Light off-axis digital holographic detection device and method based on grating synchronous phase shift

Abstract

The invention discloses a light off-axis digital holographic detection device and method based on grating synchronous phase shift, and relates to the field of digital holographic detection. In order to solve the technical defects that in the prior art, an existing synchronous phase shift light off-axis digital holographic method is prone to being influenced by the outside, poor in anti-interference capacity and limited in flexibility, the technical scheme provided by the invention is that the system comprises a collimation and beam expanding system used for collimating and expanding light beams emitted by a light source; the rectangular diaphragm is used for placing an object to be measured; the first lens is used for focusing the object light and the reference light; the transmission grating is used for diffracting the light beams to generate + 1-level, 0-level and-1-level light beams; the first baffle is used for shielding the 0-level light beam diffracted by the transmission grating; the second lens is used for focusing and guiding + 1-level and-1-level light beams; the non-polarization splitting prism is used for converging the + 1-level light beam and the-1-level light beam and generating two interference light beams; and the second baffle plate is used for shielding one interference light beam. The method is suitable for light off-axis digital holographic detection.

Description

Technical Field

[0001] The invention relates to the field of digital holographic detection, and in particular to light off-axis digital holographic detection based on grating synchronous phase shift. Background Art

[0002] Digital holography methods are widely used in micro-morphology measurement, deformation analysis, cell morphology monitoring and other fields because they can achieve high-precision full-field, non-destructive, non-contact, and non-label quantitative measurements. Among digital holography methods, the off-axis digital holographic microscopy method can perform phase recovery through a single-frame carrier frequency interference pattern, and has good dynamic testing capabilities. However, due to the presence of the DC component of the interference pattern, a corresponding zero-frequency component will be generated in the frequency domain, and interference noise will often be introduced when extracting the real image spectrum, thereby affecting the phase reconstruction quality. To solve this problem, the light off-axis digital holography method has been proven to be a feasible optimization solution. This method collects two holographic (interference) images with the same carrier frequency but different phase shifts, and subtracts the two holograms to remove the DC component interference, thereby effectively improving the phase reconstruction quality. In order to achieve dynamic measurement, scholars have made many useful attempts and gradually proposed a synchronous phase-shifted light off-axis digital holography method.

[0003] The first category is a method based on polarization state modulation technology to obtain synchronous phase shift. For example, Jin Chuan from the Institute of Optoelectronics Technology of the Chinese Academy of Sciences proposed a synchronous phase shift light off-axis digital holography method based on Mach-Zehnder (Jin C, He Y, Tang Y, Liu JB, Sun HF, Hu S. Spatial consistency calibration based on phase difference minimization for parallels lightly off-axis digital holographic microscopy. IEEE Photonics Journal, 2022, 14 (3): 5230607). Through the object parameter separation optical path device, two light beams are obtained, and then by tilting the reflector, an angle is introduced between the object light and the reference light to obtain the carrier frequency, and then the polarization state of the light beam is modulated by a combination of components such as polarizers, wave plates, and polarization splitter prisms to obtain a hologram with a specific phase shift. However, in the device that uses the object parameter classification optical path, the measurement beam and the reference beam pass through different paths, which are easily affected by external vibrations, temperature fluctuations, etc., and have poor anti-interference ability. To this end, scholars have further studied the light off-axis digital holography method based on the common-path device. For example, Shan Mingguang from Harbin Engineering University proposed a synchronous phase-shifted light off-axis digital holography method based on split-beam polarization modulation (Shan MG, Jin QQ, Zhong Z, Liu B, Yu L, Wang Y, Liu L. Parallel two-step spatial carrier polarized phase-shifting common-path digital holography. Optics and Laser Technology, 2025, 180: 111542). Through the double-window beam input, the carrier frequency is introduced and the beam is merged using a splitter prism, and then combined with a polarizer combination to load different phase shifts in the hologram. Due to the parameter limitations of the polarization element, this type of method often fixes the phase shift difference between the two holograms to π / 2, and uses more polarization devices in the optical path, which will increase the complexity of the device to a certain extent, and the system parameter requirements will also be strict.

