A compressive correlation imaging method and system with large field of view imaging capability

Abstract

The application discloses a compressive correlation imaging method and system with large field of view imaging capability, and belongs to the technical field of space active imaging. The method uses a fisheye lens 13 and a CCD camera 14 to perform fast large field of view imaging on an imaging area, and obtains a large field of view imaging result Fig; N existing regions {A1, A2,..., A i ,…,A N} of the measured objects are determined according to the imaging result Fig; compressive correlation imaging is performed in the regions {A1, A2,..., A i ,…,A N}, and N imaging results {fig1, fig2,..., fig i ,…,fig N} are obtained. The application has the beneficial effects that: (1) the whole to-be-measured region is coarsely imaged by using large field of view imaging, compressive correlation imaging is performed only on the regions where the objects exist, the imaging time can be shortened, the imaging efficiency is improved, and the imaging region is not repeatedly scanned or missed; (2) the signal-to-noise ratio of echo signals is improved, and the detection distance is improved; and (3) the staring imaging time can be shortened by using a compressive correlation imaging reconstruction algorithm, and the imaging efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of space active imaging technology, and in particular to a compressed correlation imaging active imaging method and system that takes into account both large field-of-view imaging capabilities. Technical Background

[0002] In the field of space imaging, most space targets are far away, scattered, and often faint. Therefore, space reconnaissance systems should simultaneously possess the characteristics of small aperture, high imaging resolution, large field of view, and high sensitivity. Geometric optics imaging methods require large-aperture optical systems to achieve high imaging resolution, and are significantly affected by stray light from the space background, limiting imaging sensitivity and severely restricting the imaging applications of space reconnaissance systems. Correlation imaging technology, on the other hand, has advantages such as small aperture, high sensitivity, strong anti-interference capabilities, single-pixel imaging, high theoretical resolution, and non-local imaging, showing promising application prospects in space reconnaissance. However, since correlation imaging systems require point-by-point scanning to confirm the existence of target objects and sufficient time to stare at the imaging area to acquire enough target signals for image reconstruction, large field-of-view imaging methods based solely on correlation imaging have excessively low imaging efficiency, making wide-area space imaging applications difficult.

[0003] To ensure that active imaging systems can achieve wide-area and efficient imaging while retaining the traditional advantages of correlated imaging systems, a compressed correlated imaging method and system that takes into account large field-of-view imaging capabilities is needed. Summary of the Invention

[0004] To address the aforementioned problems, this invention discloses a correlation imaging system that also possesses wide field-of-view imaging capabilities, comprising the following components arranged sequentially:

[0005] Polarized laser 1, used to emit a linearly polarized laser beam;

[0006] Mirror 2 is used to change the direction of light propagation;

[0007] Half-wave plate 3 is used to control the laser polarization direction;

[0008] Beam expander 4 is used to control the spot size covering the spatial light modulator;

[0009] Spatial light modulator 5 is used to modulate the phase of the laser beam;

[0010] Fast-reflecting mirror 6 is used to control the laser scanning area;

[0011] Aperture 7 is used to filter out ambient light to prevent it from affecting the internal optical path;

[0012] Telescope 8 is used to receive laser echo signals;

[0013] 9 beam splitter is used to split the echo into two paths: active imaging and correlated imaging.

[0014] Narrow-band pass filter 10 is used to filter out light other than laser echo, and its passing wavelength is consistent with the wavelength of the selected laser.

[0015] Convex lens 11 is used to focus the laser beam;

[0016] Optical power meter 12 is used to receive the total energy of the laser echo and convert the optical signal into a processable electrical signal.

[0017] Fisheye lens 13, used for receiving light fields in large field-of-view imaging;

[0018] CCD camera 14 is used for large field-of-view imaging and active imaging, converting light signals into processable electrical signals;

[0019] A data acquisition card is used to transmit the signals acquired by the optical power meter to a computer.

[0020] The computer is used to receive signals acquired by the digital acquisition card, output control signals for the fast-reflection mirror, load modulated images onto the spatial light modulator, and run light intensity algorithms and compressed correlation imaging reconstruction algorithms in the area to be measured to obtain imaging results.

