Single-pixel phase imaging method, system and device and storage medium

Abstract

The invention discloses a single-pixel phase imaging method, system and device and a storage medium, and the imaging system comprises a light source, a preprocessing module, a first spatial modulator, a second spatial modulator, a lens, a detector, a data collection card and a processor. After passing through the first spatial modulator, the measured object, the second spatial modulator and the lens in sequence, the light reaches the detector; the imaging method comprises the following steps: acquiring a first hologram and a second hologram which differ from a preset phase shift, calculating a hologram of a measured object according to the first hologram, the second hologram and a preset calculation formula, and calculating a reconstructed image of the measured object according to the hologram of the measured object and a preset algorithm. The embodiment of the invention improves the efficiency of phase shift holographic imaging, and can be widely applied to the technical field of imaging.

Description

Technical Field

[0001] The present invention relates to the field of imaging technology, and in particular to a single-pixel phase imaging method, system, device and storage medium. Background Art

[0002] Single-pixel imaging is a novel optical computational imaging method. Traditional imaging methods use a two-dimensional array detector to directly acquire images, while single-pixel imaging uses a series of pre-generated masks to encode the target image, and then uses a single-pixel detector to record the total light intensity corresponding to each mask, and finally restores the image through an algorithm. For actual objects, in addition to amplitude information, phase information is also included. For objects made of transparent materials, such as cells, it is especially important to obtain phase information. In order to obtain the phase information of the object, single-pixel phase imaging came into being. Currently common single-pixel phase imaging technologies include combining single-pixel imaging with holographic imaging and stacked imaging.

[0003] Currently, commonly used phase-shift holographic imaging includes four-step phase shift, three-step phase shift and two-step phase shift technologies. Four-step phase shift requires four holograms, three-step phase shift requires three holograms, and two-step phase shift requires two holograms and intensity maps of object light and reference light, and the efficiency needs to be improved. Summary of the invention

[0004] In view of this, in order to solve one of the above problems, an object of the embodiments of the present invention is to provide a single-pixel phase imaging method, system, device and storage medium to improve the efficiency of phase-shift holographic imaging.

[0005] On the one hand, an embodiment of the present invention provides a single-pixel phase imaging method, including:

[0006] Acquire a first hologram and a second hologram having a preset phase shift difference;

[0007] Calculating a hologram of the object under test according to the first hologram, the second hologram and a preset calculation formula;

[0008] A reconstructed image of the object to be measured is calculated according to the hologram of the object to be measured and a preset algorithm.

[0009] Optionally, calculating the hologram of the object under test according to the first hologram, the second hologram and a preset calculation formula includes:

[0010] determining an average value of the first hologram based on the first hologram, and determining an average value of the second hologram based on the second hologram;

[0011] determining a reference light amplitude according to the first hologram and the second hologram;

[0012] A hologram of the object to be measured is calculated according to the first hologram, the average value of the first hologram, the second hologram, the average value of the second hologram, the reference light amplitude and the preset calculation formula.

[0013] Optionally, the preset calculation formula is as follows:

[0014]

[0015] Among them, P0 represents the hologram of the object being measured, P r represents the reference light amplitude, I1 represents the first hologram, represents the average value of the first hologram, I2 represents the second hologram, represents the average value of the second hologram.

[0016] Optionally, calculating a reconstructed image of the object under test according to the hologram of the object under test and a preset algorithm includes:

[0017] Calculating a reconstructed image of the object under test according to the hologram of the object under test and an angular spectrum diffraction propagation algorithm;

[0018] or, calculating a reconstructed image of the object under test according to the hologram of the object under test and a Fresnel diffraction propagation algorithm;

[0019] Or, a reconstructed image of the object to be measured is calculated according to the hologram of the object to be measured and a Fourier diffraction propagation algorithm.

[0020] On the other hand, an embodiment of the present invention provides a single-pixel phase imaging system, including a light source, a preprocessing module, a first spatial modulator, a second spatial modulator, a lens, a detector, a data acquisition card and a processor, wherein the light emitted by the light source is collimated and attenuated by the preprocessing module, and then passes through the first spatial modulator, the object to be measured, the second spatial modulator and the lens in sequence before reaching the detector; wherein,

[0021] The first spatial modulator is used to load phase-shift fringes;

[0022] The second spatial modulator is used to load single pixel code;

[0023] The detector is used to collect light intensity signals;

[0024] The data acquisition card is used to convert the light intensity signal into a hologram corresponding to a digital signal;

[0025] The processor is used to execute the above imaging method.

