passes through an area where the light-shielding layer 135 is not formed (in this example, an area where the recess 18 is formed). The light transmission area 10a corresponds to the area where the light-shielding layer 135 is not formed. In this way, a first aperture P1, which defines the light transmission area 10a, is formed by the light-shielding layer 135 in the Fabry-Perot interference filter 10.The first aperture P1 is formed by the fact that the light-shielding layer 135 is provided in a region of the Fabry-Perot interference filter 10 which, viewed in the optical axis direction D, is not the light transmission region 10a, while the light-shielding layer 135 is not provided in the light transmission region 10a. Furthermore, the first aperture P1 is integrally formed with the Fabry-Perot interference filter 10. The width of the first aperture P1 is fixed (does not change).

[0042] The first aperture P1 is circular when viewed along the optical axis D. The entire recess 18 completely overlaps the first aperture P1 when viewed along the optical axis D. In this example, the shape of the recess 18, viewed along the optical axis D, is essentially identical to the shape of the first aperture P1, also viewed along the optical axis D. The center line of the recess 18 coincides with a center line of the first aperture P1.

[0043] A protective layer 136 is formed on the light-shielding layer 135 and on an inner surface of the recess 18. The material of the protective layer 136 is, for example, aluminum oxide or the like. It should be noted that the optical influence of the protective layer 136 can be neglected by adjusting the thickness of the protective layer 136 to 100 nm or less (preferably about 30 nm).

[0044] 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 via the plurality of terminals 16 and 17, an electrostatic force corresponding to this potential difference is generated between the first electrode 125 and the third electrode 127. Due to the generation of this electrostatic force between the first electrode 125 and the third electrode 127, the mirror section 15 is attracted to the mirror section 14, and the distance between the mirror section 14 and the mirror section 15 is adjusted. At this point, the second electrode 126, which is at the same potential as the third electrode 127, acts as a compensating electrode, and the mirror section 15 is held flat in the light transmission region 10a.

[0045] In the Fabry-Perot interference filter 10, a pair of mirror sections 14 and 15, which are opposite each other in the optical axis direction D, function as a pair of mirror sections with a variable distance between them. The wavelength of the light passing through the Fabry-Perot interference filter 10 depends on the distance between mirror section 14 and mirror section 15. Therefore, the wavelength of the light passing through the Fabry-Perot interference filter 10 can be selected by adjusting the voltage 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). In this way, the Fabry-Perot interference filter 10 allows light whose wavelength corresponds to the distance between mirror sections 14 and 15 to pass through from the incident light. [Filter unit]

[0046] As in the Fig. As shown in Figures 1 to 3, the filter unit 30 comprises the carrier 31 (aperture plate), the Fabry-Perot interference filter 10 described above, and a bandpass 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. Fig. 2 The Fabry-Perot interference filter 10 is represented by dashed lines, and the bandpass filter 32 is represented by two-dot dash lines.

[0047] The support 31 is formed, for example, in an essentially circular plate shape made of a metal material, such as stainless steel. The support 31 has a first surface 31a and a second surface 32b opposite the first surface 31a. The first surface 31a and the second surface 31b are, for example, flat surfaces that are perpendicular to the optical axis direction D. A recess 33 for arranging the Fabry-Perot interference filter 10 and the bandpass filter 32 is formed in the support 31. The recess 33 is formed on the first surface 31a and opens towards the first surface 31a.

[0048] The recess 33 comprises a first recess 34 and a second recess 35. A bottom surface 34a of the first recess 34 and a bottom surface 35a of the second recess 35 lie in the same plane, which is perpendicular to the optical axis direction D. The first recess 34 and the second recess 35 are arranged in an X-direction (a direction perpendicular to the optical axis direction D).

[0049] Viewed in the optical axis direction D, both the first recess 34 and the second recess 35 are rectangular. In this example, both the first recess 34 and the second recess 35, viewed in the optical axis direction D, are elongated, with the X-direction as its longitudinal direction. Viewed in the optical axis direction D, the first recess 34 does not extend to an outer edge of the support 31, while the second recess 35 does. That is, the second recess 35 opens onto a side surface of the support 31.

[0050] The width of the second recess 35 in a Y-direction (a direction perpendicular to both the optical axis direction D and the X-direction) is greater 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. The opening 36 and the through-hole 37 open, respectively, to the bottom surface 34a of the first recess 34 and to the second surface 31b of the support 31. The opening 36 and the through-hole 37 are arranged in the X-direction. Viewed in the optical axis direction D, both the opening 36 and the through-hole 37 are, for example, circular. The opening 36 forms a second aperture P2 through which the light L traveling towards 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 serves, for example, to allow gas that arises from an adhesive material used to attach the Fabry-Perot interference filter 10 and the bandpass filter 32 to escape during the manufacture of the filter unit 30.

[0051] An expanded section 38 is formed in the carrier 31. The expanded section 38 is expanded in the X-direction on one side opposite the second recess 35 and in the Y-direction on both sides with respect to an opening of the first recess 34. The expanded section 38 is a recess formed in the carrier 31 such that it opens towards the first surface 31a and reaches the opening of the first recess 34 with the optical axis direction D as its depth direction. In the present embodiment, the width of the expanded section 38 in the Y-direction is equal to the width of the second recess 35 in the Y-direction.

