Point target precision positioning method, device and equipment based on optical imaging motion modulation

Abstract

The invention provides a point target precision positioning method, device and equipment based on optical imaging motion modulation, and relates to the technical field of optical imaging precision measurement. The method comprises the steps that an effective PSF model of a PSF optical system is constructed, the effective PSF model represents the accurate corresponding relation between the pixel phase and the pixel response when a point target is located in an area nearby the pixel edge, and the small PSF optical system represents an optical system in which the size of the PSF in an image detector is smaller than a target size threshold value; according to the effective PSF model, the positioning precision limit of an area nearby the pixel edge is estimated, the optimal pixel phase is determined according to the positioning precision limit, the positioning precision limit represents the positioning theory uncertainty, and the optimal pixel phase represents the pixel phase corresponding to the minimum value of the positioning precision limit; and performing motion modulation measurement on point target optical imaging on the image detector according to the optimal pixel phase to obtain a positioning result of the optimal pixel phase.

Description

Technical Field

[0001] The present application relates to the field of optical imaging precision measurement technology, and in particular to a method, device and equipment for precise positioning of point targets based on optical imaging motion modulation. Background Art

[0002] Optical imaging measurement technology, with its advantages of high intuitiveness, high measurement accuracy, and wide applicability, holds a key position in high-end fields such as aerospace navigation, precision manufacturing, and biological microscopy. The sub-pixel positioning accuracy of point targets (such as stars and single biological molecules) directly determines the ultimate measurement accuracy of optical instruments. Traditional paths to improving positioning accuracy rely on increasing the focal length and aperture of the optical system or reducing the detector pixel size. However, due to the laws of physics: the volume of the optical system is positively correlated with the cube of the focal length, and the photoelectric capacity of the detector pixel is positively correlated with the square of the pixel size. As a result, existing fixed optical systems are approaching technical bottlenecks due to the constraints of volume and photosensitivity.

[0003] Motion-modulated optical systems utilize motion actuators to modulate the lens or image detector, translating the detector's micron-scale pixel perception into finer actuator motion resolution. Furthermore, according to the Cramer-Rao lower bound on positioning accuracy, the positioning accuracy of a small-scale point spread function (PSF) at a specific pixel phase can achieve extremely precise performance, surpassing the positioning accuracy of larger PSFs. Motion-modulated optical systems can effectively achieve pixel phase modulation in optical imaging and optimize positioning performance for small PSFs. However, the goal of motion modulation in existing motion-modulated optical systems is to improve image resolution and stability, rather than to achieve higher-precision positioning measurement of the target.

[0004] Therefore, in the field of precision positioning of point targets using optical imaging, measuring instruments are often fixed and unable to modulate the pixel phase of the PSF, wasting the potential for optimizing positioning performance inherent in information theory. A precision positioning method that integrates motion modulation mechanisms with positioning accuracy optimization is urgently needed to fully exploit the accuracy improvement potential offered by information theory and promote the leapfrog development of precision measurement technology. Summary of the Invention

[0005] In view of the above problems, the embodiments of the present application provide a method, apparatus and device for precise positioning of point targets based on optical imaging motion modulation, so as to overcome the above problems or at least partially solve the above problems.

[0006] In a first aspect of the embodiments of the present application, a method for precise positioning of a point target based on optical imaging motion modulation is disclosed, the method comprising: An effective PSF model of a small point spread function (PSF) optical system is constructed, wherein the effective PSF model represents the precise correspondence between the pixel phase and the pixel response when a point target is located in an area near a pixel edge. The small PSF optical system represents an optical system in which the PSF is smaller than a target size threshold when the image detector size is smaller than the target size threshold. Estimate the positioning accuracy limit of the area near the pixel edge according to the effective PSF model, and determine the optimal pixel phase according to the positioning accuracy limit, wherein the positioning accuracy limit represents the positioning theoretical uncertainty, and the optimal pixel phase represents the pixel phase corresponding to the minimum value of the positioning accuracy limit; Motion modulation measurement is performed on the optical imaging of the point target on the image detector according to the optimal pixel phase to obtain a positioning result at the optimal pixel phase.

[0007] Optionally, an effective PSF model of a small point spread function (PSF) optical system is constructed, including: Using the small PSF optical system to image the point target to be measured, adjusting the distance between the lens of the small PSF optical system and the image detector until the image is fully focused, and sequentially collecting point target images at different pixel phases; Determining a region near a pixel edge of a target pixel, wherein the point target is located in the region near the pixel edge of the target pixel; According to point target images acquired when the point target is located at different pixel phases in the area near the pixel edge, the precise correspondence between different pixel phases and pixel responses is calculated to obtain an effective PSF model.

[0008] Optionally, determining an area near a pixel edge of a target pixel includes: Compare the pixel values ​​of two adjacent pixels; When the larger pixel value of the two adjacent pixels is less than N times the smaller pixel value, the pixel corresponding to the larger pixel value is determined to be the target pixel, and the point target is located in the area near the pixel edge of the target pixel, where N is an integer greater than or equal to 10.

