A novel laser communication transmitting and receiving beam integrated monitoring system and a monitoring method

Abstract

The application provides a novel laser communication transmitting and receiving beam integrated monitoring system and a monitoring method, which comprises a polarization beam splitter, an attenuator, a corner cube, a beam splitter, a 1 / 4 wave plate, a liquid crystal polarization grating, a converging lens and a monitoring detector. The application can perform online real-time monitoring on the consistency of the transmitting optical axis and the receiving optical axis of the laser communication system and ensure that the laser transmitting beam accurately points to the opposite terminal. The same monitoring detector is used to monitor the transmitting beam and the receiving beam at the same time. In order to avoid the mutual influence of the imaging spots of the transmitting beam and the receiving beam, the liquid crystal polarization grating is used to separate the transmitting beam and the receiving beam according to the different polarization characteristics of the transmitting beam and the receiving beam, so as to ensure the spot position extraction accuracy, realize the high-precision pointing of the transmitting beam to the opposite laser terminal, reduce the alignment mismatch loss of the laser transmitting signal, and greatly improve the communication distance of the system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of communication technology, in particular to a novel laser communication transmitting and receiving beam integrated monitoring system and a monitoring method. BACKGROUND

[0002] Space laser communication has the advantages of high transmission rate, narrow beam range, strong anti-interference interception capability, small terminal volume, light weight, low power consumption, etc., and its application in the field of space communication is growing. The United States, Japan, Europe and other countries and regions have carried out a large number of inter-satellite and space-ground laser communication, and have begun to build inter-satellite laser communication networks.

[0003] The satellite laser communication terminal is affected by factors such as launch impact, weightlessness, air pressure change and thermal deformation, and the optical axes of the receiving and transmitting light paths will change after being launched, resulting in inconsistency between the receiving and transmitting optical axes. In space laser communication link establishment, laser transmission needs to be based on the receiving optical axis, and on this basis, the pointing angle is corrected in advance to ensure that the transmitted beam accurately covers the opposite laser terminal after long-distance transmission, and to reduce the mismatch loss in the tracking process. In order to reduce the mismatch loss, the pointing accuracy of the laser transmission beam is better than 1 / 6-1 / 10 of the laser beam divergence angle, and the laser beam divergence angle is in the order of tens of micro-radians, so the pointing accuracy is generally required to be in the order of micro-radians. The higher the pointing accuracy, the smaller the loss of the laser communication link. Therefore, the transmitted beam and the received beam need to be monitored in real time, and the consistency of the transmitting and receiving optical axes is calibrated in real time by the pre-aiming fast mirror.

[0004] Chinese patent publication No. CN109787686B discloses a satellite communication terminal on-orbit calibration and transmitting-receiving coaxiality correction device and method, which increases an angle reflector outside the terminal coarse pointing mechanism to calibrate and correct the transmitting-receiving coaxiality of the laser terminal on-orbit. This method needs to correct the transmitting-receiving coaxiality before communication link establishment, and cannot realize online monitoring of the transmitting-receiving coaxiality while communicating. The calibration is not real-time, and cannot meet the high-precision pointing requirements of the laser transmitting optical axis.

[0005] The document (Research on the Corner Cube Calibration Technology of Space Laser Communication, Xi'an Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, June 2018) introduces the method of laser emission / receiving channel and optical axis calibration of the OCD terminal developed by NASA. A part of the reflected emission beam is reflected by a plane mirror and focused on a photoelectric position sensor array, and the receiving beam is also focused on the sensor. On the one hand, the plane mirror method uses a plane mirror to reflect, and a small change in the normal direction of the plane mirror will cause an angle error of the returned emission beam, so that the returned emission beam cannot accurately represent the pointing direction of the emission beam. On the other hand, the emission beam and the receiving beam are imaged on the same photoelectric position sensor array at the same time, and when the pre-aiming angle is not large, the two light spots will overlap or intersect with each other, affecting the extraction accuracy of the respective light spot positions. Ultimately, the emission beam cannot be accurately pointed to the opposite laser terminal, resulting in a reduction in the communication distance of the laser communication system, and even communication interruption. SUMMARY

[0006] The present application is to solve the problems of real-time monitoring and low monitoring accuracy in the prior art, and provides a novel laser communication transmitting and receiving beam integrated monitoring system and a monitoring method, which can perform online real-time monitoring of the consistency of the emission optical axis and the receiving optical axis of the laser communication system and ensure accurate pointing of the emission beam to the opposite terminal. The same monitoring detector is used to monitor the emission beam and the receiving beam at the same time. In order to avoid the mutual influence of the imaging light spots, a liquid crystal polarization grating is used to separate the emission beam and the receiving beam in space according to their different polarization characteristics, so as to ensure the light spot position extraction accuracy, realize high-precision pointing of the emission beam to the opposite laser terminal, reduce the alignment mismatch loss of the laser emission signal, and greatly improve the communication distance of the system.

