Method, device and equipment for precise positioning of point target based on optical imaging motion modulation

Abstract

The application 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 following steps: constructing an effective PSF model of a small point spread function (PSF) optical system, the effective PSF model representing the accurate correspondence between the pixel phase and the pixel response when a point target is located in the vicinity of a pixel edge, and the small PSF optical system representing an optical system in which the size of the PSF is smaller than the size threshold of the target; estimating the positioning accuracy limit of the vicinity of the pixel edge according to the effective PSF model, and determining 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; and performing motion modulation measurement on the optical imaging of the point target on the image detector according to the optimal pixel phase, so as to obtain the positioning result at the optimal pixel phase.

Description

Technical Field

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

[0002] Optical imaging measurement technology, with its advantages of high intuitiveness, high measurement accuracy, and wide applicability, occupies an important position in high-end fields such as aerospace navigation, precision manufacturing, and biological microscopy. Among these, the sub-pixel-level positioning accuracy of point targets (such as stars or biological single molecules) directly determines the final measurement accuracy of optical instruments. Traditional approaches to improving positioning accuracy rely on increasing the focal length and aperture of the optical system or reducing the pixel size of the detector. However, due to physical laws—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—existing fixed optical systems are approaching technological bottlenecks under constraints of size and photosensitivity.

[0003] Motion modulation optical systems utilize motion actuators to modulate lenses or image detectors, transforming the detector's micrometer-level pixel perception into finer actuator motion resolution. Furthermore, based on the Cramer-Rao lower bound theory of positioning accuracy, small-sized point spread functions (PSFs) can achieve extremely precise positioning accuracy at specific pixel phases, surpassing the results of larger-sized PSFs. Motion modulation optical systems can effectively achieve pixel phase modulation in optical imaging, optimizing the positioning performance of small PSFs (small-sized PSFs). However, the motion modulation goals of existing motion modulation optical systems are primarily to improve image resolution and stability, rather than to achieve higher-precision target positioning measurements.

[0004] Therefore, in the field of precision positioning using optical imaging of point targets, measuring instruments are often fixed, making it impossible to modulate the pixel phase of the PSF, thus wasting the potential for optimizing positioning performance inherent in information theory. There is an urgent need for a precision positioning method that integrates motion modulation mechanisms with positioning accuracy optimization, in order to fully leverage the accuracy enhancement potential offered by information theory and drive the leapfrog development of precision measurement technology. Summary of the Invention

[0005] In view of the above problems, embodiments of this 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] A first aspect of this application discloses a method for precise positioning of point targets based on optical imaging motion modulation, the method comprising:

[0007] An effective PSF model for a small dot spread function (PSF) optical system is constructed. The effective PSF model characterizes the precise correspondence between pixel phase and pixel response when the point target is located in the region near the pixel edge. The small PSF optical system characterizes the PSF in an optical system where the size of the image detector is smaller than the target size threshold.

[0008] The positioning accuracy limit of the region near the pixel edge is estimated based on the effective PSF model, and the optimal pixel phase is determined based on the positioning accuracy limit. 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.

[0009] Motion modulation measurement is performed on the optical imaging of the point target on the image detector based on the optimal pixel phase to obtain the positioning result at the optimal pixel phase.

[0010] Optionally, an effective PSF model for a small dot spread function (PSF) optical system is constructed, including:

[0011] The small PSF optical system is used to image the target point under test. The distance between the lens of the small PSF optical system and the image detector is adjusted until the image is fully focused. Target images are then acquired sequentially at different pixel phases.

[0012] The region near the pixel edge of the target pixel is determined, wherein the point target is located in the region near the pixel edge of the target pixel;

[0013] Based on point target images acquired when the point target is located in the region near the pixel edge with different pixel phases, the precise correspondence between different pixel phases and pixel responses is calculated to obtain an effective PSF model.

[0014] Optionally, the region near the pixel edge of the target pixel is determined, including:

[0015] Compare the pixel values ​​of two adjacent pixels;

[0016] If the larger pixel value among two adjacent pixels is less than N times the smaller pixel value, the pixel corresponding to the larger pixel value is determined as the target pixel. The target pixel is located in the region near the pixel edge of the target pixel, where N is an integer greater than or equal to 10.

[0017] Optionally, estimating the localization accuracy limit of the region near the pixel edge based on the effective PSF model includes:

[0018] Based on the Cramer-Rao lower bound theory, the positioning accuracy limit of the point target located in the area near the pixel edge is determined according to the region 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.