[0052] The support 31 comprises a separating section 39. The separating section 39 is arranged between the first recess 34 and the second recess 35. In the present embodiment, the separating section 39 is a wall section 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. If a plane in which the bottom surface 34a and the bottom surface 35a lie is taken as the reference plane, the height of the separating section 39 in the optical axis direction D is less than the height of the first surface 31a of the support 31 in the optical axis direction D and is less than the height of a bottom surface 38a of the widened section 38 in the optical axis direction D.

[0053] The Fabry-Perot interference filter 10 is positioned on the carrier 31 such that it overlaps the second aperture P2 (opening 36) in the optical axis direction D, and its thickness direction runs parallel to the optical axis direction D. More precisely, the Fabry-Perot interference filter 10 is positioned within the first recess 34 such that it overlaps the opening 36 in the optical axis direction D, and its thickness direction runs parallel to the optical axis direction D. The Fabry-Perot interference filter 10 is in contact with the separating section 39 within the first recess 34. If the bottom surface 34a of the first depression 34 is taken as a reference point, the height of the Fabry-Perot interference filter 10 in the optical axis direction D is less than the height of the first surface 31a of the support 31 in the optical axis direction D and less than the height of the bottom surface 38a of the widened section 38 in the optical axis direction D.If the bottom surface 34a of the first depression 34 is taken as a reference point, the height of the separation section 39 in the optical axis direction D is equal to or less than the height of the Fabry-Perot interference filter 10 in the optical axis direction D.

[0054] As described above, the Fabry-Perot interference filter 10 is a rectangular, plate-shaped element whose thickness extends along the optical axis direction D. The Fabry-Perot interference filter 10 is positioned on the bottom surface 34a of the first recess 34 such that, when viewed along the optical axis direction D, each side of an outer edge of the rectangular shape is parallel to either 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 attached to the bottom surface 34a, for example, by an adhesive material. The center line of the first aperture P1 coincides with a center line of the second aperture P2.

[0055] The bandpass filter 32 is arranged on the carrier 31 such that it covers the opening of the first recess 34 and its thickness direction runs parallel to the optical axis direction D. More precisely, the bandpass filter 32 is arranged within the flared section 38 such that it covers the opening of the first recess 34 and its thickness direction runs parallel to the optical axis direction D. The bandpass filter 32 is, for example, attached to the bottom surface 38a of the flared section 38 with an adhesive material. In the present embodiment, the bandpass filter 32 covers the opening of the first recess 34 and a portion of an opening of the second recess 35. If the bottom surface 38a of the flared section 38 is taken as a reference point, the height of the bandpass filter 32 in the optical axis direction D is less than the height of the first surface 31a of the carrier 31 in the optical axis direction D.

[0056] The bandpass filter 32 is formed in a rectangular plate shape, with the optical axis direction D as its thickness direction and the X-direction as its longitudinal direction. The bandpass filter 32 is arranged on the bottom surface 38a of the widened section 38 such that each side of an outer edge of the rectangular shape, viewed in the optical axis direction D, is parallel to either the X-direction or the Y-direction. The bandpass filter 32 transmits light within a predetermined wavelength range. Additionally, although not shown in the figures, a wiring board or similar component, electrically connected to the Fabry-Perot interference filter 10, is arranged in the second recess 35. [Optical unit, lens section and camera unit]

[0057] As in Fig. As shown in Figure 1, the optical unit 2 comprises the housing 21 and the optical system 22 arranged within the housing 21. The optical system 22 comprises the Fabry-Perot interference filter 10 and the imaging lens section 23. Furthermore, the optical system 22 comprises the first aperture P1 and the second aperture P2 described above.

[0058] The housing 21 is, for example, formed in a substantially cylindrical shape. The housing 21 comprises an incidence section 21a, onto which the light L is incident; an emission section 21b, from which the light L is emitted; a first mounting section 21c, to which the lens section 4 is detachably attached; and a second mounting section 21d, to which the camera unit 5 is detachably attached. In this example, the incidence section 21a is formed by an end section on one side of the housing 21 in the optical axis direction D, and the emission section 21b is formed by an end section on the other side of the housing 21 in the optical axis direction D. In the optical unit 2, the light L incident from the incidence section 21a falls onto the Fabry-Perot interference filter 10, and the light L imaged by the imaging lens section 23 is focused by the

[0059] The first mounting section 21c is provided on the side where the incidence section 21a is located relative to the emission section 21b (one side in the optical axis direction D). In this example, the first mounting section 21c is located at the end section on one side of the incidence section 21a of the housing 21 (end section on one side in the optical axis direction D). The first mounting section 21c is detachably engaged with a mounting section 41a of the lens section 4, which will be described later. For example, if the optical unit 2 and the lens section 4 are detachably connected to each other by screws, the first mounting section 21c is provided with a screw thread or a screw groove, and the mounting section 41a is provided with the other of a screw thread and screw groove, which is screwable with the one (of a screw thread and screw groove).

