A polarizing filter and area array detector

Abstract

The application provides a polarized filter and a surface array detector, comprising: at least one rectangular array arranged polarized filter array, comprising four 2*2 rectangular array arranged sub-arrays, which are respectively a first sub-array, a second sub-array, a third sub-array and a fourth sub-array, each sub-array comprising four 2*2 rectangular array arranged polarized filter micro-units with different polarization detection modes, wherein the first sub-array and the second sub-array are symmetrical along a first axis, the second sub-array and the third sub-array are symmetrical along a second axis, the third sub-array and the fourth sub-array are symmetrical along the first axis, and the first axis and the second axis are perpendicular to each other. The polarized filter provided by the application can reduce alignment difficulties and reduce the negative effects of the grating edge by changing the arrangement mode of the polarized filter, so as to improve the polarization performance of the integrated overall surface array detector.

Description

Technical Field

[0001] This invention belongs to the field of optical measurement and metrology, and in particular relates to a polarizing filter and an area array detector. Background Technology

[0002] Polarization imaging technology is an emerging optical detection technique capable of acquiring image information in the polarization dimension, and it has applications in multiple fields. Currently, polarization imaging technology mainly includes several forms such as component measurement, amplitude measurement, aperture measurement, and focal plane measurement. Among them, the focal plane measurement method divides the focal plane so that different focal planes detect light signals with different polarization states, thereby calculating the target polarization state.

[0003] Mounting polarizing filters onto the surface of an area array detector or integrating them directly via photolithography is the most effective method for segmenting the focal plane. The idea behind this method is to integrate a tiny polarizer onto the surface of each pixel of the area array detector, similar to the Bayer filters used in color cameras; after acquisition, the pixels are merged to obtain all the polarization information of the target point. All tiny polarizers are in the form of subwavelength metal wire grids.

[0004] The 2007 paper "Development and results of NIR polarization camera [J]. International Society for Optics and Photonics" demonstrated a method for integrating four-directional metal wire grid polarizers onto a back-incident probe focal plane with a thinned substrate. Subsequently, several international research teams explored this direction, including the Forrai team and the Malone team.

[0005] Recently, Photonic Lattice of Japan launched a detector with integrated polarizing filters, featuring 1120×868 pixels, for phase detection; MOXTEK also launched a corresponding pixel-level two-dimensional polarization grating product, capable of achieving an extinction ratio of over 100:1. In China, Zhang Zhigang et al. from the University of Science and Technology of China used electron beam processing to fabricate a micro-polarization element array for phase detection, and subsequently further applied it to imaging.

[0006] However, the aforementioned pixel-level polarizing filters are all limited by the following difficulties:

[0007] 1. The single pixel area of ​​the area array detector is small (on the order of μm), and the polarization effect of the subwavelength metal wire grid edge is not good, which in turn affects the extinction ratio of the entire pixel; there are currently no products with an extinction ratio greater than 500:1.

[0008] 2. Alignment between the area array detector and the polarization filter is difficult. Unlike Bayer filters, polarization detection requires higher alignment precision. Mismatch between pixels will lead to a sharp drop in the final polarization measurement accuracy. This is also why polarization filters can achieve high polarization performance on their own, but the overall polarization performance drops sharply after being integrated into the detector. Summary of the Invention

[0009] The purpose of this invention is to provide a polarizing filter and an area array detector. By changing the arrangement of the polarizing filter, the technical problems of difficulty in aligning the area array detector and the polarizing filter, as well as the poor polarization effect at the edge of the subwavelength metal grid, are solved.

[0010] To solve the above-mentioned technical problems, the present invention is implemented through the following technical solution:

[0011] This invention provides a polarizing filter, comprising:

[0012] At least one rectangular array of polarizing filters, including four subarrays arranged in a 2×2 rectangular array, namely the first subarray, the second subarray, the third subarray and the fourth subarray, each subarray including four polarizing filter micro-units with different polarization detection methods arranged in a 2×2 rectangular array.