[0007] The present application provides a novel laser communication transmitting and receiving beam integrated monitoring system, which comprises a polarization beam splitter arranged on the output light path of a laser to be monitored, an attenuator and a corner cube arranged in sequence on the transmission light path of the polarization beam splitter, a beam splitter arranged on the reflection light path of the polarization beam splitter, and a 1 / 4 wave plate, a liquid crystal polarization grating, a converging lens and a monitoring detector arranged in sequence on the transmission light path of the beam splitter. The corner cube is a retroreflector, and the fast axis direction of the 1 / 4 wave plate is at an angle of 45° with the horizontal direction.

[0008] The reflection light path of the polarization beamsplitter is used for transmitting the optical signal of the laser to be monitored and receiving the optical signal of the opposite laser terminal, the transmitting beam and the receiving beam are linearly polarized light beams with perpendicular polarization directions, the polarization beamsplitter is used for polarization isolation of the transmitting beam and the receiving beam, the corner cube is used for 180° light path turning of the incoming beam, the reflection light path of the beamsplitter is used for communication reception, the 1 / 4 wave plate is used for changing the transmitting beam and the receiving beam with different linear polarization states into circularly polarized light with different rotation directions, the circularly polarized light includes left-handed circularly polarized light and right-handed circularly polarized light, the liquid crystal polarization grating is used for spatial position separation of the circularly polarized light with different rotation directions, the converging lens is used for converging to obtain transmitting beam spots and receiving beam spots with different positions, and the monitoring detector outputs the position images of the transmitting beam spots and the receiving beam spots through windowing and high speed.

[0009] The new laser communication transmitting and receiving beam integrated monitoring system comprises a polarization beamsplitter, a corner cube, a beamsplitter, a 1 / 4 wave plate, a liquid crystal polarization grating, a converging lens and a monitoring detector.

[0010] The optical signal output by the laser to be monitored is modulated, amplified, collimated by a collimator and aimed at the fast mirror in advance to obtain a transmitting beam and is reflected to the polarization beamsplitter, the transmitting beam is reflected by the polarization beamsplitter and then transmitted to the opposite laser terminal through the fast mirror, the 1 / 4 wave plate and the optical telescope, the optical signal of the opposite laser terminal is received by the optical telescope, the 1 / 4 wave plate and the fast mirror to obtain a receiving beam and enters the polarization beamsplitter.

[0011] The polarization beamsplitter can also combine the transmitting beam and the receiving beam.

[0012] The new laser communication transmitting and receiving beam integrated monitoring system comprises a polarization beamsplitter, a corner cube, a beamsplitter, a 1 / 4 wave plate, a liquid crystal polarization grating, a converging lens and a monitoring detector.

[0013] The new laser communication transmitting and receiving beam integrated monitoring system comprises a polarization beamsplitter, a corner cube, a beamsplitter, a 1 / 4 wave plate, a liquid crystal polarization grating, a converging lens and a monitoring detector.

[0014] The new laser communication transmitting and receiving beam integrated monitoring system comprises a polarization beamsplitter, a corner cube, a beamsplitter, a 1 / 4 wave plate, a liquid crystal polarization grating, a converging lens and a monitoring detector.

[0015] The new laser communication transmitting and receiving beam integrated monitoring system comprises a polarization beamsplitter, a corner cube, a beamsplitter, a 1 / 4 wave plate, a liquid crystal polarization grating, a converging lens and a monitoring detector.

[0016] The application discloses a novel laser communication transmitting and receiving light beam integrated monitoring system.

[0017] The application discloses a novel laser communication transmitting and receiving light beam integrated monitoring method.

