CN115236681A - Three-dimensional positioning system and positioning method based on quantum entangled photon pairs - Google Patents

Abstract

The invention belongs to the technical field of quantum navigation positioning, and particularly relates to a three-dimensional positioning system and a positioning method based on quantum entangled photon pairs. The invention utilizes a method based on a Sagnac interferometer bidirectional pumping PPKTP crystal to prepare an entangled photon pair, signal light is transmitted to a target point to be measured through a measuring light path and then reflected back to the local, and absolute distance information of the target point to be measured is calculated with idle light through a coincidence counting measurement method. Based on the unique light path structure design, the included angle between the propagation direction of the signal light beam and the coordinate axis can be obtained by reading the horizontal rotation angle and the pitch angle of the right-angle prism reflector. And then the absolute distance and azimuth angle information of the target point to be detected are combined to realize three-dimensional high-precision positioning.

Description

Three-dimensional positioning system and positioning method based on quantum entangled photon pairs

technical field

The invention belongs to the technical field of quantum navigation and positioning, and in particular relates to a three-dimensional positioning system and a positioning method based on quantum entangled photon pairs.

Background technique

Ranging technology is the basis for realizing unknown target positioning and navigation, and the ranging accuracy of the positioning system determines its positioning accuracy. Traditional ranging technologies, such as ultrasonic ranging, infrared ranging, and laser ranging, are all ranging technologies based on classical physics, and their ranging accuracy is always limited by the standard quantum limit. In order to obtain higher positioning accuracy, it is necessary to seek a new ranging technology that can break the standard quantum limit.

倍。其中M表示纠缠脉冲的个数，N表示一个脉冲中的平均光子数。该技术主要利用光子的纠缠或者压缩特性来实现对距离信息的高精度测量，使得测量精度能够突破标准量子极限的限制，达到海森堡极限。量子精密测距技术为实现高精度定位提供了新的技术支撑。With the establishment of quantum theory, quantum mechanics has gradually penetrated into physical experiments, especially the rapid development of quantum theory and application technology based on quantum entanglement. In 2001, the Giovannitti research group of the Massachusetts Institute of Technology proposed a new ranging method, namely quantum precision ranging, in the journal Nature. When a quantum light source with frequency entanglement and compression characteristics is used as the light source of the ranging system, the measurement accuracy can be improved

times. where M is the number of entangled pulses, and N is the average number of photons in a pulse. This technology mainly uses the entanglement or compression characteristics of photons to achieve high-precision measurement of distance information, so that the measurement accuracy can break through the limit of the standard quantum limit and reach the Heisenberg limit. Quantum precision ranging technology provides new technical support for the realization of high-precision positioning.

At present, with the development of entangled light source fabrication technology, entangled photon pairs with superior performance can be obtained based on spontaneous parametric down-conversion technology, which are called signal light and idle light, respectively. In the actual ranging process, the signal light is emitted to the target to be measured and then reflected back to the local area, and the arrival time difference of the entangled photon pair is obtained by the method of coincidence counting measurement with the idle light left in the local area, and then the distance information is calculated according to the time difference.

For example, the Chinese invention patent application number 202210383672X claims a two-dimensional plane positioning system and method based on quantum entangled light, the system and method rely on the coaxial transmission of visible light beams emitted by a reference light source and signal photons to realize quantum signals Through the design of the optical path structure of the auxiliary positioning device, the 360-degree transformation of the ranging direction and the extraction of the azimuth angle can be realized only by rotating the right-angle prism mirror, and the distance and azimuth angle from the target point to be measured can be used. The information can ultimately enable high-precision localization of the two-dimensional plane of quantum entangled light. However, the system and method can only achieve two-dimensional plane positioning. Most of the targets are targets located in three-dimensional space. From the current target positioning requirements, it is not enough to only achieve two-dimensional plane positioning. Only by realizing the three-dimensional positioning of the target can the real position of the target be accurately known. Therefore, how to achieve high-precision three-dimensional positioning of targets based on quantum entangled light is an urgent problem to be solved.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a three-dimensional positioning system and positioning method based on quantum entangled photon pairs, in order to solve the problem that the existing technology only realizes the two-dimensional plane positioning of the target and cannot accurately realize the precise positioning of the target located in the three-dimensional space, so as to solve the problem that the existing technology can only realize the two-dimensional plane positioning of the target and cannot accurately realize the precise positioning of the target in the three-dimensional space. Through the integration of quantum measurement technology and traditional positioning technology, high-precision three-dimensional positioning of space targets can be achieved.

