CN219996346U - Modulation structure, detector and infrared spectrometer for infrared hyperspectral imaging - Google Patents
Modulation structure, detector and infrared spectrometer for infrared hyperspectral imaging Download PDFInfo
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- PFNQVRZLDWYSCW-UHFFFAOYSA-N (fluoren-9-ylideneamino) n-naphthalen-1-ylcarbamate Chemical compound C12=CC=CC=C2C2=CC=CC=C2C1=NOC(=O)NC1=CC=CC2=CC=CC=C12 PFNQVRZLDWYSCW-UHFFFAOYSA-N 0.000 claims description 3
- 239000005083 Zinc sulfide Substances 0.000 claims description 3
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- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 3
- 229910001634 calcium fluoride Inorganic materials 0.000 claims description 3
- XASAPYQVQBKMIN-UHFFFAOYSA-K ytterbium(iii) fluoride Chemical compound F[Yb](F)F XASAPYQVQBKMIN-UHFFFAOYSA-K 0.000 claims description 3
- DRDVZXDWVBGGMH-UHFFFAOYSA-N zinc;sulfide Chemical compound [S-2].[Zn+2] DRDVZXDWVBGGMH-UHFFFAOYSA-N 0.000 claims description 3
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Abstract
The utility model discloses a modulation structure, a detector and an infrared spectrometer for infrared hyperspectral imaging, and belongs to the technical field of infrared hyperspectral imaging. The modulation structure includes: a detector window encapsulation layer; the infrared antireflection film is arranged on the surface of one side, facing the pixel array, of the detector window packaging layer, and the refractive index of the material of the infrared antireflection film is smaller than that of the material of the detector window packaging layer; the micro-structure modulation units are arranged on the surface of one side of the infrared antireflection film, which is away from the detector window packaging layer, according to a preset arrangement rule, so that partial areas of the surface of one side of the infrared antireflection film, which is away from the detector window packaging layer, are empty to form at least one empty modulation unit. According to the utility model, through the infrared antireflection film and the blank design, the luminous flux of the spectrum modulation unit of the micro-nano structure is improved, and a higher signal-to-noise ratio can be realized.
Description
Technical Field
The utility model relates to the technical field of infrared hyperspectral imaging, in particular to a modulation structure, a detector and an infrared spectrometer for infrared hyperspectral imaging.
Background
In the related technology of hyperspectral imaging, a micro-nano modulation structure (such as a micro-nano round hole structure formed by etching a silicon flat plate) made of a high refractive index material can be utilized to carry out spectrum dimension modulation on incident light, and a calculation optical method is combined for snapshot to obtain a spectrum image.
In the long-wave infrared band, the micro-structure occupies a limited area due to the small number of infrared detector pixels, so that the space occupation ratio of the micro-nano modulation structure can be increased for improving the modulation effect. However, increasing the space duty ratio results in the micro-nano modulation structure having the characteristics of high reflectivity and low light transmittance, and further results in higher signal-to-noise ratio after imaging.
Disclosure of Invention
The utility model mainly aims to provide a modulation structure, a detector and an infrared spectrometer for infrared hyperspectral imaging, and aims to solve the technical problem that the signal to noise ratio is low after hyperspectral imaging due to a spectrum modulation structure in the prior art.
To achieve the above object, the present utility model proposes a modulation structure for infrared hyperspectral imaging, comprising:
a detector window encapsulation layer;
the infrared antireflection film is arranged on the surface of one side of the detector window packaging layer facing the pixel, and the refractive index of the material of the infrared antireflection film is smaller than that of the material of the detector window packaging layer; and
the micro-structure modulation units are arranged on the surface of one side of the infrared antireflection film, which is away from the detector window packaging layer, according to a preset arrangement rule, so that partial areas of the surface of one side of the infrared antireflection film, which is away from the detector window packaging layer, are empty to form at least one air-leaving modulation unit.
In a possible embodiment of the present utility model, the preset arrangement rule includes at least one of the following:
the microstructure modulation unit is adjacent to the at least one space modulation unit;
at most two space modulation units are arranged between two adjacent microstructure modulation units in a first direction or a second direction of the pixel array, and the first direction is perpendicular to the second direction;
the structures of any two of all microstructure modulation units adjacent to each space modulation unit are different from each other.
In a possible embodiment of the utility model, the microstructure-modulating units and the air-gap-modulating units are arranged alternately with each other in the first direction, and the microstructure-modulating units and the air-gap-modulating units are arranged alternately with each other in the second direction.
In one possible embodiment of the present utility model, the infrared antireflection film includes at least two transparent film layers that are sequentially stacked, and the refractive indices of the plurality of transparent film layers gradually decrease in a direction away from the detector window encapsulation layer.
In one possible embodiment of the present utility model, the transparent film layer is made of ZnS zinc sulfide, znSe zinc selenide, baF 2 Barium fluoride, caF 2 Calcium fluoride, ybF 3 Ytterbium fluoride, ge germanium or Si silicon.
