Lensless digital holographic imaging adaptive digital focal length calculation method

Abstract

The application discloses a kind of lensless digital holographic imaging adaptive digital focal length calculation method, it is related to digital focal length calculation technical field, the present application includes step one, photographic environment analysis, step two, digital hologram reconstruction image establishment, step three, hologram reconstruction image information acquisition, step four, accurate reconstruction distance acquisition, step five, digital focal length acquisition, the vibration interference index of the present analysis digital imaging light path, and then the comprehensive stability of the shooting environment is analyzed, and the holographic image of the relatively stable shooting environment is screened, the holographic image of the object is reduced by interference degree, it is favorable for subsequent calculation of digital focal length, improve the quality of the holographic image of object, the present application reduces the influence of interference information on reconstruction distance analysis, help holographic image quickly obtain accurate reconstruction distance, efficiently realize the reproduction process of digital hologram, improve the adaptability, stability and controllability of digital holographic imaging auto focus.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of digital focal length calculation, and particularly relates to a lensless digital holographic imaging adaptive digital focal length calculation method. BACKGROUND

[0002] Digital holographic imaging is a new holographic imaging technology generated with the development of computers and CCD technology, which records holograms through CCD, and replaces the traditional optical reconstruction of object light waves with a digital reconstruction method, realizes the digitization of the whole process of holographic recording, storage and reconstruction, and has a wide application prospect in mechanical measurement, topography and deformation measurement, cell culture observation, microcircuit detection, information encryption and the like. The adaptive digital focal length calculation of holographic imaging can quickly obtain the final focal length of digital holographic imaging, help holographic imaging to obtain higher clarity, and help to improve the quality of holographic images. Therefore, the adaptive digital focal length calculation is extremely important in digital holographic imaging.

[0003] However, the current digital focal length calculation still has some problems.

[0004] 1. In the prior art, when the holographic image of an object is obtained by a digital holographic imaging light path, whether the shooting environment is stable is usually analyzed according to the stability of the environment, and the vibration of each optical device during shooting is not highly focused. The vibration of each optical device during shooting reflects the stability of the shooting environment in a certain case, which increases the interference degree of the holographic image of the object, is not conducive to the subsequent calculation of the digital focal length, and reduces the quality of the holographic image of the object.

[0005] 2. In the prior art, when analyzing the focusing criterion of the holographic image, the focusing criterion of the image is usually calculated according to the mean value of the image gray value. When the holographic image captured by the optical device has much interference, the holographic image not only captures the information of the object, but also captures the interference information. In the process of determining the criterion standard, all the interference information will affect the calculation result of the mean value, the mean value will have great fluctuation and instability, and thus the determination of the focal length is affected. SUMMARY

[0006] In view of the above technical deficiencies, the present application aims to provide a lensless digital holographic imaging adaptive digital focal length calculation method to solve the above problems.

[0007] To solve the above technical problems, the present application adopts the following technical solutions: The present application provides a lensless digital holographic imaging adaptive digital focal length calculation method, comprising: step one, photographic environment analysis: the staff sets up a digital holographic imaging light path outdoors, and deploys temperature sensors and ultrasonic sensors outdoors, obtains the temperature and air flow rate of the digital holographic imaging light path at each monitoring time point belonging to each monitoring time period, and analyzes the environmental stability evaluation index of the digital holographic imaging light path in each monitoring time period.

[0008] Step two, digital hologram reconstruction image establishment: install vibration sensors on each optical equipment belonging to the digital holographic imaging light path, take pictures of the target object according to the set shooting interval length by the digital holographic imaging light path, obtain the vibration intensity of each optical equipment belonging to the digital holographic imaging light path in each shooting, analyze the vibration interference index of the digital imaging light path in each shooting, select each suitable shooting image of the target object, convert each suitable shooting image of the target object into each holographic image by the computer, and obtain the digital holographic reconstruction image of each holographic image belonging to the target object at each reconstruction distance according to the set reconstruction distance interval.

[0009] Step three, hologram reconstruction image information acquisition: Fourier transform the digital reconstruction image of each holographic image belonging to the target object at each reconstruction distance, and perform gray scale processing to obtain the gray scale value of each pixel point corresponding to the digital reconstruction image of each holographic image belonging to the target object at each reconstruction distance.