[0060] The second mounting section 21d is provided on the side where the emission section 21b is located relative to the incidence section 21a (the other side in the optical axis direction D). In this example, the second mounting section 21d is provided at the end section on one side of the emission section 21b of the housing 21 (end section on the other side in the optical axis direction D). The second mounting section 21d is detachably engaged with a mounting section 51a of the camera unit 5, which will be described later. For example, if the optical unit 2 and the camera unit 5 are detachably connected to each other by screws, the second mounting section 21d is provided with a screw thread or a screw groove, and the mounting section 51a is provided with the other of screw thread and screw groove, which can be screwed into the one (of screw thread and screw groove).

[0061] The carrier 31 of the filter unit 30 is attached to the housing 21. The carrier 31 is, for example, attached to and secured on an outer circumferential section of the carrier 31 on the housing 21. Accordingly, the Fabry-Perot interference filter 10 is mounted on an optical axis A between the incidence section 21a and the imaging lens section 23. The filter unit 30 is mounted on the optical axis A such that the center line of the light transmission area 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 lie on the optical axis A (see Fig. 1 to 5). In this fixed state, the second surface 31b of the support 31 faces the side of the incidence section 21a, and the first aperture P1 is located on the side of the incidence section 21a with respect to the mirror sections 14 and 15 of the Fabry-Perot interference filter 10. The second aperture P2 is located between the incidence section 21a and the Fabry-Perot interference filter 10. That is, the second aperture P2 is located on the side of the incidence section 21a with respect to the first aperture P1.

[0062] The imaging lens section 23 is an imaging optical system that images the light L incident from the incident section 21a and successively passing through the second aperture P2, the first aperture P1, and the Fabry-Perot interference filter 10. In this example, the imaging lens section 23 comprises a magnifying lens section 23a and a focusing lens section 23b. The magnifying lens section 23a is a magnifying optical system that increases the width of the light L and comprises at least one lens. The focusing lens section 23b is a condenser optical system that focuses the light L from the magnifying lens section 23a and comprises at least one lens. In this example, the imaging lens section 23 is a magnifying optical system that increases the width of the light L and then focuses the light L, and the optical unit 2 is a front-mounted lens section.The imaging lens section 23 (the magnifying lens section 23a and the focusing lens section 23b) is, for example, attached and fastened to an outer circumferential section of the imaging lens section 23 on the housing 21.

[0063] The lens section 4 comprises a housing 41 and a lens section (not shown) arranged within the housing 41. The lens section 4 is an interchangeable lens device that is interchangeably (removably) attached to the optical unit 2. The housing 41 is, for example, cylindrical in shape and includes the mounting section 41a, which has a cylindrical shape on the other side in the optical axis direction D (side of the optical unit 2). The mounting section 41a is detachably engaged with the first mounting section 21c of the optical unit 2 described above. The lens section arranged within the housing 41 is a condenser optical system that focuses the light L traveling towards the incident section 21a and, for example, comprises at least one lens.

[0064] The camera unit 5 comprises the housing 51 and the image acquisition element 52 arranged within the housing 51. The housing 51 is, for example, cylindrical and includes the mounting section 51a, which has a cylindrical shape on one side in the optical axis direction D (side of the optical unit 2). The mounting section 51a is detachably engaged with the second mounting section 21d of the optical unit 2 described above.

[0065] The image acquisition element 52 is arranged within the housing 51. The image acquisition element 52 is, for example, an InGaAs image sensor. The image acquisition element 52 has a light-receiving surface 52a, which is arranged on an imaging plane of the light L shaped by the imaging lens section 23 (at the focal position of the imaging lens section 23), and receives the light L emitted by the emission section 21b. In this example, the image acquisition element 52 is housed in a package 53. Furthermore, a control circuit for controlling the image acquisition element 52, an image processing circuit for processing an image acquired by the image acquisition element 52, a cooling mechanism for cooling the image acquisition element 52, and the like are arranged within the housing 51. Fig. These components are designated with the reference numeral 54.

[0066] In the hyperspectral camera 1, the light L incident on lens section 4 is focused within lens section 4 and falls onto the incidence section 2a of the optical unit 2. The light L incident on the incidence section 21a travels towards the filter unit 30 (see Fig. 1 and Fig. 3) The light L traveling towards the filter unit 30 passes or penetrates successively / in this order the second aperture P2, the first aperture P1, the mirror sections 14 and 15 and the bandpass filter 32 (see Fig. 1, Fig. 3 and Fig. 5) The light L is spectrally separated according to wavelengths as it passes through the Fabry-Perot interference filter 10 (mirror sections 14 and 15). The light L emitted by the filter unit 30 (bandpass filter 32) is imaged by the imaging lens section 23 onto the light-receiving surface 52a of the image-receiving element 52 and is imaged by the image-receiving element 52.

