Intensity correlation based motion deblurring imaging method and device

Abstract

The application relates to a motion deblurring imaging method and device based on intensity correlation. A light beam emitted by a laser irradiates a phase modulator, the phase modulator generates a time-varying speckle field, the speckle field irradiates a to-be-detected moving object, light intensity information transmitted through the to-be-detected moving object is converged on a charge coupled device (CCD) by a lens, and light intensity distribution information recorded by the CCD after the target is transmitted is stored in a computer. During imaging, the phase modulator and the CCD are synchronously triggered and controlled to work by a synchronous signal generator, the computer extracts Fourier transform spectrum information of the object by performing correlation operation on the light intensity distribution information recorded by the CCD, phase recovery reconstruction is performed on the spectrum information, and a high-resolution real space image of the to-be-detected moving object is obtained. The imaging device provided by the application has simple structure and reconstruction algorithm, and is suitable for high-resolution imaging application scenarios with simultaneous tangential and axial relative motion.

Description

TECHNICAL FIELD

[0001] The application relates to an intensity correlation-based motion deblurring imaging method and device, and belongs to the technical field of optical imaging. BACKGROUND

[0002] For application fields such as remote sensing investigation, key point defense, biomedical imaging and detection, it is of great significance to obtain dynamic scene information in real time. However, in the actual application process, when the detection target and the imaging system exist relative motion, the long-time sampling will cause image blurring, so that it is difficult to obtain an image meeting the actual application requirements due to the limitation of the system imaging frame frequency and the detection sensitivity.

[0003] At present, the method for solving the image blurring caused by relative motion and then obtaining high-definition imaging mainly includes three kinds. One is to improve the sensitivity of the detector and shorten the sampling time as much as possible, so that the image blurring caused between the detection target and the imaging system does not exceed the size of a single pixel of the detector, however, the improvement degree of this method is limited. On the one hand, from the imaging mechanism, reducing the exposure amount will cause the image signal-to-noise ratio to decrease, so that the image quality cannot meet the application requirements; on the other hand, it is difficult to improve in many detection wavebands (such as infrared, terahertz), and increasing the detection sensitivity often needs to increase the related refrigeration device, which not only causes the system cost to increase greatly, but also increases the volume and power consumption of the system, thereby limiting its use in some application platforms. The second is the system compensation method. For example, optical image shift compensation method, mechanical image shift compensation method, integrated image shift compensation method, etc., the most representative is the motion deblurring method based on target tracking system compensation, which compensates and corrects the relative motion between the target to be measured and the imaging system in real time, so as to eliminate the motion blurring. However, this method is not only expensive, but also can only be used for high-resolution imaging of the target with only tangential motion, low motion speed and stable speed change; in addition, for the application scene with high-speed axial relative motion, the imaging resolution of this method will decrease sharply. The third is to improve the motion blurring through motion estimation and image post-processing. For example, non-blind deblurring method, blind deblurring method, motion estimation method, etc., see the document Ghost imaging of a moving target with an unknown constant speed [J]. Applied Physics Letters, 2014, 104 (25). However, such methods usually have the problems of large amount of calculation and weak generalization ability, and the improvement degree of image quality is often limited. Therefore, it is urgent to explore and develop an imaging scheme which does not need to compensate the system, has a simple system structure and can eliminate the tangential and axial motion blurring at the same time. SUMMARY

[0004] The present application aims at the deficiency of the prior motion deblurring method and technology, and provides a motion deblurring imaging method and device based on intensity correlation, which is simple in structure and reconstruction algorithm, and is suitable for high-resolution imaging application scenarios with simultaneous transverse and axial relative motion.

[0005] The technical scheme for realizing the object of the present application is a motion deblurring imaging device based on intensity correlation, which comprises a laser, a phase modulator, a lens, a charge coupled device (CCD) and a computer; the phase modulator and the CCD are synchronously triggered and controlled by a synchronous signal generator to work; a light beam emitted by the laser is irradiated on the phase modulator; the phase modulator generates a time-varying speckle field to irradiate on a to-be-detected moving object; the light intensity information transmitted through the to-be-detected moving object is converged on the CCD by the lens; the light intensity distribution information of the target after transmission is recorded by the CCD and stored in the computer; after intensity correlation operation and image reconstruction processing, a high-resolution real-space image of the to-be-detected moving object is output.