[0009] Optionally, estimating the positioning accuracy limit of an area near a pixel edge according to the effective PSF model includes: Based on the Cramer-Rao lower bound theory, the positioning accuracy limit of the point target in the area near the pixel edge is determined according to the area near the pixel edge, the effective PSF model of the target pixel, and the effective PSF model of the pixels adjacent to the target pixel.

[0010] Optionally, performing motion modulation measurement on the optical imaging of the point target on the image detector according to the optimal pixel phase to obtain a positioning result at the optimal pixel phase includes: Using the optimal pixel phase as a reference quantity and the sub-pixel positioning result obtained by motion modulation as a feedback quantity, a motion actuator is used to perform multiple motion modulations on the target optical imaging on the image detector to obtain a point target image located at the optimal pixel phase; Sub-pixel positioning is performed based on the point target image at the optimal pixel phase to obtain a positioning result at the optimal pixel phase.

[0011] Optionally, using the optimal pixel phase as a reference quantity and the sub-pixel positioning result obtained by motion modulation as a feedback quantity, a motion actuator is used to perform multiple motion modulations on the target optical imaging on the image detector to obtain a point target image located at the optimal pixel phase, including: The difference between the optimal pixel phase and the sub-pixel positioning result obtained by the last motion modulation is used as the modulation control amount; When the modulation control amount is greater than the optimal pixel phase region threshold, controlling the motion actuator to perform motion modulation according to the modulation control amount, and collecting a point target image of this motion modulation at a position after the motion modulation; Performing sub-pixel positioning based on the point target image of the current motion modulation to obtain a sub-pixel positioning result of the current motion modulation; The difference between the optimal pixel phase and the sub-pixel positioning result of this motion modulation is used as the modulation control amount for the next motion modulation, and the next motion modulation is continued until the modulation control amount is less than or equal to the optimal pixel phase area threshold. The motion modulation is ended, and the collected point target image of the current motion modulation is used as the point target image located at the optimal pixel phase.

[0012] Optionally, performing sub-pixel positioning according to the point target image of the current motion modulation to obtain the sub-pixel positioning result of the current motion modulation includes: When the modulation control amount is greater than the difference threshold, performing sub-pixel positioning on the point target image of the current motion modulation by using a centroid method to obtain a sub-pixel positioning result of the current motion modulation; When the modulation control amount is not greater than the difference threshold, the maximum likelihood method is used to perform sub-pixel positioning on the point target image of the current motion modulation to obtain the sub-pixel positioning result of the current motion modulation.

[0013] Optionally, performing sub-pixel positioning based on the point target image at the optimal pixel phase to obtain a positioning result at the optimal pixel phase includes: Performing sub-pixel positioning on the point target image at the optimal pixel phase using a maximum likelihood method to obtain a spot positioning result; The displacement of the motion actuator subjected to multiple motion modulations is subtracted from the image spot positioning result to obtain a positioning result at the optimal pixel phase.

[0014] A second aspect of the embodiments of the present application discloses a point target precision positioning device based on optical imaging motion modulation, the device comprising: A model building module is used to build an effective PSF model of a small point spread function (PSF) optical system, wherein the effective PSF model represents the precise correspondence between the pixel phase and the pixel response when a point target is located in an area near a pixel edge, and the small PSF optical system represents an optical system in which the PSF is smaller than a target size threshold when the size of the image detector is smaller than the target size threshold; a phase calculation module, configured to estimate the positioning accuracy limit of the area near the pixel edge according to the effective PSF model, and determine the optimal pixel phase according to the positioning accuracy limit, wherein the positioning accuracy limit represents the positioning theoretical uncertainty, and the optimal pixel phase represents the pixel phase corresponding to the minimum value of the positioning accuracy limit; The motion modulation module is used to perform motion modulation measurement on the optical imaging of the point target on the image detector according to the optimal pixel phase to obtain a positioning result at the optimal pixel phase.

[0015] The third aspect of the embodiments of the present application discloses an electronic device, including a memory, a processor, and a computer program stored in the memory and runnable on the processor. When the processor executes the computer program, the steps of the point target precise positioning method based on optical imaging motion modulation described in the first aspect of the embodiments of the present application are implemented.

[0016] The fourth aspect of the embodiments of the present application discloses a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the point target precision positioning method based on optical imaging motion modulation described in the first aspect of the embodiments of the present application are implemented.

[0017] The fifth aspect of the embodiments of the present application discloses a computer program product, including a computer program, which, when executed by a processor, implements the steps of the point target precise positioning method based on optical imaging motion modulation described in the first aspect of the embodiments of the present application.