[0004] The second type is to use the phase shift, diffraction and other characteristics of special devices to achieve splitting and synchronous phase shifting. For example, Shaked NT of Duke University in the United States proposed a synchronous light off-axis digital holography method using Wollaston prism (Shaked NT, Rinehart MT, Wax A. Dual-interference-channel quantitative-phase microscopy of live cell d ynamics. Optics Letters, 2009, 34 (6): 767-769). Picazo-Bueno JA of the University of Valencia in Spain proposed a synchronous light off-axis digital holography method using Stokes prism and beam splitter prism (Picazo-Bueno JA, Trusiak M, Micó V. Single-shots lightly off-axis digital holographic microscopy with add-on module based on beam splitter cube. Optics Express, 2019, 27 (4): 5655-5669). Although this type of method can effectively reduce the number of components in the system and facilitate system integration, the use of more special optical devices in the imaging device is often costly and limits the flexibility of the system. Summary of the invention

[0005] In order to solve the technical defects in the prior art that the existing synchronous phase-shift light off-axis digital holography method is easily affected by external vibrations, temperature fluctuations, etc., has poor anti-interference ability, and has a large number of polarization devices in the optical path, which increases the complexity of the device and leads to limited flexibility, the technical solution provided by the present invention is as follows:

[0006] A light off-axis digital holographic detection device based on grating synchronous phase shift, comprising:

[0007] A collimation and beam expansion system is used to collimate and expand the light beam emitted by the light source;

[0008] Rectangular aperture, used to place the object to be measured;

[0009] A first lens, used for focusing the object light and the reference light;

[0010] A transmission grating, located on a confocal plane of the first lens and the second lens, for diffracting the light beam to generate +1-order, 0-order and -1-order light beams;

[0011] A first baffle, used for shielding the 0th order light beam diffracted by the transmission grating;

[0012] A second lens for focusing and directing the +1st and -1st order light beams;

[0013] A non-polarizing beam splitter prism, used for combining the +1st order and -1st order light beams to generate two interference light beams;

[0014] The second baffle is used to block one of the interfering light beams.

[0015] Furthermore, a preferred embodiment is provided, wherein the focal lengths of the first lens and the second lens are equal.

[0016] Furthermore, a preferred embodiment is provided, wherein the transmission grating has the same light intensity modulation coefficient for the +1st and -1st order diffraction beams.

[0017] Furthermore, a preferred embodiment is provided, wherein the non-polarizing beam splitter prism can be rotated at a deflection angle α relative to the optical axis, and the light beam transmission and reflection ratio of its semi-transparent and semi-reflective surface is 1:1.

[0018] Furthermore, a preferred embodiment is provided, wherein the rectangular aperture is composed of two windows, one of which is used for placing the object to be measured.

[0019] Based on the same inventive concept, the present invention also provides a light off-axis digital holographic detection system based on grating synchronous phase shift, comprising: the above-mentioned device, and:

[0020] A light source, for emitting a light beam with a wavelength of λ;

[0021] An object to be measured, used to interact with the light beam to form object light and reference light;

[0022] Image sensor, used to generate holograms.

[0023] Based on the same inventive concept, the present invention also provides a light off-axis digital holographic detection method based on grating synchronous phase shift, the method is implemented based on the system, and includes:

[0024] The step of generating a light beam having a wavelength λ;

[0025] The step of collimating and expanding the light beam and emitting it to the object to be measured to generate object light and reference light;

[0026] Steps of diffracting +1st order, 0th order and -1st order beams through object light and reference light;

[0027] The step of combining the +1 order light beam and the -1 order light beam to obtain two interference light beams;

[0028] The steps of collecting the hologram of the object to be measured;

[0029] In the absence of an object to be detected, a step of collecting a background hologram;

[0030] The step of obtaining the phase distribution of the object to be measured according to the complex amplitude of the difference map between the hologram of the object to be measured and the background hologram.

[0031] Based on the same inventive concept, the present invention also provides a computer storage medium for storing a computer program. When the computer program is read by a computer, the computer executes the described method.

[0032] Based on the same inventive concept, the present invention also provides a computer, including a processor and a storage medium. When the processor reads a computer program stored in the storage medium, the computer executes the method described.

[0033] Based on the same inventive concept, the present invention also provides a computer program product, which is a computer program. When the computer program is executed, the method described above is implemented.