In order to solve the above technical problems, the present invention provides a three-dimensional positioning system based on quantum entangled photon pairs, including an entangled light source, a first single-photon detector, a second single-photon detector, a coincidence measurement module, a coupler, and an optical fiber circulator. , a fiber collimator, a reflector, a right-angle prism reflector and a corner cube; the entangled light source is used to generate entangled photon pairs and divide them into idle light and signal light; the corner cube is arranged at the target point;

A first single-photon detector is arranged on the optical path of the idle light, and the idle light is used to be directly received by the first single-photon detector;

A coupler, an optical fiber circulator, an optical fiber collimator, a reflector, a right-angle prism reflector, a corner cube and a second single-photon detector are arranged on the optical path of the signal light. The horizontal rotation angle and pitch of the right-angle prism reflector Angle adjustable;

A coupler, an optical fiber circulator, a reflector, a right-angle prism reflector, a corner cube and a second single-photon detector are arranged on the optical path of the signal light, and the horizontal rotation angle and pitch angle of the right-angle prism reflector can be adjusted; During the actual positioning measurement of the target point, the signal light is used to return to the right-angle prism along the original path after passing through the coupler, fiber circulator, fiber collimator, reflector, right-angle prism reflector and corner cube in turn. Then, it is received by the second single photon detector after passing through the reflector, the fiber collimator and the fiber circulator in sequence;

The coincidence measurement module is used to perform coincidence counting measurement according to the arrival time sequence of photons detected by the first single-photon detector and the second single-photon detector in the actual positioning measurement process to determine the actual measurement optical path between the idle light and the signal light. Then use the actual measured optical path difference and the inherent optical path difference between the idle light and the signal light in the calibrated system to determine the absolute distance between the target point and the reflection point on the right angle prism mirror, and according to the absolute distance and The position and attitude information of the right-angle prism reflector performs three-dimensional positioning of the target point.

The beneficial effects are as follows: the present invention is provided with a right-angle prism mirror in the entire three-dimensional positioning system, its horizontal rotation angle and pitch angle can be adjusted, and the signal light incident to the right-angle prism mirror can be changed by changing its horizontal rotation angle and pitch angle. so that in the actual positioning measurement process, the signal light is reflected to the corner cube set at the target point through the right-angle prism mirror, and then returns along the original path through the corner cube mirror, and is then received by the second single-photon detector. , according to the arrival time series of photons detected by the first single-photon detector and the second single-photon detector, perform coincidence counting measurement to determine the actual measured optical path difference between the idle light and the signal light; and then combine the actual measured optical path difference and calibration The absolute distance between the target point and the reflection point on the right-angle prism reflector can be obtained by the inherent optical path difference between the idle light and the signal light in the system, according to the absolute distance and the azimuth angle information of the right-angle prism reflector The target point can be positioned in three dimensions. Based on the unique optical path design, high-precision ranging and the measurement of corresponding position information can be realized, thereby realizing high-precision three-dimensional positioning.

Further, when calibrating the inherent optical path difference between the idle light and the signal light in the system, the signal light is used to pass through the coupler, the fiber circulator, the fiber collimator, and the reflector in sequence to reach the right angle prism reflector, and then Return to the mirror along the original path, and then pass through the fiber collimator and the fiber circulator in sequence, and then be received by the second single photon detector.

Further, the absolute distance between the target point and the reflection point on the right angle prism mirror is:

R _OA = (L _A -L ₀ )/2

In the formula, R _OA is the absolute distance between the target point A and the reflection point O on the right angle prism mirror; L _A is the optical path difference obtained during the actual positioning measurement of the target point A; L ₀ is the idle light and signal in the system The inherent optical path difference between lights.

Further, when performing three-dimensional positioning of the target point according to the absolute distance R _OA and the pose information of the right-angle prism mirror, it is necessary to determine α and β according to the pose information of the right-angle prism mirror, and mark point A' as the target point A at The projection point on the horizontal plane where the point O is located, then α is the angle between OA' and the x-axis in the coordinate system of the measurement system, and β is the angle between OA and OA'; the three-dimensional positioning result of the corresponding target point is:

In the formula, (x _A , y _A , z _A ) are the three-dimensional coordinates of the target point.

The beneficial effects are as follows: combined with the horizontal rotation angle and pitch angle of the target point in the known coordinate system, corresponding to α and β, the target point can be positioned in a high-precision three-dimensional manner.

Further, the three-dimensional positioning system further comprises a turntable, on which the optical fiber collimator, the reflector and the right-angle prism reflector are fixedly arranged; and the rotation of the right-angle prism reflector is realized by the turntable, so that the Changes the horizontal rotation angle of the right angle prism mirror.

The beneficial effect is that the rotation of the right-angle prism mirror can be realized by using the turntable, which provides a new option for changing the emission direction of the signal light.

