CN115046576A - Calibration system, method and device for physical parameters of wavefront sensor - Google Patents
Calibration system, method and device for physical parameters of wavefront sensor Download PDFInfo
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Abstract
The application discloses a calibration system, a calibration method and a calibration device for physical parameters of a wavefront sensor, wherein the calibration system, the calibration method and the calibration device comprise the following steps: spherical wave generating device, wavefront sensor and data processor to wait to mark. Firstly, generating high-precision spherical waves by a spherical wave generating device, and generating a corresponding light spot array image by a wavefront sensor to be calibrated based on the spherical waves; the data processor obtains the proportional relation between the size of the sub-lens of the micro-lens array and the pixel size of the detector, then iteratively solves each physical parameter of the wave-front sensor based on the proportional relation, the light spot array image and the constraint relation among the physical parameters to obtain the approximate value of each physical parameter, and finally determines the final calibration value of each physical parameter through the analysis of wave-front restoration precision. The technical problem that high-precision calibration cannot be carried out on the physical parameters of the wavefront sensor due to the loss of the prior art is solved, all the physical parameters are converged within a target precision range, and the measurement precision of the wavefront sensor is improved.
Description
Technical Field
The application relates to the technical field of optical measurement, in particular to a calibration system, method and device for physical parameters of a wavefront sensor.
Background
The wavefront sensor is a relative wavefront measuring instrument, can detect the shape of a wavefront, and is widely applied to the fields of astronomy, high-energy laser, fundus imaging, optical communication, optical detection and the like.
In order to obtain a high accuracy of the wavefront sensor, the physical parameters of the wavefront sensor must be calibrated. The physical parameters have great influence on the measurement precision, and because some errors are inevitably introduced by manufacturers in the production process, the factory design value and the real value of the physical parameters have certain difference, the factory design value is directly used as the real value, and the high-precision measurement of the wavefront cannot be realized.
Therefore, due to the lack of the prior art, an effective method and an effective device for calibrating the physical parameters of the wavefront sensor are needed to calibrate the physical parameters of the wavefront sensor with high precision.
Disclosure of Invention
The application provides a calibration system, a calibration method and a calibration device for physical parameters of a wavefront sensor, which solve the technical problem that the physical parameters of the wavefront sensor cannot be calibrated at high precision due to the deficiency of the prior art.
In one aspect, a calibration system for physical parameters of a wavefront sensor is provided, the system comprising: spherical wave generating device, the wavefront sensor and the data processor of treating the calibration, spherical wave generating device includes: the laser, the convergent lens and the spherical wave generator;
the laser is used for outputting laser, and the output laser is focused on the spherical wave generator through the converging lens;
the spherical wave generator is used for generating spherical waves when the laser is received, and the spherical wave generator is superposed with the focus of the converging lens;
the wavefront sensor to be calibrated is used for detecting the spherical waves and generating light spot array images corresponding to the spherical waves;
the data processor is used for acquiring a proportional relation between the size of a sub-lens of a micro-lens array in the wavefront sensor and the size of a pixel of a detector in the wavefront sensor, acquiring a constraint relation between the image of the light spot array and physical parameters of the wavefront sensor based on the proportional relation, and performing step-by-step iterative solution on the constraint relation to acquire an approximate value of the physical parameters; the physical parameters include: focal length of the micro lens array, sub lens size of the micro lens array, pixel size of the detector and pixel number;
the data processor is further configured to obtain a measurement wavefront of the wavefront sensor based on an approximate value of the physical parameter, obtain wavefront restoration accuracy of the measurement wavefront based on an original wavefront, and determine the approximate value as a final calibration value when the wavefront restoration accuracy meets a target restoration accuracy requirement.
In one possible implementation, the spherical wave generating device further includes: a glass substrate;
the glass substrate is arranged on the focal plane of the convergent lens, and the spherical wave generator is fixed on the glass substrate and is superposed with the focal point of the convergent lens;
the spherical wave generator is nano-particles.
In one possible implementation, the system further includes: the displacement platform comprises a sliding block, a linear guide rail and a grating ruler, and is used for realizing the alignment operation of the spherical wave and the wavefront sensor;
the spherical wave generating device is fixed on the sliding block, and the wavefront sensor to be calibrated is fixed on the linear guide rail;
the grating ruler is arranged on the side surface of the linear guide rail, and the grating reading head is fixed on the sliding block.
In yet another aspect, a method for calibration of a physical parameter of a wavefront sensor, the method being performed by a data processor in a system for calibration of a physical parameter of a wavefront sensor, the system comprising: spherical wave generating device, the wavefront sensor and the data processor of treating the calibration, spherical wave generating device includes: the laser, the convergent lens and the spherical wave generator; the laser is used for outputting laser, and the output laser is focused on the spherical wave generator through the converging lens; the spherical wave generator is used for generating spherical waves when the laser is received, and the spherical wave generator is superposed with the focus of the converging lens; the wavefront sensor to be calibrated is used for detecting the spherical waves and generating light spot array images corresponding to the spherical waves;
the method comprises the following steps:
acquiring a proportional relation between the size of a sub lens of a micro lens array in the wavefront sensor and the size of a pixel of a detector in the wavefront sensor;
acquiring a constraint relation between the light spot array image and physical parameters of the wavefront sensor based on the proportional relation;
carrying out step-by-step iterative solution on the constraint relation to obtain an approximate value of the physical parameter; the physical parameters include: focal length of the micro lens array, sub lens size of the micro lens array, pixel size of the detector and pixel number;
and acquiring the measurement wavefront of the wavefront sensor based on the approximate value of the physical parameter, acquiring the wavefront restoration precision of the measurement wavefront based on the original wavefront, and determining the approximate value as a final calibration value when the wavefront restoration precision meets the target restoration precision requirement.