[0067] In hyperspectral camera 1, viewed in the optical axis direction D, the width (spot width) of the light L at an incident position at the first aperture P1 is greater than the width of the first aperture P1. Accordingly, the light L traveling towards the Fabry-Perot interference filter 10 (mirror sections 14 and 15) can be narrowed by the first aperture P1. For example, the light L at the incident position at the first aperture P1 has a circular shape with a diameter of 1.6 mm, and the first aperture P1 has a circular shape with a diameter of 1.5 mm.It should be noted that in the present embodiment, the width of the light L at the point of incidence at the first aperture P1 is greater than the width of the first aperture P1 in all directions perpendicular to the optical axis direction D; however, it is sufficient if the width of the light L at the point of incidence at the first aperture P1 is greater than the width of the first aperture P1 in at least one direction perpendicular to the optical axis direction D.

[0068] In the hyperspectral camera 1, viewed in the optical axis direction D, the width of an imaging area R of the light L shaped by the imaging lens section 23 (a spot width at the focal point position of the imaging lens section 23) is greater than the width of the first aperture P1. In this example, the imaging area R is the entirety of the light-receiving surface 52a of the image-receiving element 52, and an outer edge Ra of the imaging area R is in Fig. Figure 1 illustrates this. The imaging area R, for example, has an elongated shape of 12.8 mm × 9.6 mm. The first aperture P1, for example, has a circular shape with a diameter of 1.5 mm to 5 mm, and in this case, the width of the imaging area R is at least 1.5 times wider than the width of the first aperture P1. It should be noted that, in the present embodiment, the width of the imaging area R is greater than the width of the first aperture P1 in all directions perpendicular to the optical axis direction D; however, it is sufficient if the width of the imaging area R is greater than the width of the first aperture P1 in at least one direction perpendicular to the optical axis direction D. [Functions and effects]

[0069] In the optical unit 2, viewed along the optical axis D, the width of the imaging area R of the light L shaped by the imaging lens section 23 is greater than the width of the first aperture P1. In other words, the width of the first aperture P1 is narrower than the width of the imaging area R. By reducing the width of the first aperture P1, the light L can be extracted precisely for each wavelength, thus improving the resolution. Furthermore, reducing the width of the first aperture P1 can decrease the size of the Fabry-Perot interference filter 10, thereby ensuring the productivity of the Fabry-Perot interference filter 10 and preventing a reduction in resolution. For example, if the size of the Fabry-Perot interference filter 10 is increased to approximately the same size as the imaging area R, manufacturing the Fabry-Perot interference filter 10 becomes difficult and increases the manufacturing costs, which poses a risk.Furthermore, it becomes difficult to precisely control the distance between the pair of mirror sections 14 and 15 in the Fabry-Perot interference filter 10, and the resolution decreases, which poses a risk. In this respect, the increase in manufacturing costs and the reduction in resolution described above can be mitigated in the optical unit 2, since the size of the Fabry-Perot interference filter 10 can be reduced. Moreover, since the width of the imaging area R is large, for example, a large-area image-taking element can be used as the image-taking element 52, capturing the imaged light L, and the viewing angle can be widened. In this way, according to the optical unit 2, the resolution can be improved and the increase in manufacturing costs mitigated.Furthermore, since the Fabry-Perot interference filter 10 forms the optical unit 2, and the lens section 4 and the camera unit 5 can be attached to and removed from the optical unit 2, the degree of freedom in selecting the lens section 4 and the camera unit 5 can be increased. Additionally, the image acquisition element 52, which has an area larger than the effective diameter of the Fabry-Perot interference filter 10, can be used.

[0070] The first aperture P1 is integrally formed with the Fabry-Perot interference filter 10. Therefore, the size of both the first aperture P1 and the Fabry-Perot interference filter 10 can be reduced together.

[0071] The imaging lens section 23 comprises the magnifying lens section 23a, which widens the width of the light L, and the focusing lens section 23b, which focuses the light L from the magnifying lens section 23a. Thus, the light L that has passed through the first aperture P1 can be magnified and then focused and imaged. The resolution can be improved by increasing the width of the light L using the magnifying lens section 23a.

[0072] The optical system 22 further comprises the second aperture P2, through which the light L traveling towards the Fabry-Perot interference filter 10 passes, and the imaging lens section 23, which images the light L passing through the Fabry-Perot interference filter 10, the first aperture P1 and the second aperture P2.

[0073] Therefore, the light that has passed through the first aperture P1 and the second aperture P2 can be imaged, and the resolution can be further improved.

[0074] The second aperture P2 is formed as an opening 36, which is formed in the carrier 31, and the Fabry-Perot interference filter 10 is attached / fixed to the carrier 31. Accordingly, the Fabry-Perot interference filter 10 can be suitably / appropriately attached near the second aperture P2.

[0075] The second aperture P2 is positioned between the incident section 21a and the Fabry-Perot interference filter 10. Accordingly, stray light or light with a large angle of incidence can be cut off by the second aperture P2 before it strikes the pair of mirror sections 14 and 15, and noise can be reduced.

[0076] Viewed in the optical axis direction D, the width of the imaging area R is at least 1.5 times wider than the width of the first aperture P1. Accordingly, for example, an image-taking element with a large area can be used as image-taking element 52, which captures the imaged light L.