In one possible embodiment of the utility model, the microstructure modulating unit comprises a plurality of micro-nano structure subunits arranged in a rectangular array, and the plurality of micro-nano structure subunits are spaced apart from each other.
In a possible embodiment of the present utility model, the micro-nano structural subunit is configured as a columnar structure protruding from the infrared antireflection film, and the columnar structure is made of an infrared high refractive index material; or (b)
An infrared high-refractive-index medium layer is arranged on the surface of one side of the infrared antireflection film, which is far away from the detector window packaging layer, and the micro-nano structure subunit is constructed into a hole-shaped structure penetrating through the infrared high-refractive-index medium layer along the thickness direction of the detector window packaging layer.
In one possible embodiment of the utility model, the cross-sectional shape of the micro-nano-structured subunit is configured as a rotationally symmetrical pattern with a rotation angle of 90 °.
In one possible embodiment of the present utility model, the side length of the pixels in the pixel array is n, n is less than or equal to 17 μm, the number of micro-nano structural subunits in the third direction of the rectangular array is m1, and the number of micro-nano structural subunits in the fourth direction of the rectangular array is m2, where m1 and m2 satisfy: m1 is less than or equal to 10 and m2 is less than or equal to 10; wherein the third direction is perpendicular to the fourth direction.
In one possible embodiment of the utility model, the height of the micronano-structure subunits is H, H > 5 μm.
In a second aspect, the present utility model also provides a detector comprising:
an image sensor comprising an array of picture elements; and
the modulation structure for infrared hyperspectral imaging according to the first aspect, the modulation structure is disposed on one side of the pixel array, and the microstructure modulation unit of the modulation structure and the pixel array are disposed opposite to each other.
In a third aspect, the present utility model also provides an infrared spectrometer comprising:
a detector as provided in the second aspect; and
and the image signal processor is connected with the detector.
According to the technical scheme, the infrared antireflection film is added on the detector window packaging layer, and the plurality of microstructure modulation units are arranged on the infrared antireflection film according to the preset arrangement rule, so that at least one air-reserving modulation unit is formed in a part of the area on the surface of the infrared antireflection film in a vacant manner. The microstructure modulation unit and the space modulation unit together form a spectrum modulation structure of the detector. Therefore, the embodiment of the utility model reduces the use area of the micro-nano structure in the detector window through the anti-reflection capability provided by the infrared anti-reflection film on the one hand and the unstructured air-gap modulation unit on the other hand, improves the phenomenon of transmittance reduction caused by microstructure reflection, and thus jointly improves the signal-to-noise ratio after hyperspectral imaging.
Drawings
In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present utility model, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a modulation structure for infrared hyperspectral imaging according to an embodiment of the present utility model;
FIG. 2 is a schematic diagram showing a spectral modulation structure distribution of an embodiment of a modulation structure for infrared hyperspectral imaging according to the present utility model;
FIG. 3 is a schematic diagram of a modulation structure for infrared hyperspectral imaging according to another embodiment of the present utility model, wherein the infrared antireflection film has a double-layer structure;
FIG. 4 is a schematic structural diagram of another embodiment of a modulation structure for infrared hyperspectral imaging according to the present utility model, wherein the infrared antireflection film has a three-layer structure;
FIG. 5 is a schematic diagram of a modulation structure for infrared hyperspectral imaging according to an embodiment of the present utility model, wherein the micro-nano-structure subunit is a hole-like structure;
FIG. 6 is a schematic illustration of the anti-reflection effect of example 1;
fig. 7 is a graph comparing modulation curves of 5 microstructure modulation units 21 and 4 space modulation units 22 of example 1;
FIG. 8 is a graph of average light transmission versus average light transmission for a spectrum modulation unit of example 1 versus an existing microstructure modulation unit (e.g., micro-nano-holes) on a S i window;
FIG. 9 is 9 spectral modulation graphs generated by the 9 spectral modulation units of example 1;
fig. 10 is a schematic diagram showing the arrangement of a microstructure modulating unit and a space-saving modulating unit according to example 2 of the present utility model.
Reference numerals illustrate:
the achievement of the objects, functional features and advantages of the present utility model will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
The following description of the embodiments of the present utility model will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
It should be noted that all directional indicators (such as up, down, left, right, front, and rear … …) in the embodiments of the present utility model are merely used to explain the relative positional relationship, movement, etc. between the components in a particular posture (as shown in the drawings), and if the particular posture is changed, the directional indicator is changed accordingly.
In the present utility model, unless specifically stated and limited otherwise, the terms "connected," "affixed," and the like are to be construed broadly, and for example, "affixed" may be a fixed connection, a removable connection, or an integral body; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.
In addition, if there is a description of "first", "second", etc. in the embodiments of the present utility model, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and/or" as it appears throughout includes three parallel schemes, for example "A and/or B", including the A scheme, or the B scheme, or the scheme where A and B are satisfied simultaneously. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present utility model.