In a possible implementation manner, the obtaining a constraint relationship between the spot array image and a physical parameter of the wavefront sensor based on the proportional relationship includes:
obtaining an initial constraint relationship between the spot array image and a physical parameter of the wavefront sensor by:
wherein Q represents the array pitch in the light spot array image, R represents the curvature radius of the spherical wave, P represents the size of a sub-lens of the micro-lens array, f represents the focal length of the micro-lens array, N represents the number of pixels of the detector, S represents the size of the pixels of the detector, N represents the size of the pixels of the detector, and i represents the corresponding different facula intervals when the nano particles are at different positions, i belongs to [1, k ]]，L i Denotes the distance between the nanoparticles at different positions and the target reference point on the linear guide, L 0 Representing the distance between the detector and the target reference point, wherein P, f, N and S are the physical parameters;
and acquiring a target constraint relation between the light spot array image and the physical parameters of the wavefront sensor based on the initial constraint relation and the proportional relation.
In one possible implementation, the target constraint relationship is represented by the following formula:
where w represents the ratio between the size of the sub-lenses of the microlens array and the size of the pixels of the detector.
In a possible implementation manner, the step-by-step iterative solution of the constraint relationship to obtain the approximate value of the physical parameter includes:
expressing the target constraint relation step by step through a first sub-target constraint relation and a second sub-target constraint relation;
the first sub-target constraint relation is expressed by the following formula:
the second sub-target constraint relation is expressed by the following formula:
and respectively carrying out iterative solution on the first sub-target constraint relation and the second sub-target constraint relation to obtain an approximate value of the physical parameter.
In another aspect, an apparatus for calibrating a physical parameter of a wavefront sensor is provided, the apparatus comprising:
the proportional relation acquisition module is used for acquiring the proportional relation between the size of the sub-lens of the micro-lens array and the size of the pixel of the detector;
the constraint relation obtaining module is used for obtaining a constraint relation between the light spot array image and physical parameters of the wavefront sensor based on the proportional relation;
the approximate value acquisition module is used for carrying out step-by-step iterative solution on the constraint relation to acquire an approximate value of the physical parameter; the physical parameters include: focal length of the micro lens array, sub lens size of the micro lens array, pixel size of the detector and pixel number;
and the final calibration value acquisition module is used for acquiring the measured wavefront of the wavefront sensor based on the approximate value of the physical parameter, acquiring the wavefront restoration precision of the measured wavefront based on the original wavefront, and determining the approximate value as the final calibration value when the wavefront restoration precision meets the target restoration precision requirement.
In a possible implementation manner, the constraint relation obtaining module includes:
an initial constraint relation obtaining sub-module, configured to obtain an initial constraint relation between the spot array image and a physical parameter of the wavefront sensor according to the following formula:
wherein Q represents the array pitch in the light spot array image, R represents the curvature radius of the spherical wave, P represents the size of a sub-lens of the micro-lens array, f represents the focal length of the micro-lens array, N represents the number of pixels of the detector, S represents the size of the pixels of the detector, N represents the size of the pixels of the detector, and i represents the corresponding different facula intervals when the nano particles are at different positions, i belongs to [1, k ]]，L i Denotes the distance between the nanoparticles at different positions and the target reference point on the linear guide, L 0 Representing the distance between the detector and the target reference point, wherein P, f, N and S are the physical parameters;
and the target constraint relation acquisition submodule is used for acquiring a target constraint relation between the spot array image and the physical parameters of the wavefront sensor based on the initial constraint relation and the proportional relation.
In a possible implementation manner, the target constraint relation obtaining sub-module is further configured to: the target constraint relationship is expressed by the following formula:
where w represents the ratio between the size of the sub-lenses of the microlens array and the size of the pixels of the detector.
In a possible implementation manner, the approximation obtaining module is further configured to:
expressing the target constraint relation step by step through a first sub-target constraint relation and a second sub-target constraint relation;
the first sub-target constraint relation is expressed by the following formula:
the second sub-target constraint relation is expressed by the following formula:
and respectively carrying out iterative solution on the first sub-target constraint relation and the second sub-target constraint relation to obtain an approximate value of the physical parameter.
In yet another aspect, a computer device is provided, which comprises a data processor and a memory, wherein the memory stores at least one instruction, and the at least one instruction is loaded and executed by the data processor to realize a calibration method of a physical parameter of a wavefront sensor as described above.