[0021] The linearly polarized laser beam emitted by the polarization laser 1 is redirected by the reflector 2 and then enters the half-wave plate 3. After the half-wave plate 3 controls the polarization direction of the laser, the beam passes through the beam expander 4 so that the beam size covers the spatial light modulator and then enters the spatial light modulator 5. The phase of the laser beam is modulated by the spatial light modulator 5 and then the laser scanning area is controlled by the fast reflector 6. After the beam passes through the aperture 7 to illuminate the target and returns, it enters the telescope 8. The beam is split into two beams by the beam splitter 9. One beam passes through the narrow bandpass filter 10 to filter out stray light of wavelengths other than the laser wavelength and is focused by the convex lens 11 onto the detection surface of the optical power meter 12. The other beam is focused by the convex lens 11 and enters the CCD camera 11 after the optical path is changed by the reflector 2 to ensure that the object exists in the associated imaging field of view.

[0022] Based on the above imaging system, this invention discloses a compressed correlation imaging method that also takes into account the large field of view imaging capability. The method specifically includes the following steps:

[0023] Step S1: Use the fisheye lens 13 and CCD camera 14 to perform rapid large field-of-view imaging of the imaging area and obtain the large field-of-view imaging result Fig.

[0024] Step S2: Based on the imaging results Fig, determine the regions {A1, A2, ..., A} of the N measured objects. i ,…,A N};

[0025] Step S3: In {A1,A2,…,A…i ,…,A N Compressed correlation imaging is performed within the region to obtain N imaging results {fig1,fig2,…,fig}. i ,…,fig N}

[0026] Furthermore, in step S3, region A i The compressed correlation imaging results are obtained within (i = 0, 1, ..., N) fig i The steps are as follows:

[0027] Step S31: Modulate M different patterns g r (x,y), loaded onto spatial light modulator 5, then according to the principle of spatial light modulator, the phase of the light field modulation is Φ. r (x,y);

[0028] Step S32: Irradiate the spatial light modulator 5 onto the modulation surface, so that the laser is reflected to obtain a phase-modulated laser. The phase-modulated laser is then diffracted and irradiated onto region A. i The light intensity {I1,I2,…,I} at the measured object is calculated based on diffraction. r ,…,I M};

[0029] Step S33: Use optical power meter 12 to receive M return optical signals {b1,b2,…,b} corresponding to M modulation patterns reflected by the object under test. r ,…,b M};

[0030] Step S34: Based on the m light intensities {I1, I2, ..., I...} at the measured object obtained in step 22... r ,…,I M} and the corresponding returned optical signals {b1,b2,…,b r ,…,b M Region A is obtained through a compressed correlation imaging reconstruction algorithm. i Fig of associated imaging results i ;

[0031] Step S35: Use the fast-reflection mirror 6 to control the laser to switch to another unscanned A. i+1 Correlated imaging of the region.

[0032] After repeating the S31-S35 correlation imaging process N times, sampling of all areas where the measured object exists is completed.

[0033] Furthermore, the modulation pattern g described in step S31 r(x,y) is an image composed of pixels with gray levels randomly ranging from [0,255], where the gray levels correspond to the modulation phase of the spatial light modulator, i.e.

[0034] Φ r (x,y)=kg r (x,y)f(x,y)

[0035] Where k represents the modulation depth of the spatial light modulator, and f(x,y) represents the geometric function of the spatial light modulator.

[0036] Furthermore, the specific calculation method for obtaining the light intensity at the measured object based on diffraction in step S32 is as follows:

[0037] Let the laser field be E (in) The light field after phase modulation by the spatial light modulator is:

[0038] U0(x0,y0)=E (in) e jφ(x0,y0)

[0039] Where j represents the imaginary unit, Φ represents the optical field modulation phase as described in step S31, and (x0, y0) represents the horizontal and vertical coordinates at the modulator. Fresnel diffraction calculations show that the optical field distribution at a distance z from the liquid crystal spatial light modulator is...

[0040]

[0041] Where λ is the wavelength of light and k is the wave vector. Then, based on diffraction calculations, the light intensity distribution at the measured object at a distance L from the light source is:

[0042] I r (x,y,z=L)=|U r (x,y,z=L)| 2

[0043] Where (x,y) represents the horizontal and vertical coordinates of the plane containing the object to be measured.

