A multi-target distance measurement method based on single photon technology

Abstract

The present application relates to a kind of multi-target distance measurement methods based on single-photon technology, belong to target measurement technical field.The method of the present application includes by calibration calculation, the elevation angle and azimuth angle of the detection field of view of the large field of view gated single-photon detector are converted from the elevation angle and azimuth angle output by optical tracking turntable, the elevation angle and azimuth angle of target position are converted by calibration calculation, the unique spatial position coordinates of target under polar coordinate system are calculated, the three-dimensional space coordinates of each target under Cartesian coordinate system are obtained by conversion, the distance between the selected two targets can be calculated based on Pythagorean theorem.The present application is based on Chinese invention patent ZL202411498055.X technology, simultaneously gate multiple regions of field of view, measure the distance of multiple targets, and calculate the distance between multiple targets according to geometric relationship, provide reliable solution for multi-target distance measurement based on single-photon detection technology.

Description

Technical Field

[0001] This invention belongs to the field of target measurement technology, specifically relating to a method for measuring the distance between multiple targets based on single-photon technology. Background Technology

[0002] To suppress noise, conventional single-photon ranging has a very small detection field of view, limiting its detection range. When the target is a moving, non-cooperative target, it often drifts outside the single-photon detection field of view, causing single-photon ranging to fail. Conventional single-photon ranging technology already struggles to measure the distance to a single target, making it almost impossible to simultaneously measure the distance to multiple targets or the distance between multiple targets. Since the distance between multiple aircraft is crucial for flight safety, there is a need to develop multi-target ranging technology.

[0003] Chinese invention patent ZL202411498055.X discloses a field-of-view gating method for a large field-of-view gated single-photon detector. This method proposes setting a field-of-view gating optical element at the front end of the detector to increase the single-photon gating detection field of view. A precise optical mapping exists between the target detection field of view, the gating unit of the field-of-view gating optical element, and the single-photon detector pixel. By selecting the field of view region containing the target through the field-of-view gating optical element, the target's photon signal can be introduced into the single-photon detector for distance measurement. Summary of the Invention

[0004] This invention addresses the technical problem of conventional single-photon detection technology, which, due to its small field of view, is unable to simultaneously detect multiple targets or measure the distances between them. It provides a multi-target distance measurement method based on single-photon technology. Based on Chinese invention patent ZL202411498055.X, this invention simultaneously selects multiple fields of view, measures the distances between multiple targets, and calculates the distances between them based on geometric relationships, providing a reliable solution for multi-target distance measurement using single-photon detection technology.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A method for measuring the distance between multiple targets based on single-photon technology includes the following steps: Step 1: Integrate the wide field-of-view gated single-photon detector with an optical tracking turntable capable of measuring pitch and azimuth angles; Step 2: The pitch and azimuth angles output by the optical tracking turntable are calibrated and calculated with the pitch and azimuth angles of the detection field of the large field-of-view gated single-photon detector. The pitch and azimuth angles output by the optical tracking turntable are the pitch and azimuth angles of the calibration point in the detection field of the large field-of-view gated single-photon detector. Step 3: When the large field-of-view gated single-photon detector detects a target, the distance to the target can be measured; at the same time, the position of the target in the detection field of view can be measured and calculated to determine the meta-field of view where this position is located, and the elevation angle and azimuth angle of this target position can be calculated by the field of view angle conversion formula. Step 4: Using the large field-of-view gated single-photon detector as the origin, construct a polar coordinate system. Based on the target distance output by the large field-of-view gated single-photon detector when it detects the target in Step 3, and combined with the elevation and azimuth angles of the target position calculated in Step 3, the unique spatial position coordinates of the target in the polar coordinate system are measured and calculated. Step 5: Repeat steps 3 and 4 to measure and calculate the unique spatial coordinates of the multiple targets detected by the large field-of-view gated single-photon detector in the polar coordinate system; Step 6: Using the origin of the polar coordinate system constructed in Step 4 as the origin, construct a Cartesian coordinate system. Under this Cartesian coordinate system, convert the unique spatial position coordinates of the aforementioned multiple targets in the polar coordinate system to obtain the three-dimensional spatial coordinates of each target in the Cartesian coordinate system. Step 7: Based on the law of cosines, select any two targets obtained in Step 5 and their three-dimensional spatial coordinates in the polar coordinate system to calculate the distance between the two selected targets; or based on the Pythagorean theorem, select any two targets obtained in Step 6 and their three-dimensional spatial coordinates in the Cartesian coordinate system to calculate the distance between the two selected targets.