In still another aspect, a computer-readable storage medium is provided, where at least one instruction is stored, and the at least one instruction is loaded and executed by a processor to implement a calibration method for a physical parameter of a wavefront sensor as described above.
The technical scheme provided by the application can comprise the following beneficial effects:
the spherical wave generating device is used for generating high-precision spherical waves as reference waves, the spherical waves are detected by the wavefront sensor to be calibrated and generate a light spot array image corresponding to the spherical waves, the data processor obtains the proportional relation between the size of the sub-lens of the micro-lens array and the size of the pixel of the detector through the tight coupling relation between the size of the sub-lens of the micro-lens array and the size of the pixel of the detector, the problem of nonlinearity among all physical parameters is well solved, the physical parameters of the wavefront sensor are iteratively solved based on the proportional relation, the light spot array image and the constraint relation among all the physical parameters, all the physical parameters are converged into the precision range of a target, and the measurement precision of the calibrated wavefront sensor is greatly improved.
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In order to more clearly illustrate the detailed description of the present application or the technical solutions in the prior art, the drawings needed to be used in the detailed description of the present application or the prior art description will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic diagram of a wavefront sensor physical parameter calibration system according to an exemplary embodiment.
FIG. 2 is a schematic diagram of a wavefront sensor physical parameter calibration system according to an exemplary embodiment.
FIG. 3 is a flowchart illustrating a method for calibration of a physical parameter of a wavefront sensor, according to one exemplary embodiment.
FIG. 4 is a block diagram illustrating an exemplary embodiment of an apparatus for calibrating a physical parameter of a wavefront sensor.
Fig. 5 shows a block diagram of a computer device according to an exemplary embodiment of the present application.
Detailed Description
The technical solutions of the present application will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It should be understood that in the description of the embodiments of the present application, the term "correspond" may indicate that there is a direct correspondence or an indirect correspondence between the two, may also indicate that there is an association between the two, and may also indicate and be indicated, configured and configured, and the like.
FIG. 1 is a schematic diagram of a wavefront sensor physical parameter calibration system according to an exemplary embodiment. The system comprises a spherical wave generating device 110, a wavefront sensor 120 to be calibrated, and a data processor 130.
Optionally, the spherical wave generating device 110 includes: a laser 111, a converging lens 112, and a spherical wave generator 113.
Optionally, the laser 111 is configured to output laser light, and the output laser light is focused onto the spherical wave generator 113 through the converging lens 112.
Optionally, the laser 111 is configured to emit laser light, an emitting end of the laser 111 is connected to a single-mode fiber through a fiber coupler, and a central glass core of the single-mode fiber is thin (core diameter is generally 8 μm to 10 μm) and is configured to transmit a single-mode fiber.
Optionally, the spherical wave generator 113 is configured to generate a spherical wave when receiving the laser light, and the spherical wave generator 113 coincides with the focal point of the converging lens 112.
Alternatively, the spherical wave generator 113 may be a nanoparticle that generates an ultra-high precision spherical wave upon receiving the laser light.
At present, when generating spherical waves, the following two methods are often adopted: the first is to use laser to couple into single mode fiber to generate spherical wave; the second is to use pinhole diffraction to generate spherical waves. In the first method, the core diameter of the standard single-mode optical fiber is 8-10 μm, so the method is limited by the size of the core diameter of the optical fiber, and spherical waves with high precision cannot be generated, thereby affecting the calibration precision of the physical parameters of the wavefront sensor to be calibrated. Compared with the first method, the diameter of the pinhole is smaller than the core diameter of the single-mode optical fiber, and according to the pinhole diffraction theory, the smaller the pinhole diameter is, the smaller the wavefront error of the generated spherical wave is, but the pinhole processing difficulty is also increased along with the reduction of the pinhole diameter, the more the spherical wave energy loss is, the more the wavefront sensor to be calibrated cannot respond, and finally the high-precision calibration cannot be completed.
The size of the nano particles is far smaller than the diameter of the fiber core and the size of the pinhole aperture, so that the problems caused by factors such as the diameter of the fiber core of the optical fiber, the processing difficulty of the pinhole, the energy loss and the like are well solved, and the calibration precision of the physical parameters of the wavefront sensor is further improved.
Optionally, the wavefront sensor 120 to be calibrated is configured to detect the spherical wave and generate a light spot array image corresponding to the spherical wave.
Optionally, the wavefront sensor 120 to be calibrated may be a hartmann-shack wavefront sensor, the hartmann-shack wavefront sensor is composed of a microlens array and a detector, each microlens serves as a sub-aperture, when a light beam (i.e., the spherical wave) is incident on the hartmann-shack wavefront sensor, the microlens array divides the light beam into a plurality of sub-beams (i.e., sub-apertures) which are mutually independent in space, and focuses on the focal points of the sub-apertures respectively, and forms a spot array image at the corresponding position of the detector, the wavefront slope of each sub-beam is calculated according to the deviation of the centroid position of each sub-spot on the spot array image relative to the reference centroid position of the wavefront without aberration, and then the wavefront slopes of all sub-beams are used to reconstruct the wavefront and obtain the aberration.