[0018] S1, linearly polarized light emitted by a laser to be monitored is modulated, amplified, collimated by a collimator, and reflected by a fast aiming mirror in advance to obtain a transmitting light beam, part of the transmitting light beam is reflected by a polarization beam splitter and then transmitted into a 1 / 4 wave plate through a light splitting mirror;

[0019] The light signal emitted by the opposite laser terminal is received by the optical telescope and reflected by the fast tracking mirror to obtain a receiving light beam, part of the receiving light beam is transmitted through the polarization beam splitter and then reflected by the light splitting mirror into the communication receiving unit, and the other part is transmitted through the polarization beam splitter and then transmitted into the 1 / 4 wave plate through the light splitting mirror;

[0020] S2, the transmitting light beam and the receiving light beam in different linear polarization states are changed into circularly polarized light of different rotary natures after passing through the 1 / 4 wave plate, the circularly polarized light of different rotary natures includes left-handed circularly polarized light and right-handed circularly polarized light, the circularly polarized light of different rotary natures is deflected in opposite directions by the liquid crystal polarization grating and then is finally imaged on the monitoring detector to obtain two light spots with different imaging positions, and the monitoring detector outputs the position images of the two light spots at high speed through windowing to monitor the communication transmitting path and the receiving path of the laser of the laser to be monitored.

[0021] In the step S2, the fast axis direction of the 1 / 4 wave plate is at an angle of 45 degrees with the horizontal direction, the horizontal linearly polarized light is changed into left-handed circularly polarized light after passing through the 1 / 4 wave plate, and the Jones matrix is as follows:

[0022]

[0023] Wherein, j is an imaginary number.

[0024] The vertical linearly polarized light is changed into right-handed circularly polarized light after passing through the 1 / 4 wave plate, and the Jones matrix is as follows:

[0025]

[0026] The novel laser communication transceiving light beam integrated monitoring method provided by the application, as a preferred mode, in step S2, when the left-handed circularly polarized light is incident on the liquid crystal polarization grating, the electric field is transformed into:

[0027]

[0028] wherein E out is the output light energy, Γ represents the phase delay generated by the liquid crystal layer with a thickness of d, f x is the spatial frequency; P is the orientation period of the grating;

[0029] Γ=2π(n e -n o )d / λ;

[0030] wherein n e is the refractive index of abnormal light, n o is the refractive index of normal light, and λ is the wavelength;

[0031] When the phase delay Γ is π,

[0032]

[0033] All the light energy is in the +1 order, at this time, the incident left-handed circularly polarized light is changed into the outgoing right-handed circularly polarized light, and the left deflection angle is θ=arcsin(λ / P);

[0034] When the incident is the right-handed circularly polarized light, the left-handed circularly polarized light is changed after passing through the liquid crystal polarization grating with a phase delay of π, and the right deflection angle is θ.

[0035] The technical scheme of the application is: a novel laser communication transceiving light beam integrated monitoring system, comprising a polarization beam splitter, an attenuator, a corner cube, a beam splitter, a 1 / 4 wave plate, a liquid crystal polarization grating, a converging lens, and a monitoring detector.

[0036] The linearly polarized light emitted by the laser passes through modulation, amplification, collimation of a collimator, pre-aiming reflection of a fast mirror, enters the polarization beam splitter, most of the light is reflected by the polarization beam splitter, and is transmitted to the opposite laser terminal via a fine tracking fast mirror and an optical telescope. A small part of the light transmits through the polarization beam splitter, enters the 1 / 4 wave plate via the attenuator and the corner cube.

[0037] The signal light emitted by the opposite laser terminal is received by the optical telescope, reflected by the fine tracking fast mirror, and enters the polarization beam splitter, and is transmitted through the polarization beam splitter. Most of the light is reflected by the beam splitter into the communication receiving unit, and a small part is transmitted into the 1 / 4 wave plate.

[0038] The fast axis direction of the 1 / 4 wave plate is at an angle of 45° with the horizontal direction, and the horizontal linearly polarized light becomes left-handed circularly polarized light after passing through the 1 / 4 wave plate; the vertical linearly polarized light becomes right-handed circularly polarized light. This is expressed by a Jones matrix as follows:

[0039]

[0040]

[0041] When the circularly polarized light passes through the liquid crystal polarization grating, because the liquid crystal polarization grating has a periodic orientation layer structure, when the left-handed circularly polarized light is incident and passes through the liquid crystal polarization grating, the electric field is transformed into

[0042]

[0043] where Γ = 2π(n e -n o )d / λ represents the phase delay produced by the liquid crystal layer with a thickness of d; f x is the spatial frequency; and P is the grating orientation period. When the phase delay Γ = π,

[0044]

[0045] All the light energy is in the +1 order, at which time the left-handed circularly polarized light of the incident light becomes the right-handed circularly polarized light of the outgoing light, and is deflected to the left by an angle of θ = arcsin (λ / P). Similarly, when the incident light is right-handed polarized light, it becomes left-handed polarized light after passing through the liquid crystal polarization grating with a phase delay of π, and is deflected to the right by an angle of θ.

