Single-pixel imaging method and system based on array light source coherent synthesis vortex light field

Abstract

The application provides a single-pixel imaging method and system based on array light source coherent synthesis vortex light field, which comprises the following steps: a single laser is enlarged after passing through a collimating and expanding mirror, and then is emitted and output after passing through a circular ring-shaped mask to form an array light source; specific phases are loaded on different sub-apertures of the array light source by a spatial light phase modulator to realize light field modulation; far field coherent synthesis is performed to obtain a vortex light field with a specific intensity distribution; after the vortex light field is irradiated to a target object, a back light intensity detection value is recorded by a single-pixel detector; and based on the vortex light field intensity distribution and the back light intensity detection value, and in combination with a single-pixel imaging reconstruction algorithm, an image of the target object is obtained. Compared with the prior art, the application has the advantages of fast sampling speed, high imaging quality, good noise robustness and the like, and is expected to be widely applied in the field of long-distance target detection imaging.

Description

Technical Field

[0001] This invention relates to the field of target detection imaging technology, specifically a single-pixel imaging method and system based on coherent synthesis of vortex light fields from array light sources. Background Technology

[0002] Target detection imaging technology is a crucial means for humans to perceive and understand the world, playing a vital role in scientific and social development. Single-pixel imaging is a novel computational imaging technology. Its basic principle involves modulating a laser to generate a light field with a specific spatial intensity distribution, which is then applied to the target. The reflected light intensity from the target is received by a single-pixel detector and synchronously recorded in a computer via a data acquisition card. Finally, a reconstruction algorithm is used to obtain an image of the object. This detector is mainly made of materials such as germanium and silicon, and it has advantages such as a wide response band, high detection sensitivity, and concentrated detection energy. It has great application prospects in fields such as non-visible light imaging, low-light detection, and long-distance target detection.

[0003] However, the technology still faces challenges in practical applications, such as insufficient detection range and low detection efficiency. Summary of the Invention

[0004] To address the problems of low imaging efficiency, short detection range, and susceptibility to environmental influences in current single-pixel imaging technology, this invention provides a single-pixel imaging method and system based on coherent synthesis of vortex light fields using an array light source. This invention combines coherent synthesis of vortex light field technology with single-pixel imaging technology. On the one hand, it leverages the coherent synthesis technology of the array light source to achieve high output power and improve target detection range. On the other hand, it utilizes the unique distribution of the vortex light field, combined with the basic principles of single-pixel imaging, to improve imaging quality and efficiency.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0006] On the one hand, a single-pixel imaging system based on coherent synthesis of vortex light fields from an array of light sources is provided, comprising:

[0007] The array light source generation module is used to emit an array beam, which consists of multiple sub-beams arranged in a circular distribution.

[0008] The phase modulation module is set in the output optical path of the array light source generation module and is used to perform phase modulation on each sub-beam of the array beam to generate a vortex optical field.

[0009] A converging lens is placed in the output light path of the phase modulation module to project the vortex light field onto the target object, which is located at the focal plane of the converging lens.

[0010] A collecting lens is placed in the transmitted light path of the target object to collect the transmitted light from the target object.

[0011] A single-pixel detector is positioned at the focal plane of the collecting lens to receive the transmitted light converged by the collecting lens and output the backlight intensity detection value.

[0012] The data acquisition card is electrically connected to the single-pixel detector and is used to convert the backlight intensity detection value into an electrical signal.

[0013] The computer communicates with the data acquisition card, receives electrical signals, and reconstructs the image of the target object based on the intensity distribution of the vortex light field and the detected value of the backlight intensity, combined with a single-pixel imaging reconstruction algorithm.

[0014] On the other hand, a single-pixel imaging method based on coherent synthesis of vortex light fields from an array of light sources is provided, implemented based on the system described above, including the following steps:

[0015] The array light source generation module collimates and outputs an array beam, and the phase modulation module modulates each sub-beam with a preset stepped phase M times. The array beam passes through a converging lens and coherently combines at its focal plane to generate a vortex light field, which illuminates the target object, generating a total of M frames of vortex light fields with different intensity distributions. The transmitted light from the target object is converged by a collecting lens and received by a single-pixel detector, resulting in a total of M backlight intensity detection values ​​corresponding to the M frames of vortex light fields.

