Automatic tracking ranging positioning system based on quantum entanglement signal

Abstract

Embodiments of the present application relate to the field of quantum ranging positioning, and in particular to an automatic tracking ranging positioning system based on quantum entangled signals. A specific embodiment of the system comprises: a quantum entangled light source outputs an entangled photon pair as a reference light beam and a signal light beam; the reference light beam is transmitted into a time-to-digital converter; the signal light beam is transmitted into a first input-output port of a fiber-optic circulator; the signal light beam is transmitted into a beam transceiver; the signal light beam is transmitted to an angle reflector at a target point to be measured, and the reflected signal light beam is transmitted into the fiber-optic circulator; the reflected signal light beam is transmitted into a second photon detector; the reflected signal light beam is transmitted into a time-to-digital converter; the arrival time sequences of reference photons and signal photons corresponding to the reference light beam and the reflected signal light beam, respectively, are detected; and based on the arrival time sequences of the reference photons and the signal photons, target point coordinate information of the target point to be measured is determined. This embodiment can realize the functions of automatic tracking and rapid ranging positioning of a moving target.

Description

Technical Field

[0001] The embodiments of this application relate to the field of quantum ranging and positioning, specifically to an automatic tracking ranging and positioning system based on quantum entangled signals. Background Technology

[0002] Ranging technology is fundamental for locating and navigating unknown targets, and the ranging accuracy of a positioning system directly determines its positioning accuracy. Traditional ranging technologies, such as ultrasonic ranging, infrared ranging, and laser ranging, are based on classical physics, and their ranging accuracy is limited by the standard quantum limit.

[0003] With the establishment of quantum theory, quantum mechanics has gradually penetrated into physical experiments. In particular, quantum theory and its applications based on quantum entanglement have developed rapidly, leading to quantum computing, quantum communication, and quantum measurement technologies. Quantum ranging and positioning technology is an important research direction in quantum measurement technology. In 2001, Giovannitti's research group at MIT proposed a novel ranging method, quantum precision ranging, in *Nature*. With the continuous development of quantum ranging technology, various quantum ranging schemes based on different interferometer structures have been developed, and exploratory applications are gradually being conducted in navigation and positioning, inter-satellite ranging, and quantum radar. Among these, the ranging schemes based on the HBT (Hanbury-Brown-Twiss interferometer) and the HOM (Hong-Ou-Mandel) interferometer show the greatest application potential. The ranging scheme based on the HBT interferometer mainly relies on the coincidence measurement of the reference beam and the signal beam. The HBT interferometry process is based on a coincidence measurement algorithm, enabling rapid ranging. The HOM interferometer's ranging relies primarily on the intensity interference of the reference beam and signal beam at the beam splitter. The HOM interferometry process requires adjusting the optical path difference using an adjustable delay device, resulting in a slower measurement speed, but achieving accuracy below 10 micrometers, or even down to the nanometer scale.

[0004] Because quantum signals are extremely weak and photon detection requires high precision, current research on quantum ranging systems is based on stationary targets and fiber optic links. To accelerate the development of quantum navigation and positioning technology, ranging and positioning schemes for moving targets must be developed. This invention patent primarily targets free-space links and moving targets. To ensure rapid ranging, the ranging scheme employs a measurement method based on an HBT interferometer. Summary of the Invention

[0005] The summary section of this application is intended to provide a brief overview of the concepts, which will be described in detail in the detailed description section below. This summary section is not intended to identify key or essential features of the claimed technical solutions, nor is it intended to limit the scope of the claimed technical solutions.

[0006] Some embodiments of this application propose an automatic tracking, ranging, and positioning system based on quantum entangled signals to solve one or more of the technical problems mentioned in the background section above.

[0007] Some embodiments of this application provide an automatic tracking, ranging, and positioning system based on quantum entanglement signals. This system includes: an automatic tracking, ranging, and positioning system based on quantum entanglement signals that outputs entangled photon pairs from a quantum entanglement light source; and the system designates two entangled photons from the entangled photon pairs as a reference beam and a signal beam, respectively. The wavelength of the entangled photons in the aforementioned entangled photon pair is 810 nm. The automatic tracking, ranging, and positioning system based on quantum entanglement signals further includes: a first photon detector, a time-to-digital converter, a coupler, a fiber optic circulator, a beam transceiver, and a second photon detector. The beam transceiver is mounted on a high-precision pan-tilt unit. The time-to-digital converter is linked to a computer, the beam transceiver is linked to the computer, and the high-precision pan-tilt unit is linked to the computer. The fiber optic circulator includes: The system includes a first input / output port, a second input / output port, and a third input / output port. A first photon detector receives a reference beam and transmits it to a time-to-digital converter. A coupler receives a signal beam and transmits it to the first input / output port of a fiber optic circulator. The second input / output port of the fiber optic circulator transmits the signal beam to a beam transceiver. The beam transceiver transmits the signal beam to a corner reflector at the target point and receives the reflected signal beam reflected from the corner reflector along its original path, transmitting it to the second input / output port of the fiber optic circulator. The third input / output port of the fiber optic circulator transmits the reflected signal beam to a second photon detector. The second photon detector transmits the reflected signal beam to the time-to-digital converter. The time-to-digital converter acquires the photon arrival time series of the reference beam and the signal beam and transmits the time series to a computer. The coincidence measurement software calculates the optical path difference between the signal path and the reference path. The coincidence measurement software subtracts a pre-acquired fixed optical path difference from the calculated optical path difference to obtain the distance between the target point and the measuring device. Based on the target distance and pre-acquired target angle information, the computer determines the target point coordinates.