[0010] Step four, accurate reconstruction distance acquisition: analyze the high-frequency pixel point energy of the digital reconstruction image of each holographic image belonging to the target object at each reconstruction distance, calculate the mean energy of the high-frequency pixel points corresponding to the digital reconstruction image of each holographic image belonging to the target object at each reconstruction distance, and then calculate the digital focusing criterion of the digital reconstruction image of each holographic image belonging to the target object at each reconstruction distance.

[0011] Step five, digital focal length acquisition: according to the digital focusing criterion of the digital reconstruction image of each holographic image belonging to the target object at each reconstruction distance, select each suitable focal length of the holographic imaging of the target object, and analyze the final focal length of the holographic imaging of the target object.

[0012] Preferably, the analysis of the environmental stability evaluation index of the digital holographic imaging light path at each monitoring time period is performed according to the temperature and air flow rate at each monitoring time point belonging to each monitoring time period, wherein represents the number of each monitoring time period, , is any integer greater than 2, represents the number of each monitoring time point. , is any integer greater than 2, the temperature stability evaluation index of the digital holographic imaging optical path in each monitoring time period and the air flow stability evaluation index .

[0013] the environmental stability evaluation index of the digital holographic imaging optical path in each monitoring time period corresponding to , wherein is the temperature stability proportion factor, is the air flow stability proportion factor, , The value range of each of the above-mentioned proportion factors belongs to 0 to 1.

[0014] Preferably, the temperature stability evaluation index and the air flow stability evaluation index of the digital holographic imaging optical path in each monitoring time period are analyzed by the following method: the temperature stability evaluation index of the digital holographic imaging optical path in each monitoring time period is analyzed , wherein represents the number of monitoring time points, represents the set allowed temperature deviation, represents the temperature of the digital holographic imaging optical path at the th monitoring time point belonging to the th monitoring time period.

[0015] the air flow stability evaluation index of the digital holographic imaging optical path in each monitoring time period is analyzed by , wherein represents the set allowed air flow deviation, represents the air flow rate of the digital holographic imaging optical path at the th monitoring time point belonging to the th monitoring time period.

[0016] Preferably, the vibration interference index of the digital imaging optical path in each shooting is analyzed by the following method: according to the vibration intensity of each optical equipment belonging to the digital holographic imaging optical path in each shooting , wherein represents the number of optical equipment, , is any integer greater than 2, represents the number of each shooting, , the vibration interference index of the digital imaging optical path in each shooting is analyzed by , wherein represents the number of optical equipment, represents the number of shootings.

[0017] Preferably, the suitable shooting images of the target object are obtained by the following method: obtaining the digital holographic imaging light path at each shooting time point, comparing the digital holographic imaging light path at each shooting time point with each monitoring time period, obtaining the digital holographic imaging light path at each shooting corresponding monitoring time period, and further obtaining the environmental stability evaluation index of the digital holographic imaging light path at each shooting. .

[0018] The comprehensive stability evaluation index of the digital holographic imaging light path at each shooting is analyzed. , wherein represents the influence factor of the vibration interference index, represents the influence factor of the environmental stability, , The value range of each of the above-mentioned influence factors belongs to 0 to 1.

[0019] The comprehensive stability evaluation index of the digital holographic imaging light path at each shooting is compared with the set comprehensive stability evaluation index threshold value. If the comprehensive stability evaluation index of the digital holographic imaging light path at a certain shooting is greater than or equal to the set comprehensive stability evaluation index upper limit, the shooting of the digital holographic imaging light path at this time is marked as a standard shooting, and each standard shooting of the digital holographic imaging light path is counted.

[0020] The shooting images corresponding to each standard shooting of the digital holographic imaging light path are obtained, and the shooting images corresponding to each standard shooting of the digital holographic imaging light path are marked as the suitable shooting images of the target object.