[0046] Because the deflection directions are different, the imaging positions on the monitoring detector are inconsistent after passing through the converging lens. The monitoring detector outputs two spot position images at high speed through windowing, thereby realizing the simultaneous monitoring of the laser communication transmitting light path and the receiving light path by one detector.

[0047] The fast axis direction of the 1 / 4 wave plate is at an angle of 45° with the horizontal direction, and the different linearly polarized state transmitting beams and receiving beams become circularly polarized light of different handedness after passing through the 1 / 4 wave plate, one being left-handed circularly polarized light and the other being right-handed circularly polarized light. The circularly polarized light of different handedness passes through the liquid crystal polarization grating, and the deflection directions are opposite, and the imaging positions on the monitoring detector are different after passing through the converging lens. The monitoring detector outputs two spot position images at high speed through windowing, thereby realizing the simultaneous monitoring of the laser communication transmitting light path and the receiving light path by one detector.

[0048] The polarization beamsplitter can split the linearly polarized light with mutually perpendicular polarization directions, and realize the polarization isolation of the transmitting and receiving beams. At the same time, because the isolation degree is not very ideal, a very small part of the transmitting signal light can be transmitted through the polarization beamsplitter, and also realizes the combination of the transmitting and receiving beams after being reflected by the corner cube.

[0049] The attenuator can control the intensity of the emitted light beam entering the monitoring detector, preventing the emitted light beam from causing saturation of the monitoring detector.

[0050] The corner cube can be a corner cube prism or other high-precision retroreflector, which can make the light beam entering the corner cube return along the original path with high precision.

[0051] The working wavelength of the beam splitter is consistent with the communication wavelength, and the reflection and transmission ratio is determined by the communication receiving sensitivity and the detection sensitivity of the monitoring detector.

[0052] The angle between the fast axis direction of the 1 / 4 wave plate and the horizontal direction is 45°, and the working wavelength is basically consistent with the communication wavelength.

[0053] The working wavelength of the liquid crystal polarization grating is consistent with the communication wavelength, and the deflection angle is related to factors such as the magnification of the telescope, the maximum pre-aiming angle, and the tracking accuracy.

[0054] The converging lens can be a single convex lens or a combined lens group.

[0055] The monitoring detector can be a visible light camera or an infrared focal plane detector, and the detection wavelength range includes the communication wavelength, which can simultaneously realize two window openings and high-speed output.

[0056] The present application has important application prospects in the fields of free space laser communication and laser radar.

[0057] To realize online real-time monitoring of the consistency of the transmitting optical axis and the receiving optical axis of the laser communication system, and ensure that the laser transmitting light beam accurately points to the opposite terminal, the present application returns the transmitting light beam along the original path through a corner cube prism, combines the returned transmitting light beam and the receiving light beam through a polarization beam splitter, passes the transmitting and receiving light beams through a 1 / 4 wave plate with a fast axis direction at an angle of 45° with the horizontal direction, and changes the linearly polarized light with perpendicular polarization directions into circularly polarized light with different rotations. After passing through the liquid crystal polarization grating, the circularly polarized light with different rotations has opposite deflection directions, and after converging through the converging lens, images are formed on two different positions on the monitoring detector. The monitoring detector outputs two spot position images at high speed through windowing, realizing simultaneous monitoring of the transmitting light path and the receiving light path of a detector. The present application adopts a transmitting and receiving light beam integrated monitoring system, avoiding the measurement error of the optical axis consistency caused by the position and attitude changes of the two detectors in the traditional transmitting and receiving light beam separate monitoring system; at the same time, the positions of the returned transmitting spot and the receiving spot are separated, overcoming the mutual influence of the extraction of the transmitting spot and the receiving spot, effectively improving the extraction accuracy of the spot. This improves the accuracy of the pointing of the transmitting light beam, reduces the tracking mismatch loss of the system, improves the action distance of the laser communication system, and can be widely applied in space laser communication links such as inter-satellite, satellite-ground, air-to-air, and air-to-ground.

[0058] The present invention has the following advantages:

[0059] (1) According to the different polarization directions of the transmitting and receiving beams, the present invention uses a quarter-wave plate and a liquid crystal polarization grating to separate the transmitted beam and the received beam returning from the cone in the spatial direction and image them at different positions of a detector. This avoids the crossing and overlap of the two beams, improves the accuracy of the imaging beam position extraction, realizes high-precision pointing of the transmitted beam, can greatly reduce the alignment mismatch loss of laser emission, and improve the working distance of the laser communication system.