[0008] The above embodiments of this application have the following beneficial effects: The automatic tracking, ranging, and positioning system based on quantum entanglement signals of some embodiments of this application can realize the functions of automatic tracking and rapid ranging and positioning of moving targets. Specifically, because quantum signals are very weak and photon detection requirements are high, current research on quantum ranging systems is based on stationary targets and fiber optic links. To accelerate the development of quantum navigation and positioning technology, ranging and positioning schemes for moving targets must be developed. This invention mainly targets free-space links and moving targets. To ensure the speed of ranging, the ranging scheme adopts a measurement method based on an HBT interferometer. Based on this, the automatic tracking, ranging, and positioning system based on quantum entanglement signals of some embodiments of this application mainly adopts the idea of ​​single-sided illumination. First, the beacon laser beam installed on a high-precision gimbal is transmitted to the corner reflector at the target point and reflected back to the imaging lens on the high-precision gimbal. Secondly, the reflected light is transmitted to the high-speed camera after passing through the imaging lens. By converting the incident angle of the reflected light at the high-speed imaging lens into the position information of the reflected light at the camera, a high-precision gimbal keeps the reflected light spot at the center of the high-speed camera's image, achieving the tracking function. Then, the signal beam in the quantum entanglement signal is adjusted so that it is transmitted through a telescope system to the corner mirror at the target point. The maximum number of photons reflected back to the single-photon detector is achieved when the beacon's reflected light spot is at the center of the high-speed camera image. At this point, the relative positions of the signal beam, telescope system, beacon laser, imaging lens, and high-speed camera on the high-precision gimbal are fixed. When the target moves, the high-precision gimbal automatically adjusts to track and measure the distance and three-dimensional coordinates of the target point, achieving the tracking, ranging, and positioning function. Attached Figure Description

[0009] The above and other features, advantages, and aspects of the embodiments of this application will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and elements are not necessarily drawn to scale.

[0010] Figure 1 This is a flowchart of some embodiments of the automatic tracking, ranging, and positioning system based on quantum entangled signals according to this application; Figure 2 This is a schematic diagram illustrating the principle of an automatic tracking, ranging, and positioning system based on quantum entanglement signals, according to some embodiments of the automatic tracking, ranging, and positioning system based on quantum entanglement signals in this application. Figure 3 This is a schematic diagram of the beam transceiver device according to some embodiments of the automatic tracking, ranging, and positioning system based on quantum entanglement signals in this application; Figure 4This is a schematic diagram of a spliced ​​corner reflector according to some embodiments of the automatic tracking, ranging, and positioning system based on quantum entangled signals according to this application; Figure 5 This is a schematic diagram of the coordinate system of some embodiments of the automatic tracking, ranging, and positioning system based on quantum entangled signals according to this application; Figure 6 This is a schematic diagram of the coordinate measurement of a target point according to some embodiments of the automatic tracking, ranging, and positioning system based on quantum entanglement signals according to this application. Detailed Implementation

[0011] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While some embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this application. It should be understood that the drawings and embodiments of this application are for illustrative purposes only and are not intended to limit the scope of protection of this application.

[0012] It should also be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0013] It should be noted that the concepts of "first" and "second" mentioned in this application are only used to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0014] It should be noted that the terms "a" and "a plurality of" used in this application are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0015] The names of the messages or information exchanged between multiple devices in the embodiments of this application are for illustrative purposes only and are not intended to limit the scope of these messages or information.

[0016] The present application will now be described in detail with reference to the accompanying drawings and embodiments.

[0017] Figure 1 A flowchart 100 of some embodiments of an automatic tracking, ranging, and positioning system based on quantum entanglement signals according to this application is shown. This automatic tracking, ranging, and positioning system based on quantum entanglement signals, applied to automatic tracking, ranging, and positioning systems based on quantum entanglement signals, includes the following steps: Step 101: The automatic tracking and ranging positioning system based on quantum entanglement signals includes a quantum entanglement light source that outputs entangled photon pairs, and determines the two entangled photons in the entangled photon pairs as a reference beam and a signal beam, respectively.

[0018] In some embodiments, the automatic tracking, ranging, and positioning system based on quantum entanglement signals includes a quantum entanglement light source that can output entangled photon pairs within a preset time period, and designate the two entangled photons in the entangled photon pairs as a reference beam and a signal beam, respectively. The wavelength of the entangled photons in the aforementioned entangled photon pair can be 810 nm. The aforementioned automatic tracking, ranging, and positioning system based on quantum entanglement signals can construct a quantum entanglement light source and output entangled photon pairs by pumping a PPKTP (periodically poled KTP) crystal with a laser (wavelength 405 nm). The aforementioned reference beam can include a reference photon sequence. The aforementioned reflected signal beam can include a reflected signal photon sequence. The aforementioned automatic tracking, ranging, and positioning system based on quantum entanglement signals may further include a first photon detector, a time-to-digital converter, a coupler, a fiber optic circulator, a beam transceiver, and a second photon detector. The aforementioned beam transceiver can be mounted on a high-precision pan-tilt unit. The time-to-digital converter can be linked to a computer. The beam transceiver can be linked to a computer. The high-precision pan-tilt unit can communicate with a computer. The aforementioned fiber optic circulator may include: a first input / output port, a second input / output port, and a third input / output port. The reference photon in the aforementioned reference photon sequence can represent a photon in the aforementioned reference beam. The reflected signal photon in the aforementioned reflected signal photon sequence can represent a photon in the aforementioned reflected signal beam.

[0019] The preset duration can be, but is not limited to, at least one of the following: 1 millisecond, 5 milliseconds, or 10 milliseconds.

