Imaging device and method for improving spatial sampling frequency

Abstract

The present invention discloses an imaging device and method for improving spatial sampling frequency, which belongs to the field of photogrammetry. The device for improving spatial sampling frequency comprises a silicon-based liquid crystal array, a relay lens, a CCD, a piezoelectric displacement stage and a processor; the wafers on the silicon-based liquid crystal array are grouped in N×N; after the imaging light propagates to the silicon-based liquid crystal array, each group of wafers transmits the light in sequence in a row-first-column-later time sequence; the CCD pixel is exposed N×N times, and each time receives the transmitted light from one wafer in the N×N wafer groups; the processor synthesizes the final image, breaking through the image resolution limitation of the imaging sensor.

Description

Technical Field

[0001] The invention relates to an imaging device and method for improving spatial sampling frequency, and belongs to the field of photogrammetry. Background Art

[0002] Nanolithography technology determines that the image resolution of imaging sensors cannot be increased indefinitely. The spatial sampling frequency of imaging sensors is difficult to break through the limitations of image resolution and cannot meet the needs of higher visual measurement accuracy. The current imaging sensors with extreme resolution have a large sampling data volume, which causes information redundancy and cumbersome post-processing for imaging objects that do not require high spatial sampling frequency. Summary of the invention

[0003] In view of the above-mentioned prior art, the present invention provides an imaging device and method for improving spatial sampling frequency to solve the above-mentioned problems.

[0004] The present invention provides a technical solution for realizing an imaging device with improved spatial sampling frequency: the device comprises a silicon-based liquid crystal array, a relay lens, a CCD, a piezoelectric displacement stage and a processor; the crystal elements on the silicon-based liquid crystal array are grouped in N×N order; after the imaging light is propagated to the silicon-based liquid crystal array, each group of crystal elements transmits the light in sequence in a time sequence of first row and then column; the relay lens images the silicon-based liquid crystal array to the CCD and ensures that the N×N crystal element groups correspond to the CCD pixel; the CCD pixel is exposed N×N times, and each time receives the transmitted light from one crystal element in the N×N crystal element groups; the processor receives the image of the CCD, controls the transmittance of each crystal element of the silicon-based liquid crystal array and the displacement change of the piezoelectric displacement stage in the three-axis directions of x, y and z, and synthesizes the final image with improved spatial resolution.

[0005] The present invention provides a method for improving spatial sampling frequency imaging, which uses the above-mentioned imaging device for improving spatial sampling frequency and follows the following steps:

[0006] Step 1: The processor controls the transmittance of all the cells on the liquid crystal on silicon array to be 1, and the CCD collects a low sampling rate scene image in one exposure.

[0007] Step 2: The processor processes the low sampling rate scene graph, defines the region of interest and increases the spatial sampling coefficient N of the target within the given region.

[0008] Step 3: The processor controls the position of the piezoelectric displacement stage relative to the relay lens in the z-axis direction to achieve corresponding imaging of the CCD single pixel and the N×N crystal element group in the region of interest.

[0009] Step 4: The processor controls each group of cells of the silicon-based liquid crystal array to turn on the (i, j)th cell in each group to transmit light in a time sequence of first row and then column, 1≤i≤N and 1≤j≤N.

[0010] Step 5: The CCD is exposed N×N times. In the [(j-1)N+i]th exposure, the CCD pixel receives the imaging light from the (i, j)th wafer in each wafer group and collects the image I i,j is a matrix with p columns and q rows.

[0011] Step 6: When the cell group of the silicon-based liquid crystal array is not enough to cover the pixels in the region of interest, the processor controls the piezoelectric translation stage to move to a new position in the x and y axis directions, and repeats steps 3, 4, and 5 until N×N data are collected for all pixels in the region of interest.

[0012] Step 7: The processor interpolates and arranges the N×N collected images to synthesize the final image I c , the synthesis formula is:

[0013]

[0014] Among them, Q j is a matrix with q columns and qN rows, where the lth column and the [(l-1)N+j]th row are 1, and the rest are 0, 1≤l≤q; P i It is a matrix of pN columns and p rows, where the kth row and [(k-1)N+i]th column are 1 and the rest are 0.