[0019] Optionally, motion modulation measurement is performed on the optical imaging of the point target on the image detector based on the optimal pixel phase to obtain the positioning result at the optimal pixel phase, including:

[0020] Using the optimal pixel phase as a reference and the sub-pixel positioning result obtained by motion modulation as a feedback, the target optical imaging on the image detector is subjected to multiple motion modulations by the motion actuator to obtain a point target image located at the optimal pixel phase.

[0021] Subpixel localization is performed on the point target image located at the optimal pixel phase to obtain the localization result at the optimal pixel phase.

[0022] Optionally, using the optimal pixel phase as a reference and the sub-pixel localization result obtained by motion modulation as a feedback, 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, including:

[0023] The difference between the optimal pixel phase and the sub-pixel positioning result obtained from the previous motion modulation is used as the modulation control quantity;

[0024] 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 the point target image of this motion modulation is acquired at the position after motion modulation.

[0025] Subpixel localization is performed on the point target image of the current motion modulation to obtain the subpixel localization result of the current motion modulation;

[0026] The difference between the optimal pixel phase and the subpixel localization result of the current motion modulation is used as the modulation control value for the next motion modulation. The next motion modulation is continued until the modulation control value is less than or equal to the threshold of the optimal pixel phase region. The motion modulation ends, and the point target image acquired by the current motion modulation is used as the point target image located at the optimal pixel phase.

[0027] Optionally, sub-pixel localization is performed based on the point target image of the current motion modulation to obtain the sub-pixel localization result of the current motion modulation, including:

[0028] When the modulation control amount is greater than the difference threshold, the centroid method is used to perform sub-pixel localization of the point target image of the current motion modulation to obtain the sub-pixel localization result of the current motion modulation.

[0029] If the modulation control amount is not greater than the difference threshold, the maximum likelihood method is used to perform sub-pixel localization on the point target image of the current motion modulation to obtain the sub-pixel localization result of the current motion modulation.

[0030] Optionally, sub-pixel localization is performed based on the point target image located at the optimal pixel phase to obtain the localization result at the optimal pixel phase, including:

[0031] The maximum likelihood method is used to perform sub-pixel localization of the point target image located at the optimal pixel phase to obtain the image spot localization result;

[0032] Subtracting the displacement of the motion actuator through multiple motion modulations from the image spot localization result yields the localization result at the optimal pixel phase.

[0033] A second aspect of this application discloses a point target precision positioning device based on optical imaging motion modulation, the device comprising:

[0034] The model building module is used to build an effective PSF model for a small dot spread function (PSF) optical system. The effective PSF model represents the precise correspondence between the pixel phase and the pixel response when the point target is located in the region near the pixel edge. The small PSF optical system represents an optical system where the PSF is applied when the size of the image detector is smaller than the target size threshold.

[0035] The phase calculation module is used to estimate the positioning accuracy limit of the region near the pixel edge according to the effective PSF model, and determine the optimal pixel phase according to the positioning accuracy limit. 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.

[0036] The motion modulation module is used to perform motion modulation measurement on the optical imaging of point targets on the image detector according to the optimal pixel phase, so as to obtain the positioning result at the optimal pixel phase.

[0037] A third aspect of this application discloses an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the point target precision positioning method based on optical imaging motion modulation described in the first aspect of this application.

[0038] A fourth aspect of this application discloses a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the point target precision positioning method based on optical imaging motion modulation described in the first aspect of this application.

[0039] A fifth aspect of this application discloses a computer program product, including a computer program that, when executed by a processor, implements the steps of the point target precision positioning method based on optical imaging motion modulation described in the first aspect of this application.

[0040] The embodiments of this application have the following advantages:

[0041] In this embodiment, the micrometer-level perception of light intensity distribution by pixels is transformed into a finer actuator motion resolution. An effective PSF model of the small point spread function (PSF) optical system is constructed, which more accurately characterizes the precise correspondence between pixel phase and pixel response when the point target is located near the pixel edge. Due to the effect that the small PSF achieves the optimal accuracy limit near the pixel edge, effective PSF modeling only for the pixel edge is sufficient to 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 region 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, by performing motion modulation measurement on the optical imaging of the point target on the image detector based on the optimal pixel phase, the point target can always be measured at the position with the optimal accuracy limit, obtaining the positioning result at the optimal pixel phase. Thus, 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. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a schematic diagram illustrating the principle of motion modulation point target positioning provided in an embodiment of this application;

[0044] Figure 2 This is a flowchart illustrating the steps of a precise point target positioning method based on optical imaging motion modulation, as provided in an embodiment of this application.