[0020] Specifically, the detailed structure of the aforementioned automatic tracking, ranging, and positioning system based on quantum entangled signals can be found in [reference needed]. Figure 2 The diagram illustrates the principle of an automatic tracking, ranging, and positioning system based on quantum entanglement signals, according to some embodiments of this application. Figure 2 As shown, Figure 2The entangled light source in the above-mentioned quantum entangled light source can be characterized. The signal light can be characterized as the above-mentioned signal beam. The reference light can be characterized as the above-mentioned reference beam. The coupler can be characterized as the above-mentioned coupler. Single-photon detector 1 can be characterized as the above-mentioned first photon detector. Single-photon detector 2 can be characterized as the above-mentioned second photon detector. The time-to-digital converter can be characterized as the above-mentioned time-to-digital converter. The fiber optic circulator can be characterized as the above-mentioned fiber optic circulator. The beam transceiver can be characterized as the above-mentioned beam transceiver. ① can be characterized as the first input / output port included in the above-mentioned fiber optic circulator. ② can be characterized as the second input / output port included in the above-mentioned fiber optic circulator. ③ can be characterized as the third input / output port included in the above-mentioned fiber optic circulator. The corner reflector can be characterized as the corner reflector at the target point to be measured. The corner reflector can be installed at the target point to be measured. The target point to be measured can be the location where automatic tracking, ranging, and positioning are desired. The high-precision pan-tilt unit can be characterized as the above-mentioned high-precision pan-tilt unit. The computer can be characterized as the above-mentioned computer.

[0021] The specific structure of the aforementioned beam transceiver device can be found in the following reference. Figure 3 The diagram shows a schematic representation of a beam transceiver apparatus according to some embodiments of an automatic tracking, ranging, and positioning system based on quantum entanglement signals, as described in this application. Figure 3 As shown, the beam transceiver may include: a target coupler, a long-pass dichroic mirror, an optical isolator, a telescope system, a beacon laser, a semi-reflective mirror, an imaging lens, and a high-speed camera. During operation, the relative positions of the beacon laser, long-pass dichroic mirror, semi-reflective mirror, telescope system, imaging lens, and high-speed camera remain unchanged. The high-precision gimbal can perform horizontal rotation and pitch adjustment. The aforementioned long-pass dichroic mirror can transmit light with wavelengths greater than 700 nm and reflect light with wavelengths less than 700 nm. The aforementioned optical isolator can prevent reflected beams from entering the beacon laser. The beacon laser can be a beacon laser in the visible light band (a 633 nm red laser). The telescope system may include at least one optical telescope. The imaging lens can focus light from different field-of-view angles into a single spot and project it onto the CCD (charge-coupled device) of the high-speed camera. The high-speed camera includes coarse and fine tracking functions, and different application purposes can be achieved by configuring the same high-speed camera with different parameters. Coarse tracking can quickly acquire the position information of the light spot. When the high-precision gimbal shakes, fine tracking can send the tracking offset to the high-precision gimbal in real time, controlling the high-precision gimbal to always point at the target.

[0022] Step 102: The first photon detector receives the reference beam and transmits the reference beam to the time-to-digital converter.

[0023] In some embodiments, the first photon detector described above can receive a reference beam and pass the reference beam to a time-to-digital converter.

[0024] Step 103: The coupler receives the signal beam and transmits the signal beam to the first input / output port of the fiber optic circulator.

[0025] In some embodiments, the coupler can receive a signal beam and pass the signal beam to a first input / output port of the fiber optic circulator.

[0026] Step 104: The second input / output port of the fiber optic circulator transmits the signal beam to the beam transceiver.

[0027] In some embodiments, the second input / output port of the fiber optic circulator can transmit a signal beam to a beam transceiver.

[0028] Step 105: The second input / output port of the fiber optic circulator transmits the signal beam to the beam transceiver.

[0029] In some embodiments, the second input / output port of the fiber optic circulator can transmit a signal beam to a beam transceiver.

[0030] Step 106: The beam transceiver transmits the signal beam to the corner reflector at the target point and receives the reflected signal beam reflected from the corner reflector along the original path, and transmits it to the second input / output port of the fiber optic circulator.

[0031] In some embodiments, the above-described beam transceiver can transmit the signal beam to the corner reflector at the target point to be measured, and receive the reflected signal beam reflected from the corner reflector along its original path, and transmit it to the second input / output port of the fiber optic circulator.

[0032] As an example, the specific structure of the aforementioned corner reflector can be found in [reference needed]. Figure 4 A schematic diagram of a spliced ​​corner reflector is shown, illustrating some embodiments of an automatic tracking, ranging, and positioning system based on quantum entangled signals according to this application.

[0033] Here, because the quantum entanglement signal is at the single-photon level, its intensity is extremely weak, and the entanglement signal is in an invisible wavelength band, it is difficult to complete docking in the initial stage of automatic tracking. In order to achieve precise docking quickly, that is, to make the signal beam quickly and accurately emit to the center of the corner cube prism at the target point, this invention can use devices such as a beacon laser, a semi-reflective mirror, an imaging lens, and a high-speed camera.

[0034] In some optional implementations of certain embodiments, the above-described beam transceiver device, which transmits the signal beam to the corner reflector at the target point and receives the reflected signal beam reflected from the corner reflector along its original path, and inputs it to the second input / output port of the fiber optic circulator, may include the following steps: In the first step, the beam transceiver transmits the signal beam to the target coupler, which then reaches the long-pass dichroic mirror.

[0035] The second step involves a long-pass dichroic mirror reflecting the signal beam and transmitting it into the telescope system to obtain a transmitted signal beam, as well as a corner reflector that transmits the transmitted signal beam to the target point.

[0036] Here, after long-distance transmission, the diameter of the signal beam typically expands. To maximize effective light intensity reflection, a spliced ​​corner mirror method (such as...) is used here. Figure 3 As shown, the number can be changed to achieve large-aperture light spot reflection. A spliced ​​prism uses multiple pyramidal prisms combined together, thereby increasing the effective reflective area of ​​the light spot.

[0037] The third step involves the telescope system receiving the transmitted signal beam reflected by the corner reflector at the target point and returning along the original path. This beam then passes through the long-pass dichroic mirror and the target coupler in sequence to obtain the reflected signal beam. Finally, the reflected signal beam is transmitted to the second input / output port of the fiber optic circulator.