[0044] Furthermore, the compressed correlation imaging reconstruction algorithm in step S34 can be expressed as:

[0045] Define the discretized light intensity distribution function projected onto the target at the r-th measurement as I. r (x,y)

[0046]

[0047] Each value in the matrix represents the light intensity at the target light field obtained through simulation using the light field model. This intensity is then expanded row-wise into a one-dimensional vector.

[0048]

[0049] After sampling the object M times with the measurement light, the one-dimensional vectors of light intensity at the M target light fields obtained from the simulation are stored as an M-dimensional column vector, which serves as the measurement matrix:

[0050]

[0051] Therefore, the measurement matrix has a size of M×nm, with one row representing the light intensity values ​​of all pixels at the target light field obtained by simulation in one measurement, and one column representing the light intensity values ​​at a certain coordinate point (x,y) in M ​​measurements.

[0052] The results obtained by the bucket detector can be expressed as:

[0053] B M×1 =Φ M×nm T nm×1

[0054] The result of applying discrete cosine transform to T is:

[0055] B M×1 =Φ M×nm Ψ nm×nm s nm×1

[0056] Among them, Ψ nm×nm It is a sparse matrix that is defined and known.

[0057] Solving s using the orthogonal matching tracking algorithm nm×1 And according to T nm×1 =Ψ nm×nm s nm×1 The final solution yields T. nm×1 Then T nm×1 Transformed into T n×m This refers to the reflectance function T(x,y) of the object under test. After normalizing T(x,y), the correlated imaging result fig can be obtained. i .

[0058] Furthermore, the step of switching the laser irradiation area using the fast-reflecting mirror 6 in step S34 specifically includes:

[0059] Based on the large field-of-view imaging results (Fig), the regions {A1, A2, ..., A} of N measured objects are determined using computer calculations. i ,…,A N The corresponding fast-reflecting mirror angle is determined, and then the control voltage corresponding to the fast-reflecting mirror angle is input to the fast-reflecting mirror via a computer to achieve the switching of the laser irradiation area.

[0060] The beneficial effects of this invention are:

[0061] (1) Using large field-of-view imaging to perform coarse imaging of the entire area to be measured, and only performing compressed correlation imaging on the area where objects exist, can shorten the imaging time, improve imaging efficiency, and avoid repeated scanning or omission of imaging areas.

[0062] (2) Since the spatial light modulator only modulates the laser phase, it can effectively avoid light intensity and energy loss, improve the signal-to-noise ratio of the echo signal and increase the detection distance.

[0063] (3) Since the compressed correlation imaging reconstruction algorithm can achieve better resolution than the commonly used correlation imaging reconstruction algorithm under the same number of modulated images, the compressed correlation imaging reconstruction algorithm can reduce staring imaging time and improve imaging efficiency. Attached Figure Description

[0064] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the description of the embodiments or the prior art are introduced below.

[0065] Figure 1 A flowchart illustrating a compressed correlation imaging method that balances large field-of-view imaging capability is shown in an embodiment of the present invention.

[0066] Figure 2 This invention illustrates a flowchart of compressed correlation imaging of the region where any object under test exists, as shown in an embodiment of the invention.

[0067] Figure 3 This invention illustrates a schematic diagram of the optical path for compressed correlation imaging of any region where a measured object exists, according to an embodiment of the present invention.

[0068] Figure 4 A schematic diagram of the modulated image is shown;

[0069] Figure 5 A schematic diagram of the large field-of-view imaging results is shown;

[0070] Figure 6a A schematic diagram of the object to be imaged is shown;

[0071] Figure 6b This demonstrates the reconstruction of the image using a compressed correlation imaging algorithm. Figure 5 Simulation image of the imaging.

[0072] Figure 6c This demonstrates the reconstruction of the image using a commonly used correlation imaging algorithm. Figure 5 Simulation image of the imaging.

[0073] Figure 7 A schematic diagram of the overall structure of a compressed correlation imaging system that takes into account the large field of view imaging capability in an embodiment of the present invention is shown.

