CN108732637A - Interference formula is segmented flat panel imaging detection system - Google Patents

Abstract

The invention discloses an interferometric segmented flat-panel imaging detection system, which mainly solves the problems of few lens array spectrum collection points and poor system imaging quality in the existing imaging detection system. It includes a lens array, a photonic integrated circuit, a digital signal processor, and an image calculation and reconstruction module. The photonic integrated circuit is located on the focal plane of the lens array and integrated on the PIC chip. The lens array consists of several radiating strip lenses with different lengths. Arranged radially in the shape of a concentric ring, that is, the longest radiating strip lens is embedded on a disc-shaped fixed plate, and the second-longest radiating strip lens is filled on both sides of each radiating strip lens of the wheel-disk lens array, and each sub-long radiating strip lens Both sides of the long radiating strip lens are filled with lenses shorter than the second long radiating strip lens, and so on, forming a multi-layer concentric ring distributed radiating strip lens array with different radii. The invention effectively increases the number of sampling points, thereby improving the imaging quality of the system, and can be used for space reconnaissance, monitoring and early warning, and space situation awareness.

Description

Interferometric Segmented Flat Panel Imaging Detection System

technical field

The invention belongs to the technical field of optical imaging, in particular to a segmented flat panel imaging detection system, which can be used for space reconnaissance, monitoring and early warning, space situation awareness and astronomical observation.

Background technique

In recent years, the concept of segmented planar imaging based on micro-nanophotonic integrated circuits has provided a new way for the development of ultra-thin planar ultra-high-resolution telescope systems, and has become an important frontier in the development of advanced optical remote sensing imaging technology. The structural design of traditional telescope systems is basically a bulky barrel-shaped system structure formed by stacking optical lenses or mirrors. The system size, volume, weight and power consumption are large, and the preparation cycle is long. Therefore, the development of ultra-light, large-aperture, and high-resolution optical telescopes has always been the pursuit of astronomical observation and space surveillance in the field of optical telescopic imaging. Interferometric segmented flat-panel imaging can avoid the manufacturing, polishing, and calibration of traditional large optical systems, and greatly reduce the volume, weight, and power, integration, and testing complexity.

The principle of optical imaging can be roughly divided into three categories, aberration theory imaging principle in geometric optics, diffraction imaging principle and interference imaging principle in wave optics. Geometric optics believes that the propagation path of light can be directly observed. This propagation path of light is called optical path. According to the calculation of optical system aberration and optical path, the macroscopic characteristics and geometric aberration of optical system imaging can be obtained. Diffraction imaging theory explains the light field structure and wave aberration near the image point. The imaging system is regarded as a linear system with invariant space. The imaging characteristics of the system are described by point spread function or modulation transfer function, and the image quality evaluation is solved by mathematical methods. question. The principle of interference imaging believes that the imaging process is essentially an interference process, and the light disturbance at any point on the image surface is the superposition of light disturbances formed by each point on the exit pupil on the image surface. Therefore, by controlling the shape of the entrance pupil of the optical imaging system, Quantity, distribution can obtain more image information. The principle of interference imaging also boils down the coherent imaging and incoherent imaging, which are completely separated in the analysis of the principle of diffraction imaging, into two limit cases, and considers that all imaging is essentially an interference process, so the study of the principle of interference imaging is more general.

The interferometric segmented flat-panel imaging detection system is based on the Van Sitter-Zernik theory. With the help of photonic integrated circuit technology, the miniature interference array replaces the bulky optical telescope and digital focal plane detection system array, and performs interference processing to form a computational image. This approach dramatically reduces size, weight, and power consumption, and system performance can be enhanced with additional on-chip components: use waveguide arrays behind each lenslet to increase the field of view, and arrayed waveguide gratings to disperse broadband light to different spectral channels, thereby improving spatial frequency coverage. The arrangement and pairing of the lens array determine the number of sampling points.