[0038] Optionally, before the aforementioned beam transceiver can transmit the signal beam to the corner reflector at the target point and receive the reflected signal beam reflected from the corner reflector along its original path and input it to the second input / output port of the fiber optic circulator, the aforementioned automatic tracking and ranging positioning system based on quantum entanglement signals may further include the following steps: In the first step, the beacon laser emits a beacon beam that passes through an optical isolator and a half-reflective mirror in sequence. The transmitted beam from the beacon beam is then sent to a long-pass dichroic mirror, and the reflected beam from the beacon beam is sent to a black box for absorption.

[0039] The second step involves a long-pass dichroic mirror transmitting the reflected beam from the beacon beam into the telescope system.

[0040] The third step involves the telescope system transmitting the reflected beam from the beacon beam to the corner mirror at the target point, and receiving the beacon beam reflected from the corner mirror along its original path, thus obtaining the reflected beacon beam.

[0041] The fourth step involves the telescope system transmitting the reflected beacon beam to the long-pass dichroic mirror.

[0042] The fifth step involves using a long-pass dichroic mirror to reflect the beacon beam to a semi-reflective lens.

[0043] The sixth step involves the semi-reflective mirror transmitting and reflecting the reflected beacon beam to obtain a semi-transmitted beacon beam and a semi-reflected beacon beam, and then transmitting the semi-reflected beacon beam into the imaging lens.

[0044] The seventh step involves the imaging lens transmitting the semi-reflective beacon beam into the high-speed camera to obtain an image of the beacon spot.

[0045] Step 8: The high-speed camera transmits the beacon spot image to the computer.

[0046] In the ninth step, the computer processes the beacon spot image to obtain cursor coordinate information and initiates cursor tracking mode. The computer can use a preset detection algorithm to process the beacon spot image and obtain cursor coordinate information. This cursor coordinate information represents the coordinates of the beacon spot in the beacon spot image. In the cursor tracking mode, the automatic tracking, ranging, and positioning system based on quantum entanglement signals predicts the spot's position at the next moment using Kalman filtering and uses a PID (Proportional Integral Differential) algorithm to keep the spot always centered in the high-speed camera image, achieving real-time tracking.

[0047] As an example, the aforementioned preset detection algorithm may include, but is not limited to, at least one of the following: gray-scale centroid method and least squares circle fitting method.

[0048] Step 10: In response to determining that the cursor coordinate information meets preset coordinate conditions, the computer adjusts the automatic tracking, ranging, and positioning system based on quantum entanglement signals to obtain the photon count of the signal beam. The preset coordinate conditions can be that the coordinates represented by the cursor coordinate information coincide with the center coordinates of the camera image. The aforementioned adjustment of the automatic tracking, ranging, and positioning system based on quantum entanglement signals can involve adjusting the pitch angles of each device in the system and measuring the number of quantum signal photons reflected back to the second photon detector to obtain the photon count of the signal beam.

[0049] In the eleventh step, the computer, in response to determining that the photon count of the signal beam meets a preset photon count condition, fixes the relative positions of the beacon laser, imaging lens, telescope system, and high-speed camera on the high-precision pan-tilt unit. The preset photon count condition can be that the photon count of the signal beam reaches its maximum during the adjustment process. Therefore, during the actual measurement, the positions of the beacon laser, imaging lens, telescope system, and high-speed camera on the high-precision pan-tilt unit remain unchanged.

[0050] This allows for the calibration of an automatic tracking, ranging, and positioning system based on quantum entanglement signals before formal measurements.

[0051] Step 107: The second photon detector transmits the reflected signal beam to the time-to-digital converter.

[0052] In some embodiments, the second photon detector described above can transmit the reflected signal beam to a time-to-digital converter.

[0053] Step 108: The time-to-digital converter detects the reference photon arrival time sequence and the signal photon arrival time sequence corresponding to the reference beam and the reflected signal beam, respectively, and sends the reference photon arrival time sequence and the signal photon arrival time sequence to the computer in sequence.

[0054] In some embodiments, the aforementioned time-to-digital converter can detect the reference photon arrival time sequence and the signal photon arrival time sequence corresponding to the reference beam and the reflected signal beam, respectively, and sequentially send the reference photon arrival time sequence and the signal photon arrival time sequence to a computer.

[0055] Step 109: The computer determines the target point coordinate information of the target point to be measured based on the reference photon arrival time sequence and the signal photon arrival time sequence.

[0056] In some embodiments, the computer can determine the target point coordinates of the target point to be measured based on the reference photon arrival time sequence and the signal photon arrival time sequence. Specifically, the computer can determine the target point coordinates of the target point to be measured using coincidence measurement software, based on the reference photon arrival time sequence and the signal photon arrival time sequence.

[0057] In some optional implementations of certain embodiments, determining the target point coordinate information of the target point to be measured based on the above-mentioned reference photon arrival time sequence and the above-mentioned signal photon arrival time sequence may include the following steps: The first step is to determine the transmission optical path difference based on the above-mentioned reference photon arrival time sequence and the above-mentioned signal photon arrival time sequence.

[0058] The second step involves determining the target distance value by the ratio of the difference between the transmitted optical path difference and the pre-acquired fixed optical path difference to a preset value. The pre-acquired fixed optical path difference can be obtained through the following steps: First, a plane mirror is placed at the position of the long-pass dichroic mirror and adjusted to a vertical orientation. Then, through the conformity processing steps in step 108, the optical path difference between the signal optical path and the reference optical path is obtained as ΔR, and the inherent optical path difference of the system is ΔR. The preset value can be 2.

[0059] The third step is to determine the target point coordinates based on the target distance value and the pre-acquired target angle information.

[0060] In some optional implementations of certain embodiments, determining the transmission optical path difference based on the reference photon arrival time sequence and the signal photon arrival time sequence may include the following steps: The first step is to determine the arrival time difference sequence corresponding to the above-mentioned reference photon arrival time sequence and the above-mentioned signal photon arrival time sequence.