Further, the optical fiber collimator and the optical fiber circulator are connected by flexible optical fibers.

The beneficial effect is that the optical fiber collimator and the optical fiber circulator are connected by a flexible optical fiber, so that the optical fiber collimator can perform corresponding horizontal rotation.

In order to solve the above technical problems, the present invention also provides a three-dimensional positioning method based on quantum entangled photon pairs, comprising the following steps:

1) Generate entangled photon pairs and divide them into idle light and signal light;

2) When the actual positioning measurement of the target point to be measured is performed, the generated idle light is received by the first single-photon detector; the horizontal rotation angle and pitch angle of the right-angle prism reflector are adjusted, so that the generated signal light passes through the coupler and the optical fiber ring in turn. After passing through the reflector, fiber collimator, reflector, right-angle prism reflector and corner cube, it returns to the right-angle prism reflector along the original path, and then passes through the reflector, fiber collimator, and fiber circulator in sequence, and is captured by the second single photon. The detector receives; according to the photon arrival time series detected by the first single-photon detector and the second single-photon detector, the coincidence counting measurement is performed to determine the actual measured optical path difference between the idle light and the signal light;

3) Using the inherent optical path difference between the idle light and the signal light in the system measured in the calibration process and the actual measured optical path difference measured in the actual positioning measurement process in step 2), determine the target point and the reflection on the right angle prism mirror. The absolute distance between the points, and the three-dimensional positioning of the target point is performed according to the absolute distance and the pose information of the right angle prism mirror.

The beneficial effects are: by improving the horizontal rotation angle and the pitch angle of the right-angle prism reflector, the direction of the signal light incident on the right-angle prism reflector is changed. The actual measured optical path difference between the idle light and the signal light can be obtained, and then combined with the inherent optical path difference between the idle light and the signal light in the system measured during the calibration process, the target point and the right angle can be obtained. The absolute distance between the reflection points on the prism mirror, according to the absolute distance and the pose information of the right angle prism mirror, the three-dimensional positioning of the target point can be carried out. Based on the unique optical path design, high-precision ranging and the measurement of corresponding position information can be realized, thereby realizing high-precision three-dimensional positioning.

Further, the calibration process in step 3) includes: when calibrating the inherent optical path difference of the system, the generated idle light is received by the first single-photon detector; adjusting the reflective surface of the right angle prism mirror, so that the signal light is sequentially After the coupler, fiber circulator, fiber collimator, and reflector, it reaches the right-angle prism reflector, and then returns to the reflector along the original path, and then passes through the fiber collimator and fiber circulator in turn and is received by the second single-photon detector. ; According to the arrival time series of photons detected by the first single-photon detector and the second single-photon detector, the coincidence counting measurement is performed to determine the inherent optical path difference between the idle light and the signal light in the system.

Further, the absolute distance between the target point and the reflection point on the right angle prism mirror is:

R _OA = (L _A -L ₀ )/2

In the formula, R _OA is the absolute distance between the target point A and the reflection point O on the right-angle prism mirror; L _A is the optical path difference between the signal light and the idle light during the actual positioning measurement process of the target point A; L ₀ is the measurement system. Inherent optical path difference between idle light and signal light.

Further, when performing three-dimensional positioning of the target point according to the absolute distance and the pose information of the right-angle prism mirror, it is necessary to determine α and β according to the pose information of the right-angle prism mirror, and mark point A' as the target point A at point O. The projection point on the horizontal plane, then α is the angle between OA' and the x-axis in the coordinate system of the measurement system, and β is the angle between OA and OA'; the three-dimensional positioning result of the corresponding target point is:

In the formula, (x _A , y _A , z _A ) are the three-dimensional coordinates of the target point.

The beneficial effects are as follows: combined with the horizontal rotation angle and pitch angle of the target point in the known coordinate system, corresponding to α and β, the target point can be positioned in a high-precision three-dimensional manner.

Description of drawings

Fig. 1 is the preparation schematic diagram of the quantum entangled photon pair of the present invention;

Fig. 2 is the principle schematic diagram of the three-dimensional positioning system based on quantum entanglement photon pair of the present invention;

Fig. 3 is the coordinate system schematic diagram of the present invention;

4 is a schematic diagram of obtaining a horizontal rotation angle by means of a high-precision turntable of the present invention;

FIG. 5 is a schematic diagram of the coordinate measurement of the target point of the present invention.