The hyperspectral imaging can simultaneously acquire the spatial distribution of objects and higher spectral resolution information, and has wide application in the fields of material identification, environmental monitoring, chemical industry, food safety and the like. The traditional hyperspectral imaging scheme adopts a single-point spectrometer and an additional mechanical device to carry out space scanning imaging, but the device is large in size and long in time consumption for acquiring a spectral image. In the related art, a micro-nano modulation structure (such as a micro-nano round hole structure formed by etching a silicon flat plate) made of a high refractive index material can be used for carrying out spectrum dimension modulation on incident light, and a calculated optical method is combined for carrying out snapshot to obtain a spectrum image.
In order to obtain the high-spectrum resolution image, the spectrum modulation of the micro-nano modulation structure needs to meet the conditions of large whole spectrum modulation amplitude, large number of modulation peaks, narrow peak width and the like, and the conditions further need to be realized by using high-refractive index materials of corresponding wave bands. However, due to the visible light loss and high reflection characteristics of the silicon Si material, the modulation light flux of micro-nano modulation structures such as micro-nano round hole structures formed by etching a silicon flat plate is low (often less than 50%), so that the signal to noise ratio is poor.
Particularly, in the long-wave infrared band with the wavelength of 8-14um, the infrared detector is usually photo-thermal type, has large noise, and has weak signal of an object to be detected, so that the signal-to-noise ratio is lower compared with the visible light band technology. Although germanium Ge, si and other materials have no light loss in a long-wave infrared band, the micro-nano modulation structure occupies a limited area due to the small number of pixels of the infrared detector, so that the space occupation ratio of the micro-nano modulation structure has to be increased to improve the modulation effect, high reflection and low light transmittance of the micro-nano modulation structure of the Ge, si and other materials are caused, and further the signal to noise ratio after imaging is higher.
Therefore, the embodiment of the utility model provides a modulation structure for infrared hyperspectral imaging, which is characterized in that an infrared antireflection film is added on a detector packaging layer, and a plurality of microstructure modulation units are arranged on the infrared antireflection film according to a preset arrangement rule so as to form at least one air-gap modulation unit in a part of the area on the surface of the infrared antireflection film in a vacant manner. The microstructure modulation unit and the space modulation unit together form a spectrum modulation structure of the detector. Therefore, the embodiment of the utility model reduces the use area of the micro-nano structure in the detector window through the anti-reflection capability provided by the infrared anti-reflection film on the one hand and the unstructured air-gap modulation unit on the other hand, improves the phenomenon of transmittance reduction caused by microstructure reflection, and thus jointly improves the signal-to-noise ratio after hyperspectral imaging.
The concepts of the embodiments of the present utility model are specifically described below in connection with some specific embodiments.
The embodiment of the utility model provides a modulation structure for infrared hyperspectral imaging.
It can be understood that the modulation structure of the infrared hyperspectral imaging is opposite to the pixel array 30 on the image sensor, and is used for performing spectral modulation on the incident light, and the pixel array 30 on the image sensor outputs a detection signal after receiving the modulated spectral signal.
Referring to fig. 1, in the present embodiment, a modulation structure for infrared hyperspectral imaging includes a detector window packaging layer 10, an infrared antireflection film 40, and a plurality of microstructure modulation units 21.
The infrared antireflection film 40 is disposed on a surface of the detector window packaging layer 10 facing the pixel array 30, and a refractive index of a material of the infrared antireflection film 40 is smaller than a refractive index of a material of the detector window packaging layer 10; the plurality of microstructure modulating units 21 are arranged on the surface of one side of the infrared antireflection film 40, which is away from the detector window packaging layer 10, according to a preset arrangement rule, so that a partial area of the surface of one side of the infrared antireflection film 40, which is away from the detector window packaging layer 10, is empty to form at least one air-conditioning unit 22.
Specifically, the detector has a seal cover plate, and the plate body of the seal cover plate has an infrared window region that is transparent to infrared light, i.e., the detector window sealing layer 10 in this embodiment. The detector window package layer 10 and the pixel array 30 are disposed opposite each other such that infrared light transmitted through the infrared window area is received by the pixel array 30. Wherein the detector window package layer 10 is made of germanium Ge or silicon Si.
An infrared antireflection film 40 is provided on a side surface of the detector window encapsulation layer 10 facing the pixel array 30. The surface of the side of the infrared anti-reflection film 40 facing away from the detector window encapsulation layer 10 is divided into at least 4 sub-areas arranged in a rectangular array. Of course, in the imaging field, rectangular arrays are generally constructed as square arrays with equal numbers of rows and columns, so that each sub-area is square. For example, the surface of the infrared reflection reducing film 40 is divided into 9 sub-areas arranged in a 3×3 arrangement, or into 16 sub-areas of 4×4.