[0018] The embodiments of the present application include the following advantages: In an embodiment of the present application, the micron-level perception of the pixel on the light intensity distribution is converted into a finer actuator motion resolution, and an effective PSF model of a small point spread function (PSF) optical system is constructed, which more accurately characterizes the precise correspondence between the pixel phase and the pixel response when the point target is located near the pixel edge. Since the small PSF achieves the optimal accuracy limit near the pixel edge, only the effective PSF modeling of the pixel edge can meet the algorithm requirements, reducing the workload of the effective PSF model calibration. Moreover, from the perspective of fully utilizing information theory, the positioning accuracy limit of the area near the pixel edge is estimated based on the effective PSF model of the small PSF optical system, and the optimal pixel phase is determined based on the positioning accuracy limit, forming the effect of optimizing the accuracy limit of target positioning at the pixel edge. Therefore, according to the optimal pixel phase, the optical imaging of the point target on the image detector is subjected to motion modulation measurement, and the point target can always be kept at the optimal position of the accuracy limit for measurement, and the positioning result at the optimal pixel phase is obtained. In this way, this method fully utilizes the accuracy improvement potential given by information theory, breaks through the accuracy bottleneck of traditional fixed optical systems, and achieves a significant improvement in the single-frame measurement accuracy of the target. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 This is a schematic diagram of the principle of motion-modulated point target positioning provided by an embodiment of the present application; Figure 2 This is a flowchart of the steps of a point target precision positioning method based on optical imaging motion modulation provided by an embodiment of the present application; Figure 3 This is a schematic diagram of a small PSF positioning accuracy limit and optimal pixel phase estimation result provided by an embodiment of the present application; Figure 4 This is a schematic diagram of a motion actuator modulation process provided by an embodiment of the present application; Figure 5 1 is a schematic structural diagram of a point target precision positioning device based on optical imaging motion modulation provided by an embodiment of the present application; Figure 6 This is a structural diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0021] To make the above-mentioned purposes, features, and advantages of this application more clearly understood, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of this application.

[0022] Motion-modulated optical systems use motion actuators to modulate the lens or image detector, translating the detector's micron-scale pixel perception into finer actuator motion resolution. This effectively achieves pixel phase modulation for optical imaging and optimizes small PSF positioning performance. However, existing motion-modulated optical systems, such as pixel shifting super-resolution cameras and smartphone camera autofocus (AF) and optical image stabilization (OIS) systems, utilize motion-modulated actuators (e.g., voice coil motors, piezoelectric actuators, shape memory alloys, and MEMS electrostatic actuators) for motion modulation. This is intended to improve image resolution and stability, rather than for more precise positioning measurement of the target.

[0023] In order to overcome the limitations of related technologies, the present invention provides a method for precise positioning of point targets based on optical imaging motion modulation. Figure 1 As shown, the principle of this method is to design the optical system's PSF to a small-scale focused state, close to the diffraction limit, based on the effect of a small-scale PSF achieving optimal accuracy near the pixel edge. This method then images the point target to be measured and obtains an effective PSF model (ePSF model). Furthermore, the positioning accuracy limit of the area near the pixel edge is estimated, and the pixel phase with optimal positioning accuracy is calculated. A motion actuator is used to modulate the optical imaging on the detector, positioning the target at the optimal pixel phase, achieving optimal precision measurement of point target optical imaging. In this way, motion modulation technology is introduced into the precise positioning of point target optical imaging. By utilizing a small-scale PSF design and pixel phase modulation, combined with sub-pixel positioning methods (e.g., the maximum likelihood unbiased positioning algorithm), optimal positioning of point target imaging is achieved, fully leveraging the accuracy improvement potential provided by information theory and breaking through the accuracy bottleneck of traditional fixed optical imaging measurement systems.

[0024] Reference Figure 2 As shown, Figure 2 This is a flowchart of a method for precise positioning of a point target based on optical imaging motion modulation provided by an embodiment of the present application. Figure 2 As shown, the point target precise positioning method based on optical imaging motion modulation may include steps S210 to S230: Step S210: Constructing an effective PSF model of a small point spread function (PSF) optical system, wherein the effective PSF model represents the precise correspondence between the pixel phase and the pixel response when the point target is located in the area near the pixel edge, and the small PSF optical system represents an optical system in which the PSF is smaller than the target size threshold when the size of the image detector is smaller than the target size threshold.

[0025] In an embodiment of the present application, a small PSF optical system is designed based on the effect of achieving the optimal accuracy limit of a small PSF near the pixel edge. Specifically, the small PSF optical system selects a smaller lens F number, optimizes the lens aberration, and when the object to be measured is a cooperative target, selects a smaller optical signal wavelength to make the PSF of the optical system as focused as possible. The PSF of the small PSF optical system is smaller in the image detector, that is, an optical system whose PSF size is smaller than the target size threshold is referred to as a small PSF optical system. In some embodiments, the PSF of the small PSF optical system is within 0.3 pixels in the size of the image detector.

[0026] Among them, the small PSF optical system has a smaller light spot on the imaging detector. If the light spot is located near the edge of the pixel, the energy is distributed on two adjacent pixels. The slight movement of the point target will cause a significant change in the image pixel value, so more information is provided at this position, making the positioning accuracy higher.

[0027] Considering the effect of a small PSF achieving the optimal accuracy limit near the pixel edge, the effective PSF model is only performed on the pixel edge. Among them, the effective PSF model represents the precise correspondence between the pixel phase and the pixel response when the point target is located in the area near the pixel edge. Specifically, the effective PSF model refers to the precise correspondence between the sub-pixel position and the pixel response generated after the optical PSF is sampled by the image detector pixel. Specifically, the effective PSF model can be an analytical function, that is, the convolution of the optical system PSF and the detector pixel response; the effective PSF model can also be a numerical function, that is, derived from experimental statistics and modeling of actual imaging of the point target to be measured.