[0016] The data acquisition card converts the M backlight intensity detection values ​​into voltage signals and transmits them to the computer.

[0017] The computer reconstructs the image of the target object based on the intensity distribution of the M-frame vortex light field and the corresponding M backlight intensity detection values, combined with a single-pixel imaging reconstruction algorithm.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] This invention combines coherent vortex light field synthesis technology with single-pixel imaging to further improve detection range and imaging efficiency. Coherent combining technology for array light sources is an effective way to obtain high-power light sources, ensuring good beam quality and increasing output power, and has broad application prospects in target detection and other fields. Furthermore, based on coherent combining technology, by modulating the amplitude, phase, and polarization characteristics of the beam, a structured light field with a unique distribution can be generated. A vortex light field is a typical type of structured light, possessing characteristics such as a hollow intensity distribution, carrying orbital angular momentum, and a helical phase structure, and is widely used in free-space optical communication, super-resolution optical imaging, combating atmospheric turbulence, and information extraction.

[0020] The basic principle of single-pixel imaging is that a laser beam is modulated to generate a light field with a specific spatial intensity distribution, which is then irradiated onto the target. The reflected light intensity from the target is received by a single-pixel detector and synchronously recorded in a computer via a data acquisition card. Finally, a reconstruction algorithm is used to obtain an image of the object. Therefore, increasing laser energy can effectively improve target detection range, while designing a special illumination field can enhance the quality and efficiency of single-pixel imaging.

[0021] This invention reconstructs images based on vortex light field and backlight intensity detection values, combined with a total variation-based compressed sensing algorithm. Compared with traditional linear iterative algorithms, it can efficiently extract feature information of target objects and improve noise robustness.

[0022] In summary, this invention has the advantages of high output power, high imaging quality, good noise robustness, and long detection range, and is expected to expand its application in the field of long-distance target detection. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of a single-pixel imaging system based on coherent synthesis of vortex light fields from an array of light sources, provided in one embodiment.

[0025] Figure 2 This is a schematic diagram of an array of light sources with 37 channels arranged in a circular pattern in one embodiment;

[0026] Figure 3 These are four different vortex light field patterns in one embodiment. Figure 3 (a) is the first type of vortex light field pattern. Figure 3 (b) shows the second type of vortex light field pattern. Figure 3 (c) shows the third type of vortex light field pattern. Figure 3 (d) is the fourth type of vortex light field pattern;

[0027] Figure 4 This is a target image in one embodiment;

[0028] Figure 5 This is a target image reconstructed using a total variation-based compressed sensing algorithm in one embodiment;

[0029] Explanation of the labels in the diagram:

[0030] 1. Laser; 2. Collimation and beam expansion system; 3. Circular mask; 4. Phase modulation module; 5. Converging lens; 6. Target object; 7. Collecting lens; 8. Single pixel detector; 9. Data acquisition card; 10. Computer. Detailed Implementation

[0031] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] Reference Figure 1 A single-pixel imaging system based on coherent synthesis of vortex light fields from an array of light sources includes:

[0033] The array light source generation module is used to emit an array beam, which consists of multiple sub-beams arranged in a circular distribution.

[0034] Phase modulation module 4 is set in the output optical path of the array light source generation module and is used to perform phase modulation on each sub-beam of the array beam to generate a vortex optical field.

[0035] The converging lens 5 is set in the output light path of the phase modulation module and is used to project the vortex light field onto the target object 6, which is located at the focal plane of the converging lens.

[0036] A collecting lens 7 is placed in the transmitted light path of the target object 6 to collect the transmitted light from the target object 6.

[0037] A single-pixel detector 8 is positioned at the focal plane of the collecting lens 7 to receive the transmitted light converged by the collecting lens 7 and output the backlight intensity detection value.

[0038] The data acquisition card 9 is electrically connected to the single-pixel detector 8 and is used to convert the backlight intensity detection value into an electrical signal.

[0039] Computer 10 is connected to data acquisition card 9 to receive electrical signals and reconstruct the image of the target object based on the intensity distribution of the vortex light field and the detected value of the backlight intensity, combined with a single-pixel imaging reconstruction algorithm.