Optionally, the data processor 130 is configured to obtain a proportional relationship between a size of a sub-lens of a microlens array in the wavefront sensor and a size of a pixel of a detector in the wavefront sensor, obtain a constraint relationship between the spot array image and a physical parameter of the wavefront sensor based on the proportional relationship, and perform step-by-step iterative solution on the constraint relationship to obtain an approximate value of the physical parameter; the physical parameters include: focal length of the micro lens array, sub lens size of the micro lens array, pixel size of the detector and pixel number;
optionally, the data processor 130 is further configured to obtain a measurement wavefront of the wavefront sensor based on an approximate value of the physical parameter, obtain wavefront reconstruction accuracy of the measurement wavefront based on an original wavefront, and determine the approximate value as a final calibration value when the wavefront reconstruction accuracy meets a target reconstruction accuracy requirement.
As shown in fig. 1, a calibration system for physical parameters of a wavefront sensor can output laser light through a laser 111 in a spherical wave generator 110, the output laser light is focused onto the spherical wave generator 113 through the converging lens 112, when the spherical wave generator 113 receives the laser light, a spherical wave is generated, the wavefront sensor 120 to be calibrated generates a light spot array image corresponding to the spherical wave, the data processor 130 obtains a proportional relationship between the sub-lens size of the microlens array and the pixel size of the detector through a close coupling relationship between the sub-lens size of the microlens array and the pixel size of the detector, then, the physical parameters of the wavefront sensor are iteratively solved based on the proportional relationship, the light spot array image and a constraint relationship among the physical parameters, the physical parameters are converged into a target precision range, and finally, actual values of the physical parameters are obtained, so that high-precision calibration of the physical parameters is realized.
In summary, a spherical wave generator generates a high-precision spherical wave as a reference wave, a wavefront sensor to be calibrated detects the spherical wave and generates a light spot array image corresponding to the spherical wave, a data processor obtains a proportional relationship between the size of a sub-lens of a micro-lens array and the size of a pixel of a detector through a close-coupled relationship between the size of the sub-lens and the size of the pixel of the detector, the problem of nonlinearity among physical parameters is well solved, iterative solution is performed on the physical parameters of the wavefront sensor based on the proportional relationship, the light spot array image and a constraint relationship among the physical parameters, the physical parameters are converged into a target precision range, and the measurement precision of the calibrated wavefront sensor is greatly improved.
FIG. 2 is a schematic diagram of a wavefront sensor physical parameter calibration system according to an exemplary embodiment. The system comprises a spherical wave generating device 210, a wavefront sensor 220 to be calibrated, a data processor 230 and a displacement platform 240.
Optionally, the spherical wave generating device 210 includes: a laser 211, a condenser lens 212, a spherical wave generator 213, and a glass substrate 214.
Optionally, the laser 211 is configured to output laser light, and the output laser light is focused onto the spherical wave generator 213 through the converging lens 212.
Optionally, the spherical wave generator 213 is configured to generate a spherical wave when receiving the laser light, and the spherical wave generator 213 coincides with the focal point of the focusing lens 212.
Optionally, the spherical wave generator 213 may be a nanoparticle, the nanoparticle may generate an ultra-high precision spherical wave when receiving the laser, and the size of the nanoparticle is far smaller than the fiber core diameter and the pinhole aperture, so that the problems caused by factors such as the fiber core diameter, the pinhole processing difficulty, and the energy loss can be solved well, and the calibration precision of the physical parameters of the wavefront sensor is further improved.
Alternatively, the glass substrate 214 is disposed on the focal plane of the focusing lens 212, and the spherical wave generator 213 is fixed on the glass substrate 214 to coincide with the focal point of the focusing lens 212.
Optionally, the nanoparticles (i.e., the spherical wave generator 213) are fixed on the glass substrate 214 so as to coincide with the focal point of the focusing lens 212, the laser output by the laser 211 is focused onto the nanoparticles (i.e., the spherical wave generator 213) through the focusing lens 212, the nanoparticles (i.e., the spherical wave generator 213) have a relatively strong dipole response, and can simultaneously suppress high-order multipole, and can generate dipole radiation under the impact of the laser, thereby generating an ultra-high precision spherical wave.
Optionally, the wavefront sensor 220 to be calibrated is configured to detect the spherical wave and generate a light spot array image corresponding to the spherical wave.
Alternatively, the wavefront sensor 220 to be calibrated may be a Hartmann-shack wavefront sensor.
Optionally, the displacement platform 240 includes a slider 241, a linear guide 242 and a grating scale 243, and the displacement platform 240 is configured to implement an alignment operation of the spherical wave and the wavefront sensor. The spherical wave generator 210 is fixed to the slider 241, and the wavefront sensor 220 to be calibrated is fixed to the linear guide 242. The grating ruler 243 is disposed on the side of the linear guide 242, and the grating reading head is fixed on the slider.
Optionally, the grating ruler 243 is one of gratings, and is a measurement feedback device operating by using the optical principle of the grating, which is commonly used for detecting linear displacement or angular displacement, and the signal output by the measurement is a digital pulse. The key part of the grating ruler 243 is a grating reading head, which is composed of a light source, a converging lens, an indicating grating, a photoelectric element, an adjusting mechanism and the like.
