Single-pixel imaging method and device based on spatial light modulator and light scattering effect
By using spatial light modulators and light scattering effects in non-line-sight scenarios, a single-pixel imaging method is realized, solving the problem of limited applications of traditional methods in non-line-sight scenarios, and achieving efficient and accurate imaging.
Patent Information
- Application Number
- CN202411817643.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-11
- Publication Date
- 2025-02-18
AI Technical Summary
Traditional single-pixel imaging methods are limited in applications in non-line-of-sight scenarios because they rely on the light reflection effect and the presence of reflected light paths.
Using a single pixel imaging method based on spatial light modulator and light scattering effect, an ultraviolet laser beam is emitted through a laser emitting unit. After processing by an illumination optical processing unit, the spatial light modulator is modulated into a speckle pattern and projected onto the target object. The light is scattered by the light scattering medium, and the optical processing unit at the detection end receives the scattered light, and the light intensity detector detects the light intensity information, and finally restores the image by the information processing unit.
It realizes efficient and accurate imaging without reflecting light paths in non-line-of-sight scenarios, breaking through the limitations of traditional imaging technology and being suitable for open environments.
Smart Images
Figure CN119469408A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of imaging detection, and in particular relates to a single-pixel imaging method and device based on a spatial light modulator and a light scattering effect. Background Art
[0002] Single-pixel imaging refers to the use of a single-pixel detector (photomultiplier tube PMT, etc.) to replace the charge-coupled device CCD or complementary metal oxide semiconductor CMOS array photosensitive element in the traditional imaging system to detect the intensity of light transmitted or reflected by the object. Since the single-pixel detector does not have spatial resolution, the imaging system often loads a series of masks on different types of spatial light modulators to irradiate the modulated light to the object, and then obtains a series of light intensity values corresponding to different masks from the single-pixel detector to restore the image of the object.
[0003] In non-line-of-sight scenarios, traditional single-pixel imaging methods and devices need to construct a reflective light path. However, in actual scenarios, the object to be detected and the existing single-pixel imaging device are unlikely to form a strict reflective light path. Therefore, traditional single-pixel imaging methods and devices that only use light reflection effects severely limit the application of traditional single-pixel imaging in non-line-of-sight scenarios. Therefore, the present invention proposes a single-pixel imaging method and device based on a spatial light modulator and light scattering effects. Summary of the invention
[0004] In order to solve the above technical problems, the present invention proposes a single-pixel imaging method and device based on a spatial light modulator and light scattering effect to solve the problems existing in the above-mentioned prior art.
[0005] To achieve the above object, the present invention provides a single-pixel imaging device based on a spatial light modulator and a light scattering effect, comprising:
[0006] Laser emission unit, illumination end optical processing unit, spatial light modulator, detection end optical processing unit, light intensity detector and information processing unit;
[0007] Wherein, the laser emitting unit is used to emit an ultraviolet laser beam;
[0008] The illumination end optical processing unit is used to process the laser beam so that the ultraviolet laser beam is completely irradiated onto the spatial light modulator;
[0009] The spatial light modulator is used to form the laser beam into a speckle pattern;
[0010] The optical processing unit at the detection end is used to receive scattered light of the speckle pattern after being scattered;
[0011] The light intensity detector is used to detect the scattered light to obtain light intensity information;
[0012] The information processing unit is used to receive the light intensity information and restore the image of the target object based on the light intensity information.
[0013] The present invention also provides a single-pixel imaging method based on a spatial light modulator and a light scattering effect, which is used to implement a single-pixel imaging device based on a spatial light modulator and a light scattering effect. The single-pixel imaging method comprises the following steps:
[0014] Modulating the ultraviolet laser beam to obtain a four-step phase-shifted sinusoidal speckle pattern;
[0015] Irradiating the four-step phase-shifted sinusoidal speckle pattern onto a target object and scattering it through a scattering medium in the air to obtain light intensity information;
[0016] Processing the light intensity information to obtain Fourier spectrum data;
[0017] An image of the target object is obtained by reconstructing the image based on the Fourier spectrum data.
[0018] Optionally, the process of modulating the ultraviolet laser beam to obtain a four-step phase-shifted sinusoidal speckle pattern includes:
[0019] The laser emitting unit emits an ultraviolet laser beam;
[0020] The ultraviolet laser beam is irradiated onto the spatial light modulator via the optical processing unit at the illumination end;
[0021] The spatial light modulator performs light beam modulation according to a phase sequence to obtain sinusoidal speckle patterns with different phases.