[0028] In a specific embodiment, the effective PSF model is an experimental statistical numerical model of actual imaging of the target to be measured; constructing the effective PSF model of the small point spread function (PSF) optical system may specifically include sub-steps S210-1 to S210-3: Step S210 - 1 : using the small PSF optical system to image the point target to be measured, adjusting the distance between the lens of the small PSF optical system and the image detector until the image is fully focused, and sequentially capturing point target images at different pixel phases.

[0029] Among them, the distance between the lens of the small PSF optical system and the image detector is adjusted until the image is fully focused, avoiding the defocusing operation commonly used in sub-pixel positioning of point targets. Then, the motion actuator is used to generate sub-pixel displacement of the image of the point target on the image detector, and the point target images are collected at different pixel phases in turn.

[0030] In some embodiments, a frame of image is collected when the point target is located at different pixel phases, and subsequent correspondence calculation is performed based on the one frame of point target image; in some embodiments, multiple frames of point target images are collected when the point target is located at different pixel phases and the pixel responses are averaged, and subsequent correspondence calculation is performed based on the result of averaging the multiple frames of point target images.

[0031] Step S210 - 2 : Determine an area near a pixel edge of a target pixel, wherein the point object is located in the area near the pixel edge of the target pixel.

[0032] In the embodiment of the present application, for a small PSF, an area near the edge of a pixel means that most of its energy is distributed on two adjacent pixels, while an area located in the center of a pixel means that most of its energy is distributed on one pixel. Therefore, the area near the edge of the pixel can be determined based on the energy (pixel value) distributed on different pixels.

[0033] Specifically, determining the area near the pixel edge of the target pixel includes: comparing the pixel values ​​of two adjacent pixels; when the larger pixel value of the two adjacent pixels is less than N times the smaller pixel value, determining that the pixel corresponding to the larger pixel value is the target pixel, and the point target is located in the area near the pixel edge of the target pixel, and N is an integer greater than or equal to 10.

[0034] It is understandable that since the light signal generated by a point target is much larger than the dark noise of a pixel, the effect of the pixel dark noise is not considered when estimating the positioning accuracy limit.

[0035] Step S210 - 3 : Based on the point target images captured when the point target is located at different pixel phases in the area near the pixel edge, the precise correspondence between different pixel phases and pixel responses is calculated to obtain an effective PSF model.

[0036] Specifically, for point target images captured at different pixel phases near the pixel edge, after preprocessing operations such as background removal and average filtering, the interpolation technology is used to obtain the precise correspondence between the pixel phase and the pixel response near the pixel edge of the imaging area, thereby obtaining an effective PSF model of the pixel response.

[0037] In this way, by converting the pixel's micron-level perception of light intensity distribution into a finer actuator motion resolution, an effective PSF model of a small point spread function (PSF) optical system is constructed, which more accurately characterizes the correspondence between pixel phase and pixel response.

[0038] Step S220: Estimate the positioning accuracy limit of the area near the pixel edge based on the effective PSF model, and determine the optimal pixel phase based on the positioning accuracy limit, wherein the positioning accuracy limit represents the theoretical uncertainty of positioning, and the optimal pixel phase represents the pixel phase corresponding to the minimum value satisfied by the positioning accuracy limit.

[0039] In the embodiment of the present application, the positioning accuracy limit of the area near the pixel edge can be evaluated based on the Cramer-Rao lower bound theory, so as to obtain the positioning accuracy limit of the area near the pixel edge.

[0040] The positioning accuracy limit represents the uncertainty of positioning theory. That is, the smaller the positioning accuracy limit of a point target in pixel phase, the higher the confidence level of the positioning result. The larger the positioning accuracy limit of a point target in pixel phase, the lower the confidence level of the positioning result. Therefore, when the positioning accuracy limit meets the minimum value, the optimal pixel phase is determined. This optimal pixel phase is the optimal measurement position under the accuracy limit theory.

[0041] In a specific embodiment, estimating the positioning accuracy limit of the area near the pixel edge according to the effective PSF model may specifically include sub-step S220-1: Step S220-1: Based on the Cramer-Rao lower bound theory, according to the area near the pixel edge, the effective PSF model of the target pixel, and the effective PSF model of the pixels adjacent to the target pixel, determine the positioning accuracy limit of the point target located in the area near the pixel edge.

[0042] In the embodiment of the present application, the positioning accuracy limit of the point target in the area near the edge of the pixel refers to the positioning accuracy limit of the point target in the area ROI near the edge of the pixel in the x direction. For example, the positioning accuracy limit of the point target in the area near the edge of pixel i is It can be expressed as:

[0043] Among them, x is the point target position, and x is located near the edge of the pixel; is the effective PSF model of the target pixel; is the effective PSF model of the pixels adjacent to the target pixel; K is the pixel gain that converts the number of photoelectrons into pixel values.