[0026] Optionally, the first spatial modulator comprises an amplitude spatial light modulator.

[0027] Optionally, the second spatial modulator comprises a digital micromirror device.

[0028] Optionally, the detector comprises a silicon-based multi-pixel photon counter.

[0029] On the other hand, an embodiment of the present invention provides a single-pixel phase imaging device, including:

[0030] at least one processor;

[0031] at least one memory for storing at least one program;

[0032] When the at least one program is executed by the at least one processor, the at least one processor implements the above method.

[0033] On the other hand, an embodiment of the present invention provides a computer-readable storage medium, in which a program executable by a processor is stored. When the program executable by the processor is executed by the processor, it is used to perform the above method.

[0034] The implementation of the embodiment of the present invention includes the following beneficial effects: in this embodiment, a first hologram and a second hologram with a preset phase shift are first obtained, then the hologram of the object to be measured is calculated according to the first hologram, the second hologram and a preset calculation formula, and finally, the reconstructed image of the object to be measured is calculated according to the hologram of the object to be measured and a preset algorithm. Only two holograms need to be collected to reconstruct a single-pixel phase image of the object to be measured, and there is no need to collect intensity maps of object light or reference light, thereby improving the efficiency of phase-shift holographic imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic structural diagram of a single-pixel phase imaging system provided by an embodiment of the present invention;

[0036] Figure 2 It is a schematic diagram of the steps of a single-pixel phase imaging method provided by an embodiment of the present invention;

[0037] Figure 3 It is a schematic diagram of a flow chart of steps for calculating a hologram of a measured object provided by an embodiment of the present invention;

[0038] Figure 4 is a structural block diagram of a single-pixel phase imaging system provided by an embodiment of the present invention;

[0039] Figure 5 is a structural block diagram of a single-pixel phase imaging device provided by an embodiment of the present invention;

[0040] Figure 6 These are two holograms with preset phase shifts provided by the embodiments of the present invention;

[0041] Figure 7 It is a hologram of a measured object provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only provided for the convenience of explanation and description, and the order between the steps is not limited in any way. The execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0043] See also Figure 1 An embodiment of the present invention provides a single-pixel phase imaging system, including a light source M1, a beam expander M2, an attenuation plate M3, a first spatial modulator M4, a measured object M5, a second spatial modulator M6, a lens M7, a detector M8, a data acquisition card M9 and a processor. The light emitted by the light source M1 is collimated by the beam expander M2 and attenuated by the attenuation plate M3, and then passes through the first spatial modulator M4, the measured object M5, the second spatial modulator M6 and the lens M7 in sequence before reaching the detector M8. The data acquisition card M9 collects a hologram detection signal of the detector M8, and the processor performs data processing on the collected hologram detection signal.

[0044] The working principle of the single-pixel phase imaging system is as follows: after the light source emits the light beam, it is first collimated by a beam expander, the attenuation plate reduces the light intensity to an extremely weak light level, the first spatial light modulator loads the phase-shift stripes and generates a phase-shift hologram through the object, which is propagated to the second spatial light modulator; the second spatial light modulator loads a series of pre-designed single-pixel codes to modulate the phase-shift hologram, and the modulated light signal is focused by the lens onto the detector; then the data acquisition card converts the collected light intensity signal into a digital signal, and finally the computer restores the image of the object being measured.

[0045] like Figure 2 As shown, an embodiment of the present invention provides a single-pixel phase imaging method, including:

[0046] S100, obtaining a first hologram and a second hologram with a preset phase shift difference;

[0047] S200, calculating a hologram of the object under test according to the first hologram, the second hologram and a preset calculation formula;

[0048] S300, calculating a reconstructed image of the object to be measured according to the hologram of the object to be measured and a preset algorithm.