[0013] Wherein, the first subarray and the second subarray are symmetrical about the first axis, the second subarray and the third subarray are symmetrical about the second axis, and the third subarray and the fourth subarray are symmetrical about the first axis;

[0014] The first axis and the second axis are perpendicular to each other.

[0015] In one embodiment of the present invention, the polarizing filter micro-units at the four adjacent vertices of the first subarray, the second subarray, the third subarray, and the fourth subarray are polarizing filter micro-units with the same polarization detection method, and together constitute a polarizing filter unit.

[0016] In one embodiment of the present invention, the polarizing filter unit is 2×2 pixels in size.

[0017] In one embodiment of the present invention, the four polarization filter micro-units with different polarization detection methods include a 0-degree linear polarization filter micro-unit, a 45-degree linear polarization filter micro-unit, a 90-degree linear polarization filter micro-unit, and a circular polarization filter micro-unit.

[0018] In one embodiment of the present invention, the arrangement of the polarization filter micro-units of the first sub-array includes:

[0019] The first row and first column of the first subarray are 0-degree linear polarization filter micro-units;

[0020] The first row and second column of the first subarray are 90-degree linear polarizing filter micro-units;

[0021] The second row and first column of the first subarray consists of 45-degree linear polarizing filter micro-units.

[0022] The second row and second column of the first subarray are circular polarizing filter micro-units.

[0023] In one embodiment of the present invention, if the polarizing filter comprises a plurality of polarizing filter arrays arranged in a rectangular array, the arrangement of the polarizing filter arrays extends outward periodically along a first axis and / or a second axis with reference to one of the polarizing filter arrays.

[0024] The present invention also provides an area array detector, wherein a polarizing filter is integrated on the surface of the area array detector, and the area array detector includes a polarizing filter as described in any of the preceding claims.

[0025] In one embodiment of the present invention, the method for integrating the polarizing filter on the surface of the area array detector includes bonding, mounting, and directly etching the line grid using photolithography.

[0026] In one embodiment of the present invention, the area of ​​the surface of the area array detector is smaller than the area of ​​the polarizing filter.

[0027] In one embodiment of the present invention, the area array detector includes at least four pixel arrays arranged in a 2×2 rectangular array, each pixel array being aligned with a subarray.

[0028] The present invention provides a polarizing filter comprising at least one polarizing filter array arranged in a rectangular array. The polarizing filter array includes four sub-arrays arranged in a 2×2 rectangular array, namely a first sub-array, a second sub-array, a third sub-array, and a fourth sub-array. Each sub-array includes four polarizing filter micro-units with different polarization detection methods arranged in a 2×2 rectangular array. The first sub-array and the second sub-array are symmetrical along a first axis, the second sub-array and the third sub-array are symmetrical along a second axis, and the third sub-array and the fourth sub-array are symmetrical along a first axis. The first axis and the second axis are perpendicular to each other. The polarizing filter with this arrangement provided by the present invention has a minimum polarizing unit area that is four times larger than the original, reducing the requirements for micro-nano fabrication. In addition, the polarizing filter is integrated on the surface of the area array detector. When the polarizing filter as a whole is slightly deviated to one side, the number of affected detector pixels is half that of the original scheme, thus reducing the alignment requirements. Furthermore, after the polarizing filter with this arrangement is aligned with the area array detector, the number of individual detector pixels is reduced from the original grid edges on all four sides to grid edges on only two sides, thereby reducing the negative effects of grid edges. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of an existing polarizing filter arrangement.

[0031] Figure 2 This is a schematic diagram of a polarizing filter arrangement provided for an exemplary embodiment of this application.

[0032] Figure 3 This is a schematic diagram of the smallest polarizing filter unit of a polarizing filter provided for an exemplary embodiment of this application.

[0033] Figure 4 This is a schematic diagram of a polarizing filter and an area array detector provided as an exemplary embodiment of this application.