[0034] Compared with the prior art, the technical solution provided by the present invention is beneficial in that:

[0035] The present invention can complete phase recovery by exposing two holograms collected by a physical parameter common path interference device at one time, and has good real-time measurement performance while ensuring system stability.

[0036] The present invention has a simple structure and low cost, and does not require special optical elements such as polarization elements, reflection gratings, pinhole filters, special prisms, etc., and the phase shift introduced into the hologram by the transmission grating is random, and the requirements on system component parameters are relatively low;

[0037] After the tilt angle of the non-polarization beam splitter prism is determined, no mechanical movement is required during the detection process, and the operation is simple and easy.

[0038] Specifically:

[0039] This solution introduces the light off-axis digital holography technology based on grating synchronous phase shift, and proposes an innovative solution to the problems of DC component interference, poor system stability, and high complexity of optical components in the existing technology, thereby achieving the following effects:

[0040] First, the scheme uses a physical parameter common-path interferometer to simultaneously obtain two holograms with different phase shifts through a single exposure, effectively removing the interference caused by the DC component in the traditional method. The biggest advantage of this method is that it simplifies the system design and improves the quality of phase recovery. Compared with traditional polarization modulation technology, this scheme does not require complex polarization optical elements such as polarizers, wave plates, and beam splitters, which not only reduces the number of devices, but also reduces the sensitivity and error sources of the system, thereby achieving higher stability.

[0041] Secondly, the present invention uses the random phase shift introduced by the transmission grating in the hologram to effectively reduce the dependence on optical components and the requirements for system parameters. This is different from the traditional synchronous phase shift method based on polarization modulation technology, which often requires complex optical path adjustment and strict optical component parameter requirements. The present invention reduces the sensitivity to external interference and enhances the anti-interference ability of the system through the combination of a relatively simple transmission grating and a non-polarization beam splitter prism.

[0042] Thirdly, the carrier frequency is introduced by adjusting the tilt angle of the non-polarizing beam splitter prism, and flexible interference pattern modulation is performed without any mechanical movement. Compared with the previous method that requires mechanical parts adjustment, this greatly simplifies the operation process, reduces equipment wear and maintenance costs, and also enables the equipment to respond more quickly and adapt to dynamic measurement environments.

[0043] Finally, the hologram is processed using Fourier transform and bandpass filtering techniques to effectively extract a clear object phase distribution. This method not only improves the measurement accuracy, but also significantly reduces the noise interference caused by other techniques. Compared with the traditional single-frame interferogram phase recovery method, this scheme shows better performance in noise suppression and phase recovery accuracy.

[0044] It is suitable for use in light off-axis digital holographic detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a structural schematic diagram of a light off-axis digital holographic detection device based on grating synchronous phase shift;

[0046] Figure 2 Two synchronous phase-shifted holograms of the object to be measured are collected

[0047] Figure 3 These are two synchronous phase-shifted holograms collected without the object to be measured;

[0048] Figure 4 is the final restored phase distribution of the object under test.

[0049] Among them, 1 is a light source, 2 is a collimating beam expansion system, 3 is an object to be measured, 4 is a rectangular aperture, 5 is a first lens, 6 is a transmission grating, 7 is a first baffle, 8 is a second lens, 9 is a non-polarizing beam splitter prism, 10 is a second baffle, and 11 is an image sensor. DETAILED DESCRIPTION

[0050] In order to make the advantages and benefits of the technical solution provided by the present invention more clearly reflected, the technical solution provided by the present invention is now further described in detail with reference to the accompanying drawings, specifically:

[0051] Embodiment 1: This embodiment provides a light off-axis digital holographic detection device based on grating synchronous phase shift, comprising:

[0052] The collimating and expanding system 2 is used to collimate and expand the light beam emitted by the light source 1;

[0053] A rectangular aperture 4 is used to place the object to be measured 3;

[0054] A first lens 5, used for focusing the object light and the reference light;

[0055] a transmission grating 6, located on the confocal plane of the first lens 5 and the second lens 8, for diffracting the light beam to generate +1-order, 0-order and -1-order light beams;

[0056] A first baffle 7, used for shielding the 0th order light beam diffracted by the transmission grating 6;

[0057] A second lens 8, for focusing and guiding the +1st and -1st order light beams;

[0058] A non-polarizing beam splitter prism 9, used for splitting the light beam into two beams;

[0059] The second baffle 10 is used to block one of the interfering light beams.