[0021] Preferably, the energy of each high-frequency pixel point corresponding to the digital reconstruction image of each holographic image of the target object at each reconstruction distance is analyzed by the following method: the gray value of each pixel point corresponding to the digital reconstruction image of each holographic image of the target object at each reconstruction distance is subtracted from the gray value of the adjacent pixel point, to obtain the gray value deviation of each pixel point and the adjacent pixel point corresponding to the digital reconstruction image of each holographic image of the target object at each reconstruction distance. The gray value deviation of each pixel point and the adjacent pixel point corresponding to the digital reconstruction image of each holographic image of the target object at each reconstruction distance is compared with the preset gray value deviation threshold value. If the gray value deviation of a certain pixel point and the adjacent pixel point corresponding to the digital reconstruction image of a certain holographic image of the target object at a certain reconstruction distance is greater than or equal to the preset gray value deviation threshold value, the pixel point corresponding to the digital reconstruction image of the holographic image of the target object at the reconstruction distance is marked as a high-frequency pixel point.

[0022] According to the gray value of each pixel point corresponding to the digital reconstruction image of each holographic image of the target object at each reconstruction distance, the energy of each pixel point corresponding to the digital reconstruction image of each holographic image of the target object at each reconstruction distance is obtained.

[0023] From the energy of each high-frequency pixel point corresponding to the digital reconstruction image of each holographic image of the target object at each reconstruction distance, the energy of each high-frequency pixel point corresponding to the digital reconstruction image of each holographic image of the target object at each reconstruction distance is extracted , wherein represents the number of each holographic image, , is any integer greater than 2, represents the number of each reconstruction distance, , is any integer greater than 2, represents the number of each high-frequency pixel point, , is any integer greater than 2.

[0024] Preferably, the automatic focusing criterion for analyzing the digital reconstruction image of each holographic image of the target object at each reconstruction distance is that the specific analysis method is to analyze the mean energy of the high-frequency pixel point corresponding to the digital reconstruction image of each holographic image of the target object at each reconstruction distance , wherein represents the number of high-frequency pixel points.

[0025] The statistical root mean square of the high-frequency energy corresponding to the digital reconstruction image of each holographic image of the target object at each reconstruction distance is calculated .

[0026] The automatic focusing criterion for analyzing the digital reconstruction image of each holographic image of the target object at each reconstruction distance is analyzed .

[0027] Preferably, the specific analysis method for analyzing the final focal length of the holographic imaging of the target object is to arrange the digital reconstruction image of each holographic image of the target object at each reconstruction distance in descending order according to the automatic focusing criterion, extract the reconstruction distance of the last holographic image of the target object, and mark it as the appropriate focal length of each holographic image of the target object.

[0028] The appropriate focal length of each holographic image of the target object is marked as the appropriate focal length of the holographic imaging of the target object.

[0029] The average suitable focal length of the holographic imaging of the target object is obtained by averaging each suitable focal length of the holographic imaging of the target object, and the deviation of each suitable focal length of the holographic imaging of the target object from the average suitable focal length is obtained by subtracting the average suitable focal length from each suitable focal length of the holographic imaging of the target object.

[0030] The deviation of each suitable focal length of the holographic imaging of the target object from the average suitable focal length is compared with the set allowable focal length deviation, if the deviation of a certain suitable focal length of the holographic imaging of the target object from the average suitable focal length is less than or equal to the set allowable focal length deviation, the suitable focal length of the holographic imaging of the target object is marked as a preferred focal length, and each preferred focal length of the holographic imaging of the target object is counted.

[0031] The average preferred focal length of the holographic imaging of the target object is obtained by averaging each preferred focal length of the holographic imaging of the target object, and the average preferred focal length of the holographic imaging of the target object is marked as the final focal length.

[0032] The beneficial effects of the present application are as follows: 1. When the present application obtains the holographic image of the object in the digital holographic imaging light path, the vibration intensity of each optical device during shooting is obtained, the vibration interference index of the digital imaging light path is analyzed, and the comprehensive stability of the shooting environment is analyzed, the holographic image with a relatively stable shooting environment is screened, the interference degree of the holographic image of the object is reduced, which is beneficial to the subsequent calculation of the digital focal length, and the quality of the holographic image of the object is improved.