Optionally, the slider 241 drives the spherical wave generator 210 to move, and when the spherical wave generator 210 is at any position, the displacement platform 240 realizes the alignment operation between the spherical wave and the wavefront sensor through the grating ruler 243 and the grating reading head.
Optionally, the data processor 230 is configured to obtain a proportional relationship between a size of a sub-lens of a microlens array in the wavefront sensor and a size of a pixel of a detector in the wavefront sensor, obtain a constraint relationship between the spot array image and a physical parameter of the wavefront sensor based on the proportional relationship, and perform step-by-step iterative solution on the constraint relationship to obtain an approximate value of the physical parameter; the physical parameters include: focal length of the micro lens array, sub lens size of the micro lens array, pixel size of the detector and pixel number;
optionally, the data processor 230 is further configured to obtain a measured wavefront of the wavefront sensor based on an approximate value of the physical parameter, obtain wavefront reconstruction accuracy of the measured wavefront based on an original wavefront, and determine the approximate value as a final calibration value when the wavefront reconstruction accuracy meets a target reconstruction accuracy requirement.
In summary, a spherical wave generator generates a high-precision spherical wave as a reference wave, a wavefront sensor to be calibrated detects the spherical wave and generates a light spot array image corresponding to the spherical wave, a data processor obtains a proportional relationship between the size of a sub-lens of a micro-lens array and the size of a pixel of a detector through a close-coupled relationship between the size of the sub-lens and the size of the pixel of the detector, the problem of nonlinearity among physical parameters is well solved, iterative solution is performed on the physical parameters of the wavefront sensor based on the proportional relationship, the light spot array image and a constraint relationship among the physical parameters, the physical parameters are converged into a target precision range, and the measurement precision of the calibrated wavefront sensor is greatly improved.
FIG. 3 is a flowchart illustrating a method for calibration of a physical parameter of a wavefront sensor, according to one exemplary embodiment. The method is performed by a data processor in a calibration system for physical parameters of the wavefront sensor, which may be the data processor 130 shown in FIG. 1. As shown in fig. 5, the method may include the steps of:
step S301, acquiring a proportional relation between the size of a sub lens of the micro lens array in the wavefront sensor and the size of a pixel of a detector in the wavefront sensor.
In one possible implementation, the proportional relationship is obtained by the following formula:
wherein w represents the ratio between the size of the sub-lenses of the micro-lens array and the size of the pixels of the detector, w is a specific numerical value, and S represents the size of the pixels of the detector, and the above formula is obtained by the close coupling relationship between the size P of the sub-lenses of the micro-lens array and the size S of the pixels of the detector.
And S302, acquiring a constraint relation between the light spot array image and the physical parameters of the wavefront sensor based on the proportional relation.
In one possible implementation, the initial constraint relationship between the image of the array of spots and the physical parameters of the wavefront sensor is obtained by the following formula:
wherein Q represents the array pitch in the light spot array image, R represents the curvature radius of the spherical wave, P represents the size of a sub-lens of the micro-lens array, f represents the focal length of the micro-lens array, N represents the number of pixels of the detector, S represents the size of the pixels of the detector, N represents the size of the pixels of the detector, and i represents the corresponding different facula intervals when the nano particles are at different positions, i belongs to [1, k ]]，L i Denotes the distance between the nanoparticles at different positions and a target reference point on the linear guide (which may be optionally obtained), L 0 Representing the distance between the probe and a target reference point (which may optionally be acquired) on the linear guideDistance, therefore, L i -L 0 The distance between the nanoparticle and the detector (namely the length of spherical wave generated by the nanoparticle) at different positions is shown, and P, f, N and S are all the physical parameters;
and acquiring a target constraint relation between the spot array image and the physical parameters of the wavefront sensor based on the initial constraint relation and the proportional relation.
Furthermore, formula (1) can be obtained from the constraint relationship between the image of the light spot array obtained by the wavefront sensor and the physical parameters, and formula (2) shows the initial constraint relationship between the different light spot distances and the physical parameters obtained by measuring the nanoparticles at different positions, so that the calibration process of the system can be changed into the focal length f of the micro lens array, the size P of the sub-lens of the micro lens array, the size S of the pixel of the sensor, and the distance L between the sensor and the target reference point 0 Solving the problem of four physical parameters.
Further, the solution problem of the above four physical parameters can be converted into the following least squares problem:
theoretically, at least 4 equations are needed to solve the above equation (3), that is, at least 4 different positions of the nanoparticles are needed to measure the light spot distance, and in order to reduce the influence of the nonlinearity of the system and the measurement noise, we can select the 20 different positions of the nanoparticles to perform image sampling.
In one possible implementation, the target constraint relationship is represented by the following formula:
where w represents the ratio between the size of the sub-lenses of the microlens array and the size of the pixels of the detector.
Furthermore, because the corresponding spot spacing Ni and other parameters of the nanoparticles at different positions are not in a linear relationship, the least square fitting cannot be directly carried out, and the introduction of the ratio w solves the problem.