[0060] Specifically, it includes multiple optical components, as follows:

[0061] Light source 1: This component provides a beam with a wavelength of λ, usually a laser. Its main function is to generate a stable light source 1 for use by subsequent optical systems.

[0062] Collimation and beam expansion system 2: This system includes a plurality of lenses for collimating and expanding the light beam emitted by the light source 11 to ensure uniform light intensity of the light beam and ensure that the subsequent optical system can work normally.

[0063] Object 3 to be tested: Object 3 to be tested is the core part of the device, which is used to generate object light and reference light under the irradiation of the light beam. Object 3 to be tested interacts with light source 1 to generate reflected light and transmitted light, which serve as the basis for subsequent hologram generation.

[0064] Rectangular aperture 4: The function of the rectangular aperture 4 is to control the shape and direction of the light beam. It is composed of two windows, one of which is used to place the object to be measured 3. This component can ensure that the object to be measured 3 and the reference light form a specific beam pattern and precisely control the size and shape of the beam.

[0065] First lens 5: The main function of this lens is to focus the object light and the reference light to form alternating light beams and guide them through the next optical elements. The focal length of this lens needs to be the same as the focal length of the second lens 8 to ensure that the light beam can be effectively transmitted.

[0066] Transmission grating 6: The transmission grating 6 is located on the confocal plane of the first lens 5 and the second lens 8, and can diffract the light beam to generate +1 order, 0 order and -1 order light beams. By adjusting the parameters of the transmission grating 6, the diffraction effect of the light beam can be effectively adjusted to provide different phase shift information.

[0067] The first baffle 7: The function of the baffle is to block the 0th order light beam diffracted by the transmission grating 6 and ensure that the +1st order and -1st order light beams enter the optical path of the next stage.

[0068] Second lens 8: The main function of the second lens 8 is to further focus and guide the light beam diffracted by the transmission grating 6. Its focal length is the same as that of the first lens 5, ensuring the optical accuracy of the system.

[0069] Non-polarizing beam splitter prism 9: This beam splitter prism is used for non-polarizing beam splitter prism, used to merge the +1st order and -1st order light beams and generate two interference light beams; and can rotate a specific angle to introduce different carrier frequencies into the hologram. The beam splitter prism has the characteristics of semi-transmission and semi-reflection, and can accurately reflect and transmit light beams.

[0070] The second baffle 10: The baffle is used to block one of the interfering light beams to ensure that the remaining interfering light beams generate two holograms. It helps to further improve the clarity of the image and remove interference signals.

[0071] Image sensor 11: Image sensor 11 is used to capture the interference light beam generated after passing through all optical elements, generate a corresponding hologram, and transmit it to a computer for further processing.

[0072] Embodiment 2: This embodiment is a further limitation of the slightly off-axis digital holographic detection device based on grating synchronous phase shift provided in Embodiment 1, and the focal lengths of the first lens 5 and the second lens 8 are equal.

[0073] Embodiment 3: This embodiment further limits the light off-axis digital holographic detection device based on grating synchronous phase shift provided in Embodiment 1, and the transmission grating 6 has the same light intensity modulation coefficient for the +1st and -1st order diffraction beams.

[0074] Embodiment 4. This embodiment is a further limitation of the light off-axis digital holographic detection device based on grating synchronous phase shift provided in Embodiment 1. The non-polarizing beam splitter prism 9 can rotate at a deflection angle α with respect to the optical axis, and the light beam transmission and reflection ratio of its semi-transparent and semi-reflective surface is 1:1.

[0075] Embodiment 5: This embodiment further limits the light off-axis digital holographic detection device based on grating synchronous phase shift provided in Embodiment 1. The rectangular aperture 4 is composed of two windows, one of which is used to place the object 3 to be detected.

[0076] Embodiment 6: This embodiment provides a light off-axis digital holographic detection system based on grating synchronous phase shift, comprising: the device according to claim 1, and:

[0077] A light source 1, for emitting a light beam with a wavelength of λ;

[0078] The object to be measured 3 is used to interact with the light beam to form object light and reference light;

[0079] The image sensor 11 is used to generate a hologram.