[0034] Figure 5 A front view of the alignment relationship between a polarizing filter and an area array detector, provided for an exemplary embodiment of this application.

[0035] The attached figures are labeled as follows:

[0036] 100 polarizing filter array

[0037] 110 subarrays

[0038] 111 Polarizing Filter Microunit

[0039] 200 polarizing filter unit

[0040] 300 Integrated Polarizing Filter

[0041] 400-area detector surface pixel array Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] To address the technical problems of difficult alignment between the area array detector and the polarization filter, and poor polarization effect at the edge of the subwavelength metal wire grid, this invention provides a polarization filter comprising at least one rectangular array of polarization filters 100. The polarization filters 100 includes four sub-arrays 110 arranged in a 2×2 rectangular array, namely a first sub-array, a second sub-array, a third sub-array, and a fourth sub-array. Each sub-array 110 includes four polarization filter micro-units 111 with different polarization detection methods arranged in a 2×2 rectangular array. The first sub-array and the second sub-array are symmetrical along a first axis, the second sub-array and the third sub-array are symmetrical along a second axis, and the third sub-array and the fourth sub-array are symmetrical along the first axis, wherein the first axis and the second axis are perpendicular to each other. By changing the arrangement of the polarization filters, alignment difficulties can be reduced, negative effects at the wire grid edge can be minimized, thereby improving the polarization performance of the integrated detector and achieving original pixel-level polarization detection capability. These embodiments will be discussed in detail below.

[0044] In one exemplary embodiment of this application, please refer to Figure 2 As shown, Figure 2 This is a schematic diagram of a polarizing filter arrangement provided in this application. The polarizing filter includes at least one rectangular array of polarizing filters 100. The polarizing filter array 100 includes four sub-arrays 110 arranged in a 2×2 rectangular array, namely a first sub-array, a second sub-array, a third sub-array, and a fourth sub-array. Each sub-array includes four polarizing filter micro-units 111 with different polarization detection methods arranged in a 2×2 rectangular array.

[0045] For details, please continue reading. Figure 2As shown, in this embodiment, the 4×4 rectangular array with a background color is the polarizing filter array 100. The polarizing filter is further divided into four sub-arrays 110 arranged in a 2×2 rectangular array. Starting from the sub-array in the upper left corner and proceeding clockwise, they are the first sub-array, the second sub-array, the third sub-array, and the fourth sub-array. Each sub-array includes four polarizing filter micro-units 111 with different polarization detection methods arranged in a 2×2 rectangular array. It should be noted that... Figure 2 The four letters A, B, C, and D represent four different polarization filter micro-units 111 with different polarization detection methods. In this embodiment, A, B, C, and D represent 0-degree linear polarization filter micro-units, 90-degree linear polarization filter micro-units, 45-degree linear polarization filter micro-units, and circular polarization filter micro-units, respectively. Of course, in other embodiments, A, B, C, and D can also be polarization filter micro-units 111 with other polarization detection methods.

[0046] In one exemplary embodiment of this application, please refer to Figure 2 As shown, the first subarray and the second subarray are symmetrical along a first axis, the second subarray and the third subarray are symmetrical along a second axis, and the third subarray and the fourth subarray are symmetrical along a first axis, wherein the first axis and the second axis are perpendicular to each other. It should be noted that since each subarray 110 includes four polarizing filter micro-units 111 arranged in a 2×2 rectangular array, the first subarray and the second subarray are symmetrical along the first axis. That is, the polarizing filter micro-units 111 arranged in a 2×2 rectangular array in the first subarray are also symmetrical along the first axis with the polarizing filter micro-units 111 arranged in a 2×2 rectangular array in the second subarray. Similarly, the second subarray and the third subarray are symmetrical along the second axis, and the third subarray and the fourth subarray are also symmetrical along the first axis.