Among them, 1-pump laser, 2-optical isolator, 3-1/4 wave plate, 4-first half-wave plate, 5-optical lens, 6-long-pass dichroic mirror, 7-polarization beam splitter , 8- the second half-wave plate, 9- the first mirror, 10- the second mirror, 11- the first single-photon detector, 12- time-to-digital converter, 13- the second single-photon detector, 14- Coupler, 15-fiber circulator, 16-fiber collimator, 17-third mirror, 18-right-angle prism mirror, 19-corner prism, 20-conformity measurement module.

Detailed ways

The invention utilizes photon pairs with entangled properties to obtain the absolute distance between the target point and the measurement system by means of coincidence counting measurement. Through the optical path structure designed in the present invention, the angle between the target point to be measured and the coordinate axis of the coordinate system can be measured, so that the precise coordinate value of the target point in the known coordinate system can be obtained. The present invention will be further described in detail below in conjunction with the accompanying drawings.

An example of a three-dimensional positioning system based on quantum entangled photon pairs:

An embodiment of a three-dimensional positioning system based on a quantum entangled photon pair of the present invention, its structure is shown in FIG. 2 , and the entangled light source in FIG. 2 is realized by using FIG. 1 . The three-dimensional positioning system of the present invention will be described in detail below with reference to FIG. 1 and FIG. 2 .

As shown in Figure 1, the entangled light source includes a pump laser 1, and an optical isolator 2, a quarter wave plate 3, a first half-wave are sequentially arranged on the optical path of the pump light (ie, laser) emitted by the pump laser 1 plate 4 and optical lens 5 to obtain 45° polarized light and incident on the Sagnac interferometer. Among them, the optical isolator 2 is mainly used to prevent back-reflected light from interfering with or damaging the pump laser 1; the quarter-wave plate 3 and the first half-wave plate 4 are mainly used to adjust the polarization state of the pump light and the polarization of different polarization components. relative phase. The optical lens 5 is used to converge the pump light source so that its focal point is at the center of the PPKTP crystal.

The Sagnac interferometer includes a polarization beam splitter 7, a second half-wave plate 8, a periodically polarized crystal (PPKTP), and a plane mirror (including a first mirror 9 and a second mirror 10). The second half-wave plate 8 in the Sagnac interference ring is placed in the 45° direction to change the polarization direction of the polarized beam. The horizontal polarization component in the pump light is transmitted at the polarization beam splitter 7, and then passes through the second half-wave plate 8 and the first mirror 9, and then transmits to the PPKTP crystal and undergoes parametric down-conversion. The formed entangled photons pass through the second mirror 10 to reach the polarization beam splitter 7 , wherein the horizontal polarization component is transmitted, the vertical polarization component is reflected, and is transmitted at the long-pass dichroic mirror 6 after reflection. The vertically polarized component in the pump light is reflected by the polarizing beam splitter 7, and then transmitted to the PPKTP crystal after passing through the second reflecting mirror 10, and undergoes parametric down-conversion. The formed entangled photons reach the polarization beam splitter 7 after passing through the first mirror 9 and the second half-wave plate 8, where the horizontal polarization component is transmitted again at the long-pass dichroic mirror 6, and the vertical polarization component is transmitted again. reflection occurs. Thus, signal light and idle light are finally obtained, and both the signal light and idle light finally obtained contain horizontal and vertical polarization components.

As shown in Figure 2, in addition to the entangled light source, the entire three-dimensional positioning system also includes a first single-photon detector 11, a time-to-digital converter 12, a second single-photon detector 13, a coupler 14, a fiber circulator 15, and a fiber optic calibrator. The collimator 16, the third reflector 17, the right-angle prism reflector 18, the corner cube prism 19 and the measurement module 20, and the fiber collimator 16 and the fiber circulator 15 are connected by a flexible fiber, so that the fiber collimator 16 A corresponding horizontal rotation is possible.

The first single-photon detector 11 described above is arranged on the optical path of the idle light, and the idle light is directly coupled and received by the first single-photon detector 11 .

The above-mentioned coupler 14 , fiber circulator 15 , fiber collimator 16 , fourth reflector 17 , right-angle prism reflector 18 , corner cube prism 19 , and second single-photon detector 13 are arranged on the optical path of the signal light. A corner cube 19 is provided at the target point. Among them, the horizontal rotation angle and pitch angle of the right-angle prism mirror 18 can be adjusted, so as to realize the following two processes of the signal light: 1) When the inherent optical path difference of the system is calibrated, the reflection surface of the right-angle prism mirror 18 is adjusted. To the horizontal direction, the signal light reaching the right angle prism reflecting mirror after being reflected by the third reflecting mirror 17 returns directly along the original path; 2) When positioning the target point to be measured, adjust the horizontal rotation angle and pitch of the right angle prism reflecting mirror 18 Angle, so that the signal light reflected by the third mirror 17 is reflected to the center of the corner cube 19 by the right angle prism mirror 18, and returns to the original path after being reflected by the corner cube 19. In either process, the final signal light passes through the third mirror 17 , the fiber collimator 16 , and the fiber circulator 15 , and is coupled and received by the second single-photon detector 13 .