The plurality of spectrum modulation structures 20 of the embodiment are arranged on the surface of one side of the infrared antireflection film 40, which is far away from the detector window packaging layer 10, wherein the number of spectrum modulation structures 20 is equal to the number of subareas. If the surface of the infrared anti-reflection film 40 is divided into 9 sub-areas arranged in a 3×3 manner, there are a total of 9 spectrum modulation structures 20, so that the spectrum modulation structures 20 and the pixels are in one-to-one correspondence. It is particularly noted that in the present embodiment, the spectrum modulation structure 20 includes a microstructure modulation unit 21 and a space modulation unit 22 formed by being left empty. Each microstructure-modulating unit 21 is arranged convexly on a sub-region, the interior of which supports a waveguide mode for spectral modulation. Whereas for part of the sub-areas there is no structural distribution on it and in the same height space as the microstructure-modulating elements 21, so that a unstructured space-saving modulating element 22 is formed.
It will be appreciated that, due to the smaller size of the picture elements 30 of the detector, e.g. 17 μm of the picture elements 30 corresponding to only 1-2 infrared band wavelengths, the number of microstructure-modulating elements 21 is limited, so that the edge scattering intensity of the microstructure-modulating elements 21 is larger, so that the space-saving modulating elements 22 also have spectral modulation capability under the scattering effect of the surrounding microstructure-modulating elements 21.
Compared with the existing densely arranged micro-nano structure modulation units, the empty modulation units 22 without structures in the embodiment reduce the use area of the micro-nano structure in the detector window, improve the problem of transmittance reduction caused by reflection of the micro-nano structure, namely improve the luminous flux of the spectrum modulation units of the micro-nano structure, and further improve the signal to noise ratio after hyperspectral imaging.
In addition, the refractive index of the material of the infrared anti-reflection film 40 is smaller than that of the material of the detector window encapsulation layer 10, so that a graded distribution of high refractive index material-low refractive index material-air is formed in the direction from the detector window encapsulation layer 10 to the picture element 30. It will be appreciated that when light enters one medium from the other, if the refractive index difference of the two media decreases, the energy of the reflected light decreases and the energy of the transmitted light increases. Thus, in this embodiment, when infrared light penetrates through the graded refractive index distribution area, the transmittance can be improved, and further, in this embodiment, the use area of the micro-nano structure in the detector window is reduced by combining the air-gap modulation unit, and the anti-reflection capability provided by the infrared anti-reflection film, so that the problem of transmittance reduction caused by reflection of the micro-nano structure is jointly improved, and the signal-to-noise ratio after hyperspectral imaging is jointly improved.
In addition, in this embodiment, the transmittance of the infrared band is improved through the infrared antireflection film 40, and the throughput of the spectrum modulation structure 20 of the infrared band, which is disposed on the surface of the side of the infrared antireflection film 40 facing the pixel 30, is improved, so that the light flux of the microstructure modulation unit 21 is more, and the scattering effect of the microstructure modulation unit 21 is stronger, thereby improving the spectrum modulation capability of the air-leaving modulation unit 22, further improving the signal-to-noise ratio after hyperspectral imaging, and improving the spectrum reconstruction precision.
In a possible embodiment of the present utility model, the preset configuration rule includes at least one of the following:
(1) The microstructure modulation unit 21 is adjacent to at least one space modulation unit 22;
(2) At most two space modulation units 22 are arranged between two adjacent microstructure modulation units 21 in a first direction or a second direction of the pixel array 30, and the first direction is perpendicular to the second direction;
(3) The structures of any two of all the microstructure-modulating units 21 adjacent to each space-saving modulating unit 22 are different from each other.
The pixel array 30 is arranged in a matrix, where the first direction may be a row direction of the pixel array 30 and the second direction may be a column direction of the pixel array 30. Alternatively, the first direction may be a column direction of the pixel array 30 and the second direction may be a row direction of the pixel array 30. In this embodiment, the microstructure-modulating units 21 are arranged according to the above-mentioned preset arrangement rule, so that the microstructure-modulating units 21 and the space-saving modulating units 22 form a mosaic arrangement required for spectrum reconstruction.
In the formed mosaic arrangement, each microstructure-modulating unit 21 has at least one space-saving modulating unit 22 around it. As in the first direction, the microstructure-modulating unit 21 may have two spectral-modulating structures 20 located on different sides, and in the second direction, the microstructure-modulating unit 21 may also have two spectral-modulating structures 20 located on different sides, and in either of the two diagonal directions, the microstructure-modulating unit 21 may also have two spectral-modulating structures 20 located on different sides. And at least one space modulation unit 22 is included in the above-described total of 8 adjacent spectrum modulation structures 20.
Since the spectral modulation capability of the space modulation unit 22 is provided by the surrounding microstructure modulation units 21 in the first direction or the second direction, the consecutive space modulation units 22 have a maximum of 2 in order to avoid affecting the spectral modulation capability of the space modulation unit 22.
In addition, in all microstructure modulation units 21 adjacent to the empty modulation unit 22 without structure, the structures of any two are different from each other, so that the modulation curves of the plurality of spectrum modulation structures 20 are different from each other, and the difference is larger, thereby ensuring that the spectrum reconstruction precision is higher after the spectrum is reconstructed through an algorithm.
Of course, it is preferable that the microstructure-modulating units 21 are arranged according to all of the above preset arrangement rules.