[0033] 2. Based on the statistical square root of the high-frequency energy of the reconstructed image of the digital hologram under different digital focal lengths and the average energy of the high-frequency part of the reconstructed image of the digital hologram, the quotient of the automatic focusing criterion of the reconstructed image of the digital hologram is calculated, the influence of the interference information on the analysis of the reconstruction distance is reduced, the holographic image quickly obtains the accurate reconstruction distance, the digital holographic reconstruction process is efficiently realized, and the adaptability, stability and controllability of the automatic focusing of the digital holographic imaging are improved. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating labor.

[0035] Figure 1 The method embodiment of the present application is a flowchart. DETAILED DESCRIPTION

[0036] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0037] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application. Figure 1 The present application proposes a lensless digital holographic imaging adaptive digital focal length calculation method, comprising the following steps: step one, photographic environment analysis: a staff sets up a digital holographic imaging light path outdoors, and deploys temperature sensors and ultrasonic sensors outdoors to obtain the temperature and air flow rate corresponding to each monitoring time point of the digital holographic imaging light path in each monitoring time period, and analyze the environmental stability evaluation index of the digital holographic imaging light path in each monitoring time period.

[0038] In a specific embodiment of the present application, the specific analysis method of the environmental stability evaluation index corresponding to each monitoring time period of the digital holographic imaging light path is as follows: according to the temperature and air flow rate corresponding to each monitoring time point of the digital holographic imaging light path in each monitoring time period, wherein is the number of each monitoring time period, is an arbitrary integer greater than 2, is the number of each monitoring time point, , is an arbitrary integer greater than 2, the temperature stability evaluation index and the air flow stability evaluation index of the digital holographic imaging light path in each monitoring time period are analyzed.

[0039] The environmental stability evaluation index corresponding to each monitoring time period of the digital holographic imaging light path is analyzed, wherein is the temperature stability proportion factor, is the air flow stability proportion factor, , The value range of all belongs to 0 to 1.

[0040] In another specific embodiment of the present application, the specific analysis method of the temperature stability evaluation index and the air flow stability evaluation index of the digital holographic imaging light path in each monitoring time period is as follows: the temperature stability evaluation index of the digital holographic imaging light path in each monitoring time period is analyzed, wherein is the number of monitoring time points, is the set allowed temperature deviation, represents the temperature of the digital holographic imaging optical path at the first monitoring time point belonging to the first monitoring time period; represents the temperature of the digital holographic imaging optical path at the first monitoring time point belonging to the first monitoring time period; represents the temperature of the digital holographic imaging optical path at the first monitoring time point belonging to the first monitoring time period;

[0041] analyzing the air flow stability evaluation index of the digital holographic imaging optical path at each monitoring time period, wherein represents the set allowable air flow rate deviation, represents the air flow rate of the digital holographic imaging optical path at the first monitoring time point belonging to the first monitoring time period; represents the air flow rate of the digital holographic imaging optical path at the first monitoring time point belonging to the first monitoring time period; represents the air flow rate of the digital holographic imaging optical path at the first monitoring time point belonging to the first monitoring time period; represents the air flow rate of the digital holographic imaging optical path at the first monitoring time point belonging to the first monitoring time period;

[0042] Step two, digital holographic image reconstruction image establishment: installing vibration sensors on each optical equipment belonging to the digital holographic imaging optical path, shooting the target object by the digital holographic imaging optical path according to the set shooting interval length, obtaining the vibration intensity of each optical equipment belonging to the digital holographic imaging optical path at each shooting, analyzing the vibration interference index of the digital imaging optical path at each shooting, screening each suitable shooting image of the target object, converting each suitable shooting image of the target object into each holographic image by the computer, and obtaining the digital holographic reconstruction image corresponding to each reconstruction distance of each holographic image belonging to the target object according to the set reconstruction distance interval.

[0043] It should be noted that the optical equipment includes a helium-neon laser, a lens, a beam splitter, and a mirror.

[0044] In one embodiment of the present application, the vibration interference index of the digital imaging optical path at each shooting is analyzed in the following manner: according to the vibration intensity of each optical equipment belonging to the digital holographic imaging optical path at each shooting , wherein represents the number of each optical equipment, , is any integer greater than 2, represents the number of each shooting, , is any integer greater than 2, and the vibration interference index of the digital imaging optical path at each shooting is analyzed , wherein represents the number of optical equipment, represents the number of shootings.