[0060] (2) The present invention adopts an integrated monitoring system for laser communication transceiver beams, which can further reduce the weight and power consumption of laser terminals and increase the applicability of laser communication terminals. Attached Figure Description

[0061] Figure 1 This is a block diagram of a novel integrated laser communication transceiver beam monitoring system.

[0062] Figure 2 This is a flowchart of a novel integrated monitoring method for laser communication transceiver beams.

[0063] Figure label:

[0064] 1. Polarizing beam splitter; 2. Attenuator; 3. Pyramid; 4. Beam splitter; 5. Quarter wave plate; 6. Liquid crystal polarizing grating; 7. Converging lens; 8. Monitoring detector. Detailed Implementation

[0065] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0066] Example 1

[0067] like Figure 1 As shown, a novel integrated monitoring system for laser communication transceiver beams includes a polarizing beam splitter 1 disposed on the output optical path of the laser to be monitored, an attenuator 2 and a corner cone 3 disposed sequentially on the transmission optical path of the polarizing beam splitter 1, a beam splitter 4 disposed on the reflection optical path of the polarizing beam splitter 1, and a quarter-wave plate 5, a liquid crystal polarizing grating 6, a converging lens 7, and a monitoring detector 8 disposed sequentially on the transmission optical path of the beam splitter 4. The corner cone 3 is a retroreflector, and the fast axis of the quarter-wave plate 5 forms a 45° angle with the horizontal direction.

[0068] The reflection light path of the polarization beamsplitter 1 is used for transmitting the optical signal of the laser to be monitored and receiving the optical signal of the opposite laser terminal, the transmitting beam and the receiving beam are linearly polarized light beams with perpendicular polarization directions, the polarization beamsplitter 1 is used for polarization isolation of the transmitting beam and the receiving beam, the corner cube 3 is used for 180° light path turning of the incoming beam, the reflection light path of the beamsplitter 4 is used for communication reception, the 1 / 4 wave plate 5 is used for changing the transmitting beam and the receiving beam with different linear polarization states into circularly polarized light with different rotation directions, the circularly polarized light includes left-handed circularly polarized light and right-handed circularly polarized light, the liquid crystal polarization grating 6 is used for spatial position separation of the circularly polarized light with different rotation directions, the converging lens 7 is used for converging to obtain transmitting beam spots and receiving beam spots with different positions, and the monitoring detector 8 outputs the position images of the transmitting beam spots and the receiving beam spots at high speed through windowing.

[0069] A fast mirror, a 1 / 4 wave plate for transmitting and receiving, and an optical telescope are sequentially arranged on the reflection light path of the polarization beamsplitter 1.

[0070] The optical signal output by the laser to be monitored is sequentially modulated, amplified, collimated by a collimator, and aimed at the fast mirror in advance to obtain a transmitting beam and is reflected to the polarization beamsplitter 1, the transmitting beam is sequentially transmitted to the opposite laser terminal through the polarization beamsplitter 1, the fast mirror, the 1 / 4 wave plate for transmitting and receiving, and the optical telescope after being reflected by the polarization beamsplitter 1, and the optical signal of the opposite laser terminal sequentially passes through the optical telescope, the 1 / 4 wave plate for transmitting and receiving, and the fast mirror to obtain a receiving beam and enters the polarization beamsplitter 1.

[0071] The polarization beamsplitter 1 can also combine the transmitting beam and the receiving beam.

[0072] The attenuator 2 can control the intensity of the transmitting beam entering the monitoring detector 8 to prevent the monitoring detector from being saturated by the transmitting beam.

[0073] The corner cube 3 is a corner cube prism.

[0074] The working wavelengths of the beamsplitter 4, the 1 / 4 wave plate 5, the liquid crystal polarization grating 6, and the monitoring detector 8 are the same as the communication wavelength, the reflection and transmission ratio of the beamsplitter 4 is related to the communication reception sensitivity and the detection sensitivity of the monitoring detector 8, and the deflection angle of the liquid crystal polarization grating 6 is related to the telescope magnification, the maximum pre-aiming angle, and the tracking accuracy.

[0075] The converging lens 7 is a single-piece convex lens or a combined lens group.

[0076] The monitoring detector 8 is a visible light camera or an infrared focal plane detector, and the monitoring detector 8 can simultaneously realize two windowing and high-speed output.