[0006] The technical scheme of the present application further comprises a motion deblurring imaging method based on intensity correlation, and the steps are as follows:

[0007] (1) Acquisition of a to-be-detected moving object detection signal

[0008] The phase modulator and the CCD are synchronously triggered and controlled by a synchronous signal generator to work; a light beam emitted by the laser is irradiated on the phase modulator; a time-varying speckle field is generated by the phase modulator and irradiates on a to-be-detected moving object after free propagation of the light field; the light intensity information transmitted through the to-be-detected moving object is converged on the CCD by the lens; the light intensity distribution information of the target after transmission is recorded by the CCD and stored in the computer;

[0009] (2) Extraction of a Fourier transform spectrum image of the to-be-detected moving object

[0010] The CCD acquires and records S the first k instantaneous light intensity picture is recorded as , wherein: m and n respectively represent the transverse and longitudinal pixel positions of the recorded picture; according to the obtained instantaneous light intensity picture, a Fourier transform spectrum image of the to-be-detected moving object is obtained , is the light intensity distribution of the to-be-detected object, represents Fourier transform, and intensity correlation operation is performed according to formula (1),

[0011] (1)

[0012] wherein:M and N represents the total number of pixels in the horizontal and vertical directions of the picture recorded by the CCD;

[0013] (3) high-resolution image reconstruction of the measured moving object

[0014] The obtained Fourier transform spectrum image of the measured moving object is reconstructed by using a phase retrieval algorithm to obtain a high-resolution real space image of the measured moving object.

[0015] The measured moving object in the application moves in the horizontal and axial directions within a certain range, and the horizontal movement range of the object is smaller than the effective aperture of the lens. The phase modulator is loaded with a time-varying random phase that satisfies uniform distribution.

[0016] The application can use GS or HIO phase retrieval algorithm for image reconstruction.

[0017] The technical solution provided by the application is that the horizontal movement range of the measured object is usually not greater than the effective aperture of the lens and cannot rotate within the sampling time, but can move randomly in the horizontal and axial directions between the phase modulator and the lens. Optimizing the phase distribution of the phase modulator can effectively reduce the number of samples for obtaining the Fourier transform spectrum image of the measured moving object, thereby improving the imaging speed.

[0018] Compared with the prior art, the application has the following technical effects:

[0019] (1) The application has the ability to resist image blurring caused by horizontal and axial movement from the physical principle, and has no limit requirements on the movement trajectory and speed.

[0020] (2) The device system of the application has simple structure, and does not need to use a compensation system and a subsequent motion deblurring estimation algorithm.

[0021] (3) The spatial resolution of the existing speckle illumination imaging system is usually limited by the horizontal size of the speckle field at the measured object surface, while the distance of the measured moving object from the phase modulator and the lens in the application can be far, and the spatial resolution is no longer limited by the horizontal size of the speckle field at the measured object surface, and a large-size speckle field can reduce the number of samples required for obtaining high-quality Fourier transform spectrum image. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structural schematic diagram of the intensity correlation-based motion deblurring imaging device provided by the embodiment of the application.

[0023] In the figure: 1 is a laser; 2 is a phase modulator; 3 is a measured moving object; 4 is a lens; 5 is a charge-coupled device (CCD); and 6 is a computer.

[0024] Figure 2 is the Fourier transform spectrum image of the measured moving object extracted by the embodiment of the application.

[0025] Figure 3 is the high-resolution real space image of the measured moving object reconstructed by the embodiment of the application. DETAILED DESCRIPTION

[0026] The technical solutions of the application will be further described below with reference to the drawings and specific embodiments, but the embodiments are not intended to limit the application.

[0027] Referring to the drawings Figure 1 It is a structural schematic diagram of the motion deblurring imaging device based on intensity correlation provided by the embodiment.

[0028] From the drawings Figure 1 It can be seen that the motion deblurring imaging device based on intensity correlation provided by the embodiment comprises a laser 1, a phase modulator 2, a measured moving object 3, a lens 4, a CCD 5 and a computer 6.

[0029] The light beam emitted by the laser 1 is irradiated on the phase modulator 2, and a time-varying speckle field is generated by the phase modulator 2 and irradiated on the measured moving object 3. The light intensity information transmitted by the measured moving object 3 is converged on the CCD 5 by the lens 4. The light intensity distribution information after the target is transmitted is recorded by the CCD 5 and stored in the computer 6. The phase modulator 2 and the CCD 5 are synchronously triggered and controlled to work by a synchronous signal generator. The Fourier transform spectrum information of the object is extracted by performing correlation operation on the light intensity distribution information recorded by the CCD 5, and the high-resolution image of the measured moving object can be obtained by performing phase recovery reconstruction on the spectrum information.