Both the first single-photon detector 11 and the second single-photon detector 13 transmit the collected electrical signals to the time-to-digital converter 12, and the time-to-digital converter 12 is used to record the arrival time sequence of the signal light and the idle light, and then pass the The measurement module 20 performs coincidence counting measurements to determine the optical path difference between the idle light and the signal light. The target point can be ranged according to the optical path difference.

Moreover, the three-dimensional positioning system is also provided with a turntable, and the third reflector 17 and the right-angle prism reflector 18 can be fixed on the turntable, so as to realize the adjustment of the horizontal rotation angle of the right-angle prism reflector 18 .

The entire measurement process of the three-dimensional positioning system is described below, that is, a three-dimensional positioning method based on quantum entangled photon pairs of the present invention.

In step 1, the pump light emitted by the pump laser 1 first enters the optical isolator 2 for protection, and then passes through the 1/4 wave plate 3, the first half-wave plate 4, the optical lens 5 and the long-pass dichroic mirror 6. Sagnac interferometer.

In step 2, the Sagnac interferometer is composed of a polarization beam splitter 7, a second half-wave plate 8, a periodically polarized crystal (PPKTP) and a plane mirror (including a first mirror 9 and a second mirror 10). By adjusting the quarter wave plate 3 and the first half wave plate 4, the pump beam incident on the Sagnac interferometer is 45° polarized light. The polarized light is split into horizontal (H) and vertical (V) polarized lights with equal intensities by the polarizing beam splitter 7 . The two beams of light are reflected in the Sagnac ring to reach the PPKTP crystal respectively, and undergo parametric down-conversion, thereby generating entangled photon pairs. The signal light and the idle light respectively contain horizontal and vertical polarized light components and are in an entangled state.

In step 3, the idle light is directly coupled and received by the first single-photon detector 11 at the measurement locality, and then transmitted to the time-to-digital converter 12 .

Step 4, the signal light enters the port ① of the fiber circulator 15 through the coupler 14, and then is output from the port ② of the fiber circulator 15, and then the signal light is reflected by the fiber collimator 16, the third mirror 17 and the right angle prism respectively. After mirror 18, it is transmitted to the corner cube 19 of the target point.

Step 5, the signal light reflected by the corner cube 19 is reflected to the port ② of the optical fiber circulator 15 along the original path, and then output from the port ③ of the optical fiber circulator 15, and then, the signal light is coupled and received by the second single photon detector 13 , and passed to the time-to-digital converter 12.

In step 6, a three-dimensional rectangular coordinate system is established, and the reflection point of the signal beam on the rectangular prism mirror 18 is defined as the coordinate origin. Both the horizontal rotation angle and the pitch angle of the right-angle prism mirror 18 are adjusted to the 0° direction. At this time, the angle between the reflection surface of the right-angle prism mirror 18 and the horizontal plane is 45°. Define the propagation direction of the signal beam as the x-axis. In the horizontal plane, the direction perpendicular to the x-axis is the y-axis, and the direction perpendicular to the x-axis and the y-axis and upwards is the z-axis direction. The right angle prism mirror adjusts its horizontal rotation angle by rotating along the z-axis, and adjusts its pitch angle by rotating along the y-axis.

Step 7, calibrating the inherent optical path difference between the signal light and the idle light in the three-dimensional positioning system. Adjust the reflective surface of the right angle prism mirror 18 to the horizontal direction. The time-to-digital converter 12 is used to record the arrival time series of the signal light and the idle light respectively, and the optical path difference L ₀ of the two beams of light is obtained by the method of compliance counting and measurement. L ₀ is the difference between the signal light and the idle light inside the measuring device. inherent optical path difference. After calibrating the inherent optical path difference, in the actual measurement process, even if the coordinates of the points to be measured at different positions are measured, there is no need to re-calibrate.

Step 8: During the actual positioning process, place the corner cube prism 19 on the target point A to be measured. The projection of point A in the xy plane is A'. By adjusting the horizontal rotation angle and pitch angle of the right angle prism mirror 18, the signal beam is irradiated on the center of the corner cube mirror 19, and the signal beam is reflected back to the measuring device along the original path. Record the angle α between OA' and the x-axis and the angle β between OA and OA'.