[0045] In another specific embodiment of the present application, the specific screening method of each suitable shooting image of the screening target object is as follows: obtaining the digital holographic imaging light path at each shooting time point, comparing the digital holographic imaging light path at each shooting time point with each monitoring time period, obtaining the digital holographic imaging light path at each shooting corresponding monitoring time period, and then obtaining the environmental stability evaluation index of the digital holographic imaging light path at each shooting. .

[0046] analyzing the comprehensive stability evaluation index of the digital holographic imaging light path at each shooting , wherein represents the influence factor of the vibration interference index, represents the influence factor of the environmental stability, , the value range of each of the above is between 0 and 1.

[0047] comparing the comprehensive stability evaluation index of the digital holographic imaging light path at each shooting with the set comprehensive stability evaluation index threshold value, if the comprehensive stability evaluation index of the digital holographic imaging light path at a certain shooting is greater than or equal to the set comprehensive stability evaluation index upper limit, the shooting of the digital holographic imaging light path is marked as a standard shooting, and each standard shooting of the digital holographic imaging light path is counted.

[0048] obtaining the shooting image corresponding to each standard shooting of the digital holographic imaging light path, and marking the shooting image corresponding to each standard shooting of the digital holographic imaging light path as each suitable shooting image of the target object.

[0049] When the present application obtains the holographic image of the object through the digital holographic imaging light path, the vibration intensity of each optical device during shooting is obtained, the vibration interference index of the digital imaging light path is analyzed, and then the comprehensive stability of the shooting environment is analyzed, so that the holographic image with relatively stable shooting environment is screened out, the interference degree of the holographic image of the object is reduced, which is conducive to the subsequent calculation of the digital focal length and improves the quality of the holographic image of the object.

[0050] Step three, hologram reconstruction image information acquisition: Fourier transform is performed on the digital reconstruction image of each holographic image of the target object at each reconstruction distance, and gray scale processing is performed, so as to obtain the gray scale value of each pixel point corresponding to the digital reconstruction image of each holographic image of the target object at each reconstruction distance.

[0051] Step four, accurate reconstruction distance acquisition: analyzing the energy of each high-frequency pixel point of the digital reconstruction image of each holographic image of the target object at each reconstruction distance, calculating the mean energy of the high-frequency pixel point corresponding to the digital reconstruction image of each holographic image of the target object at each reconstruction distance, and then calculating the digital focusing criterion of the digital reconstruction image of each holographic image of the target object at each reconstruction distance.

[0052] In one specific embodiment of the present application, the energy of each high-frequency pixel point corresponding to each digital reconstruction image of each holographic image of the target object at each reconstruction distance is obtained by subtracting the gray value of the adjacent pixel point from the gray value of each pixel point corresponding to each digital reconstruction image of each holographic image of the target object at each reconstruction distance, comparing the gray value deviation of each pixel point and the adjacent pixel point corresponding to each digital reconstruction image of each holographic image of the target object at each reconstruction distance with the preset gray value deviation threshold, and marking the pixel point corresponding to the digital reconstruction image of the holographic image of the target object at the reconstruction distance as a high-frequency pixel point if the gray value deviation of the pixel point and the adjacent pixel point corresponding to the digital reconstruction image of the holographic image of the target object at the reconstruction distance is greater than or equal to the preset gray value deviation threshold.

[0053] According to the gray value of each pixel point corresponding to each digital reconstruction image of each holographic image of the target object at each reconstruction distance, the energy of each pixel point corresponding to each digital reconstruction image of each holographic image of the target object at each reconstruction distance is obtained.

[0054] It should be noted that the energy of each pixel point corresponding to each digital reconstruction image of each holographic image of the target object at each reconstruction distance is obtained by extracting the energy corresponding to each gray value interval from the web database, comparing the gray value of each pixel point corresponding to each digital reconstruction image of each holographic image of the target object at each reconstruction distance with each gray value interval, obtaining the gray value interval corresponding to each pixel point corresponding to each digital reconstruction image of each holographic image of the target object at each reconstruction distance, and then obtaining the energy of each pixel point corresponding to each digital reconstruction image of each holographic image of the target object at each reconstruction distance.