[0030] The imaging method steps of the device provided by the embodiment are as follows:

[0031] First, the acquisition of the measured moving object detection signal

[0032] The phase modulator 2 and the CCD 5 are synchronously triggered and controlled to work by a synchronous signal generator.

[0033] The object 3 to be measured moves in a certain range in both lateral and axial directions, and the lateral movement range of the object needs to be less than the effective aperture of the lens. The light beam emitted by the laser 1 irradiates on the phase modulator 2, and a time-varying speckle field is generated through the phase modulator 2. After free propagation of the light field, the object 3 to be measured is irradiated. Then, the light intensity information transmitted by the object 3 to be measured is converged on the CCD 5 by the lens 4, and the light intensity distribution information after the target transmission is recorded by the CCD 5 and stored in the computer 6. For this method, the time-varying random phase loaded by the phase modulator satisfies uniform distribution. If the phase distribution of the phase modulator is optimized, the number of samples required for high-resolution imaging can be reduced to a certain extent, and the imaging speed of the system can be improved.

[0034] In this embodiment, the object 3 to be measured is a three-slit with a slit width of 200 μm, a slit pitch of 800 μm, and a slit height of 2.5 mm. The lateral movement range is 2 mm, the axial movement range is 8 cm, the distance between the phase modulator 2 and the lens 4 is 400 mm, the diameter D of the light beam emitted by the laser 1 is 3 mm, and the focal length of the lens 4 is 200 mm.

[0035] Second step, extraction of the Fourier transform spectrum image of the object to be measured

[0036] Suppose that the CCD 5 collects and records a total of S =20000 instantaneous light intensity pictures, and the total number of lateral and longitudinal pixels of the pictures recorded by the CCD 5 is k =61, =201. The Fourier transform spectrum image of the object to be measured extracted is shown in the attached m n

[0037]

[0038] M N , wherein , is the light intensity distribution of the object to be measured, and is the Fourier transform. In this embodiment, the CCD 5 collects and records S =20000 instantaneous light intensity pictures, and the total number of lateral and longitudinal pixels of the pictures recorded by the CCD 5 is M =61, N =201. The Fourier transform spectrum image of the object to be measured extracted is shown in the attached Figure 2 .

[0039] Third step, high-resolution image reconstruction of the object to be measured ​​​​

[0040] On the basis of the obtained Fourier transform spectrum image of the to-be-detected moving object, the real space image information of the to-be-detected moving object can be obtained by phase retrieval algorithm.

[0041] Generally, the GS or HIO phase retrieval algorithm can be used for image reconstruction. Taking the HIO algorithm as an example, first, the initial estimation of the amplitude and phase of the to-be-detected moving object is given , wherein is the initial amplitude distribution, is the initial phase distribution, and the amplitude and phase information thereof are updated through an iterative process. The first iterative process is as follows (wherein k =1, 2, 3…): k

[0042] (1) Fourier transform is performed on the real space image to obtain the frequency domain image .

[0043] (2) the original phase information is kept unchanged, and the Fourier transform spectrum image of the to-be-detected moving object obtained in the second step is used to replace , that is: .

[0044] (3) inverse Fourier transform is performed on the replaced frequency domain image to obtain the real space image, and calculation is performed according to the set space domain constraint to obtain the space domain image of the next iteration:

[0045]

[0046] , wherein: is an adjustable parameter, which is set according to the actual situation, and through multiple iterative operations, the high-resolution real space image of the to-be-detected moving object can be reconstructed.

[0047] Referring to the accompanying drawings, Figure 3 , the high-resolution real space image of the to-be-detected moving object reconstructed in this embodiment.

[0048] In order to explain the physical mechanism of motion deblurring of the present application, the following will be described from the theory of coherence of light field and the physical principle of intensity correlation imaging. According to the theory of coherence of light field, taking a one-dimensional case as an example, the second-order cross-correlation function can be expressed as formula (1):

[0049] (1)

[0050] , wherein: is the first-order cross-correlation function of the light beam emitted by the laser 1 after being modulated by the phase modulator 2, ​is the coordinate on the plane of phase modulator 2, is the impulse response function from the phase modulator 2 plane to the CCD5 plane, is the conjugate of the impulse response function, is the coordinate of the CCD5 plane.