[0061] The second step is to determine the set of cumulative arrival time differences corresponding to each arrival time difference in the aforementioned arrival time difference sequence. Each cumulative arrival time difference in the aforementioned set of cumulative arrival time differences can correspond to at least one arrival time difference in the aforementioned arrival time difference sequence. This determination of the set of cumulative arrival time differences corresponding to each arrival time difference in the aforementioned arrival time difference sequence can be achieved by: first, grouping the aforementioned arrival time difference sequence to obtain a sequence of arrival time difference groups. Specifically, equal arrival time differences in the aforementioned arrival time difference sequence can be defined as an arrival time difference group, and the defined arrival time difference groups can be defined as an arrival time difference group sequence. Second, for each arrival time difference group in the aforementioned arrival time difference group sequence, the number of arrival time differences in the aforementioned arrival time difference group is determined as the cumulative arrival time difference corresponding to the aforementioned arrival time difference group. Finally, the determined cumulative arrival time differences are defined as a set of cumulative arrival time differences.

[0062] The third step is to select a coarse time difference peak from the arrival time differences corresponding to the largest accumulated time difference in the set of accumulated arrival time difference values ​​of the above accumulated time difference value sequence. Specifically, one arrival time difference can be randomly selected from each of the two arrival time differences corresponding to the largest accumulated time difference in the set of accumulated arrival time difference values ​​of the above accumulated time difference value sequence as the coarse time difference peak.

[0063] The fourth step is to determine the time difference interval based on the aforementioned coarse time difference peak value. This determination can be achieved by: first, defining the difference between the coarse time difference peak value and a preset peak value as the lower limit of the time difference interval; and then, defining the sum of the coarse time difference peak value and the preset peak value as the upper limit of the time difference interval. The preset peak value can be determined based on specific experimental conditions to ensure that it includes data from the entire peak position.

[0064] As an example, the preset peak value could be 1000 picoseconds.

[0065] Fifth step: For each arrival time difference in the above arrival time difference sequence, in response to determining that the above arrival time difference is not within the above time difference interval, the above arrival time difference is deleted from the above arrival time difference sequence, and the deleted arrival time difference sequence is determined as the target arrival time difference sequence.

[0066] Therefore, since the time jitter of a single-photon detector is typically on the order of hundreds of picoseconds, the half-width at half-maximum (WHM) of the coincidence measurement curve is usually also around several hundred picoseconds. Thus, to obtain the precise peak position of the coincidence measurement curve, it is only necessary to save the time difference information within approximately 1000 picoseconds around the approximate peak position (this data can be determined based on specific experimental conditions to ensure that it includes data for the entire peak position). Data with time differences outside this approximate 1000 picosecond range are discarded. This reduces the amount of data and speeds up the coincidence measurement process.

[0067] Step 6: Based on the above-mentioned cumulative arrival time difference value set, perform conformance processing on each target arrival time difference value in the above-mentioned target arrival time difference value sequence to generate conformance arrival time difference values, and obtain a conformance arrival time difference value sequence.

[0068] Step 7: Fit the aforementioned cumulative arrival time difference set and the aforementioned sequence of arrival time differences to obtain an arrival time difference fitting curve. A preset fitting algorithm can be used to fit the aforementioned cumulative arrival time difference set and the aforementioned sequence of arrival time differences to obtain the arrival time difference fitting curve.

[0069] As an example, the preset fitting algorithm mentioned above can be a Gaussian fitting algorithm.

[0070] The eighth step is to determine the arrival time difference value corresponding to the peak position of the above arrival time difference fitting curve as the transmission time difference value.

[0071] The ninth step is to determine the transmission optical path difference by multiplying the above transmission time difference by the preset optical signal transmission speed.

[0072] As an example, the preset optical signal transmission speed can be 300,000,000 meters per second.

[0073] Therefore, after a short measurement period (on the order of milliseconds), a series of time difference values ​​and corresponding cumulative counts can be obtained. Due to the second-order correlation measurement principle, the cumulative counts tend to follow a normal distribution. The time difference corresponding to the maximum value of the cumulative count is taken as the approximate time difference of photon transmission between the signal optical path and the reference optical path, and the peak position is recorded.

[0074] Therefore, Gaussian fitting can be used to fit the processed curve to obtain the time difference TF corresponding to the peak position of the measured curve. TF is the transmission time difference between the reference optical path and the signal optical path, which can be multiplied by the transmission speed of the optical signal to obtain the transmission optical path difference between the two signals.

[0075] In some optional implementations of certain embodiments, determining the arrival time difference sequence corresponding to the reference photon arrival time sequence and the signal photon arrival time sequence may include the following steps: The first step is to determine the arrival time of the first reference photon in the reference photon arrival time sequence as the arrival time of the target reference photon.

[0076] The second step is to determine the arrival time of the first signal photon in the sequence of arrival times of the received signal photons as the arrival time of the target signal photon.

[0077] The third step involves performing the following time difference determination sub-step based on the arrival time of the target reference photon and the arrival time of the target signal photon: The first sub-step, in response to determining the next reference photon arrival time in the reference photon arrival time sequence in which the arrival time of the target reference photon has not been received, involves determining the difference between the arrival time of the target reference photon and the arrival time of the target signal photon as the photon arrival time difference, and adding the photon arrival time difference to the initial arrival time difference sequence. The initial arrival time difference sequence can initially be empty.

[0078] The second sub-step, in response to determining that the arrival time of the target reference photon satisfies a first preset iteration condition and the arrival time of the target signal photon satisfies a second preset iteration condition, determines the initial arrival time difference sequence as the arrival time difference sequence. The first preset iteration condition can be that the arrival time of the target reference photon is the arrival time of the last reference photon in the reference photon arrival time sequence. The second preset iteration condition can be that the arrival time of the target signal photon is the arrival time of the last signal photon in the signal photon arrival time sequence.