[0077] Embodiment 2

[0078] As Figure 2As shown, a new laser communication transceiver beam integrated monitoring method, comprising the following steps:

[0079] S1, linearly polarized light emitted by the laser to be monitored passes through modulation, amplification, collimation of the collimator, and reflection of the pre-aiming fast mirror to obtain the emitted beam. Part of the emitted beam is reflected by the polarizing beam splitter 1 and then transmitted to the other laser terminal via the fine tracking fast mirror and the optical telescope. Another part is reflected by the polarizing beam splitter 1 and then passes through the attenuator 2 and the corner cube 3 in turn to return to the polarizing beam splitter 1. Then the polarizing beam splitter 1 reflects the light to the polarizing beam splitter 4, and then the light is transmitted into the 1 / 4 wave plate 5.

[0080] The optical signal emitted by the other laser terminal is received by the optical telescope and reflected by the fine tracking fast mirror to obtain the received beam. Part of the received beam is transmitted through the polarizing beam splitter 1 and then reflected by the polarizing beam splitter 4 to enter the communication receiving unit. Another part is transmitted through the polarizing beam splitter 4 and then enters the 1 / 4 wave plate 5.

[0081] S2, the emitted beam and the received beam with different linear polarization states become different circularly polarized light after passing through the 1 / 4 wave plate 5. The different circularly polarized light includes left-handed circularly polarized light and right-handed circularly polarized light. The different circularly polarized light passes through the liquid crystal polarization grating 6 to make the deflection directions opposite, and then passes through the converging lens 7 to finally obtain two light spots with different imaging positions on the monitoring detector 8. The monitoring detector 8 outputs the position images of the two light spots at high speed through windowing to monitor the communication emission path and the receiving path of the laser of the laser to be monitored.

[0082] The fast axis direction of the 1 / 4 wave plate 5 is at an angle of 45° with the horizontal direction. The horizontal linearly polarized light becomes left-handed circularly polarized light after passing through the 1 / 4 wave plate 5. The Jones matrix is:

[0083]

[0084] Where j is an imaginary number;

[0085] The vertical linearly polarized light becomes right-handed circularly polarized light after passing through the 1 / 4 wave plate 5. The Jones matrix is:

[0086]

[0087] When the left-handed circularly polarized light enters the liquid crystal polarization grating 6, the electric field is transformed into:

[0088]

[0089] Where E out is the output light energy, Γ represents the phase delay generated by the liquid crystal layer with a thickness of d, f x is the spatial frequency; P is the grating orientation period.

[0090] Γ=2π(ne -n o )d / λ;

[0091] wherein n e is the refractive index of abnormal light, n o is the refractive index of normal light, and λ is wavelength;

[0092] When the phase delay Γ = π,

[0093]

[0094] All light energy is in +1 order, at this time the incident left-handed circularly polarized light becomes the outgoing right-handed circularly polarized light, and the deflection angle to the left is θ = arcsin (λ / P);

[0095] When the incident is right-handed polarized light, after passing through the liquid crystal polarization grating 6 with a phase delay of π, the light becomes left-handed polarized light, and the deflection angle to the right is θ.

[0096] Embodiment 3

[0097] As Figures 1-2 shown, a new laser communication transmitting and receiving beam integrated monitoring system and monitoring method, the monitoring system comprises a polarization beam splitter 1, an attenuator 2, a corner cube 3, a beam splitter 4, a 1 / 4 wave plate 5, a liquid crystal polarization grating 6, a converging lens 7, and a monitoring detector 8.

[0098] The polarized light emitted by the laser passes through modulation, amplification, collimation by a collimator, and is reflected by a pre-aiming fast mirror, enters the polarization beam splitter 1, and most of the light is reflected by the polarization beam splitter, transmitted to the opposite laser terminal by the fine tracking fast mirror and the optical telescope. A small part of the light transmits through the polarization beam splitter 1, returns to the polarization beam splitter 1 via the attenuator 2 and the corner cube 3, is reflected by the polarization beam splitter 1, and is transmitted by the beam splitter 4 to enter the 1 / 4 wave plate 5.

[0099] The signal light emitted by the opposite laser terminal is received by the optical telescope, reflected by the fine tracking fast mirror, and enters the polarization beam splitter, and is transmitted through the polarization beam splitter 1. Most of the light is reflected by the beam splitter 4 to enter the communication receiving unit, and a small part is transmitted to enter the 1 / 4 wave plate 5.