In a possible embodiment of the utility model, the microstructure-modulating units 21 and the space-saving modulating units 22 are arranged alternately with each other in the first direction, and the microstructure-modulating units 21 and the space-saving modulating units 22 are arranged alternately with each other in the second direction.
Specifically, on any one row of the rectangular array formed by at least 4 sub-areas, the microstructure-modulating units 21 and the space-saving modulating units 22 are alternately arranged with each other, and on any one column of the rectangular array formed by at least 4 sub-areas, the microstructure-modulating units 21 and the space-saving modulating units 22 are alternately arranged with each other.
Referring to fig. 2, for a rectangular array with 3×3 arrangement, microstructure modulating units 21 are disposed on the upper left corner sub-area, the upper right corner sub-area, the middle sub-area, the lower left corner sub-area and the lower right corner sub-area, and the remaining sub-areas are air gap modulating units 22.
In this embodiment, the microstructure modulating units 21 and the space-saving modulating units 22 are alternately arranged, so that the microstructure modulating units 21 with the edge scattering capability are distributed more uniformly around the space-saving modulating units 22, and the space-saving modulating units 22 have stronger spectrum modulation intensity.
In a possible embodiment of the present utility model, the ir-antireflection film 40 includes at least two transparent film layers sequentially stacked, and the refractive indexes of the plurality of transparent film layers gradually decrease along the direction away from the detector window packaging layer 10.
In this embodiment, the infrared antireflection film 40 includes at least two transparent film layers that are sequentially stacked, and the refractive index gradually decreases along the direction away from the detector window packaging layer 10, so as to further reduce the refractive index difference between two adjacent transparent film layers on the propagation path of the infrared band after entering from the detector window, improve the transmittance between the adjacent transparent film layers, and further improve the transmittance of the whole graded refractive index distribution area.
It will be appreciated that the specific thickness of each transparent film layer depends on the wavelength of the infrared band and the refractive index of the infrared band in each transparent film layer. In this embodiment, the transparent film layer is made of ZnS zinc sulfide, znSe zinc selenide, or BaF 2 Barium fluoride, caF 2 Calcium fluoride, ybF 3 Ytterbium fluoride, ge germanium or Si silicon. Wherein ZnS and ZnSe have refractive indices between 2 and 3, whereas BaF 2 、CaF 2 And YbF 3 The refractive index of (2) is 1-3, the refractive index of Si is more than 3, and the refractive index of Ge is more than 4.
As an example, referring to fig. 3, the material of the detector window packaging layer 10 is Si, and the infrared anti-reflection film 40 is a double-layer transparent film, and includes a ZnS transparent film 41 disposed on the detector window packaging layer 10, and a BaF transparent film 42 disposed on a side of the ZnS transparent film 41 facing away from the detector window packaging layer 10. Thus, for the ZnS transparent film layer 41, the thickness thereof is h1,0.5 μm.ltoreq.h1.ltoreq.1.5 μm; the thickness of the BaF2 transparent film 42 is h2, and h2 is less than or equal to 1 μm and less than or equal to 2 μm.
As another example, referring to fig. 4, the material of the detector window packaging layer 10 is germanium Ge, and the infrared antireflection film 40 is designed with three layers of antireflection films, including a Si-Si transparent film layer 43 disposed on the detector window packaging layer 10, a Si-transparent film layer 41 disposed on a side of the Si-transparent film layer 43 facing away from the detector window packaging layer 10, and a BaF disposed on a side of the ZnS transparent film layer 41 facing away from the S i transparent film layer 43 2 A transparent film layer 42. The thickness of the Si transparent film layer 43 is h3, and h3 is more than or equal to 0.1 μm and less than or equal to 1 μm; for the ZnS transparent film layer 41, the thickness is h1, and h1 is more than or equal to 0.5 μm and less than or equal to 1.5 μm; for BaF 2 The transparent film 42 has a thickness h2 of 0.8 μm.ltoreq.h2.ltoreq.2μm.
In a possible embodiment of the present utility model, referring to fig. 2 and 10, the microstructure modulating unit 21 includes a plurality of micro-nano structure sub-units 211 arranged in a rectangular array, and the plurality of micro-nano structure sub-units are spaced apart from each other.
At this time, among all the microstructure-modulating units 21 adjacent to each of the space-saving modulating units 22, the microstructure of the microstructure-modulating unit 21 includes at least one of the shape of the micro-nano-structure sub-unit 211, the arrangement period of the micro-nano-structure sub-unit 211, or the number of the micro-nano-structure sub-units 211, among the structures of any two of them being different from each other.
Specifically, any microstructure-modulating element 21 has a structure that affects the spectral-modulating capability of the microstructure-modulating element 21 when at least the following parameters are changed:
1) The shape of micro-nano structured subunit 211. Shape parameters of micro-nano-structure subunits 211 include, but are not limited to, a height dimension, a cross-sectional shape, or a cross-sectional dimension of each micro-nano-structure subunit 211. The cross section is a region obtained by cutting the micro-nano structure subunit 211 by a plane parallel to the plane of the detector window packaging layer 10.