[0015] It can be seen that through steps one, two, three, four, five, six and seven, imaging with increased spatial sampling frequency can be achieved.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The imaging device and method for improving spatial sampling frequency provided by the present invention adopts a silicon-based liquid crystal array structure to realize two-dimensional spatial image encoding, and uses multiple exposures in exchange for an increase in spatial sampling frequency. Compared with the prior art, the imaging method for improving spatial sampling frequency provided by the present invention breaks through the image resolution limitation of the imaging sensor. The method of improving the spatial sampling frequency for the target in the region of interest greatly reduces the redundancy of image data. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A structural diagram of an imaging device for improving spatial sampling frequency provided by the present invention;

[0019] Figure 2 It is a schematic diagram of the light transmission of the wafer sequence of the present invention.

[0020] In the figure: 1-silicon-based liquid crystal array, 2-relay lens, 3-CCD, 4-piezoelectric displacement stage, 5-processor. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with specific implementation modes.

[0022] like Figure 1 As shown, the present invention provides an imaging device for improving spatial sampling frequency, comprising a silicon-based liquid crystal array 1, a relay lens 2, a CCD3, a piezoelectric displacement stage 4 and a processor 5; the crystal elements on the silicon-based liquid crystal array 1 are grouped in N×N; after the imaging light is propagated to the silicon-based liquid crystal array 1, each group of crystal elements transmits the light in sequence in a row-first and column-later time sequence; the relay lens 2 images the silicon-based liquid crystal array 1 to the CCD3, and ensures that the N×N crystal element groups correspond to the CCD3 pixel; the CCD3 pixel is exposed N×N times, and each time receives the transmitted light from one crystal element in the N×N crystal element groups; the processor 5 receives the image of the CCD, controls the transmittance of each crystal element of the silicon-based liquid crystal array 1 and the displacement change of the piezoelectric displacement stage 4 in the x, y, and z three-axis directions, and synthesizes the final image with improved spatial resolution.

[0023] The present invention provides a method for improving spatial sampling frequency imaging, which uses the above-mentioned imaging device for improving spatial sampling frequency and follows the following steps:

[0024] Step 1: The processor 5 controls the transmittance of all the cells on the LCOS array 1 to be 1, and the CCD 3 collects a low sampling rate scene image in one exposure.

[0025] Step 2: The processor 5 processes the low sampling rate scene graph, defines the region of interest and increases the spatial sampling coefficient N of the target within the given region.

[0026] Step 3: The processor 5 controls the position of the piezoelectric displacement stage 4 relative to the relay lens 2 in the z-axis direction to achieve corresponding imaging of the CCD 3 single pixel and the N×N crystal element group in the region of interest.

[0027] Step 4: Figure 2 As shown, the processor 5 controls each group of cells of the LCOS array 1 to turn on the (i, j)th cell in each group to transmit light in a time sequence of first row and then column, 1≤i≤N and 1≤j≤N.

[0028] Step 5: The CCD3 is exposed N×N times. In the [(j-1)N+i]th exposure, the CCD3 pixel receives the imaging light from the (i, j)th wafer in each wafer group and collects the image I i,j is a matrix with p columns and q rows.

[0029] Step 6: When the cell group of the silicon-based liquid crystal array 1 is not enough to cover the pixels in the region of interest, the processor 5 controls the piezoelectric displacement stage 4 to move to a new position in the x-axis and y-axis directions, and repeats steps 3, 4, and 5 until N×N data are collected for all pixels in the region of interest.

[0030] Step 7: The processor 5 interpolates and arranges the N×N collected images to synthesize the final image I c , the synthesis formula is:

[0031]

[0032] Among them, Q j is a matrix with q columns and qN rows, where the lth column and the [(l-1)N+j]th row are 1, and the rest are 0, 1≤l≤q; P i It is a matrix of pN columns and p rows, where the kth row and [(k-1)N+i]th column are 1 and the rest are 0.

[0033] It can be seen that through steps one, two, three, four, five, six and seven, imaging with increased spatial sampling frequency can be achieved.

[0034] Example:

[0035] The present invention is further described in detail below by taking the imaging of a triangle with 4 pixels as an example:

[0036] In the low sampling rate scene image, the triangle is located at 4 pixels and its shape features cannot be identified; the 2×2 range is delineated as the region of interest, and the spatial sampling coefficient N=3 is selected to be increased according to the monotonic consistency of grayscale changes.