[0049] It should be noted that the preset phase shift between the first hologram and the second hologram is determined according to the actual application. For example, the preset phase shift between the first hologram and the second hologram is π / 2. If the phase shift of the first hologram is 0, the phase shift of the second hologram is π / 2. If the phase shift of the first hologram is π, the phase shift of the second hologram is 3π / 2.

[0050] The preset calculation formula and the preset algorithm are determined according to the actual application, and this embodiment does not impose any specific restrictions. The parameters of the preset calculation formula include relevant data of the first hologram and the second hologram. The parameters of the preset algorithm include relevant parameters of the hologram of the measured object.

[0051] Specifically, first, a first hologram and a second hologram with a preset phase shift are obtained through a data acquisition card, then, a hologram of the object under test is calculated according to the first hologram, the second hologram and a preset calculation formula, and finally, a reconstructed image of the object under test is calculated according to the hologram of the object under test and a preset algorithm.

[0052] Alternatively, if Figure 3 As shown, the hologram of the object to be measured is calculated according to the first hologram, the second hologram and a preset calculation formula, including:

[0053] S210, determining an average value of the first hologram according to the first hologram, and determining an average value of the second hologram according to the second hologram;

[0054] S220, determining a reference light amplitude according to the first hologram and the second hologram;

[0055] S230, calculating a hologram of the object under test according to the first hologram, the average value of the first hologram, the second hologram, the average value of the second hologram, the reference light amplitude and a preset calculation formula.

[0056] Specifically, first, the average value of the first hologram is calculated according to all values ​​of the first hologram, and the average value of the second hologram is calculated according to all values ​​of the second hologram; then, the first hologram and the second hologram are processed to obtain a reference light amplitude; finally, the first hologram, the average value of the first hologram, the second hologram, the average value of the second hologram and the reference light amplitude are substituted into a preset calculation formula to calculate the hologram of the object under test.

[0057] Optionally, the preset calculation formula is as follows:

[0058]

[0059] Among them, P0 represents the hologram of the object being measured, P r represents the reference light amplitude, I1 represents the first hologram, represents the average value of the first hologram, I2 represents the second hologram, represents the average value of the second hologram, and j represents an imaginary unit. It should be noted that if the hologram is normalized, 2P r =1.

[0060] Optionally, calculating a reconstructed image of the object under test according to the hologram of the object under test and a preset algorithm includes:

[0061] Calculate a reconstructed image of the object to be measured based on the hologram of the object to be measured and the angular spectrum diffraction propagation algorithm;

[0062] or, calculating a reconstructed image of the object under test based on a hologram of the object under test and a Fresnel diffraction propagation algorithm;

[0063] Or, a reconstructed image of the object to be measured is calculated based on the hologram of the object to be measured and a Fourier diffraction propagation algorithm.

[0064] Specifically, any one of the angular spectrum diffraction propagation algorithm, the Fresnel diffraction propagation algorithm or the Fourier diffraction propagation algorithm is used with the hologram of the object to be measured to calculate the reconstructed image of the object to be measured. Taking the angular spectrum diffraction propagation algorithm as an example, the calculation formula of the reconstructed image of the object to be measured is as follows:

[0065]

[0066] O=abs(E)

[0067] Among them, O represents the reconstructed image of the measured object, F represents the inverse Fourier transform, and F -1 represents inverse Fourier transform, P0 represents the hologram of the object being measured, z represents the propagation distance, λ represents the wavelength of the light source, fx and fy represent the frequency domain coordinates, and abs() represents the square of the modulus.

[0068] like Figure 4 As shown, an embodiment of the present invention provides a single-pixel phase imaging system, comprising:

[0069] A first module is used to obtain a first hologram and a second hologram with a preset phase shift;

[0070] The second module is used to calculate the hologram of the measured object according to the first hologram, the second hologram and a preset calculation formula;

[0071] The third module is used to calculate the reconstructed image of the object under test according to the hologram of the object under test and a preset algorithm.

[0072] It can be seen that the contents of the above method embodiments are all applicable to the present system embodiments, the functions specifically implemented by the present system embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0073] like Figure 5As shown, an embodiment of the present invention provides a single-pixel phase imaging device, comprising:

[0074] at least one processor;

[0075] at least one memory for storing at least one program;

[0076] When at least one program is executed by at least one processor, the at least one processor implements the above method.