[0051] Assuming that the light field generated by the laser beam 1 after random modulation by the phase modulator 2 is uniform and incoherent, the first-order mutual interference function is It can be expressed as formula (2):

[0052] (2)

[0053] For the attached Figure 1 For the optical system shown in the figure, under the condition of satisfying the paraxial approximation, the impulse response function from the phase modulator 2 plane to the CCD 5 plane can be expressed as formula (3):

[0054] (3)

[0055] in f is the focal length of lens 4, t ( x ) is the transmittance function of the object to be measured, z 1( x ) for t The distance from the object to be measured to the plane of phase modulator 2 at the moment, for t The horizontal distance from the center of the object to be measured to the optical axis of the detection system at any moment, z is the distance between the phase modulator 2 plane and the lens 4, then t The distance between the object to be measured and the lens 4 at the moment is z - z 1( t ).

[0056] Substituting equations (2) and (3) into equation (1), we can get x 1Integrating the equation (4) we can get:

[0057] (4)

[0058] If the spot size of the light beam emitted by laser 1 on phase modulator 2 is large enough, equation (4) can be simplified to equation (5):

[0059] (5)

[0060] in Express Perform Fourier transform. x tWhen '=0, we have formula (6):

[0061] (6)

[0062] From formula (5) and (6), we can see that: Figure 1 With the system structure shown, even if the object to be measured undergoes lateral and axial motion, the results obtained through the correlation operation are the same as when the object to be measured is in a stationary state, that is, the modulus square of the Fourier transform of the transmittance intensity distribution of the object to be measured. Therefore, the device and method provided by the present invention can be used to obtain a high-resolution real-space image of the moving object to be measured.

Claims

1. An intensity correlation based de-mozaicing imaging device, characterized by: It comprises a laser (1), a phase modulator (2), a lens (4), a charge coupled device (CCD) (5) and a computer (6); the phase modulator and the charge coupled device (CCD) are synchronously triggered and controlled by a synchronous signal generator, the light beam emitted by the laser is irradiated on the phase modulator, the phase modulator generates a time-varying speckle field to irradiate on the moving object to be measured, the light intensity information transmitted by the moving object to be measured is converged on the charge coupled device (CCD) by the lens, the light intensity distribution information recorded by the CCD after the target is transmitted is stored in the computer, after intensity correlation operation and image reconstruction processing, a high-resolution real space image of the moving object to be measured is outputted; wherein the Fourier transform spectrum image of the moving object under test is obtained by the intensity correlation operation processing, i.e. the CCD collects and records S the instantaneous light intensity picture of the z-th frame, which corresponds to the k the instantaneous light intensity picture of the z-th frame is recorded as wherein: m and n respectively represent the horizontal and vertical pixel positions of the recorded picture; according to the obtained instantaneous light intensity picture, the Fourier transform spectrum image of the moving object under test is obtained ， where: M and N denote the total number of pixels in the horizontal and vertical direction of the picture recorded by the CCD.

2. An intensity correlation based de-moisoning imaging method, characterized in that It comprises the following steps: (1) acquisition of a detection signal of the moving object to be measured The phase modulator and the CCD are synchronously triggered and controlled by a synchronous signal generator; the light beam emitted by the laser is irradiated on the phase modulator, a time-varying speckle field is generated by the phase modulator, and the speckle field is irradiated on the moving object to be measured after free propagation of the light field; the light intensity information transmitted by the moving object to be measured is converged on the CCD by the lens, the light intensity distribution information recorded by the CCD after the target is transmitted is stored in the computer; (2) extraction of a Fourier transform spectrum image of the moving object to be measured CCD acquires and records S The instantaneous light intensity picture of the i-th frame is denoted as k The instantaneous light intensity picture of the i-th frame is denoted as wherein: m and n respectively represent the horizontal and vertical pixel positions of the recorded picture; according to the obtained instantaneous light intensity picture, a Fourier transform spectrum image of the measured moving object is obtained , is the light intensity distribution of the measured object, denotes the Fourier transform, and the intensity correlation operation processing is performed according to formula (1), （1） wherein: M and N represents the total number of pixels in the horizontal and vertical directions of the picture recorded by the CCD; (3) high-resolution image reconstruction of the moving object to be measured The Fourier transform spectrum image of the moving object to be measured is reconstructed by using a phase recovery algorithm, and a high-resolution real space image of the moving object to be measured is obtained.

3. The method of claim 2, wherein the method is based on intensity correlation. The moving object to be measured moves in the horizontal direction and the axial direction simultaneously within a certain range, and the horizontal movement range of the object is smaller than the effective aperture of the lens.

4. The method of claim 2, wherein the method is based on intensity correlation. The phase modulator is loaded with a time-varying random phase satisfying uniform distribution.

5. The method of claim 2, wherein the method is based on intensity correlation. The GS or HIO phase recovery algorithm is used for image reconstruction.

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