[0100] The fast axis direction of the 1 / 4 wave plate 5 is at an angle of 45° with the horizontal direction. The emitted light beams and received light beams in different linear polarization states become circularly polarized light of different handedness after passing through the 1 / 4 wave plate. One is left-handed circularly polarized light, and the other is right-handed circularly polarized light. The circularly polarized light of different handedness passes through the liquid crystal polarization grating 6, and the deflection directions are opposite. After passing through the converging lens 7, the imaging positions on the monitoring detector 8 are inconsistent. The monitoring detector 8 outputs two spot position images at high speed through windowing, thereby realizing simultaneous monitoring of the laser communication emitting light path and the receiving light path by one detector.

[0101] In the embodiment, the emitted laser is S linearly polarized light, the center wavelength is 1550.12 nm, and the emitted power is 2 W; the received laser is P linearly polarized light, the center wavelength is 1550.92 nm, and the communication receiving sensitivity is -50 dBm.

[0102] In the embodiment, the polarizing beamsplitter 1 is a polarizing beamsplitting prism, which reflects S linearly polarized light and transmits P linearly polarized light, and the extinction ratio is >1000:1.

[0103] In the embodiment, the attenuation ratio of the attenuator 2 is about 100:1.

[0104] In the embodiment, the corner cube 3 is RAP110 of Nanjing Yibo Optoelectronics, the working waveband is 350 nm-2000 nm, the machining precision is ±1'', and the surface precision is λ / 10.

[0105] In the embodiment, the reflection-transmission ratio of the beamsplitter 4 is 4:1.

[0106] In the embodiment, the 1 / 4 waveplate 5 is a liquid crystal 1 / 4 waveplate, and the phase delay is π / 2 when no electricity is added.

[0107] In the embodiment, the liquid crystal polarization grating 6 has a size of 25 mm×25 mm, the applicable waveband is 1550 nm±2 nm, and the deflection direction is ±0.1°.

[0108] In the embodiment, the converging lens 7 is F810FC-1550, NA=0.24, and f=37 mm.

[0109] In the embodiment, the monitoring detector 8 is an InGaAs infrared focal plane detector, the response waveband is 900 nm-1700 nm, the pixel size is 15 μm×15 μm, the pixel number is 640×512; two 32×32 windows can be opened, and the windowed readout frame frequency is 2 kHz.

[0110] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can make equivalent replacements or changes to the technical scheme and the inventive concept of the present application within the technical scope disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A novel laser communication transceiving beam integrated monitoring system, characterized in that: The application relates to a laser monitoring device, which comprises a polarization beam splitter (1) arranged on the output light path of a laser to be monitored, an attenuator (2), a corner cube (3), a beam splitter (4), a 1 / 4 wave plate (5), a liquid crystal polarization grating (6), a converging lens (7) and a monitoring detector (8) arranged on the transmission light path of the polarization beam splitter (1) in sequence, the corner cube (3) is a retroreflector, and the fast axis direction of the 1 / 4 wave plate (5) forms a 45-degree angle with the horizontal direction. The reflection light path of the polarization beam splitter (1) is used for emitting the optical signal of the laser to be monitored and receiving the optical signal of the opposite laser terminal, the emitting beam and the receiving beam are linearly polarized light beams with mutually perpendicular polarization directions, the polarization beam splitter (1) is used for polarizing and isolating the receiving beam and the emitting beam, the corner cube (3) is used for making the entering beam turn by 180 degrees, the reflection light path of the beam splitter (4) is used for communication reception, the 1 / 4 wave plate (5) is used for changing the emitting beam and the receiving beam with different linear polarization states into circularly polarized light beams with different rotary properties, the circularly polarized light beams include left-handed circularly polarized light and right-handed circularly polarized light, the liquid crystal polarization grating (6) is used for spatially separating the circularly polarized light beams with different rotary properties, the converging lens (7) is used for converging to obtain emitting beam light spots and receiving beam light spots with different positions, and the monitoring detector (8) outputs the position images of the emitting beam light spots and the receiving beam light spots through windowing high speed.

2. The novel laser communication transceiver beam integrated monitoring system according to claim 1, characterized in that: A fast reflector, a 1 / 4 wave plate for emission and reception and an optical telescope are arranged on the reflection light path of the polarization beam splitter (1) in sequence. The optical signal output by the laser to be monitored is modulated, amplified, collimated by a collimator and aimed at the fast reflector in advance to obtain the emitting beam, and the emitting beam is reflected to the polarization beam splitter (1), the emitting beam passes through the fast reflector, the 1 / 4 wave plate for emission and reception and the optical telescope in sequence after being reflected by the polarization beam splitter (1) and is emitted to the opposite laser terminal, and the optical signal of the opposite laser terminal passes through the optical telescope, the 1 / 4 wave plate for emission and reception and the fast reflector in sequence to obtain the receiving beam and enter the polarization beam splitter (1). The polarization beam splitter (1) can also combine the emitting beam and the receiving beam.