[0006] In the above technical solution, in step 2, through calibration, the elevation angle and azimuth angle output by the optical tracking turntable are used to give the elevation angle and azimuth angle of the calibration point in the detection field of the large field of view gated single photon detector; the elevation angle and azimuth angle of all detection fields can be calculated by using the field of view angle conversion formula.

[0007] In the above technical solution, the gating optical element selected by the large field-of-view gating single-photon detector is a digital micromirror array.

[0008] In the above technical solutions, the gating units of the gating optical elements are all independently switched.

[0009] In the above technical solution, by turning off the gating unit of the gating optical element optically mapped to the target detected by the large field-of-view gating single-photon detector, the distance value of this target output by the large field-of-view gating single-photon detector will disappear, and this disappeared distance value is the distance value of this target; when the large field-of-view gating single-photon detector detects two or more targets, the gating unit of the gating optical element optically mapped to these targets is turned off in sequence, and the distance values ​​output by the large field-of-view gating single-photon detector that disappear in sequence are the distance values ​​of the corresponding targets; when the large field-of-view gating single-photon detector outputs the distance values ​​of two or more targets, the target attribution of the above distance value can be determined.

[0010] In the above technical solution, the target distance value output by the single-photon detector pixel optically mapped by the target detected by the large field-of-view gated single-photon detector is the distance value of this target.

[0011] The beneficial effects of this invention are: The multi-target distance measurement method based on single-photon technology of the present invention, based on single-photon gating detection technology (ZL202411498055.X technology), can detect multiple targets simultaneously and calculate the distance between each pair of targets, effectively expanding the application field of single-photon detection technology. Attached Figure Description

[0012] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0013] Figure 1 A schematic diagram illustrating the division of the detection field of view for a large field-of-view gated single-photon detector.

[0014] Figure 2 A schematic diagram of the gating unit of the field-of-view gating optical element selected for a large field-of-view gating single-photon detector.

[0015] Figure 3 A schematic diagram of the pixels of the single-photon detector used in a large field-of-view gated single-photon detector. Detailed Implementation

[0016] The method of the present invention will be described in more detail and clearly below through specific implementation methods and embodiments.

[0017] The multi-target spacing measurement method based on single-photon technology of the present invention includes the following steps: Step 1: Integrate the large field-of-view gated single-photon detector with an optical tracking turntable that can measure pitch and azimuth angles.

[0018] Step 2: The elevation and azimuth angles output by the optical tracking turntable are calibrated and calculated with the elevation and azimuth angles of the detection field of the large field-of-view gated single-photon detector. The elevation and azimuth angles output by the optical tracking turntable are the elevation and azimuth angles of the calibration point in the detection field of the large field-of-view gated single-photon detector.

[0019] Step 3: When the large field-of-view gated single-photon detector detects a target, the distance to the target can be measured; at the same time, the position of the target in the detection field of view can be measured and calculated, the meta-field of view number of this position can be determined, and the elevation angle and azimuth angle of this target position can be calculated by the field of view angle conversion formula.

[0020] Step 4: Construct a polar coordinate system with the large field-of-view gated single-photon detector as the origin; when the large field-of-view gated single-photon detector detects a target, it will output the target's distance. This distance, combined with the elevation and azimuth angles of the target position calculated in Step 3, allows us to measure and calculate the target's unique spatial position coordinates in the polar coordinate system.