[0077] Among them, the memory, as a non-transient computer-readable storage medium, can be used to store non-transient software programs and non-transient computer executable programs. The memory may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some embodiments, the memory may optionally include a remote memory remotely arranged relative to the processor, and these remote memories may be connected to the processor via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0078] It can be seen that the contents of the above method embodiments are all applicable to the present device embodiments, the functions specifically implemented by the present device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0079] In addition, the embodiment of the present application also discloses a computer program product or a computer program, which is stored in a computer-readable storage medium. The processor of the computer device can read the computer program from the computer-readable storage medium, and the processor executes the computer program, so that the computer device performs the above method.

[0080] The embodiment of the present invention further provides a computer-readable storage medium, which stores a program executable by a processor, and the program executable by the processor is used to implement the above method when executed by the processor. Similarly, the contents of the above method embodiment are all applicable to the present storage medium embodiment, and the functions specifically implemented by the present storage medium embodiment are the same as those of the above method embodiment, and the beneficial effects achieved are also the same as those achieved by the above method embodiment.

[0081] It is understood that all or some steps and systems in the disclosed method above can be implemented as software, firmware, hardware and appropriate combinations thereof. Some physical components or all physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, and the computer-readable medium can include a computer storage medium (or a non-transitory medium) and a communication medium (or a temporary medium). As known to those of ordinary skill in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cassette, magnetic tape, disk storage or other magnetic storage device, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically embodies computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0082] On the other hand, in biomedical imaging, in order to prevent samples from being affected by photobleaching and phototoxicity, phase imaging technology under extremely weak light conditions must be studied. The current solution still uses single-photon avalanche diodes (SPADs) or photomultiplier tubes (PMTs) to collect light intensity data. SPADs or PMTs need to be used in conjunction with time-correlated photon counters (TCSPCs) to collect data. This combination is costly and the method is complex.

[0083] See also Figure 1 The embodiment of the present invention provides a single-pixel phase imaging system, including a light source, a preprocessing module, a first spatial modulator, a second spatial modulator, a lens, a detector, a data acquisition card and a processor. The light emitted by the light source is collimated and attenuated by the preprocessing module, and then passes through the first spatial modulator, the object to be measured, the second spatial modulator and the lens in sequence before reaching the detector; wherein,

[0084] A first spatial modulator, used for loading phase-shift fringes;

[0085] A second spatial modulator, used for loading single pixel code;

[0086] A detector for collecting light intensity signals;

[0087] A data acquisition card, used to convert the light intensity signal into a hologram corresponding to a digital signal;

[0088] A processor is used to execute the above imaging method.

[0089] Specifically, the light source is determined according to the actual application, and this embodiment does not make specific restrictions. For example, a helium-neon laser (wavelength is 632.8nm) is used. The preprocessing module includes a beam expander and an attenuator. The lens is used to focus the optical signal. As for the processor, it can be different types of electronic devices, including but not limited to desktop computers, laptops, wearable devices and other terminals.

[0090] Optionally, the first spatial modulator comprises an amplitude spatial light modulator.

[0091] Optionally, the second spatial modulator comprises a digital micromirror device.

[0092] Optionally, the detector comprises a silicon-based multi-pixel photon counter.

[0093] This method uses a silicon-based multi-pixel photon counter (MPPC) as a detector to directly read the light intensity signal, avoiding the complex equipment configuration of the existing method of combining a single photon avalanche diode (SPAD) or a photomultiplier tube (PMT) with a time-correlated photon counter (TCSPC), greatly reducing the equipment cost and operation complexity, and has significant advantages such as simplicity, high reliability and high precision.

[0094] The process of the single-pixel phase imaging method is described below with a specific embodiment.