3. The novel laser communication transceiver beam integrated monitoring system according to claim 1, characterized in that: The attenuator (2) can control the intensity of the emitting beam entering the monitoring detector (8) to prevent the emitting beam from saturating the monitoring detector.

4. The novel laser communication transceiver beam integrated monitoring system according to claim 1, characterized in that: The corner cube (3) is a corner cube prism.

5. The novel laser communication transceiver beam integrated monitoring system according to claim 1, wherein: The working wavelengths of the beam splitter (4), the 1 / 4 wave plate (5), the liquid crystal polarization grating (6) and the monitoring detector (8) are the same as the communication wavelength, the reflection and transmission ratio of the beam splitter (4) is related to the communication reception sensitivity and the detection sensitivity of the monitoring detector (8), and the deflection angle of the liquid crystal polarization grating (6) is related to the telescope magnification, the maximum pre-aiming angle and the tracking precision.

6. The novel laser communication transceiver beam integrated monitoring system according to claim 1, wherein: The converging lens (7) is a single-piece convex lens or a combined lens group.

7. The novel laser communication transceiver beam integrated monitoring system according to claim 1, wherein: The monitoring detector (8) is a visible light camera or an infrared focal plane detector, and the monitoring detector (8) can simultaneously realize 2-window windowing and high-speed output.

8. A novel laser communication transceiving beam integrated monitoring method, characterized in that: The method comprises the following steps: S1, linearly polarized light emitted by a laser to be monitored passes through modulation, amplification, collimation of a collimator, and is reflected by a fast aiming mirror to obtain an emission beam, a part of the emission beam is reflected by a polarizing beam splitter (1) and then transmitted to an opponent laser terminal via a precision tracking fast mirror and an optical telescope, and another part of the emission beam is reflected by the polarizing beam splitter (1) and then sequentially passes through an attenuator (2) and a corner cube (3) to return to the polarizing beam splitter (1) and then is reflected by the polarizing beam splitter (1) to a beam splitter (4) and then is transmitted into a 1 / 4 wave plate (5); The light signal emitted by the opponent laser terminal is received by the optical telescope and reflected by the precision tracking fast mirror to obtain a received beam, a part of the received beam is transmitted through the polarizing beam splitter (1) and then reflected by the beam splitter (4) into a communication receiving unit, and another part of the received beam is transmitted through the beam splitter (4) into the 1 / 4 wave plate (5); S2, the emission beam and the received beam in different linear polarization states become different circularly polarized light after passing through the 1 / 4 wave plate (5), the different circularly polarized light includes left-handed circularly polarized light and right-handed circularly polarized light, the different circularly polarized light passes through a liquid crystal polarization grating (6) to make the deflection directions opposite and then passes through a converging lens (7) to finally obtain two light spots with different imaging positions on a monitoring detector (8), and the monitoring detector (8) outputs position images of the two light spots at high speed through windowing to monitor the communication emission path and the receiving path of the laser of the laser to be monitored.

9. The novel laser communication transceiver beam integrated monitoring method according to claim 8, characterized in that: In step S2, the fast axis direction of the 1 / 4 wave plate (5) forms a 45° angle with the horizontal direction, the horizontal linearly polarized light becomes left-handed circularly polarized light after passing through the 1 / 4 wave plate (5), and the Jones matrix is: wherein j is an imaginary number; The vertical linearly polarized light becomes right-handed circularly polarized light after passing through the 1 / 4 wave plate (5), and the Jones matrix is:

10. The novel laser communication transceiver beam integrated monitoring method according to claim 8, characterized in that: In step S2, when the left-handed circularly polarized light is incident on the liquid crystal polarization grating (6), the electric field is transformed into: where E out is the output light energy, Γ represents the phase retardation of light passing through a liquid crystal layer with a thickness of d, f x is the spatial frequency; P is the grating orientation period; Γ = 2π(n e -n o )d / λ; where n e is the refractive index of the abnormal light, n o is the refractive index of the normal light, and λ is the wavelength. When the phase delay Γ is π, All the light energy is in the +1 order, at this time, the incident left-handed circularly polarized light becomes the outgoing right-handed circularly polarized light, and the deflection angle to the left is θ = arcsin (λ / P); When the incident right-handed circularly polarized light passes through the liquid crystal polarization grating (6) with a phase delay of π, it becomes left-handed circularly polarized light and deflects to the right by an angle θ.

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