Step S303, carrying out step-by-step iterative solution on the constraint relation to obtain an approximate value of the physical parameter; the physical parameters include: focal length of the micro lens array, sub-lens size of the micro lens array, pixel size of the detector and pixel number.
In a possible implementation manner, the target constraint relation is expressed step by step through a first sub-target constraint relation and a second sub-target constraint relation;
the first sub-goal constraint relation is expressed by the following formula:
the second sub-target constraint relation is expressed by the following formula:
and respectively carrying out iterative solution on the first sub-target constraint relation and the second sub-target constraint relation to obtain an approximate value of the physical parameter.
Further, the scale w may be fixed (i.e. an initial value of the scale w is obtained first), where the initial value of the scale w is a ratio between a factory design value of a sub-lens size of the microlens array and a factory design value of a pixel size of the detector, and the focal length f of the microlens array and the distance L between the detector and the target reference point are determined by formula (5) 0 Solving is carried out, and then the focal length f of the micro lens array and the distance L between the detector and the target reference point are fixed 0 The ratio w is solved by equation (6). After 3 iterations in this way, w, f and L 0 Will converge to an acceptable accuracy range, again because the ratio w represents the ratio between the sub-lens size P of the microlens array and the pixel size s of the detectorIf the ratio w is approximated, the size P of the sub-lenses of the microlens array and the size s of the pixels of the detector are also approximated accordingly.
Further, the focal length f of the micro-lens array or the distance L between the detector and the target reference point may be firstly determined 0 Fixing (i.e. obtaining f or L first) 0 Is the initial value of f) is the factory design value of the focal length of the microlens array, L 0 Is the distance between the probe and the target reference point measured in advance, and when the focal length f of the microlens array is fixed first, w and L are paired by the equations (5) and (6) 0 Solving is carried out firstly, and then w, f and L are obtained through iteration 0 Approximate values of the three; when the distance L between the detector and the target reference point is fixed 0 Then, the formula (5) and the formula (6) are used to solve w and f first, and then w, f and L are iterated 0 Approximate values of the three.
Step S304, obtaining the measuring wavefront of the wavefront sensor based on the approximate value of the physical parameter, obtaining the wavefront restoration precision of the measuring wavefront based on the original wavefront, and determining the approximate value as a final calibration value when the wavefront restoration precision meets the target restoration precision requirement.
In one possible implementation, the physical parameters (the focal length f of the microlens array, the distance L between the detector and the target reference point) obtained in step S303 are compared 0 And the approximate value of the proportion w) is brought into the existing wave front restoration program to obtain the measurement wave front of the wave front sensor, the original wave front of a spherical wave (reference wave) is measured, the measurement wave front and the original wave front are analyzed for the wave front restoration precision to obtain the wave front restoration precision of the measurement wave front, and when the wave front restoration precision meets the target restoration precision requirement, the approximate value is determined as a final calibration value; and when the wavefront restoration precision does not meet the target restoration precision requirement, repeating the operations from S301 to S303 until the wavefront restoration precision meets the target restoration precision requirement, and ending the calibration process.
Further, if the nanoparticles are selected to perform image sampling at 20 different positions, the objects obtained in step S303Physical parameters (focal length f of the microlens array, distance L between the detector and the target reference point 0 And the approximate values of the proportion w) are correspondingly 20, and the 20 approximate values are subjected to analysis of wave front restoration precision to obtain a final calibration value meeting the requirement of target restoration precision. The target restoration precision requirement is preset according to an actual application scene and actual requirements.
In summary, a spherical wave generator generates a high-precision spherical wave as a reference wave, a wavefront sensor to be calibrated detects the spherical wave and generates a light spot array image corresponding to the spherical wave, a data processor obtains a proportional relationship between the size of a sub-lens of a micro-lens array and the size of a pixel of a detector through a close-coupled relationship between the size of the sub-lens and the size of the pixel of the detector, the problem of nonlinearity among physical parameters is well solved, iterative solution is performed on the physical parameters of the wavefront sensor based on the proportional relationship, the light spot array image and a constraint relationship among the physical parameters, the physical parameters are converged into a target precision range, and the measurement precision of the calibrated wavefront sensor is greatly improved.
FIG. 4 is a schematic diagram illustrating an apparatus for calibration of physical parameters of a wavefront sensor, according to one exemplary embodiment, the apparatus comprising: the device comprises:
a proportional relation obtaining module 401, configured to obtain a proportional relation between a size of a sub-lens of the microlens array and a size of a pixel of the detector;
a constraint relation obtaining module 402, configured to obtain a constraint relation between the spot array image and a physical parameter of the wavefront sensor based on the proportional relation;
an approximate value obtaining module 403, configured to perform step-by-step iterative solution on the constraint relationship to obtain an approximate value of the physical parameter; the physical parameters include: focal length of the micro lens array, sub lens size of the micro lens array, pixel size of the detector and pixel number;
and a final calibration value obtaining module 404, configured to obtain a measurement wavefront of the wavefront sensor based on the approximate value of the physical parameter, obtain wavefront restoration accuracy of the measurement wavefront based on an original wavefront, and determine the approximate value as a final calibration value when the wavefront restoration accuracy meets a target restoration accuracy requirement.