[0080] Embodiment 7: This embodiment provides a light off-axis digital holographic detection method based on grating synchronous phase shift, which is implemented based on the system provided in Embodiment 6 and includes:

[0081] The step of generating a light beam having a wavelength λ;

[0082] The step of collimating and expanding the light beam and emitting it to the object to be measured 3 to generate object light and reference light;

[0083] Steps of diffracting +1st order, 0th order and -1st order beams through object light and reference light;

[0084] The step of combining the +1 order light beam and the -1 order light beam to obtain two interference light beams;

[0085] The step of collecting a hologram of the object to be measured 3;

[0086] In the absence of an object to be detected, a step of collecting a background hologram;

[0087] A step of obtaining the phase distribution of the object to be measured 3 according to the complex amplitude of the difference map between the hologram of the object to be measured 3 and the background hologram.

[0088] Specifically, the implementation process is:

[0089] Step 1: Light Source 1 Adjustment

[0090] First, adjust the light source 1 to emit a light beam with a wavelength of λ. After passing through the collimating beam expansion system 2, the object to be measured 3 and the rectangular aperture 4, the light beam forms an object light and a reference light. After these light beams are focused by the first lens 5, the transmission grating 6 diffracts the light beams into +1, 0 and -1 order light beams. The 0 order light beam is blocked by the first baffle 7, and the +1 and -1 order light beams enter the second lens 8 and continue to be reflected and transmitted by the non-polarizing beam splitter prism 9. In this way, two interference light beams are generated.

[0091] Step 2: Carrier frequency introduction and hologram acquisition

[0092] In the second step, the carrier frequency is introduced by adjusting the tilt angle of the non-polarizing beam splitter prism 9. This process changes the frequency of the fringes in the hologram. By mirror-flipping the hologram I2, I2' is obtained, and the intensity distribution of I1 and I2' is collected by the image sensor 11. At this time, the mutual interference of the object light and the reference light generates two holograms I1 and I2 with different phase shifts.

[0093] Step 3: Background hologram acquisition

[0094] In this step, the image sensor 11 will collect background holograms I3 and I4 without the object to be measured 3. These holograms provide reference information without the object to be measured 3 for subsequent data processing. Next, I4 is mirror-flipped to obtain I4', and its intensity distribution is recorded.

[0095] Step 4: Difference calculation to remove DC component

[0096] By calculating the difference between I1 and I2', and between I3 and I4', the DC component in the hologram is removed. In this way, the DC background noise of the light beam can be effectively removed, and the accuracy of the data can be improved.

[0097] Step 5: Calculate the complex amplitude

[0098] Next, the complex amplitudes of the holograms I1 and I2', I3 and I4' after the DC component is removed are calculated respectively. The complex amplitudes r1(x, y) and r2(x, y) are obtained through Fourier transform and bandpass filtering operations.

[0099] Step 6: Phase Recovery

[0100] In the last step, the phase distribution of the object to be measured 3 is restored by calculating the imaginary and real parts of the complex amplitude. Through precise mathematical processing, the phase information of the object is obtained, thus completing the measurement.

[0101] According to the above technical solution, the following methods can be adopted for implementation:

[0102] A laser with a wavelength of 533 nm is used as the light source 1 to ensure its stability and adjustability;

[0103] A 60mm focal length lens system and 80 Lines / mm Ronchi grating are used, combined with a standard laboratory environment to ensure the repeatability of the experiment;

[0104] The angle adjustment of the non-polarizing beam splitter prism 9 can optimize the introduction of the carrier frequency under different measurement conditions, thereby improving the resolution of the measurement;

[0105] All optical components are made of high-precision materials to ensure the high efficiency and long-term stability of the device in practical applications.

[0106] Embodiment 8: This embodiment provides a computer storage medium for storing a computer program. When the computer program is read by a computer, the computer executes the method provided in embodiment 7.

[0107] Embodiment 9: This embodiment provides a computer, including a processor and a storage medium. When the processor reads a computer program stored in the storage medium, the computer executes the method provided in embodiment 7.

[0108] Embodiment 10: This embodiment provides a computer program product, which is a computer program. When the computer program is executed, the method provided in embodiment 7 is implemented.