[0045] Figure 3 This is a schematic diagram of the small PSF positioning accuracy limit and optimal pixel phase estimation result provided in an embodiment of this application;

[0046] Figure 4 This is a schematic diagram of a motion actuator modulation process provided in an embodiment of this application;

[0047] Figure 5 This is a schematic diagram of the structure of a point target precision positioning device based on optical imaging motion modulation provided in an embodiment of this application;

[0048] Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0049] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0050] Motion modulation optical systems utilize motion actuators to modulate lenses or image detectors, transforming the detector's micrometer-level pixel perception into finer actuator motion resolution. This effectively achieves pixel phase modulation in optical imaging, optimizing the positioning performance of small PSFs. However, existing motion modulation optical systems, such as pixel-shifting super-resolution cameras and smartphone camera autofocus (AF) and optical image stabilization (OIS) systems, use motion modulation actuators (e.g., voice coil motors, piezoelectric actuators, shape memory alloys, and MEMS electrostatic drivers) for motion modulation to improve image resolution and stability, rather than for more precise target positioning and measurement.

[0051] To overcome the limitations of related technologies, embodiments of this application provide a precise point target positioning method based on optical imaging motion modulation, such as... Figure 1As shown, the principle of this method lies in the effect of achieving optimal accuracy limits near pixel edges with a small-sized PSF. The optical system's PSF is designed to be small-sized and focused, approaching the diffraction limit, to image the target point and obtain an effective PSF model (ePSF model). The positioning accuracy limit in the region near pixel edges is estimated, and the pixel phase with optimal positioning accuracy is calculated. A motion actuator modulates the optical imaging on the detector, controlling the target to be positioned at the optimal pixel phase, thus achieving optimal accuracy measurement of point target optical imaging. In this way, motion modulation technology is introduced into precise positioning of point target optical imaging. By utilizing a small-sized PSF design and pixel phase modulation, combined with sub-pixel positioning methods (e.g., maximum likelihood unbiased positioning algorithm), optimal positioning of point target imaging is achieved, fully leveraging the accuracy enhancement potential granted by information theory and breaking through the accuracy bottleneck of traditional fixed optical imaging measurement systems.

[0052] Reference Figure 2 As shown, Figure 2 This is a flowchart illustrating the steps of a precise point target positioning method based on optical imaging motion modulation, as provided in an embodiment of this application. Figure 2 As shown, the precise point target localization method based on optical imaging motion modulation may include steps S210 to S230:

[0053] Step S210: Construct an effective PSF model for a small dot spread function (PSF) optical system. The effective PSF model represents the precise correspondence between the pixel phase and the pixel response when the point target is located in the region near the pixel edge. The small PSF optical system represents an optical system where the PSF is applied to an image detector with a size smaller than the target size threshold.

[0054] In this embodiment, a small PSF optical system is designed based on the effect of achieving optimal accuracy near pixel edges with a small PSF. Specifically, the small PSF optical system selects a smaller lens F-number, optimizes lens aberrations, and selects a smaller optical signal wavelength when the object under test is a cooperative target, so that the PSF of the optical system is focused as much as possible. The PSF of the small PSF optical system is small in size in the image detector; that is, an optical system with a PSF size smaller than the target size threshold is considered a small PSF optical system. In some embodiments, the PSF of the small PSF optical system is within 0.3 pixels in the image detector.

[0055] Among them, the small PSF optical system has a smaller spot size on the imaging detector. If the spot size is located near the edge of a 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. Therefore, more information is provided at this location, resulting in higher positioning accuracy.

[0056] Considering the effect of small PSF reaching its optimal accuracy limit near pixel edges, effective PSF modeling is only performed for pixel edges. The effective PSF model characterizes the precise correspondence between pixel phase and pixel response when the point target is located near the pixel edge. Specifically, the effective PSF model refers to the precise correspondence between sub-pixel position and pixel response generated by the optical PSF after pixel sampling by the image detector. Specifically, the effective PSF model can be an analytical function, i.e., the convolution of the optical system PSF and the detector pixel response; the effective PSF model can also be a numerical function, i.e., experimental statistics and modeling derived from the actual imaging of the target point.

[0057] In one specific implementation, the effective PSF model is an experimental statistical numerical model of the actual imaging of the target under test; constructing the effective PSF model of the small point spread function PSF optical system may specifically include sub-steps S210-1 to S210-3:

[0058] Step S210-1: Use the small PSF optical system to image the target point under test, adjust the distance between the lens of the small PSF optical system and the image detector until the image is fully focused, and collect the target image at different pixel phases in sequence.

[0059] In this process, 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 subpixel positioning of point targets. Then, the motion actuator is used to generate subpixel displacement of the image of the point target on the image detector, and the point target image is acquired sequentially at different pixel phases.

[0060] In some embodiments, a single frame of image is acquired when the target point is located at different pixel phases, so as to perform subsequent correspondence calculations based on the single frame of target point image; in some embodiments, multiple frames of target point images are acquired when the target point is located at different pixel phases and the pixel responses are averaged, so as to perform subsequent correspondence calculations based on the result of averaging multiple frames of target point images.