[0022] Optionally, the process of acquiring sinusoidal speckle patterns of different phases further includes calculating a Fourier matrix, wherein the calculation formula of the Fourier matrix is:
[0023]
[0024] In the formula, represents the phase, f x 、f y Represent the spatial frequencies of the image in the x and y dimensions respectively, and m and n represent the image pixels.
[0025] Optionally, the calculation formula for obtaining light intensity information is:
[0026] S φ (f x ,f y )=∫∫P φ (x,y;f x ,f y )O(x,y)dxdy
[0027] In the formula, Sφ (f x ,f y ) represents the light intensity information, and O(x,y) represents the two-dimensional information of the target object itself.
[0028] Optionally, the process of processing the light intensity information to obtain Fourier spectrum data includes:
[0029] The Fourier coefficients are obtained by calculating the detected light intensity information;
[0030] An inverse Fourier transform operation is performed on the Fourier coefficients to obtain an image of the target object.
[0031] Optionally, the expression for calculating the Fourier coefficient is:
[0032]
[0033] In the formula, represents Fourier transform, k represents parameters related to PMT gain, etc., F(f x ,f y ) means (f x ,f y ) frequency.
[0034] Optionally, the expression for calculating the reconstructed image of the target object is:
[0035]
[0036] In the formula, O m×n (x,y) represents the reconstructed image of the target object.
[0037] Compared with the prior art, the present invention has the following advantages and technical effects:
[0038] The present invention provides a single-pixel imaging device based on a spatial light modulator and light scattering effect. The device emits an ultraviolet laser beam through a laser emitting unit, which is processed by an optical processing unit at the illumination end and modulated into a speckle pattern by a spatial light modulator, and then projected onto a target object. After the speckle pattern is scattered by the object, the scattered light is received by the optical processing unit at the detection end, the light intensity detector detects the light intensity information, and finally the image is restored by the information processing unit. The device breaks through the dependence of traditional imaging technology on the reflected light path, is particularly suitable for non-line-of-sight scenarios, and realizes efficient and accurate imaging of target objects in open environments, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0039] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:
[0040] Figure 1 A diagram of a single-pixel imaging device based on a spatial light modulator and light scattering effect according to an embodiment of the present invention;
[0041] Marking description: 1. Laser emitting unit; 2. Optical processing unit at the illumination end; 3. Spatial light modulator; 4. Target object; 5. Scattering media such as gas molecules and suspended particles in the air; 6. Optical processing unit at the detection end; 7. Light intensity detector; 8. Information processing unit. DETAILED DESCRIPTION
[0042] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.
[0043] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.
[0044] Embodiment 1
[0045] In view of the problem that the existing single-pixel imaging technology relies on light reflection effect and reflection light path, a single-pixel imaging method and device based on spatial light modulator and light scattering effect is proposed, which provides a new solution for the application of single-pixel imaging in non-line-of-sight scenarios. Specifically, the following steps are included:
[0046] Step 1: If Figure 1 As shown, the laser emitting unit 1 emits an ultraviolet laser beam, and passes through the illumination end optical processing unit 2 to ensure that the laser beam is completely irradiated onto the spatial light modulator 3, thereby forming a series of modulated speckle patterns, and by setting the spatial light modulator 3, these speckle patterns are projected onto the target object at a certain frequency and in a specific order.
[0047] Step 2: The speckle light modulated by the spatial light modulator 3 is irradiated on the target object 4 and scattered by the scattering medium 5 such as gas molecules and suspended particles in the space. Then the scattered light passes through the optical processing unit 6 at the detection end and is detected by the light intensity detector 7.
[0048] Step 3: The information processing unit 8 processes the light intensity information detected by the light intensity detector 7 and restores the image of the target object.
[0049] As a specific implementation of this embodiment, a single-pixel imaging device based on a spatial light modulator and a light scattering effect includes a laser emitting unit 1, an illumination end optical processing unit 2 (such as a beam expander and a collimator, etc.), a spatial light modulator 3 (such as a digital micromirror device DMD, etc.), a target object 4, a detection end optical processing unit 6 (such as a focusing lens, etc.), a light intensity detector 7 (such as a photomultiplier tube PMT, etc.), and an information processing unit 8 (such as a computer, etc.).