[0095] The HeNe laser is first expanded and collimated by a beam expander, and then the light intensity is reduced to an extremely weak light level by an attenuator. The amplitude spatial light modulator (first spatial modulator) is loaded with a 0-phase shift fringe pattern and generates a 0-phase shift hologram through the object being measured, which is then transmitted to a digital micromirror device (second spatial modulator); the digital micromirror device loads Hadamard-based coding to modulate the hologram, and the modulated light signal is focused by a lens onto a multi-pixel photon counter; the data acquisition card converts the collected light intensity signal into a voltage value, which constitutes the Hadamard spectrum coefficient, and then reconstructs the 0-phase shift hologram through an inverse Hadamard transform, as shown in FIG. Figure 6 As shown in (a). Then, a π / 2 phase-shifted fringe pattern is loaded on the amplitude-type spatial light modulator (first spatial modulator), and a π / 2 phase-shifted hologram is generated through the object, which is then transmitted to the digital micromirror device (second spatial modulator). The digital micromirror device loads the Hadamard basis code to modulate the hologram, and the modulated light signal is focused by the lens onto the multi-pixel photon counter; the data acquisition card converts the collected light intensity signal into a voltage value, which constitutes the Hadamard spectrum coefficient, and then reconstructs the π / 2 phase-shifted hologram through the inverse Hadamard transform, as shown in Figure 6Then, the two phase-shifted holograms are substituted into the reconstruction formula, and the angular spectrum diffraction algorithm is used to reconstruct the object image. The result is shown in Figure 7 shown.

[0096] It can be seen that the contents of the above method embodiments are all applicable to the present system embodiments, the functions specifically implemented by the present system embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0097] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A single pixel phase imaging method, characterized in that: include: Acquire a first hologram and a second hologram having a preset phase shift difference; Calculating a hologram of the object under test according to the first hologram, the second hologram and a preset calculation formula; A reconstructed image of the object to be measured is calculated according to the hologram of the object to be measured and a preset algorithm.

2. The imaging method according to claim 1, characterized in that: The step of calculating the hologram of the object to be measured according to the first hologram, the second hologram and a preset calculation formula includes: determining an average value of the first hologram based on the first hologram, and determining an average value of the second hologram based on the second hologram; determining a reference light amplitude according to the first hologram and the second hologram; A hologram of the object to be measured is calculated according to the first hologram, the average value of the first hologram, the second hologram, the average value of the second hologram, the reference light amplitude and the preset calculation formula.

3. The imaging method according to claim 2, characterized in that: The preset calculation formula is as follows: Among them, P0 represents the hologram of the object being measured, P r represents the reference light amplitude, I1 represents the first hologram, represents the average value of the first hologram, I2 represents the second hologram, represents the average value of the second hologram.

4. The imaging method according to claim 1, characterized in that: Calculating a reconstructed image of the object under test according to the hologram of the object under test and a preset algorithm includes: Calculating a reconstructed image of the object under test according to the hologram of the object under test and an angular spectrum diffraction propagation algorithm; or, calculating a reconstructed image of the object under test according to the hologram of the object under test and a Fresnel diffraction propagation algorithm; Or, a reconstructed image of the object to be measured is calculated according to the hologram of the object to be measured and a Fourier diffraction propagation algorithm.

5. A single-pixel phase imaging system, characterized in that: The device comprises a light source, a preprocessing module, a first spatial modulator, a second spatial modulator, a lens, a detector, a data acquisition card and a processor. The light emitted by the light source is collimated and attenuated by the preprocessing module, and then passes through the first spatial modulator, the object to be measured, the second spatial modulator and the lens in sequence before reaching the detector. The first spatial modulator is used to load phase-shift fringes; The second spatial modulator is used to load single pixel code; The detector is used to collect light intensity signals; The data acquisition card is used to convert the light intensity signal into a hologram corresponding to a digital signal; The processor is used to execute the imaging method according to any one of claims 1 to 4.

6. The imaging system according to claim 5, characterized in that: The first spatial modulator comprises an amplitude spatial light modulator.

7. The imaging system according to claim 5, characterized in that: The second spatial modulator includes a digital micromirror device.

8. The imaging system according to claim 5, characterized in that: The detector includes a silicon-based multi-pixel photon counter.

9. A single-pixel phase imaging device, characterized in that: include: at least one processor; at least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the method according to any one of claims 1 to 4.

10. A computer-readable storage medium storing a program executable by a processor, characterized in that: The processor-executable program is used to perform the method according to any one of claims 1 to 4 when executed by the processor.

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