[0061] Step S210-2: Determine the region near the pixel edge of the target pixel, wherein the point target is located in the region near the pixel edge of the target pixel.

[0062] In this embodiment of the application, for a small PSF, the region near the pixel edge means that most of its energy is distributed on two adjacent pixels, while the region in the center of the pixel means that most of its energy is distributed on one pixel. Therefore, the region near the pixel edge can be determined based on the energy (pixel value) distributed on different pixels.

[0063] Specifically, determining the region near the pixel edge of the target pixel includes: comparing the pixel values ​​of two adjacent pixels; if the larger pixel value of the two adjacent pixels is less than N times the smaller pixel value, determining the pixel corresponding to the larger pixel value as the target pixel, wherein the target pixel is located in the region near the pixel edge of the target pixel, and N is an integer greater than or equal to 10.

[0064] It is understandable that the influence of pixel dark noise was not considered when estimating the positioning accuracy limit because the light signal generated by the point target is much greater than the dark noise of the pixel.

[0065] Step S210-3: Based on the point target images acquired when the point target is located in the region near the pixel edge with different pixel phases, calculate the precise correspondence between different pixel phases and pixel responses to obtain an effective PSF model.

[0066] Specifically, for point target images acquired when the point target is located near the pixel edge at different pixel phases, after preprocessing operations such as background removal and average filtering, interpolation techniques are used to obtain the precise correspondence between the pixel phase and the pixel response near the pixel edge of the imaging region, thereby obtaining an effective PSF model of the pixel response.

[0067] Thus, by transforming the pixel's micron-level perception of light intensity distribution into a finer actuator motion resolution, an effective PSF model of the small dot spread function (PSF) optical system is constructed, which more accurately characterizes the correspondence between pixel phase and pixel response.

[0068] Step S220: Estimate the positioning accuracy limit of the region near the pixel edge according to the effective PSF model, and determine the optimal pixel phase according to the positioning accuracy limit. 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.

[0069] In this embodiment of the application, the positioning accuracy limit of the region near the pixel edge can be evaluated based on the Cramer-Rao lower bound theory, thereby obtaining the positioning accuracy limit of the region near the pixel edge.

[0070] The positioning accuracy limit characterizes the uncertainty of the positioning theory. In other words, the smaller the positioning accuracy limit of a point target in the pixel phase, the higher the reliability of the positioning result; conversely, the larger the positioning accuracy limit of a point target in the pixel phase, the lower the reliability of the positioning result. Therefore, when the positioning accuracy limit satisfies its minimum value, the optimal pixel phase is determined, and this optimal pixel phase is the optimal measurement position under the accuracy limit theory.

[0071] In one specific implementation, estimating the positioning accuracy limit of the region near the pixel edge based on the effective PSF model may specifically include sub-step S220-1:

[0072] Step S220-1: Based on the Cramerlow lower bound theory, determine the positioning accuracy limit of the point target located in the area near the pixel edge according to the region 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.

[0073] In this embodiment, the positioning accuracy limit of a point target located in the region near the pixel edge refers to the positioning accuracy limit of the region (ROI) near the pixel edge in the pixel x-direction. For example, the positioning accuracy limit of a point target located in the region near the edge of pixel i... It can be represented as:

[0074]

[0075] Where x is the target point location, and x is located in the region near the edge of the pixel; An effective PSF model for the target pixel; For the effective PSF model of pixels adjacent to the target pixel; K converts the number of photoelectrons into pixel gain of pixel value.

[0076] In one specific implementation, determining the optimal pixel phase based on the positioning accuracy limit includes: calculating the position of the target pixel i that satisfies the positioning accuracy limit. The pixel phase that satisfies the minimum value is taken as the optimal pixel phase. For example... Figure 3 As shown, Figure 3 The results show the accuracy limit estimation and optimal pixel phase estimation of a non-ideal small PSF image spot. The optimal accuracy limit can be achieved at a position of about 0.05 pixels, which can achieve a single-frame positioning accuracy performance better than 0.005 pixels.

[0077] Thus, from the perspective of fully utilizing information theory, the positioning accuracy limit of the region 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, thereby achieving the effect of optimizing the accuracy limit of target positioning at the pixel edge.

[0078] Step S230: Perform motion modulation measurement on the optical imaging of the point target on the image detector according to the optimal pixel phase to obtain the positioning result at the optimal pixel phase.

[0079] In this embodiment, 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 to keep the image spot of the point target at the optimal pixel phase. This allows for optimal precision measurement of the point target at the optimal pixel phase, resulting in a positioning result at the optimal pixel phase.