Step 9: Obtain the optical path difference L _A between the signal light reflected by point A and the idle light by means of counting and measuring, then the distance between point A and point O is R _OA =(L _A -L ₀ )/2 .

Step ten, suppose the coordinate value of A is (x _A , y _A , z _A ). Through the obtained distance value R _OA , and angle values α and β, the coordinate value of point A can be solved:

The above method is applied to a specific example for description and description below.

Step 1, as shown in Figure 1, the 405nm pump light emitted by the pump laser 1 first enters an optical isolator 2 for protection, and then the laser beam passes through the 1/4 wave plate 3, the first half wave plate 4, and the optical lens 5. and the long-wave pass dichroic mirror 6 to reach the Sagnac interferometer.

In step 2, the Sagnac interferometer is composed of a polarization beam splitter 7, a second half-wave plate 8, a periodically polarized crystal (PPKTP) and a plane mirror (including a first mirror 9 and a second mirror 10). By adjusting the quarter wave plate 3 and the first half wave plate 4, the pump beam incident on the Sagnac interferometer is 45° polarized light. The second half-wave plate 8 in the Sagnac interference ring is placed in the 45° direction to change the polarization direction of the polarized beam. The horizontal polarization component in the pump light is transmitted at the polarization beam splitter 7, and then passes through the second half-wave plate 8 and the first mirror 9, and then transmits to the PPKTP crystal and undergoes parametric down-conversion. The formed entangled photons pass through the second mirror 10 to reach the polarization beam splitter 7, where the horizontal polarization component is transmitted and the vertical polarization component is reflected. The vertically polarized component in the pump light is reflected by the polarizing beam splitter 7, and then transmitted to the PPKTP crystal after passing through the second reflecting mirror 10, and undergoes parametric down-conversion. The formed entangled photons pass through the first mirror 9 and the second half-wave plate 8 and then reach the polarization beam splitter 7, where the horizontal polarization component is transmitted and the vertical polarization component is reflected. Therefore, both the signal light and the idle light contain horizontally and vertically polarized components.

Step 3, as shown in FIG. 2 , the idle light is directly coupled and received by the first single-photon detector 11 at the measurement site, and the electrical signal is transmitted to the time-to-digital converter 12 .

Step 4, the signal light enters the port ① of the fiber circulator 15 through the coupler 14, and then is output from the port ② of the fiber circulator 15, and then the signal light is reflected by the fiber collimator 16, the third mirror 17 and the right angle prism respectively. After mirror 18, it is transmitted to the corner cube 19 of the target point.

Step 5, the signal light reflected by the corner cube 19 is reflected to the port ② of the optical fiber circulator 15 along the original path, and then output from the port ③ of the optical fiber circulator 15, and then, the signal light is coupled and received by the second single photon detector 13 , and passed to the time-to-digital converter 12.

Step 6, as shown in FIG. 3 , a three-dimensional rectangular coordinate system is established, and the reflection point of the signal light on the rectangular prism mirror 18 is defined as the coordinate origin. Both the horizontal rotation angle and the pitch angle of the right-angle prism mirror 18 are adjusted to the 0° direction. At this time, the angle between the reflection surface of the right-angle prism mirror 18 and the horizontal plane is 45°. Define the propagation direction of the signal light as the x-axis. The direction perpendicular to the x-axis in the horizontal plane is the y-axis. The direction which is perpendicular to the x-axis and the y-axis and is directed upward is the z-axis direction. When the right angle prism mirror 18 is rotated along the z-axis, the propagation direction of the signal beam in the horizontal plane can be changed. When the right-angle prism mirror 18 rotates along the y-axis, the pitch angle of the propagation direction of the signal beam in space can be changed, thereby realizing the three-dimensional positioning of the target point.

For acquiring the horizontal rotation angle of the signal light, in addition to rotating the right-angle prism mirror 18 along the z-axis, it can also be achieved by means of a high-precision turntable. As shown in FIG. 4, the fiber collimator 16, the third mirror 17 and the right angle prism mirror 18 are fixed on a high-precision turntable. The rotation axis of the turntable coincides with the z-axis of the coordinate system. Since the optical fiber collimator 16 and the optical fiber circulator 15 are connected by a flexible optical fiber, corresponding horizontal rotation can be performed, thereby obtaining the horizontal rotation angle of the light beam.