[0074] Figure 8A schematic diagram of the components of a compressed correlation imaging system that combines large field-of-view imaging capability is shown in an embodiment of the present invention. Detailed Implementation

[0075] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0076] This embodiment discloses a correlation imaging system that also takes into account a large field of view imaging capability, such as... Figure 7 As shown, the components within the system are as follows Figure 8 As shown, including those set sequentially

[0077] Polarized laser 1, used to emit a linearly polarized laser beam;

[0078] Mirror 2 is used to change the direction of light propagation;

[0079] Half-wave plate 3 is used to control the laser polarization direction;

[0080] Beam expander 4 is used to control the spot size covering the spatial light modulator;

[0081] Spatial light modulator 5 is used to modulate the phase of the laser beam;

[0082] Fast-reflecting mirror 6 is used to control the laser scanning area;

[0083] Aperture 7 is used to filter out ambient light to prevent it from affecting the internal optical path;

[0084] Telescope 8 is used to receive laser echo signals;

[0085] 9 beam splitter is used to split the echo into two paths: active imaging and correlated imaging.

[0086] Narrow-bandpass filter 10 is used to filter out light other than laser echo;

[0087] Convex lens 11 is used to focus the laser beam;

[0088] Optical power meter 12 is used to receive the total energy of the laser echo and convert the optical signal into a processable electrical signal.

[0089] Fisheye lens 13, used for receiving light fields in large field-of-view imaging;

[0090] CCD camera 14 is used for large field-of-view imaging and active imaging, converting light signals into processable electrical signals;

[0091] A data acquisition card is used to transmit the signals acquired by the optical power meter to a computer.

[0092] The computer is used to receive signals acquired by the digital acquisition card, output control signals for the fast-reflection mirror, load modulated images onto the spatial light modulator, and run light intensity algorithms and compressed correlation imaging reconstruction algorithms in the area to be measured to obtain imaging results.

[0093] The linearly polarized laser beam emitted by the polarization laser 1 is redirected by the reflector 2 and then enters the half-wave plate 3. After the half-wave plate 3 controls the polarization direction of the laser, the beam passes through the beam expander 4 so that the beam size covers the spatial light modulator and then enters the spatial light modulator 5. The phase of the laser beam is modulated by the spatial light modulator 5 and then the laser scanning area is controlled by the fast reflector 6. After the beam passes through the aperture 7 to illuminate the target and returns, it enters the telescope 8. The beam is split into two beams by the beam splitter 9. One beam passes through the narrow bandpass filter 10 to filter out stray light of wavelengths other than the laser wavelength and is focused by the convex lens 11 onto the detection surface of the optical power meter 12. The other beam is focused by the convex lens 11 and enters the CCD camera 11 after the optical path is changed by the reflector 2 to ensure that the object exists in the associated imaging field of view.

[0094] Based on the above-described device, this embodiment discloses a compressed correlation imaging method that also considers large field-of-view imaging capabilities, such as... Figure 1 As shown, the method specifically includes the following steps:

[0095] Step S1: Perform rapid large field-of-view imaging using the imaging area of ​​the large field-of-view imaging system to obtain the large field-of-view imaging result Fig, as shown. Figure 5 As shown;

[0096] Step S2: Based on the imaging results Fig, determine the regions {A1, A2, ..., A} of the N measured objects. i ,…,A N},like Figure 5 The area highlighted by the dashed line is shown below.

[0097] Step S3: In {A1,A2,…,A… i ,…,A N Compressed correlation imaging is performed within the region to obtain N imaging results {fig1,fig2,…,fig}. i ,…,fig N}

[0098] Furthermore, step S3 in region A i The compressed correlation imaging results obtained within (i = 0, 1…N) are shown in figure. i The specific steps are as follows: Figure 2 As shown, the specific schematic diagram is as follows: Figure 3 As shown:

[0099] Step S31: [The following text appears to be a separate, unrelated section:] ... Figure 4 The M different modulation patterns g shown r If (x, y) is loaded onto a spatial light modulator, then according to the principle of spatial light modulators, the phase of the light field modulation is Φ. r (x,y);