[0050] The laser emitting unit 1 is used to emit an ultraviolet laser beam; the optical processing unit 2 at the illumination end is used to process the ultraviolet laser beam so that the ultraviolet laser beam is completely irradiated onto the spatial light modulator 3; the spatial light modulator 3 is used to modulate the laser beam into a speckle pattern; the optical processing unit 6 at the detection end is used to receive scattered light after the speckle pattern is scattered; the light intensity detector 7 is used to detect the scattered light to obtain light intensity information; the information processing unit 8 is used to receive the light intensity information and restore the imaging of the target object based on the light intensity information.
[0051] Furthermore, taking an ultraviolet laser light source with strong scattering characteristics and a spatial light modulator DMD as an example, the ultraviolet laser beam is modulated by the Fourier matrix at the same time, and a four-step phase-shifted sinusoidal speckle pattern is generated by the DMD. The object is illuminated by the four-step phase-shifted sinusoidal light, which is then irradiated onto the target object and then scattered by the scattering medium. The Fourier spectrum is obtained by collecting the light intensity distribution of the detector, and finally the image is reconstructed using the Fourier spectrum, thus realizing single-pixel imaging technology that does not require the array-type photosensitive elements in the traditional imaging system.
[0052] That is, the ultraviolet laser beam is modulated to obtain a four-step phase-shifted sinusoidal speckle pattern; the four-step phase-shifted sinusoidal speckle pattern is irradiated onto the target object and scattered by the scattering medium in the air to obtain light intensity information; the light intensity information is processed to obtain Fourier spectrum data; and the image is reconstructed based on the Fourier spectrum data to obtain the image of the target object.
[0053] The proposed single pixel imaging method will be described in detail below. The specific implementation includes the following steps:
[0054] Step 1: The laser emitting unit 1 emits an ultraviolet laser beam; the ultraviolet laser beam is irradiated onto the spatial light modulator 3 through the illumination end optical processing unit 2; the spatial light modulator 3 modulates the beam according to the phase sequence to obtain sinusoidal speckle patterns with different phases.
[0055] The ultraviolet laser beam first passes through a beam expander and a collimator, and then is projected onto a digital micromirror device to realize a four-step phase-shifted sinusoidal light.
[0056] From the Fourier analysis theory, we know that any continuous signal can be expressed as a linear combination of Fourier bases, and two-dimensional image signals can be expressed in the form of spatial frequency using two-dimensional Fourier transform. Therefore, in Fourier transform, a trigonometric function array is selected as a set of orthogonal functions to adjust the intensity of light irradiated on different parts of the sample.
[0057] For a rectangular image of m×n pixels, let f x 、f y Represent the spatial frequencies of the x- and y-dimensions of the image respectively, and the resulting Fourier matrix can be expressed as:
[0058]
[0059] in, Indicates the phase. Specifically, different phase values need to be set at the same frequency to solve and obtain the Fourier coefficients.
[0060] The four-step phase shift method requires the use of four mask matrices P0, P1, P2 with different phases and the same spatial frequency. π / 2 , P π , P 3π / 2 Modulate the target image, which means that for a rectangular image of m×n pixels, 4mn sampling times are required to fully restore its image information.
[0061] Step 2: Assume that the four spatial frequencies are (f x ,f y )'s mask matrix P0, P π / 2 , P π , P 3π / 2 , the four have the same frequency and only different phases.
[0062] Change (f x ,f y ) and repeat the above steps 4mn times to obtain the Fourier spectrum of the rectangular image of m×n pixels.
[0063] After the sinusoidal speckle pattern modulated by the set DMD is irradiated onto the target object, the ultraviolet light carrying the object information is scattered by the air, that is, the photons are scattered once or multiple times before they can be gathered by the converging lens and received by the PMT.
[0064] Step 3: Calculate the detected light intensity information to obtain Fourier coefficients; perform inverse Fourier transform on the Fourier coefficients to obtain an image of the target object.
[0065] The detection value of PMT can be expressed as:
[0066] S φ (f x ,f y )=∫∫Pφ (x,y;f x ,f y )O(x,y)dxdy (2)
[0067] S φ (f x ,f y ) represents the light intensity information, and O(x,y) represents the two-dimensional information of the target object itself.