[0044] In a specific embodiment, determining the optimal pixel phase according to the positioning accuracy limit includes: calculating the optimal pixel phase so that the positioning accuracy limit is The pixel phase that satisfies the minimum value is taken as the optimal pixel phase. Figure 3 As shown, Figure 3 The accuracy limit estimation results and optimal pixel phase estimation results of a non-ideal small PSF image spot are shown. The optimal accuracy limit can be achieved at a position of about 0.05 pixels, and a single-frame positioning accuracy performance better than 0.005 pixels can be achieved.

[0045] In this way, from the perspective of making full use of information theory, the positioning accuracy limit of the area near the pixel edge is estimated according to the effective PSF model of the small PSF optical system, and the optimal pixel phase is determined based on the positioning accuracy limit, thus achieving the effect of optimizing the accuracy limit of target positioning at the pixel edge.

[0046] Step S230: performing motion modulation measurement on the optical imaging of the point target on the image detector according to the optimal pixel phase to obtain a positioning result at the optimal pixel phase.

[0047] In an embodiment of the present application, a motion actuator is used to drive the image detector to move, and motion modulation is performed on the optical imaging of the point target on the image detector, so that the image spot of the point target is always maintained at the optimal pixel phase, so that the point target can be measured with optimal precision at the optimal pixel phase, and the positioning result at the optimal pixel phase is obtained.

[0048] In a specific embodiment, performing motion modulation measurement on the optical imaging of the point target on the image detector according to the optimal pixel phase to obtain a positioning result at the optimal pixel phase specifically includes sub-steps S230-1 to S230-2: Step S230-1: Using the optimal pixel phase as a reference quantity and the sub-pixel positioning result obtained by motion modulation as a feedback quantity, the target optical imaging on the image detector is subjected to multiple motion modulations by a motion actuator to obtain a point target image located at the optimal pixel phase.

[0049] In an embodiment of the present application, the target optical imaging on the image detector is subjected to multiple motion modulations until the image spot of the point target is adjusted to the optimal pixel phase, the motion modulation is stopped, and the image of the point target at the optimal pixel phase is collected for subsequent sub-pixel positioning.

[0050] like Figure 4 As shown, step S230-1 may specifically include steps A1 to A5: Step A1: The difference between the optimal pixel phase and the sub-pixel positioning result obtained by the last motion modulation is used as the modulation control amount.

[0051] Each time the motion is adjusted, the optimal pixel phase is used as the reference, and the sub-pixel positioning result (target image spot position) obtained from the previous motion modulation is used as nonlinear feedback. The difference between the two is used as the modulation control variable, that is, the input of the motion actuator. For example, the modulation control variable It can be expressed as:

[0052] in, is the optimal pixel phase; It is a sub-pixel positioning method, which can be a centroid method, a maximum likelihood method, etc. It is a point target image (point target spot image) acquired at the position after motion modulation.

[0053] It is understandable that if the modulation is performed for the first time, the sub-pixel positioning result obtained by the last motion modulation is the sub-pixel positioning result obtained without modulation.

[0054] Step A2: When the modulation control amount is greater than the optimal pixel phase region threshold, the motion actuator is controlled to perform motion modulation according to the modulation control amount, and a point target image of this motion modulation is collected at the position after the motion modulation.

[0055] In the embodiment of the present application, the optimal pixel phase region threshold is set , the difference between the optimal pixel phase and the sub-pixel positioning result (modulation control amount) is controlled within the optimal pixel phase region threshold If the modulation control amount is greater than the optimal pixel phase region threshold , then the motion actuator is used for motion modulation, that is, the motion actuator is moved according to the modulation control, which can be specifically expressed as:

[0056] in, is the position of the motion actuator after this motion modulation, is the position of the motion actuator for the last motion modulation. After the motion actuator performs motion modulation, the point target image of this motion modulation is collected at the position after the motion modulation through the small PSF optical system.

[0057] Step A3: performing sub-pixel positioning according to the point target image of the current motion modulation to obtain the sub-pixel positioning result of the current motion modulation.

[0058] A sub-pixel positioning method can be used to perform sub-pixel positioning on the point target image of this motion modulation to obtain the sub-pixel positioning result of this motion modulation. The sub-pixel positioning method can be a centroid method or a maximum likelihood method.

[0059] Step A4: Use the difference between the optimal pixel phase and the sub-pixel positioning result of this motion modulation as the modulation control amount for the next motion modulation, and continue the next motion modulation until the modulation control amount is less than or equal to the optimal pixel phase area threshold, end the motion modulation, and use the collected point target image of the current motion modulation as the point target image located at the optimal pixel phase.

[0060] In an embodiment of the present application, after obtaining the sub-pixel positioning result of this motion modulation, the sub-pixel positioning result of this motion modulation is used as nonlinear feedback for the next motion modulation, and the modulation control amount of the next motion modulation is calculated. If the modulation control amount of the next motion modulation is greater than the optimal pixel phase area threshold, step A2 is executed to continue the motion modulation; otherwise, the motion modulation is terminated, and the point target image with the optimal pixel phase is output through the small PSF optical system.

[0061] Furthermore, the step A3 of “performing sub-pixel positioning according to the point target image of the current motion modulation to obtain the sub-pixel positioning result of the current motion modulation” may specifically include sub-steps A31 and A32: Step A31: When the modulation control amount is greater than the difference threshold, the centroid method is used to perform sub-pixel positioning on the point target image of the current motion modulation to obtain the sub-pixel positioning result of the current motion modulation.