In a possible implementation manner, the constraint relation obtaining module 402 includes:
an initial constraint relation obtaining submodule, configured to obtain an initial constraint relation between the spot array image and a physical parameter of the wavefront sensor according to the following formula:
wherein Q represents the array pitch in the light spot array image, R represents the curvature radius of the spherical wave, P represents the size of the sub-lens of the micro-lens array, f represents the focal length of the micro-lens array, N represents the focal length of the micro-lens array i Represents the corresponding different facula intervals when the nano particles are at different positions, i belongs to [1, k ]]，L i Denotes the distance between the nanoparticles at different positions and the target reference point on the linear guide, L 0 Representing the distance between the detector and the target reference point, wherein P, f, N and S are the physical parameters;
and the target constraint relation acquisition submodule is used for acquiring a target constraint relation between the spot array image and the physical parameters of the wavefront sensor based on the initial constraint relation and the proportional relation.
In a possible implementation manner, the target constraint relation obtaining sub-module is further configured to: the target constraint relationship is expressed by the following formula:
where w represents the ratio between the size of the sub-lenses of the microlens array and the size of the pixels of the detector.
In a possible implementation manner, the approximate value obtaining module 403 is further configured to:
the target constraint relation is expressed step by step through a first sub-target constraint relation and a second sub-target constraint relation;
the first sub-goal constraint relation is expressed by the following formula:
the second sub-target constraint relation is expressed by the following formula:
and respectively carrying out iterative solution on the first sub-target constraint relation and the second sub-target constraint relation to obtain an approximate value of the physical parameter.
In summary, a spherical wave generator generates a high-precision spherical wave as a reference wave, a wavefront sensor to be calibrated detects the spherical wave and generates a light spot array image corresponding to the spherical wave, a data processor obtains a proportional relationship between the size of a sub-lens of a micro-lens array and the size of a pixel of a detector through a close-coupled relationship between the size of the sub-lens and the size of the pixel of the detector, the problem of nonlinearity among physical parameters is well solved, iterative solution is performed on the physical parameters of the wavefront sensor based on the proportional relationship, the light spot array image and a constraint relationship among the physical parameters, the physical parameters are converged into a target precision range, and the measurement precision of the calibrated wavefront sensor is greatly improved.
Please refer to fig. 5, which is a schematic diagram of a computer device according to an exemplary embodiment of the present application, the computer device includes a memory and a processor, the memory is used for storing a computer program, and the computer program is executed by the processor to implement the above-mentioned calibration method for physical parameters of a wavefront sensor.
The processor may be a Central Processing Unit (CPU). The Processor may also be other general purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components, or a combination thereof.
The memory, which is a non-transitory computer readable storage medium, may be used to store non-transitory software programs, non-transitory computer executable programs, and modules, such as program instructions/modules corresponding to the methods of the embodiments of the present invention. The processor executes various functional applications and data processing of the processor by executing non-transitory software programs, instructions and modules stored in the memory, that is, the method in the above method embodiment is realized.
The memory may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created by the processor, and the like. Further, the memory may include high speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, the memory optionally includes memory located remotely from the processor, and such remote memory may be coupled to the processor via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
In an exemplary embodiment, a computer readable storage medium is also provided for storing at least one computer program, which is loaded and executed by a processor to implement all or part of the steps of the above method. For example, the computer-readable storage medium may be a Read-Only Memory (ROM), a Random Access Memory (RAM), a Compact Disc Read-Only Memory (CD-ROM), a magnetic tape, a floppy disk, an optical data storage device, and the like.
Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims.
It will be understood that the present application is not limited to the precise arrangements that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the application is limited only by the appended claims.
Claims (10)
1. A system for calibration of physical parameters of a wavefront sensor, said system comprising: spherical wave generating device, the wavefront sensor and the data processor of treating the calibration, spherical wave generating device includes: the laser, the convergent lens and the spherical wave generator;
the laser is used for outputting laser, and the output laser is focused on the spherical wave generator through the converging lens;
the spherical wave generator is used for generating spherical waves when the laser is received, and the spherical wave generator is superposed with the focus of the converging lens;
the wavefront sensor to be calibrated is used for detecting the spherical waves and generating light spot array images corresponding to the spherical waves;
the data processor is used for acquiring a proportional relation between a sub-lens scale of a micro-lens array in the wavefront sensor and the pixel size of a detector in the wavefront sensor, acquiring a constraint relation between the light spot array image and physical parameters of the wavefront sensor based on the proportional relation, and performing step-by-step iterative solution on the constraint relation to acquire an approximate value of the physical parameters; the physical parameters include: focal length of the micro lens array, sub lens size of the micro lens array, pixel size of the detector and pixel number;
the data processor is further configured to obtain a measurement wavefront of the wavefront sensor based on an approximate value of the physical parameter, obtain wavefront restoration accuracy of the measurement wavefront based on an original wavefront, and determine the approximate value as a final calibration value when the wavefront restoration accuracy meets a target restoration accuracy requirement.