Domestically, there is a good accumulation of synthetic aperture interferometric imaging theory and technology for radio telescopes and optical telescopes, but there are relatively few studies on interferometric segmented flat-panel imaging detection systems. Currently, the reconstruction image quality of segmented flat-panel imaging systems is widespread. Defects of poor contrast, loss of information, insufficient resolution. Numerical simulation and optimal design of Segmented Planar Imaging Detector for Electro-Optical Reconnaissance published on Optics Communications by Chu qiuhui, Shenyijie, Yuan Meng and others from Tsinghua University proposed a method for adjusting the baseline pair of segmented planar imaging detection system, and passed Adjusting the Nyquist sampling interval, optimizing the baseline pairing method, and increasing the number of spectral channels of the arrayed waveguide grating have improved the imaging quality of the segmented flat-panel imaging detection system, but there are still problems of poor image quality contrast and serious information loss, which affect the system. image quality.

Contents of the invention

Aiming at the deficiencies of the above-mentioned prior art, the present invention proposes an optimized design of an interferometric segmented flat-panel imaging detection system to change the arrangement of lens arrays, increase the number of frequency collection points, reduce information loss, and effectively improve imaging quality.

In order to achieve the above object, the interferometric segmented flat-panel imaging detection system of the present invention includes a lens array, a photonic integrated circuit, a digital signal processor and an image calculation and reconstruction module, and the lens array is embedded on a fixed plate, including: a lens array, a photonic integrated circuit , a digital signal processor and an image calculation and reconstruction module, the lens array is inlaid on the fixed plate, the photonic integrated circuit is located on the focal plane of the lens array, and is integrated on the PIC chip, and it is characterized in that: the lens array consists of several radiation strips with different lengths Lenses are arranged radially in the shape of concentric rings, that is, the longest radiating strip lens is inlaid on a disc-shaped fixed plate to form a roulette lens array, which is filled on both sides of each radiating strip lens of the roulette lens array. There are sub-long radiating strip lenses, and the two sides of each sub-long radiating strip lens are filled with lenses shorter than the sub-long radiating strip, and so on, forming a multi-layer concentric ring distributed radiating strip lens array with different radii , and the number of lenses on each layer of concentric rings increases layer by layer.

Further, the radii of the multi-layer concentric rings of the lens array are different, and its calculation is as follows:

The radius of the 1st layer circle is:

The radius of the 2nd layer circle is:

The circle radius of the kth layer is:

Wherein, d is the diameter of the small lens, α is the angle between two radiating strip lenses, and its size is 2π/p; p is the number of radiating strip lens arrays.

Further, in the multi-layer concentric ring distributed radiation strip lens array, the position of each radiation strip lens is different, and the calculation formula is as follows:

Where (x _lens (i, j), y _lens (i, j)) is the position coordinate of the center of the ith small lens corresponding to the jth radiating strip lens, and D is two adjacent radiating strip lens arrays The interval between small lenses, j=1,2,...p, i=1,2,...n,p is the number of radiating strip lens arrays, n is the corresponding jth radiating strip lens The maximum number of sub-lenses.

Description of drawings

Fig. 1 is the schematic diagram of the interferometric segmented flat panel imaging detection system of the present invention;

Fig. 2 is the distribution schematic diagram of the lens array in the existing segmented flat panel imaging detection system;

Fig. 3 is a lens array structure diagram among the present invention;

Fig. 4 is the U-V spatial frequency coverage contrast figure of the system of the present invention and existing system;

Fig. 5 is a comparison chart of imaging results using the system of the present invention and the existing system.

Detailed ways

The structure and effects of the present invention will be further described in detail below with reference to the accompanying drawings.

Referring to Fig. 1, the present invention includes a lens array, a photonic integrated circuit, a digital signal processor and an image calculation and reconstruction module. The lens array is embedded on a fixed plate, and the photonic integrated circuit is located on the focal plane of the lens array and integrated on a PIC chip.