[0100] Step S32: Irradiate the spatial light modulator onto the modulation surface, so that the laser is reflected to obtain a phase-modulated laser. The phase-modulated laser is then diffracted and irradiated onto region A. i The light intensity at the object being measured is calculated based on diffraction. In this embodiment, the object being imaged is, for example,... Figure 6a As shown;

[0101] Step S33: Use an optical power meter to receive the M return optical signals {b1,b2,…,b...} corresponding to the M modulation patterns reflected by the object under test. r ,…,b M In this embodiment, M is set to 2500;

[0102] Step S34: Based on the M light intensities {I1, I2, ..., I...} at the measured object calculated in step 32... r ,…,I M} and the corresponding returned optical signals {b1,b2,…,b r ,…,b M Region A is obtained through a compressed correlation imaging reconstruction algorithm. i Fig of associated imaging results i like Figure 6b As shown;

[0103] Step S35: Use a fast-reflection mirror to control the laser to switch to another unscanned A. i+1 Correlated imaging of the region.

[0104] After repeating the S31-S35 correlation imaging process N times, sampling of all areas where the measured object exists is completed.

[0105] Furthermore, the modulation pattern g described in step S31 r (x, y) is an image composed of pixels with gray levels randomly ranging from [0, 255], such as... Figure 4 As shown, its grayscale corresponds to the modulation phase of the spatial light modulator, i.e.

[0106] Φ r (x,y)=kg r (x,y)f(x,y)

[0107] Where k represents the modulation depth of the spatial light modulator, and f(x,y) represents the geometric function of the spatial light modulator.

[0108] Furthermore, the light intensity at the object being measured is calculated based on diffraction in step S32, and its optical path diagram is shown below. Figure 3 As shown, the specific calculation method is as follows:

[0109] Let the laser field be E (in) The light field after phase modulation by the spatial light modulator is:

[0110] U0(x0,y0)=E (in) e jφ(x0,y0)

[0111] Where j represents the imaginary unit, Φ represents the optical field modulation phase as described in step S31, and (x0, y0) represents the horizontal and vertical coordinates at the modulator. Fresnel diffraction calculations show that the optical field distribution at a distance z from the liquid crystal spatial light modulator is...

[0112]

[0113] Where λ is the wavelength of light and k is the wave vector. Then, based on diffraction calculations, the light intensity distribution at the measured object at a distance L from the light source is:

[0114] I r (x,y,z=L)=|U r (x,y,z=L)| 2

[0115] Where (x,y) represents the horizontal and vertical coordinates of the plane containing the object to be measured.

[0116] Furthermore, the compressed correlation imaging reconstruction algorithm in step S34 can be expressed as:

[0117] Define the discretized light intensity distribution function projected onto the target at the r-th measurement as I. r (x,y)

[0118]

[0119] Each value in the matrix represents the light intensity at the target light field obtained through simulation using the light field model. This intensity is then expanded row-wise into a one-dimensional vector.

[0120]

[0121] After sampling the object M times with the measurement light, the one-dimensional vectors of light intensity at the M target light fields obtained from the simulation are stored as M-dimensional column vectors, which serve as the measurement matrix:

[0122]

[0123] Therefore, the measurement matrix has a size of M×nm, with one row representing the light intensity values ​​of all pixels at the target light field obtained by simulation in one measurement, and one column representing the light intensity values ​​at a certain coordinate point (x,y) in M ​​measurements.

[0124] The results obtained by the bucket detector can be expressed as:

[0125] B M×1 =Φ M×nm T nm×1

[0126] The result of applying discrete cosine transform to T is:

[0127] B M×1 =Φ M×nm Ψ nm×nm s nm×1

[0128] Among them, Ψ nm×nm It is a sparse matrix that is defined and known.

[0129] Solving s using the orthogonal matching tracking algorithm nm×1 And according to T nm×1 =Ψ nm×nm s nm×1 The final solution yields T. nm×1 Then T nm×1 Transformed into T n×m This refers to the reflectance function T(x,y) of the object under test. After normalizing T(x,y), the correlated imaging result fig can be obtained. i .

[0130] Furthermore, the step of switching the laser irradiation area using a fast-reflecting mirror in step S34 specifically includes:

[0131] Based on the large field-of-view imaging results (Fig), the regions {A1, A2, ..., A} of N measured objects are determined using computer calculations. i ,…,A N The corresponding fast-reflecting mirror angle is determined, and then the control voltage corresponding to the fast-reflecting mirror angle is input to the fast-reflecting mirror via a computer to achieve the switching of the laser irradiation area.