[0109] Implementation Method XI: Combination Figure 1-4 This embodiment is described in detail by using specific examples to further describe the technical solution provided above. Specifically:

[0110] First example:

[0111] Figure 1 The structure of the first embodiment is shown in FIG. Figure 1 The light off-axis digital holographic device based on grating synchronous phase shift comprises: a light source 1, a collimating beam expansion system 2, an object to be measured 3, a rectangular aperture 4, a first lens 5, a transmission grating 6, a first baffle 7, a second lens 8, a non-polarizing beam splitter prism 9, a second baffle 10, and an image sensor 11, characterized in that: the light beam emitted by the light source 1 is incident on the rectangular aperture 4 after passing through the collimating beam expansion system 2 and the object to be measured 3 in sequence, forming an object light and a reference light; the light beams of the object light and the reference light focused by the first lens 5 are diffracted by the transmission grating 6 The grating diffracts the +1st, 0th and -1st order beams; the 0th order beam diffracted by the grating is blocked by the first baffle 7, and the +1st and -1st order beams are incident on the second lens 8; the two diffracted beams transmitted by the second lens 8 are reunited into two interference beams after reflection and transmission by the non-polarization beam splitter prism 9; one of the interference beams is blocked by the second baffle 10, and the other interference beam will generate two holograms, which are collected by the image sensor 11 into the computer; the rectangular aperture 4 is composed of two windows, and the object to be measured 3 is placed in front of one of the windows. The focal lengths of the first lens 5 and the second lens 8 are equal; the transmission grating 6 is located on the confocal plane of the first lens 5 and the second lens 8; the transmission grating 6 has the same light intensity modulation coefficient for the +1st and -1st order diffracted beams; the non-polarization beam splitter prism 9 can be rotated at an angle of α with respect to the optical axis to introduce different carrier frequencies in the hologram; the beam transmission and reflection ratio of the semi-transparent and semi-reflective surface of the non-polarization beam splitter prism 9 is 1:1.

[0112] Second embodiment: A light off-axis digital holographic detection method based on grating synchronous phase shift.

[0113] The light off-axis digital holographic detection method based on grating synchronous phase shift comprises the following steps:

[0114] (1) The light source is adjusted so that the light beam with a wavelength of λ emitted by the light source 1 passes through the collimating beam expansion system 2, the object to be measured 3 and the rectangular aperture 4 in sequence to form an object beam and a reference beam; the object beam and the reference beam are focused by the first lens 5 and diffracted by the transmission grating 6 into +1-order, 0-order and -1-order beams; the 0-order beam is blocked by the first baffle 7, and the +1-order and -1-order beams are incident on the second lens 8 and then merged into two beams by the non-polarizing beam splitter prism 9; one of the beams is blocked by the second baffle 10, and the object light and the reference light in the other beam interfere with each other to generate two holograms I1 and I2 with different phase shifts, which are simultaneously collected by the image sensor 11 and input into a computer.

[0115] (2) Move the non-polarizing beam splitter prism 9 to create an inclination angle α with the optical axis to introduce a carrier frequency into the hologram and mirror-flip the hologram I2 to obtain the intensity distributions of I2′, I1 and I2′:

[0116]

[0117] Among them, E O is the object light field distribution, E R is the light field distribution of the reference light, is the phase distribution of the object to be measured, C is the light intensity modulation coefficient of the transmission grating for the +1st and -1st order diffraction beams, 2πf x x is the carrier phase shift, f x = sinα / λ is the carrier frequency of the hologram fringes, θ0 is the random initial phase shift introduced by the initial offset of the transmission grating;

[0118] (3) When no object is placed, the image sensor collects background holograms I3 and I4, and mirrors and flips hologram I4 to obtain I4′. The intensity distributions of I3 and I4′ are:

[0119]

[0120] (4) respectively calculating the difference between I1 and I2′, and between I3 and I4′ to remove the DC term in the hologram;

[0121] (5) Calculate the complex amplitudes r1(x, y) and r2(x, y) of the two difference holograms respectively;

[0122] r1(x,y)=IFT{FT[I1(x,y)-I2′(x,y)]×BPF}

[0123] r2(x,y)=IFT{FT[I3(x,y)-I4′(x,y)]×BPF}

[0124] Among them, FT stands for Fourier transform, IFT stands for inverse Fourier transform, and BPF stands for bandpass filtering;

[0125] (6) Calculate the phase distribution of the object to be measured;

[0126]

[0127] Among them, Im means taking the imaginary part, and Re means taking the real part.