The lens array is filled on the basis of the existing lens array. The distribution of the existing lens array is shown in Figure 2. The lens array is composed of 19 radiating strip lenses, and each radiating strip lens has 30 sub-lenses . In the present invention, the diameter d of the small lens is 3.6 mm, but not limited, and based on these radiating strips, the radiating strip lenses are filled to form a lens array. It is filled as follows:

Taking each radiating strip lens of the lens array shown in Figure 2 as the longest radiating strip lens, the second longest radiating strip lens is filled on both sides of each radiating strip lens for the first time, that is, adding the second longest radiating strip lens The number of radiating strip lenses is 38, and each sub-long radiating strip lens is provided with 22 small lenses to form the first layer of ring, and the radius of the first layer of ring is

For the second time, lenses shorter than the sub-long radiating strip lens are filled on both sides of the sub-long radiating strip lens, that is, the number of lenses shorter than the sub-long radiating strip lens is added to be 76, each of which is shorter than the sub-long radiating strip lens. The short lens of the strip lens is provided with 10 small lenses to form the second layer of ring, and the radius of the second layer of ring is

By analogy, the number of radiating strip lenses filled for the kth time is 19×2k, where k=0, 1, 2, ..., and the radius of the ring at the kth layer is Wherein d is the diameter of the small lens, α is the angle between two radiating strip lenses, α=2π/p; p is the quantity of the radiating strip lens array;

If the number of longest radiating strip lenses is m, the number of radiating strip lenses filled for the kth time is m×2k, where k=0,1,2..., m=1,2,... , the circular radius of the kth layer is R _k =d/2tan[α/(8k)], wherein d is the diameter of the small lens, α is the angle between two radiating strip lenses, α=2π/p; p is the number of radiating strip lens arrays, and the position of each small lens is calculated according to the following formula:

Where (x _lens (i, j), y _lens (i, j)) is the position coordinate of the center of the ith small lens corresponding to the jth radiating strip lens, and D is two adjacent radiating strip lens arrays The interval between small lenses, j=1,2,...p, i=1,2,...n,p is the number of radiating strip lens arrays, n is the corresponding jth radiating strip lens The maximum number of sub-lenses.

In this example, k=2, and after filling twice, the distribution of the lens array is shown in FIG. 3 . The radius of the ring in the third layer is the product of the number of the longest radiating strip lens and the diameter of the small lens, that is, R ₃ =30×3.6mm+43.52mm−10×3.6mm=115.52mm.

The photonic integrated circuit is sequentially integrated with a waveguide array, an arrayed waveguide grating and a balanced quadrature detector, and the entire photonic integrated circuit is integrated on a PIC chip. The PIC chip is a photonic integrated circuit fabricated using a standard photolithographic complementary metal-oxide-semiconductor fabrication process.

The working principle of the present invention is as follows:

The radiation light field of the long-distance scene is converged through different baseline lens arrays, and the light fields converged by different lens pupil surfaces are transmitted to the corresponding waveguide array, and the converged light field is coupled and split in space through the waveguide array. It is still a wide-spectrum radiation field, and then transmitted to the arrayed waveguide grating. The arrayed waveguide grating performs quasi-monochromatic light splitting on the transmitted wide-spectrum radiation field. The quasi-monochromatic light passes through the balanced four-orthogonal detector to realize different baselines of the same object point in the scene. The quasi-monochromatic light coherently superimposes and outputs interference fringes. The information extracted from the interference fringes is transmitted to the digital signal processor and the U-V space spectrum is output, and the image calculation reconstruction is completed through the image reconstruction module.

Effect of the present invention can be further illustrated by following simulation:

Simulation 1. carry out information extraction to the interference fringe of system output of the present invention and the interference fringe of existing system output respectively by digital signal processor, the U-V spatial spectrum coverage of synthesizing different spatial frequencies, result as shown in Figure 4, wherein Figure 4 (a ) is the U-V spatial frequency coverage of the system of the present invention, and Fig. 4(b) is the U-V spatial frequency coverage of the existing system.