[0047] In one exemplary embodiment of this application, please refer to Figure 3 As shown, the polarizing filter micro-units 111 at the four adjacent vertices of the first sub-array, the second sub-array, the third sub-array, and the fourth sub-array are polarizing filter micro-units 111 with the same polarization analysis method, and together constitute a polarizing filter unit 200. It should be noted that... (See also...) Figure 3 As shown, Figure 3 and Figure 2Using the same filter arrangement, adjacent polarizing filter micro-units 111 of the same type are integrated to form a polarizing filter unit 200. In this embodiment, since the area of ​​each polarizing filter micro-unit 111 is one pixel, the polarizing filter unit 200 is composed of four polarizing filter micro-units 111 with the same polarization detection method. That is, the area of ​​the polarizing filter unit 200 is 2×2 pixels. On the one hand, this arrangement of polarizing filters can still maintain pixel-level polarization detection effect after integration with the area array detector. On the other hand, it reduces the difficulty of manufacturing. In other words, since the minimum polarizing filter unit area processed by this arrangement is four times that of the original, the requirements for micro-nano fabrication are reduced.

[0048] In one exemplary embodiment of this application, please refer to Figure 2 As shown, the arrangement of the polarization filter micro-units 111 in the first sub-array includes: the first row and first column of the first sub-array contains 0-degree linear polarization filter micro-units; the first row and second column of the first sub-array contains 90-degree linear polarization filter micro-units; the second row and first column of the first sub-array contains 45-degree linear polarization filter micro-units; and the second row and second column of the first sub-array contains circular polarization filter micro-units. It should be noted that, based on the axial symmetry relationship between the first, second, third, and fourth sub-arrays, when the arrangement of the polarization filter micro-units 111 in the first sub-array is determined, the arrangement of the polarization filter micro-units 111 in the second, third, and fourth sub-arrays is also determined, and will not be elaborated further here. Furthermore, the first sub-array may include, but is not limited to, this arrangement. In other embodiments, the first sub-array may also be an arrangement of any combination of polarization filter micro-units 111 of different polarization detection types.

[0049] In an exemplary embodiment of this application, if the polarizing filter includes a plurality of polarizing filter arrays 100 arranged in a rectangular array, the arrangement of the arrays extends outward periodically along a first axis and / or a second axis with reference to one of the polarizing filter arrays 100.

[0050] This application also provides an area array detector, wherein a polarization filter is integrated on the surface of the area array detector, and the area array detector includes a polarization filter as described in any of the above embodiments.

[0051] In one exemplary embodiment of this application, please refer to Figure 4 As shown, Figure 4The structure of a surface pixel array 400 of an area array detector and an integrated polarizing filter 300 is shown. The surface of the area array detector is a pixel array, and the individual pixels of the pixel array on the surface of the area array detector are the same size as the pixels of the polarizing filter. In this embodiment, Figure 4 The 0°, 90°, 45°, and C values ​​represent a 0° linear polarizing filter unit, a 90° linear polarizing filter unit, a 45° linear polarizing filter unit, and a circular polarizing filter unit, respectively. The method for integrating the polarizing filter onto the surface of the area array detector includes bonding, mounting, and directly etching the grid lines using photolithography. Of course, in other embodiments, without affecting the performance of the area array detector, the polarizing filter can also be integrated onto the surface of the area array detector using other methods. Furthermore, in this embodiment, the area of ​​the area array detector surface is smaller than the area of ​​the polarizing filter.

[0052] In one exemplary embodiment of this application, please refer to Figure 5 As shown, the alignment relationship between the area array detector and the polarizing filter includes: the area array detector comprises at least four pixel arrays arranged in a 2×2 rectangular array, and each pixel array is aligned with a sub-array of the polarizing filter. It should be noted that... Figure 5 The arrangement of the polarizing filters shown is similar to Figure 2 The polarizing filters shown are arranged in the same way, but... Figure 5 The polarizing filter shown is presented in the form of a polarizing filter unit 200 as the smallest unit, wherein the polarizing filter unit 200 is... Figure 2 The polarizing filter arrangement consists of four adjacent polarizing filter micro-units 111 of the same type. This arrangement reduces the alignment requirements with the area array detector. When the polarizing filter as a whole deviates slightly to one side, the number of affected area array detector pixels is half that of the original scheme, thus reducing the alignment requirements. Furthermore, this arrangement of the polarizing filters reduces the number of individual area array detector pixels from having four sides that are grating edges that cause polarization state changes to only two sides that are grating edges, thereby reducing the negative effects of grating edges.