[0021] Step 5: When the large field-of-view gated single-photon detector detects two targets, it will output the distances between the two targets. Using the method in Step 4, the spatial coordinates of the two targets in the polar coordinate system can be calculated.

[0022] Step 6: Construct a Cartesian coordinate system using the origin of the polar coordinate system from Step 4 as the origin. After conversion, the three-dimensional spatial coordinates of the two targets in the Cartesian coordinate system can be obtained.

[0023] Step 7: Based on the law of cosines, select any two targets obtained in Step 5 and calculate the distance between them in the three-dimensional space of the polar coordinate system. Alternatively, based on the Pythagorean theorem, the distance between the two targets can be calculated from their three-dimensional space coordinates in the Cartesian coordinate system.

[0024] Similarly, when the wide field-of-view gated single-photon detector detects multiple targets, repeating steps 3 and 4 allows for the measurement and calculation of the unique spatial coordinates of the multiple targets detected by the wide field-of-view gated single-photon detector in the polar coordinate system. The distance between each pair of targets can then be calculated using the method in step 7.

[0025] In this invention, the gating optical element selected by the large field-of-view gating single-photon detector is a digital micromirror device (DMD), and the gating unit of the gating optical element is an independent switch gating.

[0026] When the gating unit of the gating optics corresponding to the optically mapped target detected by the large field-of-view gating single-photon detector is turned off, the range value of this target output by the large field-of-view gating single-photon detector will disappear. This disappeared range value is the range value of the target. When the large field-of-view gating single-photon detector detects two or more targets, the gating units of the gating optics corresponding to the optically mapped targets of these targets are turned off sequentially. The range values ​​output by the large field-of-view gating single-photon detector that disappear sequentially are the range values ​​of the corresponding targets. When the large field-of-view gating single-photon detector outputs the range values ​​of two or more targets, the target attribution of the above range values ​​can be determined by this method.

[0027] The target distance value output by the single-photon detector pixel mapped to the target detected by the large field-of-view gated single-photon detector is the distance value of that target. This method can be used to determine the target attribution of the distance value output by the large field-of-view gated single-photon detector.

[0028] Example The multi-target spacing measurement method based on single-photon technology of the present invention includes the following steps: Step 1: Integrate the wide field-of-view gated single-photon detector with an optical tracking turntable capable of measuring pitch and azimuth angles; Step 2: Calibrate the pitch and azimuth angles output by the optical tracking turntable with the pitch and azimuth angles of the detection field of view of the large field-of-view gated single-photon detector (e.g., align the optical tracking turntable with reference target point 1 and record the pitch and azimuth angles at this time; align the center of the field of view of the large field-of-view gated single-photon detector with reference target point 1, and then lock the optical tracking turntable and the large field-of-view gated single-photon detector; record the pitch and azimuth angles of the optical tracking turntable). At this moment, the elevation and azimuth angles of the detection field center of the large field-of-view single-photon detector are the same as those of the optical tracking turntable after it locks with the large field-of-view gated single-photon detector. Through calibration calculation, the elevation and azimuth angles of the detection field center point of the large field-of-view gated single-photon detector can be obtained from the elevation and azimuth angles output by the optical tracking turntable.

[0029] In the same image acquired by a large field-of-view gated single-photon detector, several reference target points are selected. The meta-field of view of each reference target point is determined, and the number of meta-fields contained in the horizontal direction (denoted as S) and the number of meta-fields contained in the vertical direction (denoted as D) between this meta-field of view and the meta-field of view of the center of the detection field of view are calculated. Based on the locking combination of the large field-of-view gated single-photon detector and the optical tracking turntable, the elevation angle (denoted as α) and azimuth angle (denoted as β) of each reference point are measured in the field. S, D, α, and β of each reference target point constitute a set of data. The fitting functions α=g(S,D) and β=f(S,D) are used, which are the field-of-view angle conversion formulas. The α and β of each meta-field of view can be calculated from S and D of each meta-field of view. The more reference target points selected and the more times the above-mentioned in-situ physical measurements are performed, the higher the accuracy of the functions α=g(S,D) and β=f(S,D).