[0055] The energy of each high-frequency pixel point corresponding to each digital reconstruction image of each holographic image of the target object at each reconstruction distance is extracted from the energy of each pixel point corresponding to each digital reconstruction image of each holographic image of the target object at each reconstruction distance. wherein represents the number of each holographic image, , is any integer greater than 2, represents the number of each reconstruction distance, , is any integer greater than 2, represents the number of each high-frequency pixel point, , is any integer greater than 2.

[0056] Step five, digital focal length acquisition: according to the digital focusing criterion of the digital reconstruction image of each holographic image of the target object at each reconstruction distance, screening each suitable focal length of the holographic imaging of the target object, and analyzing the final focal length of the holographic imaging of the target object.

[0057] In one specific embodiment of the present application, the automatic focusing criterion of the digital reconstruction image of each holographic image of the target object at each reconstruction distance is specifically analyzed by: analyzing the mean energy of the high-frequency pixel points corresponding to the digital reconstruction image of each holographic image of the target object at each reconstruction distance , wherein represents the number of high-frequency pixel points.

[0058] calculating the statistical root-mean-square of the high-frequency energy corresponding to the digital reconstruction image of each holographic image of the target object at each reconstruction distance .

[0059] analyzing the automatic focusing criterion of the digital reconstruction image of each holographic image of the target object at each reconstruction distance .

[0060] In another specific embodiment of the present application, the final focal length of the holographic imaging of the target object is specifically analyzed by: arranging the digital reconstruction image of each holographic image of the target object at each reconstruction distance in descending order according to the automatic focusing criterion, extracting the reconstruction distance of the last position in each holographic image of the target object, and marking it as the suitable focal length of each holographic image of the target object.

[0061] Marking the suitable focal length of each holographic image of the target object as each suitable focal length of the holographic imaging of the target object.

[0062] Performing mean value processing on each suitable focal length of the holographic imaging of the target object to obtain the average suitable focal length of the holographic imaging of the target object, and subtracting each suitable focal length of the holographic imaging of the target object from the average suitable focal length to obtain the deviation of each suitable focal length of the holographic imaging of the target object from the average suitable focal length.

[0063] Comparing the deviation of each suitable focal length of the holographic imaging of the target object from the average suitable focal length with the set allowable focal length deviation, if the deviation of a suitable focal length of the holographic imaging of the target object from the average suitable focal length is less than or equal to the set allowable focal length deviation, marking the suitable focal length of the holographic imaging of the target object as the preferred focal length, and counting each preferred focal length of the holographic imaging of the target object.

[0064] Performing mean value processing on each preferred focal length of the holographic imaging of the target object to obtain the average preferred focal length of the holographic imaging of the target object, and marking the average preferred focal length of the holographic imaging of the target object as the final focal length.

[0065] The application is based on the quotient of the statistical root mean square of high frequency energy of the digital hologram reconstruction image at different digital focal lengths and the mean energy of the high frequency part of the digital hologram reconstruction image, which reduces the influence of interference information on the analysis of the reconstruction distance, helps the holographic image to quickly obtain the accurate reconstruction distance, efficiently realizes the reproduction process of the digital hologram, and improves the adaptability, stability and controllability of the digital holographic imaging automatic focusing.

[0066] The above is only an example and description of the concept of the application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or replace them with similar ways, as long as they do not deviate from the concept of the application or exceed the scope defined in the specification, which shall belong to the protection scope of the application.