[0053] In summary, the polarization filter provided in this application includes: at least one rectangular array of polarization filters 100, comprising four sub-arrays 110 arranged in a 2×2 rectangular array, namely a first sub-array, a second sub-array, a third sub-array, and a fourth sub-array. Each sub-array includes four polarization filter micro-units 111 with different polarization detection methods arranged in a 2×2 rectangular array. The first sub-array and the second sub-array are symmetrical along a first axis, the second sub-array and the third sub-array are symmetrical along a second axis, and the third sub-array and the fourth sub-array are symmetrical along the first axis. The first axis and the second axis are perpendicular to each other. By changing the arrangement of the polarization filters, alignment difficulties can be reduced, negative effects at the grid edges can be minimized, thereby improving the overall polarization performance of the integrated detector.

[0054] The above description is merely a preferred embodiment of this application and an explanation of the technical principles used. Those skilled in the art should understand that the scope involved in this application is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept. For example, technical solutions formed by replacing the above-mentioned features with technical features with similar functions disclosed in this application (but not limited to) each other.

[0055] Apart from the technical features described in the specification, the other technical features are known to those skilled in the art. To highlight the innovative features of this invention, the other technical features will not be described in detail here.

Claims

1. A polarization filter, characterized by, The application relates to a polarized filter array and a surface array detector. The polarized filter array comprises at least one rectangular array of polarized filters, which comprises four 2*2 rectangular arrays of polarized filters, namely a first array, a second array, a third array and a fourth array, each of which comprises four 2*2 rectangular arrays of polarized filters with different polarized modes. The first array and the second array are symmetrical along a first axis, the second array and the third array are symmetrical along a second axis, and the third array and the fourth array are symmetrical along the first axis. The first axis and the second axis are perpendicular to each other.

2. A polarization filter according to claim 1, characterized in that The polarized filters at the four adjacent corner positions of the first array, the second array, the third array and the fourth array are polarized filters with the same polarized mode, and together form a polarized filter unit.

3. A polarization filter according to claim 2, characterized in that The polarized filter unit has a 2*2 pixel size.

4. A polarization filter according to claim 1, characterized in that The four polarized filters with different polarized modes comprise a 0-degree linear polarized filter, a 45-degree linear polarized filter, a 90-degree linear polarized filter and a circular polarized filter.

5. A polarization filter according to claim 4, characterized in that The arrangement mode of the polarized filters in the first array comprises: The first row and the first column of the first array are 0-degree linear polarized filters. The first row and the second column of the first array are 90-degree linear polarized filters. The second row and the first column of the first array are 45-degree linear polarized filters. The second row and the second column of the first array are circular polarized filters.

6. A polarization filter according to claim 1, wherein If the polarized filter comprises a plurality of rectangular arrays of polarized filters, the arrangement mode of the polarized filters is periodically extended along the first axis and / or the second axis outwardly based on one of the rectangular arrays of polarized filters.

7. A focal plane array detector, characterized by, The surface array detector is integrated with the polarized filter.

8. A focal plane array detector according to claim 7, wherein, The method for integrating the polarized filter on the surface of the surface array detector comprises bonding, mounting and directly etching a wire grid by using a photolithography technology.

9. A focal plane array detector according to claim 7, wherein, The area of the surface of the surface array detector is smaller than the area of the polarized filter.

10. A focal plane array detector according to claim 9, wherein, The alignment relationship between the surface array detector and the polarized filter comprises: The surface array detector comprises at least four 2*2 rectangular arrays of pixels, each of which is aligned with one of the arrays.

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