[0040] The array light source generating module includes a laser 1 and a beam splitting element. Without loss of generality, such as Figure 1As shown, the array light source generation module includes a laser 1, a collimation and beam expansion system 2, and a circular mask 3. The collimation and beam expansion system 2 collimates and expands the light emitted by the laser 1, and the circular mask 3 divides the collimated and expanded light output by the collimation and beam expansion system 2 into multiple sub-beams to form an array beam.

[0041] Phase modulation module 4 employs a spatial light phase modulator, preferably a liquid crystal spatial light phase modulator. The array beam output from the array light source consists of multiple sub-beams arranged in a circular distribution. The array beam includes, from the inside out, […]. There are several sub-rings, namely the 1st sub-ring, the 2nd sub-ring, and so on. A circular ring, Each sub-beam is loaded with a preset special stepped phase through a spatial optical phase modulator to obtain a vortex optical field. Specifically, for the array beam, the first sub-beam... A single ring, which has Path beam, number The first of the rings The phase of the path beam is ,in, , i Represents the fractional-order coefficients, and the phase difference between adjacent unit beams is... By simulating far-field coherent synthesis using a converging lens 5, a vortex light field can be obtained, which is expected to enable rapid refreshing and sampling of the illumination light field, effectively improving imaging efficiency.

[0042] The wavelength of laser 1 is not limited; for example, in one embodiment, laser 1 is a fiber laser operating in the non-visible light band with a wavelength of 1064 nm. The collimating and beam-expanding system 2 consists of two converging lenses with focal lengths of 50 mm and 400 mm, respectively, which collimate and expand the light emitted from laser 1. A circular mask 3 splits the collimated and expanded beam into multiple array beams. Figure 2 The diagram shows a schematic of an array of beams arranged in a circular pattern in one embodiment. The circular mask 3 is an array of 37 sub-beams with a beam aperture of 6 mm, a beam spacing of 7 mm, and a duty cycle of 0.86. The light emitted from the circular mask 3 is the array beam (with consistent frequency and polarization). The array beam is further incident on a liquid crystal spatial light phase modulator. The computer 10 controls the liquid crystal spatial light phase modulator to apply a stepped phase to the array light source sub-beams to generate the desired vortex light field.

[0043] Specifically, the liquid crystal spatial light phase modulator applies a stepped phase to each sub-beam of the array beam to achieve optical field modulation, including:

[0044] An array of beams consisting of 37 sub-beams arranged in a ring-shaped distribution with 3 sub-rings, which, from the inside out, includes a central beam and the first, second, and third sub-rings outside the central beam.

[0045] For the first sub-ring of the array beam, it has Path beam, the first sub-ring of the first sub-circle The phase of the path beam is ,in, i Representing the fractional-order coefficients, the phase difference between the six adjacent unit beams in the first sub-ring is... .

[0046] For the second sub-ring of the array beam, it has Path beam, the second sub-ring of the first The phase of the path beam is ,in, i Representing the fractional-order coefficients, the phase difference between the 12 adjacent unit beams in the second sub-ring is... .

[0047] For the third sub-ring of the array beam, it has Path beam, the third sub-ring The phase of the path beam is ,in, i Representing the fractional-order coefficients, the phase difference between the 18 adjacent unit beams in the third sub-ring is... .

[0048] The vortex light field passes through converging lens 5, at the focal point of which is placed target object 6 (target object 6 is a transmissive object, pattern: three slits). The transmitted light from target object 6 is converged by collecting lens 7, and the light intensity is received at its focal point by single-pixel detector 8. Data acquisition card 9 converts the light intensity signal into a voltage signal and records it in computer 10 for subsequent processing. In addition, the data acquisition card acquires signals by receiving external trigger signals output from the liquid crystal spatial light phase modulator to ensure a one-to-one correspondence between the vortex light field and the detected value.