[0079] Therefore, the arrival time of the first detected photon can be recorded as TA0, and this time value can be saved. When the time-to-digital converter detects a new reference photon, the time at this moment is recorded as TA1. The arrival time of the new photon, TA1, overwrites the arrival time of the previous photon, TA0. When a signal photon arrives at the time-to-digital converter, the time at this moment is recorded as TB0. The time difference Δt is calculated by subtracting the arrival time of the latest reference photon saved in the reference optical path (assuming it is recorded as TA1) from the arrival time of the signal photon.

[0080] Optionally, the above-mentioned automatic tracking, ranging, and positioning system based on quantum entangled signals may further include the following steps: In the first step, in response to determining the arrival time of the next reference photon in the reference photon arrival time sequence, the arrival time of the next reference photon in the reference photon arrival time sequence is determined as the arrival time of the target reference photon, and the time difference determination step described above is performed again.

[0081] The second step involves determining, in response to the determination that the arrival time of the target reference photon does not meet the first preset iteration condition or the arrival time of the target signal photon does not meet the second preset iteration condition, the next reference photon arrival time in the reference photon arrival time sequence is determined as the target reference photon arrival time, and the next signal photon arrival time in the signal photon arrival time sequence is determined as the target signal photon arrival time, so as to perform the above time difference determination step again.

[0082] In some optional implementations of certain embodiments, the above-mentioned processing of each target arrival time difference in the target arrival time difference sequence based on the above-mentioned accumulated arrival time difference set to generate a consistent arrival time difference may include the following steps: The first step is to determine, in response to the determination that the aforementioned target arrival time difference is not within a preset interval, that the aforementioned target arrival time difference is defined as a valid arrival time difference. The preset interval can be an open interval with an upper limit of the difference between the largest target arrival time difference in the aforementioned target arrival time difference sequence and a preset time difference, and a lower limit of the sum of the smallest target arrival time difference in the aforementioned target arrival time difference sequence and the preset time difference.

[0083] As an example, the aforementioned preset time difference can be the ratio of a preset threshold to a target value. The aforementioned preset threshold can be 300 picoseconds or 500 picoseconds. The aforementioned target value can be 2.

[0084] The second step, in response to determining that the aforementioned target arrival time difference is within a preset interval, is to execute the following sub-steps: The first sub-step involves determining the time difference interval based on the aforementioned target arrival time difference. This determination can be achieved by first defining the difference between the target arrival time difference and the aforementioned preset time difference as the lower limit of the accumulated time difference interval. Then, the sum of the target arrival time difference and the aforementioned preset time difference is defined as the upper limit of the accumulated time difference interval. Finally, the accumulated time difference interval is obtained.

[0085] The second sub-step involves determining the arrival time differences of each target within the aforementioned time difference interval in the above target arrival time difference sequence as a set of arrival time differences.

[0086] The third sub-step involves determining the cumulative arrival time difference value corresponding to each conforming arrival time difference value in the above-mentioned cumulative arrival time difference value set and the above-mentioned conforming arrival time difference value set as the conforming arrival time difference cumulative value, thus obtaining the conforming arrival time difference cumulative value set.

[0087] The fourth sub-step is to determine the sum of the cumulative time difference values ​​in the above-mentioned cumulative time difference value set and the ratio of it to a preset threshold as the time difference of arrival.

[0088] Optionally, the aforementioned pre-acquired target angle information can be obtained through the following steps: The first step is to establish a rectangular coordinate system. Here, the rectangular coordinate system mentioned above can be referenced... Figure 5 A schematic diagram of the coordinate system shown is provided for some embodiments of the automatic tracking, ranging, and positioning system based on quantum entangled signals according to this application. Figure 5 As shown, point O in the rectangular coordinate system can be defined as the intersection of the signal beam and the long-pass dichroic mirror. The x-axis represents the horizontal direction of the signal beam emission, the y-axis is the direction perpendicular to the x-axis in the horizontal plane, and the z-axis is the vertically upward direction.

[0089] The second step is to convert the target distance value into target point coordinates in a Cartesian coordinate system based on the pre-acquired target angle information using the following formula: .

[0090] Here, we can assume that the coordinates of A are .

[0091] Specifically, the aforementioned pre-acquired target angle information can be obtained through the following steps: First, adjust the horizontal rotation angle and pitch angle of the high-precision gimbal to 0°. Then, using a beacon laser and a high-speed camera, adjust the horizontal rotation and pitch angles of the high-precision gimbal so that the reflected light spot of the beacon beam is positioned at the center of the high-speed camera's image. Next, record the horizontal rotation and pitch angles at this point. Finally, determine the horizontal rotation and pitch angles as the target angle information. Here, the aforementioned pre-acquired target angle information can be referenced... Figure 6 The diagram illustrates coordinate measurement of a target point according to some embodiments of the automatic tracking, ranging, and positioning system based on quantum entanglement signals of this application. Figure 6 As shown, we can assume that the center point of the corner reflector of the target point is point A, and the transmission optical path difference is determined as RA. Then the target distance (true distance) between point A and point O is ROA = (RA - ΔR) / 2. This can represent the projection of point A onto the xOy plane.

[0092] Therefore, when the target point moves, the reflected spot of the beacon laser will deviate from the image center of the high-speed camera. The system then analyzes this deviation and predicts the spot's position in the next moment using a Kalman filter. A PID algorithm is then used to control a high-precision pan-tilt unit to track the spot in real time, ensuring the reflected spot remains centered on the high-speed camera image, ultimately achieving the tracking, ranging, and positioning function.