[0030] Specifically: For the division of the detection field of view of the large field-of-view gated single-photon detector, please refer to [link to relevant documentation]. Figure 1The entire detection field of view was divided into quadrants 1 to 4. Each quadrant was further divided into 36 element-wise field-of-views: 1a~1i, 2a~2i, 3a~3i, and 4a~4i. Three targets were observed within the detection field of view: a circular target in element 3b, a triangular target in element 3f, and a rectangular target in element 4e.

[0031] By calibrating the elevation and azimuth angles of the detection field of view of the large field-of-view gated single-photon detector with the elevation and azimuth angles of the optical tracking turntable, the field-of-view angle conversion formulas α=g(S,D) and β=f(S,D) are constructed. Figure 1 As shown, the single-photon gating detector detected targets in the 3b, 3f, and 4e quadrant fields of view. Two targets appeared in the 3rd quadrant field of view: a circular target in the 3b quadrant and a triangular target in the 3f quadrant. One target appeared in the 4th quadrant field of view, specifically in the 4e quadrant. Assuming that after conversion, the elevation angles of the 3b, 3f, and 4e quadrant fields of view are α-3b, α-3f, and α-4e respectively (α-3b represents the elevation angle of the 3b field of view, and so on), the azimuth angles of the 3b, 3f, and 4e quadrant fields of view are β-3b, β-3f, and β-4e respectively (β-3b represents the azimuth angle of the 3b field of view, and so on).

[0032] Step 3: When the large field-of-view gated single-photon detector detects the target, measure and calculate the target's position in the detection field of view, and calculate the elevation and azimuth angles of the target position using the field-of-view angle conversion formula.

[0033] The wide field-of-view gated single-photon detector uses a digital micromirror device (DMD) array as its gating optics. A schematic diagram of the gating unit of the gating optics can be found here. Figure 2 . Figure 2 The system contains 36 independently switchable gating units, numbered 1A~1I, 2A~2I, 3A~3I, and 4A~4I, which are then optically mapped sequentially. Figure 1 There are 36 element-fields of view (1a~1i, 2a~2i, 3a~3i, 4a~4i). Gating any gating unit allows the optical signal from the element-field of view mapped to that gating unit to be introduced into the single-photon detector pixel mapped to that gating unit. For example, gating gating unit 3B allows the photon signal of a circular target in the 3b element-field of view to be introduced into the single-photon detector pixel mapped by gating unit 3B. Figure 3 The third single-photon detector pixel in the 3f-element field of view outputs the distance value of the circular target. By gating the 3F gating unit, the photon signal of the triangular target in the 3f-element field of view can be introduced into the range mapped by the 3F gating unit. Figure 3The third single-photon detector pixel outputs the distance value of the triangular target. By gating the 4E gating unit, the photon signal of the rectangular target in the 4e-e element's field of view can be introduced into the range of the target mapped by the 4E gating unit. Figure 3 The fourth single-photon detector pixel in the middle outputs the distance value of the rectangular target.

[0034] See the pixel diagram of the single-photon detector in the large field-of-view gated single-photon detector. Figure 3 The pixel mapping of detector 1 Figure 2 Gating units 1A to 1I are used to map... Figure 1 The 1a~1i elements of the field of view receive photon signals from targets within these elements and output the distance values ​​of those targets. Pixel mapping for detector 2... Figure 2 Gating units 2A to 2I are used to map... Figure 1 The 2a~2i pixels in the field of view receive photon signals from targets within these pixels and output the distance values ​​of those targets. Pixel mapping for detector 3... Figure 2 Gating units 3A to 3I are used to map... Figure 1 The 3a-3i pixels in the field of view receive photon signals from targets within these pixels and output the distance values ​​of those targets. Pixel mapping for detector 4 is also included. Figure 2 Gating units 4A to 4I are used to map... Figure 1 The 4a~4i elements of the field of view receive the photon signals of the targets in the 4a~4i elements of the field of view and output the distance values ​​of the targets in the 4a~4i elements of the field of view.