[0080] In one specific implementation, motion modulation measurement is performed on the optical imaging of the point target on the image detector based on the optimal pixel phase to obtain the positioning result at the optimal pixel phase, specifically including sub-steps S230-1 to S230-2:

[0081] Step S230-1: Using the optimal pixel phase as a reference and the sub-pixel positioning result obtained by motion modulation as a feedback, the target optical imaging on the image detector is subjected to multiple motion modulations by the motion actuator to obtain a point target image located at the optimal pixel phase.

[0082] In this embodiment, the optical imaging of the target 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 then stopped, and the point target image located at the optimal pixel phase is acquired for subsequent subpixel localization.

[0083] like Figure 4 As shown, step S230-1 may specifically include steps A1 to A5:

[0084] Step A1: Use the difference between the optimal pixel phase and the sub-pixel positioning result obtained from the previous motion modulation as the modulation control quantity.

[0085] During each motion adjustment, the optimal pixel phase is used as a reference, and the sub-pixel localization result (target spot position) obtained from the previous motion modulation is used as non-linear feedback. The difference between the two is used as the modulation control variable, i.e., the input to the motion actuator. For example, the modulation control variable... It can be represented as:

[0086]

[0087] in, For optimal pixel phase; This refers to sub-pixel localization methods, which can include centroid method, maximum likelihood method, etc. This refers to a point target image (point target patch image) acquired at the motion-modulated location.

[0088] It is understandable that if the modulation is run for the first time, the subpixel localization result obtained from the previous motion modulation will be the subpixel localization result obtained without modulation.

[0089] Step A2: When the modulation control amount is greater than the optimal pixel phase region threshold, control the motion actuator to perform motion modulation according to the modulation control amount, and acquire the point target image of this motion modulation at the position after motion modulation.

[0090] In this embodiment, an optimal pixel phase region threshold is set. The difference (modulation control amount) between the optimal pixel phase and the sub-pixel localization result is controlled within the threshold of the optimal pixel phase region. If the modulation control amount is greater than the optimal pixel phase region threshold, then... Then, motion modulation is performed using a motion actuator, that is, the motion actuator is moved according to the modulation control, which can be specifically expressed as:

[0091]

[0092] in, This is the position of the motion actuator after motion modulation. This represents the position of the motion actuator during the previous motion modulation. After the motion actuator performs motion modulation, a point target image for the current motion modulation is acquired at the position after motion modulation using a small PSF optical system.

[0093] Step A3: Perform subpixel localization based on the point target image of the current motion modulation to obtain the subpixel localization result of the current motion modulation.

[0094] Subpixel localization methods can be used to perform subpixel localization on the motion-modulated point target image, yielding the subpixel localization result. These methods can be either the centroid method or the maximum likelihood method.

[0095] Step A4: Use the difference between the optimal pixel phase and the sub-pixel positioning result of the current motion modulation as the modulation control value for the next motion modulation, and continue to perform the next motion modulation until the modulation control value is less than or equal to the optimal pixel phase region threshold, then end the motion modulation, and use the acquired point target image of the current motion modulation as the point target image located at the optimal pixel phase.

[0096] In this embodiment of the application, after obtaining the sub-pixel localization result of the current motion modulation, the sub-pixel localization result of the current motion modulation is used as the nonlinear feedback of the next motion modulation to calculate the modulation control amount of the next motion modulation. If the modulation control amount of the next motion modulation is greater than the optimal pixel phase region threshold, then step A2 is executed to continue motion modulation; otherwise, motion modulation is terminated, and the point target image with the optimal pixel phase is output through the small PSF optical system.

[0097] Furthermore, step A3 above, "performing sub-pixel localization based on the point target image of the current motion modulation to obtain the sub-pixel localization result of the current motion modulation," may specifically include sub-steps A31 and A32:

[0098] Step A31: When the modulation control amount is greater than the difference threshold, the centroid method is used to perform sub-pixel localization of the point target image of the current motion modulation to obtain the sub-pixel localization result of the current motion modulation.

[0099] Step A32: If the modulation control amount is not greater than the difference threshold, the maximum likelihood method is used to perform sub-pixel localization on the point target image of the current motion modulation to obtain the sub-pixel localization result of the current motion modulation.

[0100] In this embodiment, to ensure the efficiency and accuracy of point target measurement, different sub-pixel localization methods are used when the point target image spot is located in different regions of a pixel. Specifically, a 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... If the point target image spot is located near the pixel center, then the centroid method is used to perform sub-pixel localization of the point target image modulated by the current motion (i.e., step A31). Although the centroid method has systematic errors, it has low computational cost and can quickly obtain the sub-pixel localization result of the current motion modulation. If the modulation control amount is not greater than the difference threshold... If the image spot is located near the pixel edge, then the maximum likelihood method is used to perform sub-pixel localization of the motion-modulated image spot (i.e., step A32). The maximum likelihood method has high localization accuracy, so the position can be fine-tuned by using the maximum likelihood method.