2) The arrangement period of the micro-nano structure subunit 211. It is understood that the plurality of micro-nano structure sub-units 211 are also arranged in a rectangular array, and in this case, the arrangement period of the micro-nano structure sub-units 211 is the distance between the axes of adjacent micro-nano structure sub-units 211 in the row direction and the column direction of the rectangular array.
3) Number of micro-nano structured subunits 211. The number of micro-nano-structure subunits 211 determines the overall arrangement of the array of micro-nano-structure subunits 211. Such as the same shape micro-nano-structure sub-unit 211, which is arranged in a 2 x 2 arrangement in one sub-area, but in a 3 x 3 arrangement in another sub-area.
Of course, in order to make the spectrum modulation capability of the microstructure modulating units 21 around each of the space modulation units 22 differ greatly to facilitate the subsequent spectrum reconstruction, the shape of the micro-nano structure sub-units 211, the arrangement period of the micro-nano structure sub-units 211, and the number of the micro-nano structure sub-units 211 of the microstructure modulating units 21 around each of the space modulation units 22 are all different.
In a possible embodiment of the present utility model, the micro-nano structure subunit 211 is configured as a columnar structure protruding from the ir-antireflection film, and the columnar structure is made of an ir-high refractive index material.
Alternatively, the surface of the side of the infrared antireflection film 40 facing away from the detector window packaging layer 10 is provided with an infrared high refractive index dielectric layer 212, and the micro-nano structure subunit 211 is configured as a hole-like structure 213 penetrating through the infrared high refractive index dielectric layer 212 along the thickness direction of the detector window packaging layer 10.
Specifically, the micro-nano structure subunit 211 may alternatively be configured as a micro-nano dielectric pillar formed from an infrared high refractive index material, the micro-nano dielectric pillar extending in a direction away from the detector window encapsulation layer 10 to protrude from the infrared anti-reflection film 40. Waveguide modes for spectral modulation are supported within each micro-nano dielectric pillar.
Alternatively, referring to fig. 5, an infrared high refractive index dielectric layer 212 formed of an infrared high refractive index material is disposed on a side of the sub-region corresponding to the microstructure modulating elements 21 facing away from the detector window packaging layer 10. At this time, the infrared high refractive index dielectric layer 212 is provided with a hole structure 213 penetrating the infrared high refractive index dielectric layer 212 in the thickness direction of the detector window package layer 10. It is worth mentioning that the infrared high refractive index material is Ge or Si.
The micro-nano-structure subunits 211 have a height H, H > 5 μm such that each micro-nano-structure subunit 211 internally supports a plurality of waveguide modes for spectral modulation.
In a possible embodiment of the present utility model, in order to ensure high transmittance of the micro-nano structure subunit 211, the spectral modulation of the micro-nano structure subunit 211 should have polarization independence, and in this case, the cross-sectional shape of the micro-nano structure subunit 211 is configured as a rotationally symmetrical pattern with a rotation angle of 90 °, such as a square, a circle, etc.
In a possible embodiment of the present utility model, the side length of the pixel is n, the number of micro-nano structural sub-units in the third direction of the rectangular array is m1, and the number of micro-nano structural sub-units in the fourth direction of the rectangular array is m2, and m1 and m2 satisfy: m1 is less than or equal to 10 and m2 is less than or equal to 10; wherein the third direction is perpendicular to the fourth direction.
Wherein the third direction may be a row extension direction of the rectangular array and the fourth direction may be a column extension direction of the rectangular array. Alternatively, the third direction may be a column extending direction of the rectangular array, and the fourth direction may be a row extending direction of the rectangular array. Further, the third direction may be parallel to the first direction, and at this time, the fourth direction may be parallel to the second direction.
Specifically, for the pixel size generally below 17 μm, so the side length of the sub-region is also below 17 μm, and 17 μm corresponds to only 1-2 wavelengths, at this time, the number of the micro-nano structure sub-units 211 that can be arranged in the sub-region is limited, so as to further improve the edge scattering of the micro-nano structure sub-units 211, thereby ensuring the spectrum modulation capability of the space modulation unit 22, and the specification of the micro-nano structure sub-units 211 in the sub-region is less than 10×10.
In this embodiment, when the specification of the micro-nano structure subunit 211 in the sub-area is smaller than 10×10, the spectrum modulation capability of the space modulation unit 22 can be equivalent to that of the micro-structure modulation unit 21.
It will be appreciated that m picture elements in the array of picture elements form a macro-pixel, each macro-pixel corresponding to m spectral modulation structures 20. The m spectrum modulation structures 20 comprise n spectrum channels in total, and the incidence spectrum of the region is phi. At this time, the energy value I received by the macro pixel 1 ,I 2 ,…I m Satisfying the underdetermined equation.
The underdetermined equation is:
wherein M is m Is a high transmittance modulation profile for the mth spectral modulation structure 20. Of course, if the required spectrum channel number is more, i.e. n is more than or equal to m, the compressive sensing algorithm can be utilized to solve the above-mentioned underdetermined equation to obtain the incident spectrum phi at the macro-pixel position, and the whole infrared spectrogram image can be obtained by solving the macro-pixel by macro-pixel.