[0077] The housing 21 includes the emission section 21b, through which the light from the imaging lens section 23 is emitted. Accordingly, for example, the light L, spectrally separated in wavelengths, can be imaged by capturing the light L emitted from the emission section 21b.

[0078] The housing 21 comprises the first mounting section 21c, which is provided on the side where the incident section 21a is located relative to the emission section 21b, and to which the lens section 4 (first optical device) is detachably attached, and a second mounting section 21d, which is provided on the side where the emission section 21b is located relative to the incident section 21a, and to which the camera unit 5 (second optical device) is detachably attached. Accordingly, for example, the hyperspectral camera 1 can be configured such that the lens section 4 is attached to the first mounting section 21c and the camera unit 5, which includes the image acquisition element 52, is attached to the second mounting section 21d.

[0079] The Fabry-Perot interference filter 10 comprises the substrate 11 with the first surface 11a and the second surface 11b, and the first laminated structure 12, which is arranged on the first surface 11a. The first laminated structure 12 comprises the first laminate 122, which is arranged on the first surface 11a and includes the mirror section 14, and the second laminate 124, which is arranged on the side opposite the substrate 11 with respect to the first laminate 122 and includes the mirror section 15. In this case as well, a satisfactory image can be acquired with the hyperspectral camera 1.

[0080] The Fabry-Perot interference filter 10 comprises the second laminated structure 13, which is arranged on the second surface 11b of the substrate 11, and the recess 18 is formed on the surface 13a of the second laminated structure 13 opposite the substrate 11. The recess 18 overlaps the first aperture P1 when viewed in the optical axis direction D. Because of the recess 18, the light L can therefore easily pass through a section of the Fabry-Perot interference filter 10 that overlaps the first aperture P1, and the light utilization efficiency can be improved.

[0081] The first aperture P1 is formed by placing the light-shielding layer 135 in a region of the Fabry-Perot interference filter 10 that differs from the light transmission region 10a, while the light-shielding layer 135 is not placed in the light transmission region 10a. Accordingly, the first aperture P1 can be formed integrally with the Fabry-Perot interference filter 10. [Modification examples]

[0082] As in a first modification example in Fig. As shown in Figure 6, the optical system 22 can further comprise a reduction optical system 26 (additional optical system) arranged between the incidence section 21a and the Fabry-Perot interference filter 10, reducing the width of the light L. In this example, the reduction optical system 26 is arranged between the incidence section 21a and the second aperture P2. The reduction optical system 26 comprises, for example, a plurality of lenses. With this first modification example, as with the embodiment described above, the resolution can be improved and an increase in manufacturing costs suppressed. Furthermore, the light utilization efficiency can be improved by reducing the width of the light L before it enters the Fabry-Perot interference filter 10 using the reduction optical system 26.

[0083] In a second modification example, which is in Fig. As shown in Figure 7, the reduction optical system 26 is designed as an optical system that reduces the width of the light L and collimates the light L (reduces the angle of incidence on the Fabry-Perot interference filter 10, namely the angle with respect to the optical axis direction D). Specifically, the reduction optical system 26 makes the angle of incidence of the light L on the Fabry-Perot interference filter 10 smaller than the angle of the light L traveling from the incident section 21a towards the Fabry-Perot interference filter 10 (reduction optical system 26). In this case, the imaging lens section 23 further comprises an optical system (lens) that restores the angle of the light L to an angle prior to collimation (restores the angle with respect to the optical axis direction D to an original angle). This optical system is arranged, for example, between the Fabry-Perot interference filter 10 and the magnifying lens section 23a.In the second modification example, as in the embodiment described above, the resolution can be improved and an increase in manufacturing costs suppressed. Additionally, the light utilization efficiency can be improved by reducing the width of the light L before it strikes the Fabry-Perot interference filter 10. Furthermore, the occurrence of a wavelength shift in the Fabry-Perot interference filter 10 can be suppressed by collimating the light L before it strikes the Fabry-Perot interference filter 10. It should be noted that in the second modification example, the optical system 22 can include an additional optical system instead of the reduction optical system 26. This additional optical system collimates the light L without reducing its width. In this case as well, the occurrence of a wavelength shift can be suppressed.

[0084] As in Fig. As shown in Figure 8, in the embodiment described above or in the second modification example, the optical unit 2 and the camera unit 5 can be integrated into a single optical unit 2A. The optical unit 2A comprises a housing 21A with a cylindrical shape corresponding to the housing 21 and housing 51 described above. The housing 21A includes the inlet section 21a and the first mounting section 21c, but not the emission section 21b, the second mounting section 21d, and the mounting section 51a. In example (a) of Fig. In 8, the filter unit 30 (the Fabry-Perot interference filter 10, the first aperture P1 and the second aperture P2), the imaging lens section 23 and the image receiving element 52 are arranged within the housing 21A. In example (b) of Fig. In Figure 8, the reduction optics system 26 is additionally arranged within the housing 21A. With these modifications, as with the embodiment described above, the resolution can be improved and an increase in manufacturing costs suppressed. Furthermore, the light L, spectrally separated into wavelengths, can be imaged by the image acquisition element 52 within the housing 21A. Since the image acquisition element 52 is arranged within the integrated housing 21A, the adhesion of particles to the light-receiving surface 52a of the image acquisition element 52 can also be suppressed. Moreover, since an optical design comprising a section corresponding to the camera unit 5 can be implemented, the occurrence of stray light or the like can be effectively suppressed.It should be noted that in the first modification example, the optical unit 2 and the camera unit 5 can be integrated in such a way that they form a single optical unit 2A.