[0132] For example, Figure 6a The image in the middle is a pre-defined target for imaging. Under the condition of M=2500, the imaging effect of the compressed correlation imaging method disclosed in this invention is as follows: Figure 6b As shown, to compare the imaging effects of compressed correlation imaging, under the same M sets of input data, the imaging structures obtained by commonly used correlation imaging reconstruction algorithms are as follows: Figure 6cAs shown in the image results, the compressed correlation imaging algorithm achieves better resolution imaging results compared to the commonly used correlation imaging reconstruction algorithm.

Claims

1. A correlation imaging system that also possesses large field-of-view imaging capabilities, characterized in that, Including the following settings in sequence: A polarized laser (1) is used to emit a linearly polarized laser beam; A reflector (2) is used to change the direction of light propagation; A half-wave plate (3) is used to control the laser polarization direction; Beam expander (4) is used to control the size of the light spot covering the spatial light modulator; Spatial light modulator (5) is used to modulate the phase of the laser beam; Quick-reflection mirror (6) is used to control the laser scanning area; Aperture (7) is used to filter out ambient light to avoid affecting the internal optical path; Telescope (8) is used to receive laser echo signals; The beam splitter (9) is used to split the echo into two paths: active imaging and correlated imaging. A narrow-band pass filter (10) is used to filter out light other than the laser echo; its passing wavelength is the same as the wavelength of the selected laser. To; A convex lens (11) is used to focus the laser beam; An optical power meter (12) is used to receive the total energy of the laser echo and convert the optical signal into a processable electrical signal. Fisheye lens (13) is used for large field of view imaging and receiving light field; CCD camera (14) is used for large field-of-view imaging and active imaging, converting light signals into processable electrical signals; A data acquisition card is used to transmit the signals acquired by the optical power meter to a computer. The computer is used to receive signals acquired by the digital acquisition card, output control signals for the fast-reflecting mirror, and operate in the spatial light modulator. The modulated image is loaded and used to run the light intensity algorithm and the compressed correlation imaging reconstruction algorithm in the area to be measured to obtain the image. result; The linearly polarized laser beam emitted by the polarized laser (1) enters the mirror after its propagation direction is changed by the mirror (2). After the half-wave plate (3) controls the laser polarization direction, the beam passes through the beam expander (4) to make the spot size cover the space. After passing through the optical modulator, the beam enters the spatial optical modulator (5). The phase of the laser beam is modulated by the spatial optical modulator (5) before passing through the spatial optical modulator (5). The quick-reflecting mirror (6) controls the laser scanning area, and then the beam passes through the aperture (7) to illuminate the target and returns to the telescope (8). The beam is split into two beams by a beam splitter (9), one of which is filtered out by a narrow-bandpass filter (10) to remove wavelengths other than the laser wavelength. Stray light of a certain wavelength is focused onto the detection surface of the optical power meter (12) by a convex lens (11), while another beam of light passes through the convex lens (12). The light rays converge and, after their path is altered by the reflector (2), enter the CCD camera (14) to ensure that objects within the associated imaging field of view are properly associated. exist.