Step 7, calibrating the inherent optical path difference of the system. Adjust the reflective surface of the right angle prism mirror 18 to the horizontal direction. The signal light first enters the port ① of the optical fiber circulator 15 through the coupler 14 , and then is output from the port ② of the optical fiber circulator 15 . Subsequently, the signal light passes through the fiber collimator 16 , the third reflecting mirror 17 and the right angle prism reflecting mirror 18 respectively, and then returns to the third reflecting mirror 17 along the original path. After that, the signal light is reflected to the port ② of the optical fiber circulator 15 along the original path, and then output from the port ③ of the optical fiber circulator 15 . Finally, the signal light is coupled and received by the second single-photon detector 13 and transmitted to the time-to-digital converter 12 . The time-to-digital converter 12 is used to record the arrival time series of the signal light and the idle light respectively, and the optical path difference L ₀ of the two beams of light is obtained by the method of compliance counting and measurement. L ₀ is the difference between the signal light and the idle light inside the measuring device. inherent optical path difference.

Step 8, as shown in FIG. 5 , place the corner cube prism 19 on the target point A to be measured. The projection point of point A in the xy plane is A'. The horizontal rotation angle and the pitch angle of the right-angle prism mirror 18 are adjusted so that the signal light is transmitted to the center of the corner cube prism 19 . The signal light reflected by the corner cube 19 is reflected to the port ② of the optical fiber circulator 15 along the original path, and then output from the port ③ of the optical fiber circulator 15 . It is then coupled and received by the second single photon detector 13 , and the electrical signal is transmitted to the time-to-digital converter 12 . Record the angle α between OA' and the x-axis and the angle β between OA and OA'.

Step 9: Obtain the optical path difference L _A between the signal light reflected by point A and the idle light by means of counting and measuring, then the distance between point A and point O is R _OA =(L _A -L ₀ )/2 .

Step ten, suppose the coordinate value of A is (x _A , y _A , z _A ). Through the obtained distance value R _OA , and angle values α and β, the coordinate value of point A can be solved:

To sum up, the entangled photon pair is prepared based on the bidirectional pumping of PPKTP crystal by the Sagnac interferometer. The signal light is transmitted to the target point to be measured through the measurement system and then reflected back to the local area, and the target point to be measured is calculated by the method of coincidence counting with the idle light. absolute distance information. Based on the unique optical path structure design, by reading the horizontal rotation angle and pitch angle of the right angle prism mirror, the angle between the propagation direction of the signal beam and the coordinate axis can be obtained. Finally, combined with the absolute distance and azimuth information of the target point to be measured, three-dimensional high-precision positioning can be realized.

Embodiments of three-dimensional positioning methods based on quantum entangled photon pairs:

An embodiment of a three-dimensional positioning method based on quantum entangled photon pairs of the present invention has the same overall process as a three-dimensional positioning method based on quantum entangled photon pairs introduced in the embodiment of the three-dimensional positioning system based on quantum entangled photon pairs. Repeat.

Claims (10)

1. a three-dimensional positioning system based on quantum entangled photon pair, is characterized in that, comprises entangled light source, the first single-photon detector, the second single-photon detector, conformity measurement module, coupler, optical fiber circulator, optical fiber collimation a reflector, a mirror, a right-angle prism mirror and a corner cube; the entangled light source is used to generate entangled photon pairs and split into idle light and signal light; the corner cube is arranged at the target point; A first single-photon detector is arranged on the optical path of the idle light, and the idle light is used to be directly received by the first single-photon detector; A coupler, an optical fiber circulator, an optical fiber collimator, a reflector, a right-angle prism reflector, a corner cube and a second single-photon detector are arranged on the optical path of the signal light. The horizontal rotation angle and pitch of the right-angle prism reflector The angle can be adjusted; during the actual positioning measurement of the target point, the signal light is used to return to the the right-angle prismatic reflector, which is then received by the second single-photon detector after passing through the reflector, the fiber collimator and the fiber optic circulator in sequence; The coincidence measurement module is used to perform coincidence counting measurement according to the arrival time sequence of photons detected by the first single-photon detector and the second single-photon detector in the actual positioning measurement process to determine the actual measurement optical path between the idle light and the signal light. Then use the actual measured optical path difference and the inherent optical path difference between the idle light and the signal light in the calibrated system to determine the absolute distance between the target point and the reflection point on the right angle prism mirror, and according to the absolute distance and The position and attitude information of the right-angle prism reflector performs three-dimensional positioning of the target point. 2. The three-dimensional positioning system based on quantum entangled photon pairs according to claim 1, characterized in that, when calibrating the inherent optical path difference between idle light and signal light in the system, the signal light is used to sequentially pass through the coupling The fiber collimator, fiber circulator, fiber collimator, and reflector reach the right-angle prism reflector, and then return to the reflector along the original path, and then pass through the fiber collimator and fiber circulator in turn and are received by the second single-photon detector. 3. the three-dimensional positioning system based on quantum entanglement photon pair according to claim 2, is characterized in that, the absolute distance between the reflection point on the described target point and the right angle prism mirror is: R _OA = (L _A -L ₀ )/2 In the formula, R _OA is the absolute distance between the target point A and the reflection point O on the right-angle prism mirror; L _A is the actual measurement optical path difference obtained during the actual positioning measurement of the target point A; L ₀ is the idle light in the system. and the inherent optical path difference between the signal light. 4. the three-dimensional positioning system based on quantum entanglement photon pair according to claim 3, is characterized in that, when carrying out three-dimensional positioning to the target point according to the position and attitude information of the absolute distance and the right-angle prism reflecting mirror, need according to the right-angle prism reflecting mirror's three-dimensional positioning system. The pose information determines α and β, and mark point A' as the projection point of target point A on the horizontal plane where point O is located, then α is the angle between OA' and the x-axis in the coordinate system of the measurement system, and β is the difference between OA and OA'. The included angle between , and the three-dimensional positioning result of the corresponding target point is:

In the formula, (x _A , y _A , z _A ) are the three-dimensional coordinates of the target point. 5 . The three-dimensional positioning system based on quantum entangled photon pairs according to claim 1 , wherein the three-dimensional positioning system further comprises a turntable, and the optical fiber collimator, the reflector and the right angle prism reflector are fixedly arranged on the on the turntable; and the rotation of the right-angle prism mirror is realized by the turntable, so as to change the horizontal rotation angle of the right-angle prism mirror. 6 . The three-dimensional positioning system based on quantum entangled photon pairs according to claim 1 , wherein the optical fiber collimator and the optical fiber circulator are connected by a flexible optical fiber. 7 . 7. a three-dimensional positioning method based on quantum entangled photon pair, is characterized in that, comprises the steps: 1) Generate entangled photon pairs and divide them into idle light and signal light; 2) When the actual positioning measurement of the target point to be measured is performed, the generated idle light is received by the first single-photon detector; the horizontal rotation angle and pitch angle of the right-angle prism reflector are adjusted, so that the generated signal light passes through the coupler and the optical fiber ring in turn. After passing through the reflector, fiber collimator, reflector, right-angle prism reflector and corner cube, it returns to the right-angle prism reflector along the original path, and then passes through the reflector, fiber collimator, and fiber circulator in sequence, and is captured by the second single photon. The detector receives; according to the photon arrival time series detected by the first single-photon detector and the second single-photon detector, the coincidence counting measurement is performed to determine the actual measured optical path difference between the idle light and the signal light; 3) Using the inherent optical path difference between the idle light and the signal light in the system measured in the calibration process and the actual measured optical path difference measured in the actual positioning measurement process in step 2), determine the target point and the reflection on the right angle prism mirror. The absolute distance between the points, and the three-dimensional positioning of the target point is performed according to the absolute distance and the pose information of the right angle prism mirror. 8. the three-dimensional positioning method based on quantum entanglement photon pair according to claim 7, is characterized in that, the calibration process in step 3) comprises: When the inherent optical path difference of the system is calibrated, the generated idle light is received by the first single-photon detector; the reflecting surface of the right-angle prism mirror is adjusted so that the signal light passes through the coupler, fiber circulator, and fiber collimator in sequence , The reflector reaches the right-angle prism reflector, and then returns to the reflector along the original path, and then passes through the fiber collimator and fiber circulator in turn and is received by the second single-photon detector; according to the first single-photon detector and the second single-photon detector. The photon arrival time sequence detected by the photon detector is measured by coincidence counting to determine the inherent optical path difference between the idle and signal light in the system. 9. the three-dimensional positioning method based on quantum entanglement photon pair according to claim 8, is characterized in that, the absolute distance between the reflection point on the described target point and the right angle prism mirror is: R _OA = (L _A -L ₀ )/2 In the formula, R _OA is the absolute distance between the target point A and the reflection point O on the right-angle prism mirror; L _A is the actual measurement optical path difference obtained during the actual positioning measurement of the target point A; L ₀ is the idle light in the system. and the inherent optical path difference between the signal light. 10. The three-dimensional positioning method based on quantum entangled photon pairs according to claim 9, wherein when performing three-dimensional positioning of the target point according to the absolute distance and the pose information of the right-angle prism mirror, it is necessary to use the right-angle prism mirror to perform three-dimensional positioning. Determine α and β from the pose information of , and mark point A' as the projection point of target point A on the horizontal plane where point O is located, then α is the angle between OA' and the x-axis in the coordinate system of the measurement system, and β is OA and OA' The included angle between ; the three-dimensional positioning result of the corresponding target point is:

In the formula, (x _A , y _A , z _A ) are the three-dimensional coordinates of the target point.

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