[0085] Instead of the Fabry-Perot interference filter 10, a Fabry-Perot interference filter 400 from a third modification example can be used, which is described in Fig. Figure 9 shows the Fabry-Perot interference filter 400, which comprises a substrate layer 411 (first substrate), a mirror section 412, and a drive electrode 413. The substrate layer 411 has a surface 411a and a surface 411b facing each other. The substrate layer 411 is made of a transparent material. The mirror section 412 is, for example, a metal foil, a dielectric multilayer film, or a composite film made of these materials. The drive electrode 413 is made, for example, of a metal material.

[0086] The Fabry-Perot interference filter 400 further comprises a substrate layer 421 (second substrate), a mirror section 422, and a drive electrode 423. The substrate layer 421 has a surface 421a and a surface 421b facing each other. The substrate layer 421 consists of a transparent material. The mirror section 422 is, for example, a metal layer, a dielectric multilayer film, or a composite film thereof. The drive electrode 423 consists, for example, of a metal material.

[0087] A depression 414 is formed on the surface 411a of the substrate layer 411. A projection 415 is provided on a bottom surface 414a of the depression 414. When the bottom surface 414a is taken as a reference point, the height of an end face 415a of the projection 415 is less than the height of the surface 411a of the substrate layer 411. The mirror section 412 is provided on the end face 415a (first surface) of the projection 415. The drive electrode 413 is provided on the bottom surface 414a of the depression 414 such that it surrounds the projection 415. The drive electrode 413 is electrically connected, for example, via wiring (not shown) provided on the substrate layer 411 to an electrode pad (not shown). The electrode pad is provided, for example, in an externally accessible area of ​​the substrate layer 411.

[0088] Surface 421b of substrate layer 421 is connected to surface 411a of substrate layer 411, for example, by plasma welding. Mirror section 422 and drive electrode 423 are located on surface 421b (second surface) of substrate layer 421. Surface 421b of substrate layer 421 faces the end face 415a of substrate layer 411 in the optical axis direction D. Mirror section 422 faces mirror section 412 with an air gap S between them in the optical axis direction D. Drive electrode 423 is located on surface 421b of substrate layer 421 such that it surrounds mirror section 422 and faces drive electrode 413 with an air gap S between them. Drive electrode 423 is electrically connected to an electrode pad (not shown), for example, via wiring (not shown) provided on substrate layer 421.The electrode pad is provided, for example, in an area of ​​the substrate layer 421 that is accessible from the outside.

[0089] A groove 424 is formed on the surface 421a of the substrate layer 421, surrounding the mirror section 422 and the drive electrode 423 in the viewing direction of the optical axis D. The groove 424 extends in an annular shape. A section of the substrate layer 421 surrounded by the groove 424 is movable in a direction in which the pair of mirror sections 412 and 422 are opposite each other, with a section in which the groove 424 is formed serving as a retaining section 425, which has a membrane shape.

[0090] Additionally, the retaining section 425 can be configured with a membrane shape by forming a groove on the surface 421a and / or the surface 421b of the substrate layer 421, which surrounds the mirror section 422 and the drive electrode 423 in the optical axis direction D. A retaining section with a membrane shape can be formed in the substrate layer 411 by forming a groove in the substrate layer 411 that surrounds the mirror section 412 and the drive electrode 413 in the optical axis direction D. Instead of the retaining section with a membrane shape, the retaining section can be configured as a plurality of radially arranged columns.

[0091] When a potential difference is generated between the drive electrodes 413 and 423 in the Fabry-Perot interference filter 400 by applying a voltage to them, an electrostatic force corresponding to this potential difference is generated between the drive electrodes 413 and 423. Due to the generation of this electrostatic force, the section of the substrate layer 421 surrounded by the groove 424 is drawn to one side of the substrate layer 411, and the distance between the mirror sections 412 and 422 is adjusted. Consequently, light with a wavelength corresponding to the distance between the mirror sections 412 and 422 passes through the Fabry-Perot interference filter 400.