For a better understanding of the scope of the present claims. The following description is made by way of specific examples in specific application scenarios, and it is to be understood that the following examples are only for explaining the present utility model and are not intended to limit the scope of the claims.
Example 1: referring to fig. 1 and 3, the detector window package layer 10 is a Si window, a dual-layer anti-reflection film is adopted on the Si window, and a first transparent film layer close to the Si window is a ZnS transparent film layer 41, and the thickness is 0.88um. The second transparent film layer arranged on the ZnS transparent film layer 41 and deviating from the Si window is BaF 2 The transparent film 42 has a thickness of 1.26um. BaF (Baf) 2 The transparent film layer contains 3×3 spectrum modulation structures 30, and the specification of each subarea is 17um×17um. The left upper corner subarea, the right upper corner subarea, the middle subarea, the left lower corner subarea and the right lower corner subarea are provided with a microstructure modulation unit 21, and the rest 4 subareas are blank modulation units 22.
The micro-nano-structure sub-units 211 are Ge cylinders arranged periodically. Wherein, the arrangement period of the Ge cylindrical array in 5 subareas is between 2.5 and 8um, the cylindrical duty ratio is between 0.2 and 0.8, and the height is between 5 and 30 um. The arrangement period of Ge cylinders in the upper left corner sub-area is 3um, the duty ratio of the cylinders is 0.45, and the height is 20um; the arrangement period of Ge cylinders in the right upper corner subarea is 4um, the duty ratio of the cylinders is 0.45, and the height is 20um; the arrangement period of Ge cylinders in the middle subarea is 5.5um, the duty ratio of the cylinders is 0.5, and the height is 20um; the arrangement period of Ge cylinders in the lower left subarea is 6.5um, the duty ratio of the cylinders is 0.55, and the height is 20um; the arrangement period of the Ge cylinders in the right lower corner subarea is 7.5um, the duty ratio of the cylinders is 0.55, and the height is 20um.
As shown in fig. 6, the Si window was used as a comparative example, the Si window had a single-sided transmittance of about 70%, and the double-sided transmittance was reduced to less than 50%, and the transmittance was severely reduced. In the example, the average value of the single-sided transmittance wavelength of the Si window can reach more than 98%, and the anti-reflection effect is obvious.
Fig. 7 is a graph comparing modulation curves of 5 microstructure modulating units 21 and 4 space-saving modulating units 22, and the modulation curve of the space-saving modulating unit 22 has stronger modulation intensity, more modulation peak numbers and narrower peak widths due to edge scattering of the microstructure modulating units 21, which is similar to the modulation curve characteristics of the microstructure modulating units 21.
Fig. 8 is a graph comparing the average light transmission of the present example spectrum modulation unit with the average light transmission of the existing microstructure modulation unit (e.g., micro-nano holes) on the Si window, and the light transmission of the present example is increased from 48% to 82% on average, so that the reconstruction spectrum signal-to-noise ratio is expected to be increased by 71%.
Fig. 9 is a spectrum reconstruction result of a series of gaussian spectra of different bandwidths in the range of 8-14um, from 9 spectral modulation curves generated by 9 spectral modulation units of the present example. In the figure, the solid line is the true spectrum and the broken line is the reconstructed spectrum. The gaussian spectral bandwidths of the series from left to right are 400nm, 300nm and 200nm respectively, wherein the gaussian spectral reconstruction effect with the bandwidth as narrow as 300nm (about 2.7% lambda) is still better. It can be seen that the high luminous flux spectral modulation curve of the present example can maintain a high reconstructed spectral resolution.
Example 2: referring to fig. 4 and 10, the detector window packaging layer 10 is a Ge window, a three-layer anti-reflection film design is adopted on the Ge window, and a first transparent film layer close to the Ge window is a Si transparent film layer 43, and the thickness is between 0.1 μm and 1 μm. The second transparent film layer which is arranged on the Si transparent film layer and is far away from the Ge window is a ZnS transparent film layer 41, and the thickness is between 0.5 and 1.5 mu m. The third transparent film layer arranged on the ZnS transparent film layer 41 and away from the Si transparent film layer 43 is BaF 2 The transparent film 42 has a thickness of between 0.8 and 2um.
BaF 2 The transparent film 42 contains 4×4 spectrum modulation structures 30, and each sub-region has a specification of 12×12um. Wherein, from left to right, each of the spectrum modulation units in the first column and the fourth column is a microstructure modulation unit 21, and each of the spectrum modulation units in the second column and the third column is a space modulation unit 22.
The 8 spectrally modulated micro-nano-structure subunits 211 are periodically arranged Si cylinders. Wherein, the arrangement period of the Si cylindrical array is between 3 and 10um, the cylindrical duty ratio is between 0.2 and 0.8, and the height is between 5 and 30 um.