[0035] like Figure 1 , 2 As shown in Figures 3 and 3, the field of view of elements 3b and 3f is optically mapped by gating units 3B and 3F, respectively. Figure 3 Pixel 3 of the detector will output the distance value of the circular target in the 3b field of view, and will also simultaneously output the distance value of the triangular target in the 3f field of view. In other words, pixel 3 will output two distance values, and these two distance values ​​will be recorded. (Close) Figure 2 The 3B gating unit in the middle, then Figure 1 The photon signal of a circular target in the 3b-element field of view will not enter the [field of view]. Figure 3If the third detector pixel in the field of view is not output, then the third detector pixel will no longer output the range value of the circular target; at this time, the third detector pixel will only output one range value, and one range value will disappear. The disappearing range value is the range value of the circular target in the 3b-element field of view, denoted as R-3b. The range value continuously output by the third detector pixel is the range value of the triangular target in the 3f-element field of view, denoted as R-3f. Additionally, in Figure 1 In the 4th quadrant field of view, if a rectangular target appears only in the 4e-e element field of view, then the 4th detector pixel mapped to the 4e-e element field of view will output a distance value. This distance value is the distance value of the rectangular target, denoted as R-4e. Here, R represents the distance between the target and the origin (in polar or Cartesian coordinate systems).

[0036] Step 4: Construct a polar coordinate system with the large field-of-view gated single-photon detector as the origin. When the large field-of-view gated single-photon detector detects a target, it will output the target's distance. This distance, combined with the elevation and azimuth angles of the target position calculated in Step 3, allows for the measurement and calculation of the target's unique spatial position coordinates in the polar coordinate system. Specifically: A polar coordinate system is established with the large field-of-view gated single-photon detector as the origin. Based on the measurement results of steps 2 and 3, the polar coordinates of the circular target in the 3b-element field of view are (R-3b, α-3b, β-3b), the polar coordinates of the triangular target in the 3f-element field of view are (R-3f, α-3f, β-3f), and the polar coordinates of the rectangular target in the 4e-element field of view are (R-4e, α-4e, β-4e). A Cartesian coordinate system is established with the large field-of-view gated single-photon detector as the origin. The Cartesian three-dimensional coordinates of the three targets can be calculated from their polar coordinates. Let the Cartesian 3D coordinates of a circular target in a 3b-element field of view be (x-3b, y-3b, z-3b), the Cartesian 3D coordinates of a triangular target in a 3f-element field of view be (x-3f, y-3f, z-3f), and the Cartesian 3D coordinates of a rectangular target in a 4e-element field of view be (x-4e, y-4e, z-4e). Here, x is the target's coordinate on the X-axis in the Cartesian coordinate system, and x-3b is the target's coordinate on the X-axis in the 3b-element field of view; y is the target's coordinate on the Y-axis in the Cartesian coordinate system, and y-3b is the target's coordinate on the Y-axis in the 3b-element field of view; z is the target's coordinate on the Z-axis in the Cartesian coordinate system, and z-3b is the target's coordinate on the Z-axis in the 3b-element field of view; and so on.

[0037] Step 5: According to the Pythagorean theorem, select any two targets obtained above in the three-dimensional space coordinates of the Cartesian coordinate system, and then calculate the distance between the two selected targets. Calculate the distance between the circular target and the triangular target. : ; Calculate the distance between the circular target and the rectangular target. : ; Calculate the distance between the triangular target and the rectangular target. : .