It can be seen from Fig. 4 that the interference fringes output by the present invention are extracted through a digital signal processor, and the synthesized U-V spatial frequency covers more frequency acquisition points and less information loss.

Simulation 2. process the U-V spatial frequency coverage of the system of the present invention and the existing system by the image reconstruction algorithm, and complete the image reconstruction. The result is as shown in Figure 5, wherein:

Fig. 5 (a) carries out information extraction to the interference fringe output of the system of the present invention by digital signal processor, and the result of image reconstruction by image reconstruction algorithm after synthetic U-V spatial spectrum coverage;

Figure 5(b) is the result of image reconstruction by image reconstruction algorithm after extracting information from the interference fringes output by the existing system through a digital signal processor and synthesizing U-V spatial spectrum coverage.

It can be seen from Fig. 5 that the information is extracted from the interference fringes output by the system of the present invention through the digital signal processor, and after the U-V spatial frequency coverage is synthesized, the image reconstructed by the image reconstruction algorithm has high contrast and good image quality.

In summary, the present invention improves the imaging quality by optimizing the structure of the lens array. The lens array is not only limited to the interferometric segmented flat panel imaging detection system, but can also be used in the light field imaging system. All modifications based on the idea of the present invention And applying the idea of the present invention to other interferometric segmented flat-panel imaging detection systems is still within the protection scope of the claims of the present invention.

Claims (5)

1. An interferometric segmented flat-panel imaging detection system, comprising: a lens array, a photonic integrated circuit, a digital signal processor and an image calculation and reconstruction module, the lens array is embedded on a fixed plate, and the photonic integrated circuit is located on the focal plane of the lens array, And integrated on the PIC chip, it is characterized in that: the lens array is composed of several radiating strip lenses with different lengths arranged radially in the shape of a concentric ring, that is, the longest radiating strip lens is embedded on a disc-shaped fixed plate to form a round Disc lens array, on both sides of each radiating strip lens of the roulette lens array is filled with sub-long radiating strip lenses, and on both sides of each sub-long radiating strip lens are filled with holes shorter than the sub-long radiating strip Lenses, and so on, form a multi-layer concentric ring distributed radiation strip lens array with different radii, and the number of lenses on each layer of concentric rings increases layer by layer. 2. system as claimed in claim 1 is characterized in that: the radius of the multilayer concentric ring of lens array is different, and its calculation is as follows: The radius of the 1st layer circle is: The radius of the 2nd layer circle is: The circle radius of the kth layer is: Wherein, d is the diameter of the small lens, α is the angle between two radiating strip lenses, and its size is 2π/p; p is the number of radiating strip lens arrays. 3. The system according to claim 1, characterized in that: the multi-layer concentric ring distributed radiation strip lens array, the position of each radiation strip lens is different, and the calculation formula is as follows: Where (x _lens (i, j), y _lens (i, j)) is the position coordinate of the center of the ith small lens corresponding to the jth radiating strip lens, and D is two adjacent radiating strip lens arrays The interval between small lenses, j=1,2,...p, i=1,2,...n,p is the number of radiating strip lens arrays, n is the corresponding jth radiating strip lens The maximum number of sub-lenses. 4. The system according to claim 1, characterized in that: photonic integrated circuit comprises: waveguide array, arrayed waveguide grating and balanced four quadrature detectors, and are integrated on the PIC chip successively; After the arrays are converged, the corresponding waveguide arrays are used to perform spatial dimension light splitting, and then transmitted to the arrayed waveguide grating for spectral splitting and output quasi-monochromatic light. Visibility measurement, extract information from interference fringes and transmit to digital signal processor and output U-V space spectrum, and complete image calculation and reconstruction through image calculation and reconstruction module. 5. The system of claim 1, wherein the PIC chip is a photonic integrated circuit fabricated using a standard photolithographic CMOS fabrication process.