2. The system of claim 1, wherein the spherical wave generating device further comprises: a glass substrate;
the glass substrate is arranged on the focal plane of the convergent lens, and the spherical wave generator is fixed on the glass substrate and is superposed with the focal point of the convergent lens;
the spherical wave generator is nano-particles.
3. The system according to claim 1 or 2, characterized in that the system further comprises: the displacement platform comprises a sliding block, a linear guide rail and a grating ruler, and is used for realizing the alignment operation of the spherical wave and the wavefront sensor;
the spherical wave generating device is fixed on the sliding block, and the wavefront sensor to be calibrated is fixed on the linear guide rail;
the grating ruler is arranged on the side surface of the linear guide rail, and the grating reading head is fixed on the sliding block.
4. A method for calibration of a physical parameter of a wavefront sensor, the method being performed by a data processor in a system for calibration of a physical parameter of a wavefront sensor, the system comprising: spherical wave generating device, the wavefront sensor and the data processor of treating the calibration, spherical wave generating device includes: the laser, the convergent lens and the spherical wave generator; the laser is used for outputting laser, and the output laser is focused on the spherical wave generator through the converging lens; the spherical wave generator is used for generating spherical waves when the laser is received, and the spherical wave generator is superposed with the focus of the converging lens; the wavefront sensor to be calibrated is used for detecting the spherical waves and generating light spot array images corresponding to the spherical waves;
the method comprises the following steps:
acquiring a proportional relation between the size of a sub-lens of a micro-lens array in the wavefront sensor and the size of a pixel of a detector in the wavefront sensor;
acquiring a constraint relation between the light spot array image and physical parameters of the wavefront sensor based on the proportional relation;
carrying out step-by-step iterative solution on the constraint relation to obtain an approximate value of the physical parameter; the physical parameters include: focal length of the micro lens array, sub lens size of the micro lens array, pixel size of the detector and pixel number;
and the wavefront reconstruction device is also used for acquiring the measured wavefront of the wavefront sensor based on the approximate value of the physical parameter and acquiring the wavefront reconstruction precision of the measured wavefront based on the original wavefront, and when the wavefront reconstruction precision meets the target reconstruction precision requirement, the approximate value is determined as a final calibration value.
5. The method of claim 4, wherein the obtaining a constrained relationship between the image of the array of spots and a physical parameter of the wavefront sensor based on the proportional relationship comprises:
obtaining an initial constraint relationship between the spot array image and a physical parameter of the wavefront sensor by:
wherein Q represents the array pitch in the light spot array image, R represents the curvature radius of the spherical wave, P represents the size of a sub-lens of the micro-lens array, f represents the focal length of the micro-lens array, N represents the number of pixels of the detector, S represents the size of the pixels of the detector, N represents the size of the pixels of the detector, and i represents the corresponding different light spot intervals when the nano particles are at different positions, i belongs to [1, k ]]，L i Denotes the distance between the nanoparticles at different positions and the target reference point on the linear guide, L 0 Representing the distance between the detector and the target reference point, wherein P, f, N and S are the physical parameters;
and acquiring a target constraint relation between the light spot array image and the physical parameters of the wavefront sensor based on the initial constraint relation and the proportional relation.
6. The method of claim 5, wherein the target constraint relationship is represented by the following formula:
where w represents the ratio between the size of the sub-lenses of the microlens array and the size of the pixels of the detector.
7. The method according to any one of claims 4-6, wherein said step-and-iteration solving said constraint relationship to obtain an approximation of said physical parameter comprises:
the target constraint relation is expressed step by step through a first sub-target constraint relation and a second sub-target constraint relation;
the first sub-target constraint relation is expressed by the following formula:
the second sub-target constraint relation is expressed by the following formula:
and respectively carrying out iterative solution on the first sub-target constraint relation and the second sub-target constraint relation to obtain an approximate value of the physical parameter.
8. An apparatus for calibrating a physical parameter of a wavefront sensor, the apparatus comprising:
the proportional relation acquisition module is used for acquiring the proportional relation between the size of the sub-lens of the micro-lens array and the size of the pixel of the detector;
the constraint relation obtaining module is used for obtaining a constraint relation between the light spot array image and physical parameters of the wavefront sensor based on the proportional relation;
the approximate value acquisition module is used for carrying out step-by-step iterative solution on the constraint relation to acquire an approximate value of the physical parameter; the physical parameters include: focal length of the micro lens array, sub lens size of the micro lens array, pixel size of the detector and pixel number;
and the final calibration value acquisition module is used for acquiring the measured wavefront of the wavefront sensor based on the approximate value of the physical parameter, acquiring the wavefront restoration precision of the measured wavefront based on the original wavefront, and determining the approximate value as the final calibration value when the wavefront restoration precision meets the target restoration precision requirement.
9. A computer device comprising a data processor and a memory, wherein at least one instruction is stored in the memory, and wherein the at least one instruction is loaded and executed by the data processor to implement a method for calibration of a physical parameter of a wavefront sensor as claimed in any one of claims 4 to 7.
10. A computer-readable storage medium, wherein at least one instruction is stored in the storage medium, and the at least one instruction is loaded and executed by a processor to implement a method for calibration of a physical parameter of a wavefront sensor as defined in any one of claims 4 to 7.
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