[0101] For example, the subpixel localization results of this motion modulation. It can be represented as:

[0102]

[0103]

[0104] in, For the maximum likelihood method, This is the center-of-mass method.

[0105] Thus, during motion modulation, the sub-pixel positioning results calculated by the centroid method can be used for coarse position adjustment in the feedback stage, and then the sub-pixel positioning results calculated by the maximum likelihood method can be used for fine position adjustment, thereby gradually and quickly obtaining the point target image with the optimal pixel phase.

[0106] Step S230-2: Perform sub-pixel localization based on the point target image located at the optimal pixel phase to obtain the localization result at the optimal pixel phase.

[0107] Specifically, the maximum likelihood method is used to perform sub-pixel localization of the point target image located at the optimal pixel phase to obtain the image spot localization result; the displacement of the motion actuator through multiple motion modulations is subtracted from the image spot localization result to obtain the localization result at the optimal pixel phase.

[0108] The specific process of using the maximum likelihood method to perform sub-pixel localization of the point target image located at the optimal pixel phase is as follows: the number of photoelectrons detected by the pixel is set to follow a Poisson distribution, the probability of the pixel response of the point target image located at the optimal pixel phase is set to the negative natural logarithm as the maximum likelihood fitting cost function, and the position that minimizes the maximum likelihood fitting cost function is taken as the image spot localization result.

[0109] Since the point target image located at the optimal pixel phase is obtained based on motion modulation, the spot localization result obtained based on the point target image located at the optimal pixel phase fits the movement displacement of the motion actuator. Therefore, it is necessary to subtract the displacement of the motion actuator after multiple motion modulations from the spot localization result in order to obtain an accurate localization result.

[0110] The technical solution implemented in this application transforms the micrometer-level perception of light intensity distribution by pixels into a finer actuator motion resolution, constructing an effective PSF model for a small point spread function (PSF) optical system. This more accurately characterizes the precise correspondence between pixel phase and pixel response when a point target is located near the pixel edge. Due to the effect of the small PSF achieving optimal accuracy near the pixel edge, effective PSF modeling only for the pixel edge is sufficient to meet the algorithm's requirements, reducing the workload of effective PSF model calibration. Furthermore, from the perspective of fully utilizing information theory, the positioning accuracy limit 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 this limit. This achieves the effect of optimizing the accuracy limit of target positioning at the pixel edge. Therefore, by performing motion modulation measurement on the optical imaging of the point target on the image detector based on the optimal pixel phase, the point target can always be measured at the position with the optimal accuracy limit, obtaining the positioning result at the optimal pixel phase. Thus, this method fully leverages the accuracy improvement potential provided by information theory, breaking through the accuracy bottleneck of traditional fixed optical systems and achieving a significant improvement in the single-frame measurement accuracy of the target.

[0111] This application also provides a point target precision positioning device based on optical imaging motion modulation, referring to... Figure 5 As shown, Figure 5This is a schematic diagram of a point target precision positioning device based on optical imaging motion modulation provided in an embodiment of this application. The device includes:

[0112] The model building module 510 is used to build an effective PSF model of a small dot spread function (PSF) optical system. The effective PSF model represents the precise correspondence between the pixel phase and the pixel response when the point target is located in the region near the pixel edge. The small PSF optical system represents an optical system where the PSF is applied when the size of the image detector is smaller than the target size threshold.

[0113] The phase calculation module 520 is used to estimate the positioning accuracy limit of the region near the pixel edge according to the effective PSF model, and determine the optimal pixel phase according to the positioning accuracy limit. 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.

[0114] The motion modulation module 530 is used to perform motion modulation measurement on the optical imaging of point targets on the image detector according to the optimal pixel phase, so as to obtain the positioning result at the optimal pixel phase.

[0115] In one optional embodiment, the model building module includes:

[0116] The image acquisition module is used to image the target point under test using the small PSF optical system, adjust the distance between the lens of the small PSF optical system and the image detector until the image is fully focused, and acquire the target image at different pixel phases in sequence.

[0117] The region determination module is used to determine the region near the pixel edge of the target pixel, wherein the point target is located in the region near the pixel edge of the target pixel;

[0118] The relationship calculation module is used to calculate the precise correspondence between different pixel phases and pixel responses based on point target images acquired when the point target is located in the region near the pixel edge, thereby obtaining an effective PSF model.