[0049] A single-pixel imaging method based on coherent synthesis of vortex light fields using an array light source, implemented by computer 10, includes:

[0050] In the data simulation program, combining a preset specific step-type phase, the actual propagation distance, and optical theories such as Fraunhofer diffraction, the vortex light field distribution at the focal plane of the converging lens 5 is calculated as the illumination light field during the reconstruction process. Simultaneously, the transmitted light intensity value after the array light source illuminates the target object 6, collected by the single-pixel detector 8, is obtained. For example... Figure 3 As shown, this is one embodiment of four different vortex light field patterns. Figure 3 (a) is the first type of vortex light field pattern. Figure 3 (b) shows the second type of vortex light field pattern. Figure 3 (c) shows the third type of vortex light field pattern. Figure 3 (d) is the fourth type of vortex light field pattern.

[0051] Based on the system provided in the above embodiments, a single-pixel imaging method based on coherent synthesis of vortex light fields from array light sources is proposed, including the following steps:

[0052] The array light source generation module collimates and outputs an array beam, and the phase modulation module modulates each sub-beam with a preset stepped phase M times. The array beam passes through a converging lens and coherently combines at its focal plane to generate a vortex light field, which illuminates the target object, generating a total of M frames of vortex light fields with different intensity distributions. The transmitted light from the target object is converged by a collecting lens and received by a single-pixel detector, resulting in a total of M backlight intensity detection values ​​corresponding to the M frames of vortex light fields.

[0053] The data acquisition card converts the M backlight intensity detection values ​​into voltage signals and transmits them to the computer.

[0054] The computer reconstructs the image of the target object based on the intensity distribution of the M-frame vortex light field and the corresponding M backlight intensity detection values, combined with a single-pixel imaging reconstruction algorithm.

[0055] Specifically, based on the intensity distribution of the M-frame vortex light field and the corresponding M backlight intensity detection values, combined with a single-pixel imaging reconstruction algorithm, an image of the target object is reconstructed, including:

[0056] (1) The first m Each backlight intensity detection value is represented as:

[0057] ;

[0058] in Indicates the first m One backlight intensity detection value, A two-dimensional image representing the target object. Indicates the first m The intensity distribution of the frame vortex light field, where <·> represents the inner product;

[0059] (2) Construct an optimization model for the compressed sensing algorithm based on total variation:

[0060] ;

[0061] in, c Represents the gradient of the target object. Represents the gradient calculation matrix. This represents the expression used to calculate the total variation of the target object. L The vector consists of the 1-norm and M backlight intensity detection values. The intensity distribution of the M-frame vortex light field constitutes a vector. The two-dimensional image of the target object is straightened according to a fixed scanning sequence. dimensional column vector , This represents the total number of pixels.

[0062] (3) Optimize and solve the optimization model to reconstruct the image of the target object. .

[0063] The optimization algorithm in step (3) is not limited, and the technical solution in this field can be based on conventional optimization algorithms in this field to solve the above optimization model. Optionally, in step (3), the existing Augmented Lagrange multiplier (ALM) method is introduced to optimize the optimization model within the framework of gradient descent in order to solve the problem. L Norm 1 minimization. The optimal solution, i.e., the final reconstructed image of the target object, is derived by adjusting the Lagrange multipliers and balance parameters in the Augmented Lagrange Multiplier Method (ALM). This method utilizes the inherent sparse prior information of natural images and the uncorrelated characteristics of illumination light fields to achieve high-quality image reconstruction under undersampling conditions.

[0064] In one embodiment, the structure of a single-pixel imaging system based on coherent synthesis of vortex light fields from an array of light sources is as follows: Figure 1 As shown, the spatial light phase modulator is a UPOLabs HDSLM80R Plus, and the target object 6 is a transmissive binary object image with a "three-slit" shape, as shown. Figure 4 As shown. The single-pixel detector 8 used is a germanium gain-adjustable detector (Thorlabs PDA-100A2), and the data acquisition card 9 is an ART USB2872. During system operation, the spatial light phase modulator loading phase process and the return light intensity detection process must be completely synchronized. The reconstructed image is as follows. Figure 5 As shown.