[0093] Therefore, the automatic tracking, ranging, and positioning system of the present invention includes control software to assist in the realization of the automatic tracking, ranging, and positioning function. The control software can control the rotation of the gimbal, control the spot detection of the high-speed camera, receive the time series data from the time-to-digital converter, and perform coincidence measurement. The system interface can display the coincidence measurement curve, the beacon spot information, the real-time coordinates of the target point, and information such as the gimbal's pitch and rotation angles.

[0094] The above embodiments of this application have the following beneficial effects: The automatic tracking, ranging, and positioning system based on quantum entanglement signals of some embodiments of this application can realize the functions of automatic tracking and rapid ranging and positioning of moving targets. Specifically, because quantum signals are very weak and photon detection requirements are high, current research on quantum ranging systems is based on stationary targets and fiber optic links. To accelerate the development of quantum navigation and positioning technology, ranging and positioning schemes for moving targets must be developed. This invention mainly targets free-space links and moving targets. To ensure the speed of ranging, the ranging scheme adopts a measurement method based on an HBT interferometer. Based on this, the automatic tracking, ranging, and positioning system based on quantum entanglement signals of some embodiments of this application mainly adopts the idea of ​​single-sided illumination. First, the beacon laser beam installed on a high-precision gimbal is transmitted to the corner reflector at the target point and reflected back to the imaging lens on the high-precision gimbal. Secondly, the reflected light is transmitted to the high-speed camera after passing through the imaging lens. By converting the incident angle of the reflected light at the high-speed imaging lens into the position information of the reflected light at the camera, a high-precision gimbal keeps the reflected light spot at the center of the high-speed camera's image, achieving the tracking function. Then, the signal beam in the quantum entanglement signal is adjusted so that it is transmitted through a telescope system to the corner mirror at the target point. The maximum number of photons reflected back to the single-photon detector is achieved when the beacon's reflected light spot is at the center of the high-speed camera image. At this point, the relative positions of the signal beam, telescope system, beacon laser, imaging lens, and high-speed camera on the high-precision gimbal are fixed. When the target moves, the high-precision gimbal automatically adjusts to track and measure the distance and three-dimensional coordinates of the target point, achieving the tracking, ranging, and positioning function.

[0095] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0096] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of this application.

Claims

1. An automatic tracking, ranging, and positioning system based on quantum entangled signals, applied to an automatic tracking, ranging, and positioning system based on quantum entangled signals, comprising: The automatic tracking, ranging, and positioning system based on quantum entanglement signals includes a quantum entanglement light source that outputs entangled photon pairs, and two entangled photons in the entangled photon pairs are respectively designated as a reference beam and a signal beam. The wavelength of the entangled photons in the entangled photon pair is 810 nm. The system further includes a first photon detector, a time-to-digital converter, a coupler, a fiber optic circulator, a beam transceiver, and a second photon detector. The beam transceiver is mounted on a high-precision pan-tilt unit. The time-to-digital converter, the beam transceiver, and the high-precision pan-tilt unit are all linked in communication. The fiber optic circulator includes a first input / output port, a second input / output port, and a third input / output port. The first photon detector receives the reference beam and transmits the reference beam to the time-to-digital converter. The coupler receives the signal beam and transmits the signal beam to the first input / output port of the fiber optic circulator; The second input / output port of the fiber optic circulator transmits the signal beam to the beam transceiver. The beam transceiver transmits the signal beam to the corner reflector at the target point and receives the reflected signal beam reflected from the corner reflector along the original path, and transmits it to the second input / output port of the fiber optic circulator. The third input / output port of the fiber optic circulator transmits the reflected signal beam to the second photon detector; The second photon detector transmits the reflected signal beam to the time-to-digital converter; The time-to-digital converter detects the reference photon arrival time sequence and the signal photon arrival time sequence corresponding to the reference beam and the reflected signal beam, respectively, and sequentially sends the reference photon arrival time sequence and the signal photon arrival time sequence to the computer; The computer determines the target point coordinate information of the target point to be measured based on the reference photon arrival time sequence and the signal photon arrival time sequence.

2. The automatic tracking, ranging, and positioning system based on quantum entangled signals according to claim 1, wherein, The beam transceiver includes: a target coupler, a long-pass dichroic mirror, and a telescope system; and the beam transceiver transmits the signal beam to a corner reflector at the target point, and receives the reflected signal beam reflected from the corner reflector along its original path, and inputs it to the second input / output port of the fiber optic circulator, including: After the beam transceiver transmits the signal beam to the target coupler, it reaches the long-pass dichroic mirror. A long-pass dichroic mirror reflects the signal beam and transmits it into the telescope system to obtain a transmitted signal beam, and a corner reflector transmits the transmitted signal beam to the target point. The telescope system receives the transmitted signal beam reflected by the corner reflector at the target point and returned along the original path. After passing through the long-pass dichroic mirror and the target coupler in sequence, the reflected signal beam is obtained, and the reflected signal beam is transmitted to the second input / output port of the fiber optic circulator.

3. The automatic tracking, ranging, and positioning system based on quantum entangled signals according to claim 2, wherein, The beam transceiver further includes: a beacon laser, an optical isolator, a semi-reflective mirror, an imaging lens, and a high-speed camera; and before the beam transceiver transmits the signal beam to the corner reflector at the target point, and receives the reflected signal beam reflected from the corner reflector along its original path, and transmits it to the second input / output port of the fiber optic circulator, the system further includes: The beacon laser emits a beacon beam that passes through an optical isolator and a half-reflective mirror in sequence. The transmitted beam from the beacon beam is then sent to a long-pass dichroic mirror, and the reflected beam from the beacon beam is sent to a black box for absorption. The long-pass dichroic mirror transmits the reflected beam from the beacon beam into the telescope system; The telescope system transmits the reflected beam from the beacon beam to the corner mirror at the target point, and receives the beacon beam reflected from the corner mirror along the original path to obtain the reflected beacon beam; The telescope system transmits the reflected beacon beam to the long-pass dichroic mirror; A long-pass dichroic mirror reflects the beacon beam to a semi-reflective lens; A semi-reflective mirror transmits and reflects a reflected beacon beam to obtain a semi-transmitted beacon beam and a semi-reflected beacon beam, and transmits the semi-reflected beacon beam into the imaging lens; The imaging lens transmits the semi-reflective beacon beam to the high-speed camera, obtaining an image of the beacon spot. The high-speed camera transmits the beacon spot image to the computer; The computer detects and processes the beacon spot image to obtain cursor coordinate information and initiates cursor tracking mode; In response to determining that the cursor coordinate information meets the preset coordinate conditions, the computer adjusts the automatic tracking and ranging positioning system based on quantum entanglement signals to obtain the photon count value of the signal beam; The computer responds to determining that the number of photons in the signal beam meets the preset photon count condition, and fixes the relative positions of the beacon laser, imaging lens, telescope system, and high-speed camera on a high-precision gimbal.