[0038] In summary, the multi-target distance measurement method based on single-photon technology of the present invention, based on single-photon gating detection technology, simultaneously selects the field of view of multiple regions, measures the distance of multiple targets, and calculates the distance between multiple targets according to geometric relationships, providing a reliable solution for multi-target distance measurement based on single-photon detection technology.

[0039] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for measuring the distance between multiple targets based on single-photon technology, characterized in that, Includes the following steps: Step 1: Integrate the wide field-of-view gated single-photon detector with an optical tracking turntable capable of measuring pitch and azimuth angles; Step 2: Perform calibration calculations by comparing the pitch and azimuth angles output from the optical tracking turntable with the pitch and azimuth angles of the detection field of view of the large field-of-view gated single-photon detector; the pitch and azimuth angles output from the optical tracking turntable are the pitch and azimuth angles of the calibration point in the detection field of view of the large field-of-view gated single-photon detector. Step 3: When the large field-of-view gated single-photon detector detects a target, the distance to the target can be measured; at the same time, the position of the target in the detection field of view can be measured and calculated to determine the meta-field of view where this position is located, and the elevation angle and azimuth angle of this target position can be calculated by the field of view angle conversion formula. Step 4: Using the large field-of-view gated single-photon detector as the origin, construct a polar coordinate system. Based on the target distance output by the large field-of-view gated single-photon detector when it detects the target in Step 3, and combined with the elevation and azimuth angles of the target position calculated in Step 3, the unique spatial position coordinates of the target in the polar coordinate system are measured and calculated. Step 5: Repeat steps 3 and 4 to measure and calculate the unique spatial coordinates of the multiple targets detected by the large field-of-view gated single-photon detector in the polar coordinate system; Step 6: Using the origin of the polar coordinate system constructed in Step 4 as the origin, construct a Cartesian coordinate system. Under this Cartesian coordinate system, convert the unique spatial position coordinates of the aforementioned multiple targets in the polar coordinate system to obtain the three-dimensional spatial coordinates of each target in the Cartesian coordinate system. Step 7: Based on the law of cosines, select any two targets obtained in Step 5 and their three-dimensional spatial coordinates in the polar coordinate system to calculate the distance between the two selected targets; or based on the Pythagorean theorem, select any two targets obtained in Step 6 and their three-dimensional spatial coordinates in the Cartesian coordinate system to calculate the distance between the two selected targets.

2. The multi-target spacing measurement method based on single-photon technology according to claim 1, characterized in that, In step 2, through calibration, the elevation and azimuth angles output by the optical tracking turntable are used to give the elevation and azimuth angles of the calibration point in the detection field of the large field-of-view gated single-photon detector; the elevation and azimuth angles of all detection fields can be calculated using the field-of-view angle conversion formula.

3. The multi-target spacing measurement method based on single-photon technology according to claim 1, characterized in that, The gating optical element used in the large field-of-view gating single-photon detector is a digital micromirror array.

4. The multi-target spacing measurement method based on single-photon technology according to claim 3, characterized in that, The gating units of the gating optical elements are all independently switched.

5. The multi-target spacing measurement method based on single-photon technology according to claim 1, characterized in that, When the gating unit of the gating optical element optically mapped to the target detected by the wide field-of-view gating single-photon detector is turned off, the distance value of this target output by the wide field-of-view gating single-photon detector will disappear, and this disappeared distance value is the distance value of this target. When the wide field-of-view gating single-photon detector detects two or more targets, the gating unit of the gating optical element optically mapped to these targets is turned off in sequence, and the distance values ​​output by the wide field-of-view gating single-photon detector that disappear in sequence are the distance values ​​of the corresponding targets. When the wide field-of-view gating single-photon detector outputs the distance values ​​of two or more targets, the target attribution of the above distance values ​​can be determined.

6. The multi-target spacing measurement method based on single-photon technology according to claim 1, characterized in that, The target distance value output by the single-photon detector pixel optically mapped to the target detected by the wide field-of-view gated single-photon detector is the distance value of this target.

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