Claims

1. A lensless digital holographic imaging adaptive digital focal length calculation method, characterized in that, include: Step 1: Photographic Environment Analysis: Staff will set up a digital holographic imaging optical path outdoors and deploy temperature and ultrasonic sensors outdoors to obtain the temperature and air velocity corresponding to each monitoring time point of the digital holographic imaging optical path in each monitoring period, and analyze the environmental stability assessment index of the digital holographic imaging optical path in each monitoring period. Step 2: Digital Holographic Reconstruction Image Establishment: Vibration sensors are installed on each optical device in the digital holographic imaging optical path. The digital holographic imaging optical path takes pictures of the target object at a set shooting interval. The vibration intensity of each optical device in the digital holographic imaging optical path is obtained in each shooting. The vibration interference index of the digital imaging optical path in each shooting is analyzed. Suitable pictures of the target object are selected. The computer converts each suitable picture of the target object into a holographic image. According to the set reconstruction distance interval, the digital holographic reconstruction image of each holographic image of the target object at each reconstruction distance is obtained. Step 3: Obtaining Holographic Reconstruction Image Information: Perform Fourier transform on the digitally reconstructed images of each holographic image belonging to the target object at each reconstruction distance, and perform grayscale processing to obtain the grayscale value of each pixel corresponding to the digitally reconstructed images of each holographic image belonging to the target object at each reconstruction distance. Step 4: Accurate Reconstruction Distance Acquisition: Analyze the energy of each high-frequency pixel in the digital reconstructed image of each holographic image of the target object at each reconstruction distance, calculate the mean energy of the corresponding high-frequency pixels in the digital reconstructed image of each holographic image of the target object at each reconstruction distance, and then calculate the autofocus criterion of the digital reconstructed image of each holographic image of the target object at each reconstruction distance. Step 5: Digital focal length acquisition: Based on the autofocus criteria of the digital reconstructed images of each holographic image of the target object at each reconstruction distance, select the appropriate focal lengths for the holographic imaging of the target object, and analyze the final focal length of the holographic imaging of the target object.

2. The adaptive digital focal length calculation method for lensless digital holographic imaging according to claim 1, characterized in that, The specific analysis method for the environmental stability assessment index of the digital holographic imaging optical path in each monitoring time period is as follows: Based on the temperature corresponding to each monitoring time point in each monitoring period according to the digital holographic imaging optical path air velocity ,in This indicates the number of each monitoring time period. , It is any integer greater than 2. This indicates the number of each monitoring time point. , For any integer greater than 2, analyze the temperature stability evaluation index of the digital holographic imaging optical path during each monitoring time period. and airflow stability assessment index ; Analysis of the environmental stability assessment index of the digital holographic imaging optical path during different monitoring time periods ,in This is a factor representing the proportion of temperature stability. This is a factor contributing to the stability of airflow. , The value range is from 0 to 1.

3. The adaptive digital focal length calculation method for lensless digital holographic imaging according to claim 2, characterized in that, The specific analysis method for the temperature stability evaluation index and air flow stability evaluation index of the digital holographic imaging optical path in each monitoring time period is as follows: Analysis of temperature stability evaluation index of digital holographic imaging optical path during various monitoring time periods ,in Indicates the number of monitoring time points. This indicates the set allowable temperature deviation. This indicates the optical path of digital holographic imaging in the first... The monitoring time period belongs to the [number]th [period]. Temperature at each monitoring time point; Analysis of the airflow stability assessment index of the digital holographic imaging optical path during different monitoring time periods ,in This indicates the set allowable airflow velocity deviation. This indicates the optical path of digital holographic imaging in the first... The monitoring time period belongs to the [number]th [period]. Air velocity at each monitoring time point.

4. The adaptive digital focal length calculation method for lensless digital holographic imaging according to claim 1, characterized in that, The specific analysis method for the vibration interference index of the digital imaging optical path in each shooting is as follows: Based on the vibration intensity of each optical device in the digital holographic imaging optical path during each capture. ,in This indicates the serial number of each optical device. , It is any integer greater than 2. This indicates the number of each shooting session. , Let be any integer greater than 2, and analyze the vibration interference index of the digital imaging optical path during each capture. ,in Indicates the number of optical devices. Indicates the number of times the photo was taken.

5. The adaptive digital focal length calculation method for lensless digital holographic imaging according to claim 4, characterized in that, The specific method for selecting suitable images of the target object is as follows: The time points of the digital holographic imaging optical path in each shooting session are obtained. These time points are then compared with the monitoring time periods to obtain the corresponding monitoring time periods for each shooting session. Finally, the environmental stability assessment index of the digital holographic imaging optical path in each shooting session is obtained. ; Analysis of the comprehensive stability evaluation index of the optical path in digital holographic imaging for each shooting session ,in Indicating the influencing factors of the vibration disturbance index, Factors influencing environmental stability , The values ​​of are all within the range of 0 to 1; Compare the comprehensive stability evaluation index of the digital holographic imaging optical path in each shooting with the set comprehensive stability evaluation index threshold. If the comprehensive stability evaluation index of the digital holographic imaging optical path in a certain shooting is greater than or equal to the set comprehensive stability evaluation index upper limit, then the shooting of the digital holographic imaging optical path in that shooting is marked as a standard shooting, and the standard shooting of the digital holographic imaging optical path is counted. Acquire the captured images corresponding to each standard capture of the digital holographic imaging optical path, and mark the captured images corresponding to each standard capture of the digital holographic imaging optical path as suitable captured images of the target object.