In a second aspect, an embodiment of the present utility model further provides a detector, including: an image sensor and a modulation structure for infrared hyperspectral imaging. The image sensor comprises a pixel array, a modulation structure is arranged on one side of the pixel array, and a microstructure modulation unit of the modulation structure is arranged opposite to the pixel array.
The specific structure of the modulation structure for infrared hyperspectral imaging in this embodiment refers to the above embodiment, and since the detector adopts all the technical solutions of all the embodiments, at least has all the beneficial effects brought by the technical solutions of the embodiments, and will not be described in detail herein.
In a third aspect, an embodiment of the present utility model further provides an infrared spectrometer, including: the image signal processor is connected with the detector.
The image signal processor is used for receiving the spectral image of the detector and outputting the image after processing.
The specific structure of the detector in this embodiment refers to the foregoing embodiments, and since the infrared spectrometer adopts all the technical solutions of all the foregoing embodiments, at least the advantages brought by the technical solutions of the foregoing embodiments are provided, and will not be described in detail herein.
The foregoing description is only of the optional embodiments of the present utility model, and is not intended to limit the scope of the utility model, and all equivalent structural modifications made by the present description and accompanying drawings or direct/indirect application in other related technical fields are included in the scope of the present utility model.
Claims (12)
1. A modulation structure for infrared hyperspectral imaging, comprising:
a detector window encapsulation layer;
the infrared antireflection film is arranged on the surface of one side, facing the pixel array, of the detector window packaging layer, and the refractive index of the infrared antireflection film material is smaller than that of the detector window packaging layer material; and
the micro-structure modulation units are arranged on the surface of one side of the infrared antireflection film, which is away from the detector window packaging layer, according to a preset arrangement rule, so that the partial area of the surface of one side of the infrared antireflection film, which is away from the detector window packaging layer, is empty to form at least one air-reservation modulation unit.
2. The modulation structure for infrared hyperspectral imaging according to claim 1 wherein the preset arrangement rules include at least one of:
the microstructure modulation unit is adjacent to at least one of the space modulation units;
at most two space modulation units are arranged between two adjacent microstructure modulation units in a first direction or a second direction of the pixel array, and the first direction is perpendicular to the second direction;
the structures of any two of all the microstructure modulation units adjacent to each space modulation unit are different from each other.
3. The modulation structure for infrared hyperspectral imaging according to claim 2, wherein the microstructure modulating units and the space modulation units are alternately arranged with each other in the first direction, and the microstructure modulating units and the space modulation units are alternately arranged with each other in the second direction.
4. The modulation structure for infrared hyperspectral imaging as claimed in claim 2, wherein the infrared antireflection film comprises at least two transparent film layers which are sequentially laminated, and refractive indexes of a plurality of the transparent film layers gradually decrease in a direction away from the detector window encapsulation layer.
5. The modulating structure for infrared hyperspectral imaging according to claim 4, wherein the transparent film layer is made of ZnS zinc sulfide, znSe zinc selenide, baF 2 Barium fluoride, caF 2 Calcium fluoride, ybF 3 Ytterbium fluoride, ge germanium or Si silicon.
6. The modulation structure for infrared hyperspectral imaging according to any one of claims 1 to 5 wherein the microstructure modulation unit includes a plurality of micro-nano structure subunits arranged in a rectangular array, and a plurality of the micro-nano structure subunits are spaced apart from each other.
7. The modulation structure for infrared hyperspectral imaging according to claim 6, wherein the micro-nano structure subunit is configured as a columnar structure protruding from the infrared antireflection film, and the columnar structure is made of an infrared high refractive index material; or (b)
An infrared high-refractive-index medium layer is arranged on the surface of one side, away from the detector window packaging layer, of the infrared antireflection film, and the micro-nano structure subunit is constructed to penetrate through a hole-shaped structure of the infrared high-refractive-index medium layer along the thickness direction of the detector window packaging layer.
8. The modulation structure for infrared hyperspectral imaging according to claim 7 wherein the cross-sectional shape of the micro-nano structured subunit is configured as a rotationally symmetrical pattern with a rotation angle of 90 °.
9. The modulation structure for infrared hyperspectral imaging according to claim 6 wherein the side length of the pixels in the array of pixels is n, n is 17 μm or less, the number of micro-nano structural subunits in the third direction of the rectangular array is m1, and the number of micro-nano structural subunits in the fourth direction of the rectangular array is m2, m1 and m2 satisfy: m1 is less than or equal to 10 and m2 is less than or equal to 10; wherein the third direction is perpendicular to the fourth direction.
10. The modulation structure for infrared hyperspectral imaging according to claim 6 wherein the micro-nano structured subunits have a height H, H > 5 μm.
11. A detector, comprising:
an image sensor comprising an array of picture elements; and
a modulation structure for infrared hyperspectral imaging as claimed in any one of claims 1 to 10 which is disposed on one side of an array of picture elements and the microstructure modulation elements of the modulation structure are disposed opposite the array of picture elements.
12. An infrared spectrometer, comprising:
the detector of claim 11; and
and the image signal processor is connected with the detector.
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