[0119] In one optional embodiment, the region determination module is specifically used to compare the pixel values ​​of two adjacent pixels;

[0120] If the larger pixel value among two adjacent pixels is less than N times the smaller pixel value, the pixel corresponding to the larger pixel value is determined as the target pixel. The target pixel is located in the region near the pixel edge of the target pixel, where N is an integer greater than or equal to 10.

[0121] In one optional embodiment, the phase calculation module includes:

[0122] The limit determination module is used to determine the positioning accuracy limit of the point target located in the area near the pixel edge based on the Cramerlow 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.

[0123] The optimal phase determination module is used to determine the optimal pixel phase based on the positioning accuracy limit.

[0124] In one optional embodiment, the motion modulation module includes:

[0125] The motion modulation submodule is used to perform multiple motion modulations on the target optical imaging on the image detector through a motion actuator, using the optimal pixel phase as a reference and the subpixel positioning result obtained by motion modulation as a feedback, to obtain a point target image located at the optimal pixel phase.

[0126] The result localization module is used to perform sub-pixel localization based on the point target image located at the optimal pixel phase, and obtain the localization result at the optimal pixel phase.

[0127] In an optional embodiment, the motion modulation submodule is specifically configured to: use the difference between the optimal pixel phase and the sub-pixel positioning result obtained from the previous motion modulation as a modulation control quantity; when the modulation control quantity is greater than the optimal pixel phase region threshold, control the motion actuator to perform motion modulation according to the modulation control quantity, and acquire the point target image of the current motion modulation at the position after motion modulation; perform sub-pixel positioning based on the point target image of the current motion modulation to obtain the sub-pixel positioning result of the current motion modulation; use the difference between the optimal pixel phase and the sub-pixel positioning result of the current motion modulation as the modulation control quantity for the next motion modulation, and continue to perform the next motion modulation until the modulation control quantity is less than or equal to the optimal pixel phase region threshold, end the motion modulation, and take the acquired point target image of the current motion modulation as the point target image located at the optimal pixel phase.

[0128] In an optional embodiment, the result localization module is specifically used to: perform sub-pixel localization of the point target image located at the optimal pixel phase using the maximum likelihood method to obtain a spot localization result; and subtract the displacement of the motion actuator through multiple motion modulations from the spot localization result to obtain the localization result at the optimal pixel phase.

[0129] This application also provides an electronic device, which is described in reference to... Figure 6 , Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. For example... Figure 6As 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 for communication. The memory 610 stores a computer program that can run on the processor 620 to implement the steps of the point target precision positioning method based on optical imaging motion modulation described in the embodiments of this application.

[0130] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the point target precision positioning method based on optical imaging motion modulation described in this application.

[0131] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the point target precision positioning method based on optical imaging motion modulation described in this application.

[0132] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0133] This application describes embodiments of methods and apparatus according to flowchart illustrations and / or block diagrams. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0134] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing terminal device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0135] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal equipment, causing a series of operational steps to be performed on the computer or other programmable terminal equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable terminal equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0136] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0137] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0138] The above provides a detailed description of a point target precision positioning method, apparatus, and device based on optical imaging motion modulation provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for precise positioning of point targets based on optical imaging motion modulation, characterized in that, The method includes: An effective PSF model for a small PSF optical system is constructed. The effective PSF model represents the precise correspondence between the pixel phase and the pixel response when the point target is located in the region near the pixel edge. The small PSF optical system represents an optical system where the PSF is smaller than the target size threshold. The positioning accuracy limit of the region near the pixel edge is estimated based on the effective PSF model, and the optimal pixel phase is determined based on the positioning accuracy limit. 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 based on the optimal pixel phase to obtain the positioning result at the optimal pixel phase; The construction of an effective PSF model for the small PSF optical system includes: using the small PSF optical system to image the target point; adjusting the distance between the lens of the small PSF optical system and the image detector until the image is fully focused; sequentially acquiring target images at different pixel phases; determining the region near the pixel edge of the target pixel, wherein the target point is located in the region near the pixel edge of the target pixel; and calculating the precise correspondence between different pixel phases and pixel responses based on the target images acquired when the target point is located in the region near the pixel edge, thereby obtaining an effective PSF model. Estimating the positioning accuracy limit of the region near the pixel edge based on the effective PSF model includes: determining the positioning accuracy limit of the point target located in the region near the pixel edge based on the Cramerlow lower bound theory, the effective PSF model of the target pixel, and the effective PSF model of the pixels adjacent to the target pixel; Motion modulation measurement is performed on the optical imaging of the point target on the image detector based on the optimal pixel phase to obtain the positioning result at the optimal pixel phase. This includes: using the optimal pixel phase as a reference quantity and the sub-pixel positioning result obtained by motion modulation as a feedback quantity, performing multiple motion modulations on the optical imaging of the target on the image detector through a motion actuator to obtain a point target image located at the optimal pixel phase; and performing sub-pixel positioning based on the point target image located at the optimal pixel phase to obtain the positioning result at the optimal pixel phase.