[0068] In order to obtain (f x ,f y ) frequency, for four mask matrices P0, P π / 2 , P π , P 3π / 2 , PMT obtains four measurement values I1, I2, I3, I4. Next, the computer first performs the following calculations on these four values:
[0069] F(f x ,f y )=(I2-I1)+j(I4-I3) (3)
[0070] Let k be a parameter related to PMT gain, etc. represents Fourier transform, then (f x ,f y ) frequency can be expressed as:
[0071]
[0072] After 4 minutes of data collection, the computer performs an inverse Fourier transform on the obtained spectrum. The reconstructed image, that is, the reconstructed rectangular image of m×n pixels is obtained as follows:
[0073]
[0074] O m×n (x,y) represents the reconstructed image of the target object.
[0075] The present invention proposes to use a spatial light modulator and the scattering effect of light to achieve single-pixel imaging in a scene without a reflective surface, so that single-pixel imaging can be applied to open non-line-of-sight scenes.
[0076] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.
Claims
1. A single-pixel imaging device based on a spatial light modulator and light scattering effect, characterized in that: include: A laser emitting unit (1), an illumination end optical processing unit (2), a spatial light modulator (3), a detection end optical processing unit (6), a light intensity detector (7) and an information processing unit (8); Wherein, the laser emitting unit (1) is used to emit an ultraviolet laser beam; The illumination end optical processing unit (2) is used to process the ultraviolet laser beam so that the ultraviolet laser beam is completely irradiated onto the spatial light modulator (3); The spatial light modulator (3) is used to form the laser beam into a speckle pattern; The detection end optical processing unit (6) is used to receive scattered light of the speckle pattern after being scattered; The light intensity detector (7) is used to detect the scattered light to obtain light intensity information; The information processing unit (8) is used to receive the light intensity information and restore the image of the target object based on the light intensity information.
2. A single pixel imaging method based on a spatial light modulator and light scattering effect, characterized in that: The single-pixel imaging device based on a spatial light modulator and a light scattering effect according to claim 1 is used to implement the single-pixel imaging method, which comprises the following steps: Modulating the ultraviolet laser beam to obtain a four-step phase-shifted sinusoidal speckle pattern; Irradiating the four-step phase-shifted sinusoidal speckle pattern onto a target object and scattering it through a scattering medium in the air to obtain light intensity information; Processing the light intensity information to obtain Fourier spectrum data; An image of the target object is obtained by reconstructing the image based on the Fourier spectrum data.
3. The single pixel imaging method based on spatial light modulator and light scattering effect according to claim 2, characterized in that: The process of modulating the ultraviolet laser beam to obtain a four-step phase-shifted sinusoidal speckle pattern includes: The laser emitting unit (1) emits an ultraviolet laser beam; The ultraviolet laser beam is irradiated onto the spatial light modulator (3) via the illumination end optical processing unit (2); The spatial light modulator (3) performs light beam modulation according to a phase sequence to obtain sinusoidal speckle patterns with different phases.
4. The single pixel imaging method based on spatial light modulator and light scattering effect according to claim 3, characterized in that: The process of obtaining sinusoidal speckle patterns of different phases also includes calculating the Fourier matrix, wherein the calculation formula of the Fourier matrix is: In the formula, represents the phase, f x 、f y Represent the spatial frequencies of the image in the x and y dimensions respectively, and m and n represent the image pixels.
5. The single pixel imaging method based on spatial light modulator and light scattering effect according to claim 4, characterized in that: The calculation formula for obtaining light intensity information is: S φ (f x ,f y )=∫∫P φ (x,y;f x ,f y )O(x,y)dxdy In the formula, S φ (f x , f y ) represents the light intensity information, and O(x, y) represents the two-dimensional information of the target object itself.
6. The single pixel imaging method based on spatial light modulator and light scattering effect according to claim 5, characterized in that: The process of processing the light intensity information to obtain Fourier spectrum data includes: The Fourier coefficients are obtained by calculating the detected light intensity information; An inverse Fourier transform operation is performed on the Fourier coefficients to obtain an image of the target object.
7. The single pixel imaging method based on spatial light modulator and light scattering effect according to claim 6, characterized in that: The expression for calculating the Fourier coefficient is: In the formula, represents Fourier transform, k represents parameters related to PMT gain, etc., F(f x , f y ) means (f x , f y ) frequency.
8. The single pixel imaging method based on spatial light modulator and light scattering effect according to claim 7, characterized in that: The expression for calculating the reconstructed image of the target object is: In the formula, O m×n (x,y) represents the reconstructed image of the target object.