[0128] experiment:

[0129] The light source 1 uses a laser with a wavelength of λ=533nm. The focal lengths of the first lens and the second lens are equal, both 60mm. The width of the rectangular aperture is 2.7mm. The transmission grating uses a Ronchi grating with a line count of 80 lines / mm.

[0130] The synchronous phase-shifted holograms of two objects to be measured obtained by one exposure are shown in Figure 2. Figure 2 As shown in the figure, two synchronous phase-shifted holograms without the object to be measured are as follows Figure 3 As shown, the final recovered phase of the object to be measured is as follows Figure 4 shown.

[0131] This implementation example has very good stability and can optimize the resolution by the tilt angle of the non-polarizing beam splitter prism. Only one exposure is required to collect two synchronous phase-shifted holograms of the object to be measured, which are used to restore the phase of the object to be measured. While taking into account the real-time measurement, the method is simple and easy to implement, and does not require any special optical elements such as polarization elements, reflection gratings, pinhole filters, special prisms, etc., and the complexity of the system is further reduced.

[0132] The technical solution provided by the present invention is further described in detail above through several specific implementation modes in order to highlight the advantages and benefits of the technical solution provided by the present invention. However, the several specific implementation modes described above are not intended to be used as limitations on the present invention. Any reasonable modification and improvement of the present invention, combination of implementation modes and equivalent substitution within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A light off-axis digital holographic detection device based on grating synchronous phase shift, characterized in that: include: A collimation and beam expansion system is used to collimate and expand the light beam emitted by the light source; Rectangular aperture, used to place the object to be measured; A first lens, used for focusing the object light and the reference light; A transmission grating, located on a confocal plane of the first lens and the second lens, for diffracting the light beam to generate +1-order, 0-order and -1-order light beams; A first baffle, used for shielding the 0th order light beam diffracted by the transmission grating; A second lens for focusing and directing the +1st and -1st order light beams; A non-polarizing beam splitter prism, used for combining the +1st order and -1st order light beams to generate two interference light beams; The second baffle is used to block one of the interfering light beams.

2. The light off-axis digital holographic detection device based on grating synchronous phase shift according to claim 1, characterized in that: The focal lengths of the first lens and the second lens are equal.

3. The light off-axis digital holographic detection device based on grating synchronous phase shift according to claim 1 is characterized in that: The transmission grating has the same light intensity modulation coefficient for the +1st order and -1st order diffracted light beams.

4. The light off-axis digital holographic detection device based on grating synchronous phase shift according to claim 1, characterized in that: The non-polarizing beam splitter prism can be rotated at a deflection angle α with respect to the optical axis, and the light beam transmission and reflection ratio of its semi-transparent and semi-reflective surface is 1:

1.

5. The light off-axis digital holographic detection device based on grating synchronous phase shift according to claim 1, characterized in that: The rectangular aperture is composed of two windows, one of which is used for placing the object to be measured.

6. A light off-axis digital holographic detection system based on grating synchronous phase shift, characterized in that: include: The device of claim 1, and: A light source, for emitting a light beam with a wavelength of λ; An object to be measured, used to interact with the light beam to form object light and reference light; Image sensor, used to generate holograms.

7. A light off-axis digital holographic detection method based on grating synchronous phase shift, characterized in that: The method is implemented based on the system of claim 6, comprising: The step of generating a light beam having a wavelength λ; The step of collimating and expanding the light beam and emitting it to the object to be measured to generate object light and reference light; Steps of diffracting +1st order, 0th order and -1st order beams through object light and reference light; The step of combining the +1 order light beam and the -1 order light beam to obtain two interference light beams; The steps of collecting the hologram of the object to be measured; In the absence of an object to be detected, a step of collecting a background hologram; The step of obtaining the phase distribution of the object to be measured according to the complex amplitude of the difference map between the hologram of the object to be measured and the background hologram.

8. A computer storage medium for storing a computing program, characterized in that: When the computer program is read by a computer, the computer executes the method of claim 7.

9. A computer, comprising a processor and a storage medium, characterized in that: When the processor reads the computer program stored in the storage medium, the computer executes the method of claim 7 .

10. A computer program product, being a computer program, characterized in that When the computer program is executed, the method of claim 7 is implemented.

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