2. The method according to claim 1, characterized in that, Identify the region near the pixel edge of the target pixel, including: Compare the pixel values ​​of two adjacent pixels; If the larger pixel value among two adjacent pixels is less than N times the smaller pixel value, the pixel corresponding to the larger pixel value is determined as the target pixel. The target pixel is located in the region near the pixel edge of the target pixel, where N is an integer greater than or equal to 10.

3. The method according to claim 1, characterized in that, Using the optimal pixel phase as a reference and the sub-pixel localization result obtained by motion modulation as a feedback, 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, including: The difference between the optimal pixel phase and the sub-pixel positioning result obtained from the previous motion modulation is used as the modulation control quantity; 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 the point target image of this motion modulation is acquired at the position after motion modulation. Subpixel localization is performed on the point target image of the current motion modulation to obtain the subpixel localization result of the current motion modulation; The difference between the optimal pixel phase and the subpixel localization result of the current motion modulation is used as the modulation control value for the next motion modulation. The next motion modulation is continued until the modulation control value is less than or equal to the threshold of the optimal pixel phase region. The motion modulation ends, and the point target image acquired by the current motion modulation is used as the point target image located at the optimal pixel phase.

4. The method according to claim 3, characterized in that, Sub-pixel localization is performed on the point target image of the current motion modulation to obtain the sub-pixel localization result of the current motion modulation, including: When the modulation control amount is greater than the difference threshold, the centroid method is used to perform sub-pixel localization of the point target image of the current motion modulation to obtain the sub-pixel localization result of the current motion modulation. If the modulation control amount is not greater than the difference threshold, the maximum likelihood method is used to perform sub-pixel localization on the point target image of the current motion modulation to obtain the sub-pixel localization result of the current motion modulation.

5. The method according to claim 1, characterized in that, Sub-pixel localization is performed on the point target image located at the optimal pixel phase to obtain the localization result at the optimal pixel phase, including: The maximum likelihood method is used to perform sub-pixel localization of the point target image located at the optimal pixel phase to obtain the image spot localization result; Subtracting the displacement of the motion actuator through multiple motion modulations from the image spot localization result yields the localization result at the optimal pixel phase.

6. A point target precision positioning device based on optical imaging motion modulation, characterized in that, The device includes: The model building module is used to build an effective PSF model for a small PSF optical system. The effective PSF model represents the precise correspondence between the pixel phase and the pixel response when the point target is located in the region near the pixel edge. The small PSF optical system represents an optical system where the PSF is smaller than the target size threshold. The phase calculation module is used to estimate the positioning accuracy limit of the region near the pixel edge according to the effective PSF model, and determine the optimal pixel phase according to the positioning accuracy limit. 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. A motion modulation module is used to perform motion modulation measurements on the optical imaging of point targets on the image detector based on the optimal pixel phase, so as to obtain the positioning result at the optimal pixel phase; The construction of an effective PSF model for the small PSF optical system includes: using the small PSF optical system to image the target point; adjusting the distance between the lens of the small PSF optical system and the image detector until the image is fully focused; sequentially acquiring target images at different pixel phases; determining the region near the pixel edge of the target pixel, wherein the target point is located in the region near the pixel edge of the target pixel; and calculating the precise correspondence between different pixel phases and pixel responses based on the target images acquired when the target point is located in the region near the pixel edge, thereby obtaining an effective PSF model. Estimating the positioning accuracy limit of the region near the pixel edge based on the effective PSF model includes: determining the positioning accuracy limit of the point target located in the region near the pixel edge based on the Cramerlow lower bound theory, the effective PSF model of the target pixel, and the effective PSF model of the pixels adjacent to the target pixel; Motion modulation measurement is performed on the optical imaging of the point target on the image detector based on the optimal pixel phase to obtain the positioning result at the optimal pixel phase. This includes: using the optimal pixel phase as a reference quantity and the sub-pixel positioning result obtained by motion modulation as a feedback quantity, performing multiple motion modulations on the optical imaging of the target on the image detector through a motion actuator to obtain a point target image located at the optimal pixel phase; and performing sub-pixel positioning based on the point target image located at the optimal pixel phase to obtain the positioning result at the optimal pixel phase.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the point target precision positioning method based on optical imaging motion modulation as described in any one of claims 1-5.

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