[0092] Even if the Fabry-Perot interference filter 400 is used instead of the Fabry-Perot interference filter 10 in the third modification example, an image can be satisfactorily acquired with the hyperspectral camera 1, similar to the embodiment described above. Additionally, the first aperture P1 in the Fabry-Perot interference filter 400 can also be formed integrally with the Fabry-Perot interference filter 400, for example, by forming a light-shielding layer on the surface 411b of the substrate layer 411, which faces the substrate layer 421. Similar to the embodiment described above, the first aperture P1 can be formed by providing a light-shielding layer in a region of the Fabry-Perot interference filter 400 that is located outside a light transmission area, while the light-shielding layer is not provided in the light transmission area.Alternatively, the first aperture P1 can be formed integrally with the Fabry-Perot interference filter 400 by forming a light-shielding layer on the surface 421a of the substrate layer 421, which is opposite the substrate layer 411. In this case, the first aperture P1 is located on one side opposite the incidence section 21a (side of the emission section 21b) with respect to the mirror sections 412 and 422 of the Fabry-Perot interference filter 400.

[0093] The present disclosure is not limited to the embodiment and modification examples described above. For example, the material and shape of each configuration are not limited to the material and shape described above, and various materials and shapes may be used.

[0094] In the embodiment described above, the Fabry-Perot interference filter 10 is in contact with the support 31; however, the Fabry-Perot interference filter 10 can also be arranged remotely from the support 31. For example, an air gap can be formed between the Fabry-Perot interference filter 10 and the support 31, or a glass element can be arranged between the Fabry-Perot interference filter 10 and the support 31.

[0095] The first aperture P1 can be arranged on the side opposite the incidence section 21a (side of the emission section 21b) with respect to the mirror sections 14 and 15 of the Fabry-Perot interference filter 10. In this case, the light L passing through the Fabry-Perot interference filter 10 passes through the first aperture P1. For example, in the embodiment described above, such an arrangement can be realized by attaching the Fabry-Perot interference filter 10 to the support 31 in a direction opposite to the optical axis direction D.Alternatively, instead of forming the light-shielding layer 135 on the side of the incidence section 21a with respect to the mirror sections 14 and 15 to provide the first aperture P1 in the embodiment described above, the arrangement described above can also be realized by forming the light-shielding layer 135 on the side opposite the incidence section 21a with respect to the mirror sections 14 and 15 (for example, on a surface of the Fabry-Perot interference filter 10 opposite the incidence section 21a) to provide the first aperture P1.

[0096] The second aperture P2 can be located on the side opposite the incident section 21a (side of the emission section 21b) with respect to mirror sections 14 and 15 of the Fabry-Perot interference filter 10. Specifically, the second aperture P2 can be located between the Fabry-Perot interference filter 10 and the imaging lens section 23. In this case, the light L passing through the Fabry-Perot interference filter 10 passes through the second aperture P2. Alternatively, both the first aperture P1 and the second aperture P2 can be located on the side opposite the incident section 21a (side of the incident section 21a) with respect to mirror sections 14 and 15 of the Fabry-Perot interference filter 10.

[0097] The first aperture P1 may also not be integrally formed with the Fabry-Perot interference filter 10. For example, an aperture element in which an opening forming the first aperture P1 is formed may be provided separately from the Fabry-Perot interference filter 10. Viewed in the optical axis direction D, the width of the light L at the point of incidence at the first aperture P1 may be narrower than the width of the first aperture P1. This is because the light L is not necessarily constricted by the first aperture P1. Viewed in the optical axis direction D, the width of the light L at the point of incidence at the second aperture P2 may be narrower than the width of the second aperture P2. This is because the light L is not necessarily constricted by the second aperture P2.

[0098] The Fabry-Perot interference filter 10 need not be fixed to the carrier 31, but can be attached to an element that is separate (formed) from the element in which the second aperture P2 is formed. The second aperture P2 can also be other than an opening 36 formed in the carrier 31; for example, an aperture element in which an opening forming the second aperture P2 is formed can be provided separately from the carrier 31. The diameter (width) of the second aperture P2 can be smaller than the diameter (width) of the first aperture P1. The second aperture P2 can be omitted.

[0099] The imaging lens section 23 may also not contain the magnifying lens section 23a. In this case, the imaging lens section 23 can focus and image the light L that has passed through and expanded from the Fabry-Perot interference filter 10 using the focusing lens section 23b. Viewed in the optical axis direction D, the width of the imaging area R can be narrower than 1.5 times the width of the first aperture P1.

[0100] It is sufficient if at least part of the recess 18 overlaps the first aperture P1 when viewed in the optical axis direction D, and if, when viewed in the optical axis direction D, an outer edge of the recess 18 can lie outside an outer edge of the first aperture P1, or the outer edge of the first aperture P1 can lie outside the outer edge of the recess 18. In the embodiment described above, the light-shielding layer 135 need not extend over the entire surface 13a of the second laminated structure 13, and, viewed in the Z direction, the outer edge of the first aperture P1 can lie outside the outer edge of the recess 18. The recess 18 may also be omitted.