2. A compressed correlation imaging method based on the system described in claim 1, which also considers the large field-of-view imaging capability, characterized by comprising the following steps: Step S1: Use a fisheye lens (13) and a CCD camera (14) to quickly image the imaging area with a large field of view, and obtain... Fig; Result of large field of view imaging; Step S2: Determine based on the imaging results (Fig). N The measured object exists in the region { A 1, A 2, … , A i , … , A N }; Step S3: In { A 1, A 2, … , A i , … , A N Compressed correlation imaging was performed separately within the region to obtain... n One imaging result {fig1, fig2, … , fig i , … , fig N }; Furthermore, in step S3, the region A i ( i =0, 1… N The compressed correlation imaging results were obtained within the figure. i The steps are as follows: Step S31: ... M Different styles of modulation patterns g r ( x , y ), loaded onto the spatial light modulator (5), then according to the principle of the spatial light modulator, the phase of the light field modulation is Φ r ( x , y ); Step S32: Irradiate the spatial light modulator (5) with laser light, so that the laser light is reflected to obtain phase-modulated laser light, and then the phase-modulated laser light is diffracted to illuminate the region. A i The light intensity at the measured object is obtained by calculating the diffraction within the object. I 1, I 2, … , I r , … , I M }; Step S33: Receive the corresponding light reflected from the object under test using an optical power meter (12). M A modulation pattern M One returned optical signal { b 1, b 2, … , b r , … , b M }; Step S34: According to m The light intensity at the measured object calculated in step 32 { I 1, I 2, … , I r , … , I M } and the corresponding return optical signal { b 1, b 2, … , b r , … , b M The region was obtained through a compressed correlation imaging reconstruction algorithm. A i Fig of associated imaging results i ; Step S35: Use the fast-reflection mirror (6) to control the laser to switch to another unscanned area. A i+1 Correlated imaging of the region; After repeating the S31-S35 correlation imaging process N times, sampling of all areas where the measured object exists is completed.

3. The compressed correlation imaging method as described in claim 2, which also takes into account the large field-of-view imaging capability, is characterized in that, Modulation pattern in step S31 It is an image composed of pixels with gray levels randomly ranging from [0, 255], and its gray level corresponds to the modulation phase of the spatial light modulator, i.e. Where k represents the modulation depth of the spatial light modulator, and f(x,y) represents the geometric function of the spatial light modulator.

4. The compressed correlation imaging method as described in claim 2, which also takes into account the large field-of-view imaging capability, is characterized in that, The specific calculation method for obtaining the light intensity at the measured object based on diffraction in step S32 is as follows: Let the laser field be E (in) The light field after phase modulation by the spatial light modulator is: Where j represents the imaginary unit, and Φ represents the optical field modulation phase as described in step S31. The coordinates of the modulator are represented by the x and y coordinates; Fresnel diffraction calculations show that the light field distribution at a distance z from the spatial light modulator is... in, λ The wavelength of light k Let the wave vector be denoted by ; then the distance to the light source can be calculated based on diffraction. L The light intensity distribution at the measured object is Where (x,y) represents the horizontal and vertical coordinates of the plane containing the object to be measured.

5. The compressed correlation imaging method as described in claim 2, which also takes into account the large field-of-view imaging capability, is characterized in that, The compressed correlation imaging reconstruction algorithm in step S34 is expressed as follows: Definition of the first r The discretized light intensity distribution function projected onto the target during the second measurement is represented as follows: I r ( x , y ) Each value in the matrix represents the light intensity at the target light field obtained through simulation using the light field model. This intensity is then expanded row-wise into a one-dimensional vector. Measuring light on an object M After the second sampling, the simulation results will be obtained. M A one-dimensional vector of light intensity at each target light field is stored columnarly as follows: M 3D column vectors, serving as measurement matrices: Therefore, the size of the measurement matrix is M × nm One row represents the light intensity values ​​of all pixels at the target light field obtained from simulation in a single measurement, and one column represents the light intensity values ​​at a certain coordinate point ( x , y ) below M The light intensity value in this measurement; The results obtained by the bucket detector can be expressed as: Will T After discrete cosine transform, we obtain: in, It is a sparse matrix that is defined and known. Solving using the orthogonal matching tracking algorithm s nm×1 and according to The final solution is obtained T nm×1 Then T nm×1 Transform into T n×m That is, the reflectivity function of the object being measured. T ( x,y );Will T ( x,y After normalization, the correlation imaging result (fig) can be obtained. i .

6. The compressed correlation imaging method as described in claim 2, which also takes into account the large field-of-view imaging capability, is characterized in that, The step of switching the laser irradiation area using the fast-reflecting mirror (6) in step S34 specifically includes: Based on the large field-of-view imaging results (Fig), computer calculations were used to determine... N The measured object exists in the region { A 1, A 2, … , A i , … , A N The corresponding fast-reflecting mirror angle is determined, and then the control voltage corresponding to the fast-reflecting mirror angle is input to the fast-reflecting mirror via a computer to achieve the switching of the laser irradiation area.

Images