[0062] Step A32: When the modulation control amount is not greater than the difference threshold, the maximum likelihood method is used to perform sub-pixel positioning on the point target image of the current motion modulation to obtain the sub-pixel positioning result of the current motion modulation.

[0063] In the embodiment of the present application, in order to ensure the efficiency and accuracy of point target measurement, different sub-pixel positioning methods are used for sub-pixel positioning when the point target image spot is located in different areas of the pixel. Specifically, the difference threshold is used to determine the position of the current point target image spot. If the modulation control amount is greater than the difference threshold, , it means that the point target image spot is located near the center of the pixel. At this time, the centroid method is used to perform sub-pixel positioning on the point target image of this motion modulation (i.e., step A31). Although the centroid method has systematic errors, it has a small amount of calculation and can quickly obtain the sub-pixel positioning result of this motion modulation. If the modulation control amount is not greater than the difference threshold , it means that the point target image spot is in the area near the pixel edge. At this time, the maximum likelihood method is used to perform sub-pixel positioning on the point target image modulated by this motion (i.e., step A32). The maximum likelihood method has high positioning accuracy, so the position can be fine-tuned by the maximum likelihood method.

[0064] For example, the sub-pixel positioning result of this motion modulation is It can be expressed as:

[0065]

[0066] in, is the maximum likelihood method, It is the center of mass method.

[0067] In this way, during the motion modulation process, in the feedback link, the sub-pixel positioning result calculated by the centroid method can be used to perform coarse position adjustment, and then the sub-pixel positioning result calculated by the maximum likelihood method can be used to perform fine position adjustment, so as to gradually and quickly obtain the point target image with the optimal pixel phase.

[0068] Step S230 - 2 : performing sub-pixel positioning based on the point target image at the optimal pixel phase to obtain a positioning result at the optimal pixel phase.

[0069] Specifically, the maximum likelihood method is used to perform sub-pixel positioning on the point target image at the optimal pixel phase to obtain a spot positioning result; the displacement of the motion actuator performing multiple motion modulations is subtracted from the spot positioning result to obtain a positioning result at the optimal pixel phase.

[0070] Among them, the specific process of using the maximum likelihood method to perform sub-pixel positioning on the point target image at the optimal pixel phase is: setting the number of photoelectrons detected by the pixel to obey the Poisson distribution, letting the probability of the pixel response of the point target image at the optimal pixel phase take the negative natural logarithm as the maximum likelihood fitting cost function, and making the position that minimizes the maximum likelihood fitting cost function as the image spot positioning result.

[0071] Since the point target image at the optimal pixel phase is obtained based on motion modulation, the image spot positioning result obtained based on the point target image at the optimal pixel phase is fitted with the movement displacement of the motion actuator. Therefore, it is necessary to subtract the displacement of the motion actuator undergoing multiple motion modulations from the image spot positioning result to obtain an accurate positioning result.

[0072] The technical solution implemented in this application converts the pixel's micron-level perception of light intensity distribution into a finer actuator motion resolution, constructs an effective PSF model for a small point spread function (PSF) optical system, and more accurately characterizes the precise correspondence between the pixel phase and the pixel response when the point target is located near the pixel edge. Since the small PSF achieves the optimal accuracy limit near the pixel edge, only effective PSF modeling of the pixel edge can meet the algorithm requirements, reducing the workload of effective PSF model calibration. Furthermore, from the perspective of fully utilizing information theory, the positioning accuracy limit of the area near the pixel edge is estimated based on the effective PSF model of the small PSF optical system, and the optimal pixel phase is determined based on the positioning accuracy limit, resulting in the effect of optimizing the accuracy limit of target positioning at the pixel edge. Therefore, based on the optimal pixel phase, motion modulation measurement of the optical imaging of the point target on the image detector is performed, and the point target can always be measured at the optimal position of the accuracy limit, obtaining a positioning result at the optimal pixel phase. In this way, this method fully utilizes the accuracy improvement potential given by information theory, breaks through the accuracy bottleneck of traditional fixed optical systems, and achieves a significant improvement in the single-frame measurement accuracy of the target.

[0073] The present application also provides a point target precision positioning device based on optical imaging motion modulation, referring to Figure 5 As shown, Figure 5 : is a schematic structural diagram of a point target precision positioning device based on optical imaging motion modulation provided by an embodiment of the present application, the device comprising: A model construction module 510 is configured to construct an effective PSF model for a small point spread function (PSF) optical system, wherein the effective PSF model represents the precise correspondence between the pixel phase and the pixel response when a point target is located near a pixel edge. The small PSF optical system represents an optical system in which the PSF is smaller than a target size threshold when the image detector size is smaller than the target size threshold. Phase calculation module 520, configured to estimate the positioning accuracy limit of the area near the pixel edge based on the effective PSF model, and determine the optimal pixel phase based on the positioning accuracy limit, wherein the positioning accuracy limit represents the positioning theoretical uncertainty, and the optimal pixel phase represents the pixel phase corresponding to the minimum value of the positioning accuracy limit; The motion modulation module 530 is configured to perform motion modulation measurement on the optical imaging of the point target on the image detector according to the optimal pixel phase, and obtain a positioning result at the optimal pixel phase.