6. The adaptive digital focal length calculation method for lensless digital holographic imaging according to claim 1, characterized in that, The specific analysis method for the energy of each high-frequency pixel in the digitally reconstructed image of each holographic image of the target object at each reconstruction distance is as follows: Subtract the gray value of each pixel in the digital reconstructed image of each holographic image of the target object at each reconstruction distance from the gray value of the adjacent pixel to obtain the gray value deviation between each pixel and the adjacent pixel in the digital reconstructed image of each holographic image of the target object at each reconstruction distance. Compare the gray value deviation between each pixel and the adjacent pixel in the digital reconstructed image of each holographic image of the target object at each reconstruction distance with a preset gray value deviation threshold. If the gray value deviation between a pixel and the adjacent pixel in the digital reconstructed image of a certain holographic image of the target object at a certain reconstruction distance is greater than or equal to the preset gray value deviation threshold, then mark the corresponding pixel in the digital reconstructed image of the holographic image of the target object at that reconstruction distance as a high-frequency pixel. Based on the gray values ​​of each pixel in the digital reconstructed image of each holographic image of the target object at each reconstruction distance, the energy of each pixel in the digital reconstructed image of each holographic image of the target object at each reconstruction distance is obtained. Extract the energy of each high-frequency pixel in the digitally reconstructed image of each holographic image of the target object at each reconstruction distance from the energy of each pixel in the digitally reconstructed image of each holographic image of the target object at each reconstruction distance. ,in This indicates the number of each holographic image. , It is any integer greater than 2. The numbers representing the reconstruction distances, , It is any integer greater than 2. This indicates the number of each high-frequency pixel. , It can be any integer greater than 2.

7. The adaptive digital focal length calculation method for lensless digital holographic imaging according to claim 1, characterized in that, The automatic focus criterion for calculating the digital reconstructed images of each holographic image of the target object at each reconstruction distance is specifically analyzed as follows: Analyze the mean energy of high-frequency pixels in the digitally reconstructed images of each holographic image of the target object at each reconstruction distance. ,in Indicates the number of high-frequency pixels; Calculate the root mean square of the high-frequency energy corresponding to the digitally reconstructed image of each holographic image of the target object at each reconstruction distance. ; Analyze the autofocus criteria of the digitally reconstructed images of the target object at various reconstruction distances for each holographic image of the target object. .

8. The adaptive digital focal length calculation method for lensless digital holographic imaging according to claim 1, characterized in that, The specific analysis method for the final focal length of the holographic image to which the target object belongs is as follows: The digital reconstructed images of each holographic image belonging to the target object at each reconstruction distance are arranged in descending order of the autofocus criterion. The reconstruction distance at the last position in each holographic image belonging to the target object is extracted and marked as the appropriate focal length of each holographic image belonging to the target object. The appropriate focal lengths of each holographic image of the target object are marked as the appropriate focal lengths for holographic imaging of the target object; The average suitable focal length of the holographic imaging of the target object is obtained by averaging the suitable focal lengths of each suitable focal length. The deviation between the suitable focal lengths of each suitable focal length and the average suitable focal length is obtained by subtracting the average suitable focal length from the average suitable focal length. The deviations of each suitable focal length and the average suitable focal length of the holographic imaging of the target object are compared with the set allowable focal length deviation. If the deviation of a certain suitable focal length of the holographic imaging of the target object from the average suitable focal length is less than or equal to the set allowable focal length deviation, then the suitable focal length of the holographic imaging of the target object is marked as the preferred focal length, and the preferred focal lengths of the holographic imaging of the target object are counted. The average preferred focal length of the holographic imaging of the target object is obtained by averaging the preferred focal lengths of the holographic imaging of the target object, and the average preferred focal length of the holographic imaging of the target object is marked as the final focal length.

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