4. The automatic tracking, ranging, and positioning system based on quantum entangled signals according to claim 1, wherein, The step of determining the target point coordinate information of the target point to be measured based on the reference photon arrival time sequence and the signal photon arrival time sequence includes: Based on the reference photon arrival time sequence and the signal photon arrival time sequence, the transmission optical path difference is determined; The ratio of the difference between the transmitted optical path difference and the pre-acquired fixed optical path difference to a preset value is determined as the target distance value; Based on the target distance value and the pre-acquired target angle information, the target point coordinate information of the target point to be measured is determined.

5. The automatic tracking, ranging, and positioning system based on quantum entangled signals according to claim 4, wherein, Determining the transmission optical path difference based on the reference photon arrival time sequence and the signal photon arrival time sequence includes: Determine the arrival time difference sequence corresponding to the reference photon arrival time sequence and the signal photon arrival time sequence; Determine the set of cumulative arrival time differences corresponding to each arrival time difference in the arrival time difference sequence, wherein one cumulative arrival time difference in the set of cumulative arrival time differences corresponds to at least one arrival time difference in the arrival time difference sequence; Select a rough time difference peak value from the arrival time difference values ​​corresponding to the largest cumulative arrival time difference value in the set of cumulative arrival time difference values; Based on the aforementioned approximate time difference peak value, the time difference interval is determined; For each arrival time difference in the arrival time difference sequence, in response to determining that the arrival time difference is not within the time difference interval, the arrival time difference is deleted from the arrival time difference sequence, and the deleted arrival time difference sequence is determined as the target arrival time difference sequence. Based on the cumulative arrival time difference set, each target arrival time difference in the target arrival time difference sequence is subjected to conformation processing to generate conformation arrival time difference, thus obtaining a conformation arrival time difference sequence. The cumulative arrival time difference set and the sequence of arrival time difference values ​​are fitted to obtain an arrival time difference fitting curve. The arrival time difference value corresponding to the peak position of the arrival time difference fitting curve is determined as the transmission time difference value; The product of the transmission time difference and the preset optical signal transmission speed is determined as the transmission optical path difference.

6. The automatic tracking, ranging, and positioning system based on quantum entangled signals according to claim 5, wherein, Determining the arrival time difference sequence corresponding to the reference photon arrival time sequence and the signal photon arrival time sequence includes: The first reference photon in the reference photon arrival time sequence is determined as the arrival time of the target reference photon; In response to the arrival time of the first signal photon in the received signal photon arrival time sequence, the arrival time of the first signal photon in the signal photon arrival time sequence is determined as the arrival time of the target signal photon; Based on the arrival time of the target reference photon and the arrival time of the target signal photon, the following time difference determination steps are performed: In response to determining that the next reference photon arrival time in the reference photon arrival time sequence is not received, the difference between the arrival time of the target reference photon and the arrival time of the target signal photon is determined as the photon arrival time difference, and the photon arrival time difference is added to the initial arrival time difference sequence, wherein the initial arrival time difference sequence is initially empty; In response to the determination that the arrival time of the target reference photon satisfies the first preset iteration condition and the arrival time of the target signal photon satisfies the second preset iteration condition, the initial arrival time difference sequence is determined as the arrival time difference sequence.

7. The automatic tracking, ranging, and positioning system based on quantum entangled signals according to claim 6, wherein, The system also includes: In response to determining the arrival time of the next reference photon in the reference photon arrival time sequence, the next reference photon arrival time in the reference photon arrival time sequence is determined as the arrival time of the target reference photon, and the time difference determination step is performed again. In response to determining that the arrival time of the target reference photon does not meet the first preset iteration condition or the arrival time of the target signal photon does not meet the second preset iteration condition, the next reference photon arrival time in the reference photon arrival time sequence is determined as the target reference photon arrival time, and the next signal photon arrival time in the signal photon arrival time sequence is determined as the target signal photon arrival time, so as to perform the time difference determination step again.

8. The automatic tracking, ranging, and positioning system based on quantum entangled signals according to claim 5, wherein, The step of performing conformance processing on each target arrival time difference value in the target arrival time difference value sequence based on the accumulated arrival time difference value set to generate a conformance arrival time difference value includes: In response to determining that the target arrival time difference is not within a preset range, the target arrival time difference is determined to be a valid arrival time difference; In response to determining that the time difference of arrival of the target is within a preset interval, the following steps are performed: Based on the time difference of the target arrival time, determine the time difference range; Each target arrival time difference within the time difference interval in the target arrival time difference sequence is determined as a set of arrival time differences. The cumulative arrival time difference value corresponding to each conforming arrival time difference value in the cumulative arrival time difference value set and the conforming arrival time difference value set is determined as the conforming arrival time difference cumulative value, thus obtaining the conforming arrival time difference cumulative value set; The sum of all the cumulative time difference values ​​in the cumulative time difference set and the ratio of this sum to a preset threshold are determined as the time difference of arrival.

Images