[0065] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A single-pixel imaging system based on coherent synthesis of vortex light fields from an array of light sources, characterized in that, include: The array light source generation module is used to emit an array beam, which consists of multiple sub-beams arranged in a circular distribution. The phase modulation module is set in the output optical path of the array light source generation module and is used to perform phase modulation on each sub-beam of the array beam to generate a vortex optical field. A converging lens is placed in the output light path of the phase modulation module to project the vortex light field onto the target object, which is located at the focal plane of the converging lens. A collecting lens is placed in the transmitted light path of the target object to collect the transmitted light from the target object. A single-pixel detector is positioned at the focal plane of the collecting lens to receive the transmitted light converged by the collecting lens and output the backlight intensity detection value. The data acquisition card is electrically connected to the single-pixel detector and is used to convert the backlight intensity detection value into an electrical signal. A computer, connected to a data acquisition card, receives electrical signals and, based on the intensity distribution of the vortex light field and the detected backlight intensity, reconstructs an image of the target object using a single-pixel imaging reconstruction algorithm. The single-pixel imaging method includes the following steps: The array light source generation module collimates the output array beam, and the phase modulation module modulates each sub-beam with a preset stepped phase M times. The array beam passes through a converging lens and coherently combines at its focal plane to generate a vortex light field, which illuminates the target object, generating a total of M frames of vortex light fields with different intensity distributions. The transmitted light from the target object is converged by a collecting lens and received by a single-pixel detector, resulting in a total of M backlight intensity detection values ​​corresponding to the vortex light field. The data acquisition card converts the M backlight intensity detection values ​​into voltage signals and transmits them to the computer. The computer reconstructs an image of the target object based on the intensity distribution of the M-frame vortex light field and the corresponding M backlight intensity detection values, combined with a single-pixel imaging reconstruction algorithm. This includes: (1) The first m Each backlight intensity detection value is represented as: in Indicates the first m One backlight intensity detection value, A two-dimensional image representing the target object. Indicates the first m The intensity distribution of the frame vortex light field, where <·> represents the inner product; (2) Construct an optimization model for the compressed sensing algorithm based on total variation: in, c Represents the gradient of the target object. Represents the gradient calculation matrix. This represents the expression used to calculate the total variation of the target object. L The vector consists of the 1-norm and M backlight intensity detection values. The intensity distribution of the M-frame vortex light field constitutes a vector. The two-dimensional image of the target object is straightened according to a fixed scanning sequence. dimensional column vector , This represents the total number of pixels. (3) Optimize and solve the optimization model to reconstruct the image of the target object. .

2. The single-pixel imaging system based on coherent synthesis of vortex light fields using an array of light sources according to claim 1, characterized in that, The array light source generation module includes a laser and a beam splitter.

3. The single-pixel imaging system based on coherent synthesis of vortex light fields using an array light source according to claim 1, characterized in that, The array light source generation module includes a laser, a collimation and beam expansion system, and a circular mask. The collimation and beam expansion system collimates and expands the light emitted by the laser, and the circular mask divides the collimated and expanded light output by the collimation and beam expansion system into multiple sub-beams to form an array beam.

4. The single-pixel imaging system based on coherent synthesis of vortex light fields from an array light source according to claim 1, 2, or 3, characterized in that, The phase modulation module is a liquid crystal spatial light phase modulator.

5. The single-pixel imaging system based on coherent synthesis of vortex light fields from an array light source according to claim 4, characterized in that, The array beam includes, from the inside out There are several sub-rings, namely the 1st sub-ring, the 2nd sub-ring, and so on. A circular ring, .

6. The single-pixel imaging system based on coherent synthesis of vortex light fields using an array light source according to claim 5, characterized in that, For the array beam A single ring, which has Path beam, number The first of the rings The phase of the path beam is ,in, , i Represents the fractional-order coefficients, and the phase difference between adjacent unit beams is... .

7. The single-pixel imaging system based on coherent synthesis of vortex light fields from an array light source according to claim 1, 2, 3, 5, or 6, characterized in that, In step (3), the augmented Lagrange multiplier method is introduced to optimize the optimization model within the framework of gradient descent in order to solve the problem. L The optimal solution, i.e., the final reconstructed image of the target object, is derived by minimizing the L1 norm and adjusting the Lagrange multipliers and balance parameters in the augmented Lagrange multiplier method. .

Images