[0037] The processor 5 controls the position of the piezoelectric displacement stage 4 relative to the relay lens 2 in the z-axis direction to achieve corresponding imaging of the four pixels and a group of 3×3 crystal elements in the region of interest.

[0038] A CCD with a resolution of 720×1080 is selected, that is, p=1080, q=720, and the CCD3 is exposed 3×3 times to obtain an image I 1,1 ,I 1,2 ,I 1,3 ,I 2,1 ,I 2,2 ,I 2,3 ,I 3,1 ,I 3,2 ,I 3,3 .

[0039] Substitute the above nine image matrices into

[0040]

[0041] The final image matrix I is obtained c , the rows are 720×3 and the columns are 1080×3.

[0042]

[0043]

[0044] In the present invention, the method of defining the region of interest and corresponding imaging of a single pixel and an N×N chip group is common knowledge in the art and will not be described in detail. The present invention can set N and select CCDs with different resolutions according to requirements and is not limited to this embodiment.

[0045] Although the present invention has been described above in conjunction with the drawings, the present invention is not limited to the above-mentioned specific embodiments, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can make many modifications without departing from the purpose of the present invention, all of which are within the protection of the present invention.

Claims

1. An imaging device for increasing spatial sampling frequency, characterized in that: The invention comprises a silicon-based liquid crystal array (1), a relay lens (2), a CCD (3), a piezoelectric displacement stage (4) and a processor (5); the crystal elements on the silicon-based liquid crystal array (1) are grouped in N×N; after the imaging light is transmitted to the silicon-based liquid crystal array (1), each group of crystal elements transmits the light in a time sequence of first row and then column; the relay lens (2) images the silicon-based liquid crystal array (1) to the CCD (3) and ensures that the N×N crystal element groups correspond to the single pixel of the CCD (3); the single pixel of the CCD (3) is exposed N×N times, and each time receives the transmitted light from one crystal element in the N×N crystal element groups; the processor (5) receives the image of the CCD, controls the light transmittance of each crystal element of the silicon-based liquid crystal array (1) and the displacement change of the piezoelectric displacement stage (4) in the three-axis directions of x, y and z, and synthesizes a final image with improved spatial resolution.

2. A method for improving spatial sampling frequency imaging, characterized in that: Imaging using the imaging device for increasing the spatial sampling frequency as claimed in claim 1 comprises the following steps: Step 1: the processor (5) controls the transmittance of all cells on the liquid crystal on silicon array (1) to be 1, and the CCD (3) collects a low sampling frequency scene image through a single exposure; Step 2, the processor (5) processes the low sampling frequency scene graph, demarcates the region of interest and increases the spatial sampling coefficient N of the target within the given region; Step 3, the processor (5) controls the position of the piezoelectric displacement stage (4) relative to the relay lens (2) in the z-axis direction to achieve corresponding imaging of the CCD (3) single pixel and the N×N crystal element group in the region of interest; Step 4, the processor (5) controls each group of cells of the liquid crystal on silicon array (1) to turn on the (i, j)th cell of each group to transmit light in a time sequence of first row and then column, 1≤i≤N and 1≤j≤N; Step 5: The CCD (3) is exposed N×N times. In the [(j-1)N+i]th exposure, the CCD (3) pixel receives the imaging light from the (i, j)th wafer in each wafer group and collects the image I i,j is a matrix with p columns and q rows; Step 6: When the cell group of the liquid crystal on silicon array (1) is not enough to cover the pixels in the region of interest, the processor (5) controls the piezoelectric displacement stage (4) to move to a new position in the x-axis and y-axis directions, and repeats steps 3, 4, and 5 until N×N data are collected for all the pixels in the region of interest; Step 7: The processor (5) interpolates and arranges the N×N collected images to synthesize the final image I c , the sampling frequency is increased, and the synthesis formula is: Among them, Q j is a matrix with q columns and qN rows, where the lth column and the [(l-1)N+j]th row are 1, and the rest are 0, 1≤l≤q; P i It is a matrix of pN columns and p rows, where the kth row and [(k-1)N+i]th column are 1 and the rest are 0.

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