[0074] In an optional embodiment, the model building module includes: An image acquisition module is used to use the small PSF optical system to image the point target to be measured, adjust the distance between the lens of the small PSF optical system and the image detector until the image is fully focused, and sequentially acquire point target images at different pixel phases; an area determination module, configured to determine an area near a pixel edge of a target pixel, wherein the point target is located in the area near the pixel edge of the target pixel; The relationship calculation module is used to calculate the precise correspondence between different pixel phases and pixel responses based on the point target image collected when the point target is located at different pixel phases in the area near the pixel edge, so as to obtain an effective PSF model.

[0075] In an optional embodiment, the region determination module is specifically configured to compare pixel values ​​of two adjacent pixels; When the larger pixel value of the two adjacent pixels is less than N times the smaller pixel value, the pixel corresponding to the larger pixel value is determined to be the target pixel, and the point target is located in the area near the pixel edge of the target pixel, where N is an integer greater than or equal to 10.

[0076] In an optional embodiment, the phase calculation module includes: The limit determination module is used to determine the positioning accuracy limit of the point target in the area near the pixel edge based on the Cramer-Rao lower bound theory and the effective PSF model of the area near the pixel edge, the target pixel, and the effective PSF model of the pixels adjacent to the target pixel.

[0077] The optimal phase determination module is used to determine the optimal pixel phase according to the positioning accuracy limit.

[0078] In an optional embodiment, the motion modulation module includes: a motion modulation submodule, configured to use the optimal pixel phase as a reference quantity and the sub-pixel positioning result obtained by motion modulation as a feedback quantity, and to perform multiple motion modulations on the target optical imaging on the image detector through a motion actuator to obtain a point target image located at the optimal pixel phase; The result positioning module is used to perform sub-pixel positioning according to the point target image located at the optimal pixel phase to obtain a positioning result at the optimal pixel phase.

[0079] In an optional embodiment, the motion modulation submodule is specifically used to: use the difference between the optimal pixel phase and the sub-pixel positioning result obtained by the last motion modulation as the modulation control amount; when the modulation control amount is greater than the optimal pixel phase area threshold, control the motion actuator to perform motion modulation according to the modulation control amount, and collect the point target image of this motion modulation at the position after the motion modulation; perform sub-pixel positioning according to the point target image of this motion modulation to obtain the sub-pixel positioning result of this motion modulation; use the difference between the optimal pixel phase and the sub-pixel positioning result of this motion modulation as the modulation control amount for the next motion modulation, continue the next motion modulation until the modulation control amount is less than or equal to the optimal pixel phase area threshold, end the motion modulation, and use the collected point target image of the current motion modulation as the point target image located at the optimal pixel phase.

[0080] In an optional embodiment, the result positioning module is specifically used to: use the maximum likelihood method to perform sub-pixel positioning on the point target image located at the optimal pixel phase to obtain a spot positioning result; subtract the displacement of the motion actuator performing multiple motion modulations from the spot positioning result to obtain a positioning result at the optimal pixel phase.

[0081] The present application also provides an electronic device, Figure 6 , Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. Figure 6 As shown, the electronic device 600 includes: a memory 610 and a processor 620. The memory 610 and the processor 620 are connected via a bus communication. A computer program is stored in the memory 610. The computer program can be run on the processor 620 to implement the steps of the point target precise positioning method based on optical imaging motion modulation described in the embodiment of the present application.

[0082] An embodiment of the present application also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the point target precision positioning method based on optical imaging motion modulation described in the embodiment of the present application are implemented.

[0083] An embodiment of the present application also provides a computer program product, including a computer program, which, when executed by a processor, implements the steps of the point target precise positioning method based on optical imaging motion modulation described in the embodiment of the present application.

[0084] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0085] The embodiments of the present application are described with reference to the flowcharts and / or block diagrams of the methods and devices according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing terminal device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0086] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0087] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device so that a series of operating steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, thereby providing instructions for executing on the computer or other programmable terminal device to implement the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0088] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they become aware of the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0089] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or terminal device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or terminal device that includes the element.

[0090] The above is a detailed introduction to the method, device and equipment for precise positioning of point targets based on optical imaging motion modulation provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for general technical personnel in this field, based on the ideas of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A point target precision positioning method based on optical imaging motion modulation, characterized in that: The method comprises: An effective PSF model of a small point spread function (PSF) optical system is constructed, wherein the effective PSF model represents the precise correspondence between the pixel phase and the pixel response when a point target is located in an area near a pixel edge. The small PSF optical system represents an optical system in which the PSF is smaller than a target size threshold when the image detector size is smaller than the target size threshold. Estimate the positioning accuracy limit of the area near the pixel edge according to the effective PSF model, and determine the optimal pixel phase according to the positioning accuracy limit, wherein the positioning accuracy limit represents the positioning theoretical uncertainty, and the optimal pixel phase represents the pixel phase corresponding to the minimum value of the positioning accuracy limit; Motion modulation measurement is performed on the optical imaging of the point target on the image detector according to the optimal pixel phase to obtain a positioning result at the optimal pixel phase.