[0101] An optical device other than the lens section 4 may be attached to the first mounting section 21c of the housing 21. An optical device other than the camera unit 5 may be attached to the second mounting section 21d of the housing 21. Reference symbol list

[0102] 1: Hyperspectral camera, 2: Optical unit (optical unit for hyperspectral camera), 4: Lens section (first optical device), 5: Camera unit (second optical device), 10: Fabry-Perot interference filter, 10a: Light transmission area, 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 section, 18: Recess, 21: Housing, 21a: Incident section, 21b: Emission section, 21c: First attachment section, 21d: Second attachment section, 23: Imaging lens section, 23a: Magnifying lens section, 23b: Focusing lens section 26: Reduction optical system (additional optical system), 31: Support / Mount, 36: Aperture, 52: Image receiving element, 400: Fabry-Perot interference filter, 411: Substrate layer (first substrate), 412, 422: Mirror section, 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 area. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2020 - 525 830 A

[0002]

Claims

[1] Optical unit for a hyperspectral camera, comprising: a Fabry-Perot interference filter comprising a pair of mirror sections with a variable distance between them, allowing incident light to pass through according to the distance between the pair of mirror sections; a first aperture through which the light traveling towards the Fabry-Perot interference filter or the light passing through the Fabry-Perot interference filter passes; an imaging lens section that images the light passing through the Fabry-Perot interference filter and the first aperture; and a housing that accommodates the Fabry-Perot interference filter, the first aperture and the imaging lens section, and includes an incidence section for the light incident on the Fabry-Perot interference filter, where, viewed in an optical axis direction, the width of an imaging area of ​​the light shaped by the imaging lens section is greater than the width of the first aperture. [2] Optical unit for a hyperspectral camera according to claim 1, wherein the first aperture is formed integrally with the Fabry-Perot interference filter. [3] Optical unit for a hyperspectral camera according to claim 1 or 2, wherein the imaging lens section comprises a magnifying lens section which widens the width of the light and a focusing lens section which focuses the light from the magnifying lens section. [4] Optical unit for a hyperspectral camera according to one of claims 1 to 3, further comprising: a second aperture through which the light traveling towards the Fabry-Perot interference filter or the light passing through the Fabry-Perot interference filter passes, wherein the imaging lens section images the light that has passed through the Fabry-Perot interference filter, the first aperture and the second aperture. [5] Optical unit for a hyperspectral camera according to claim 4, wherein the second aperture is designed as an opening formed in a carrier, and The Fabry-Perot interference filter is fixed to the support. [6] Optical unit for a hyperspectral camera according to claim 4 or 5, wherein the second aperture is arranged between the incident section and the Fabry-Perot interference filter. [7] Optical unit for a hyperspectral camera according to one of claims 1 to 6, wherein, viewed in the optical axis direction, the width of the imaging area is at least 1.5 times greater than the width of the first aperture. [8] Optical unit for a hyperspectral camera according to one of claims 1 to 7, further comprising: an additional optical system that is positioned between the incident section and the Fabry-Perot interference filter and that reduces the width of the light. [9] Optical unit for a hyperspectral camera according to any one of claims 1 to 7, further comprising: an additional optical system that is positioned between the incidence section and the Fabry-Perot interference filter and collimates the light. [10] Optical unit for a hyperspectral camera according to claim 9, wherein the additional optical system reduces a width of the light. [11] Optical unit for a hyperspectral camera according to one of claims 1 to 10, wherein the housing further comprises an emission section from which the light from the imaging lens section is emitted. [12] Optical unit for a hyperspectral camera according to claim 11, wherein the housing further comprises a first mounting section provided on a side where the incident section is located in relation to the emission section, and to which a first optical device is detachably attached, and a second mounting section provided on a side where the emission section is located in relation to the incident section, and to which a second optical device is detachably attached. [13] Optical unit for a hyperspectral camera according to one of claims 1 to 12, further comprising: an image capture element that is located inside the housing and captures light from the imaging lens section. [14] Optical unit for a hyperspectral camera according to any one of claims 1 to 13, wherein the Fabry-Perot interference filter comprises a substrate with a first surface and a second surface opposite the first surface and a first laminated structure arranged on the first surface, and the first laminated structure comprises a first laminate arranged on the first surface and comprising one of the pair of mirror sections, and a second laminate arranged on one side opposite the substrate with respect to the first laminate and comprising the other of the pair of mirror sections. [15] Optical unit for a hyperspectral camera according to claim 14, wherein the Fabry-Perot interference filter further comprises a second laminated structure arranged on the second surface of the substrate, a depression is formed on a surface of the second laminated structure opposite the substrate, and At least part of the recess overlaps the first aperture when viewed in the direction of the optical axis. [16] Optical unit for a hyperspectral camera according to one of claims 1 to 13, wherein the Fabry-Perot interference filter comprises a first substrate with a first surface, a second substrate with a second surface opposite the first surface, one of the pair of mirror sections being formed on the first surface and the other of the pair of mirror sections being formed on the second surface. [17] Optical unit for a hyperspectral camera according to one of claims 1 to 16, wherein the first aperture is formed by providing a light-shielding layer in a region of the Fabry-Perot interference filter that is distinct from a light transmission region, while the light-shielding layer is not provided in the light transmission region. [18] Hyperspectral camera which features: the optical unit for a hyperspectral camera according to any one of claims 1 to 17; and a camera unit which has an image capture element that captures the light emitted from the housing and which is attached to the housing.

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