2. The method according to claim 1, characterized in that Construct an effective PSF model for a small point spread function (PSF) optical system, including: Using the small PSF optical system to image the point target to be measured, adjusting the distance between the lens of the small PSF optical system and the image detector until the image is fully focused, and sequentially collecting point target images at different pixel phases; Determining a region near a pixel edge of a target pixel, wherein the point target is located in the region near the pixel edge of the target pixel; According to point target images acquired when the point target is located at different pixel phases in the area near the pixel edge, the precise correspondence between different pixel phases and pixel responses is calculated to obtain an effective PSF model.

3. The method according to claim 2, characterized in that Determine the area near the pixel edge of the target pixel, including: Compare the pixel values ​​of two adjacent pixels; When the larger pixel value of the two adjacent pixels is less than N times the smaller pixel value, the pixel corresponding to the larger pixel value is determined to be the target pixel, and the point target is located in the area near the pixel edge of the target pixel, where N is an integer greater than or equal to 10.

4. The method according to claim 1 or 2, characterized in that Estimating the positioning accuracy limit of the area near the pixel edge according to the effective PSF model includes: Based on the Cramer-Rao lower bound theory, the positioning accuracy limit of the point target in the area near the pixel edge is determined according to the area near the pixel edge, the effective PSF model of the target pixel, and the effective PSF model of the pixels adjacent to the target pixel.

5. The method according to claim 1, wherein Performing motion modulation measurement on the optical imaging of the point target on the image detector according to the optimal pixel phase to obtain a positioning result at the optimal pixel phase includes: Using the optimal pixel phase as a reference quantity and the sub-pixel positioning result obtained by motion modulation as a feedback quantity, a motion actuator is used to perform multiple motion modulations on the target optical imaging on the image detector to obtain a point target image located at the optimal pixel phase; Sub-pixel positioning is performed based on the point target image at the optimal pixel phase to obtain a positioning result at the optimal pixel phase.

6. The method according to claim 5, characterized in that Using the optimal pixel phase as a reference quantity and the sub-pixel positioning result obtained by motion modulation as a feedback quantity, a motion actuator is used to perform multiple motion modulations on the target optical imaging on the image detector to obtain a point target image located at the optimal pixel phase, including: The difference between the optimal pixel phase and the sub-pixel positioning result obtained by the last motion modulation is used as the modulation control amount; When the modulation control amount is greater than the optimal pixel phase region threshold, controlling the motion actuator to perform motion modulation according to the modulation control amount, and collecting a point target image of this motion modulation at a position after the motion modulation; Performing sub-pixel positioning according to the point target image of the current motion modulation to obtain a sub-pixel positioning result of the current motion modulation; The difference between the optimal pixel phase and the sub-pixel positioning result of this motion modulation is used as the modulation control amount for the next motion modulation, and the next motion modulation is continued until the modulation control amount is less than or equal to the optimal pixel phase area threshold. The motion modulation is ended, and the collected point target image of the current motion modulation is used as the point target image located at the optimal pixel phase.

7. The method according to claim 6, characterized in that Performing sub-pixel positioning according to the point target image of the current motion modulation to obtain the sub-pixel positioning result of the current motion modulation includes: When the modulation control amount is greater than the difference threshold, a centroid method is used to perform sub-pixel positioning on the point target image of the current motion modulation to obtain a sub-pixel positioning result of the current motion modulation; When the modulation control amount is not greater than the difference threshold, the maximum likelihood method is used to perform sub-pixel positioning on the point target image of the current motion modulation to obtain the sub-pixel positioning result of the current motion modulation.

8. The method according to claim 5, characterized in that Performing sub-pixel positioning based on the point target image at the optimal pixel phase to obtain a positioning result at the optimal pixel phase includes: Performing sub-pixel positioning on the point target image at the optimal pixel phase using a maximum likelihood method to obtain a spot positioning result; The displacement of the motion actuator subjected to multiple motion modulations is subtracted from the image spot positioning result to obtain a positioning result at the optimal pixel phase.

9. A point target precision positioning device based on optical imaging motion modulation, characterized in that: The device comprises: A model building module is used to build an effective PSF model of a small point spread function (PSF) optical system, wherein the effective PSF model represents the precise correspondence between the pixel phase and the pixel response when a point target is located in an area near a pixel edge, and the small PSF optical system represents an optical system in which the PSF is smaller than a target size threshold when the size of the image detector is smaller than the target size threshold; a phase calculation module, configured to estimate the positioning accuracy limit of the area near the pixel edge according to the effective PSF model, and determine the optimal pixel phase according to the positioning accuracy limit, wherein the positioning accuracy limit represents the positioning theoretical uncertainty, and the optimal pixel phase represents the pixel phase corresponding to the minimum value of the positioning accuracy limit; The motion modulation module is used to perform motion modulation measurement on the optical imaging of the point target on the image detector according to the optimal pixel phase to obtain a positioning result at the optimal pixel phase.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the point target precise positioning method based on optical imaging motion modulation according to any one of claims 1 to 8 are implemented.

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