CN106125445B - Liquid crystal optical phased array diffraction efficiency optimization system and method - Google Patents

Liquid crystal optical phased array diffraction efficiency optimization system and method Download PDF

Info

Publication number
CN106125445B
CN106125445B CN201610804695.8A CN201610804695A CN106125445B CN 106125445 B CN106125445 B CN 106125445B CN 201610804695 A CN201610804695 A CN 201610804695A CN 106125445 B CN106125445 B CN 106125445B
Authority
CN
China
Prior art keywords
liquid crystal
phased array
light
voltage
laser
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CN201610804695.8A
Other languages
Chinese (zh)
Other versions
CN106125445A (en
Inventor
汪相如
许剑华
吴亮
谭庆贵
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University of Electronic Science and Technology of China
Original Assignee
University of Electronic Science and Technology of China
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University of Electronic Science and Technology of China filed Critical University of Electronic Science and Technology of China
Priority to CN201610804695.8A priority Critical patent/CN106125445B/en
Publication of CN106125445A publication Critical patent/CN106125445A/en
Application granted granted Critical
Publication of CN106125445B publication Critical patent/CN106125445B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
    • G02F1/292—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection by controlled diffraction or phased-array beam steering

Landscapes

  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Liquid Crystal (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)

Abstract

The invention discloses a system and a method for optimizing diffraction efficiency of a liquid crystal optical phased array, which are particularly based on the collection of reflected light of a triangular cone, and can ensure that the position of a main lobe light spot of the reflected light in a CCD array surface is kept unchanged no matter how the angle of the liquid crystal phased array is adjusted, so that additional errors caused by readjusting a light path can be saved, and most of energy of grating lobes can be collected at the same time; and the diffraction efficiency of the liquid crystal phased array can be calculated by calculating the ratio of the main spot to all main lobes and the deleting lobes in the image collected by the CCD, the SPGD algorithm iteration is carried out until the loading voltage of all the electrodes meets the condition that the diffraction efficiency reaches the maximum value, the high efficiency of the diffraction efficiency of the liquid crystal phased array can be realized, the optimization can be carried out quickly, and the problem of the existing wavefront-free detection system is solved.

Description

Liquid crystal optical phased array diffraction efficiency optimization system and method
Technical Field
The invention belongs to the field of liquid crystal optoelectronic devices, and particularly relates to a liquid crystal optical phased array technology.
Background
The liquid crystal optical phased array technology is an inertia-free, multifunctional, real-time and programmable electric control beam scanning technology. The core device adopts nematic liquid crystal as an electro-optic material for phase modulation, has the physical characteristics of low driving voltage, large phase modulation depth and the like, has the advantages of light weight, small size, low power consumption, easy realization of a microelectronic control circuit and the like, solves the problems of rapid pointing, flexible control and space scanning of laser beams, and ensures that the electro-optic system has higher integration level, stronger flexible control capability and lower manufacturing cost. However, due to factors such as a return stroke area and process errors, the diffraction efficiency of the liquid crystal optical phased array is reduced, and therefore insertion loss of an optical path of the system is increased.
The method for optimizing the diffraction efficiency of the liquid crystal optical phased array is mainly divided into two types, namely an adaptive optical method with wave front detection and an adaptive optical method without wave front detection.
The method comprises the following steps: the method comprises the steps of loading an initial voltage code, obtaining interference fringes through shearing an interference light path, recording the fringes by using a CCD camera, solving a wave front from the fringes by using a wave front reconstruction algorithm, comparing the measured wave front with an ideal linear inclined wave front, adjusting the voltage code to enable the measured wave front to be gradually close to the ideal wave front, continuously iterating, and finally obtaining optimal wave control data to enable the wave front to be closest to the ideal wave front.
The wavefront-free detection method comprises the following steps: light spots of light beams passing through the liquid crystal phased array in a far field are collected through the CCD, voltage is continuously adjusted through a corresponding random optimization algorithm, and iterative optimization is carried out until the diffraction efficiency of the light beams collected by the CCD is the highest.
The wavefront detection system has the defects that the optical path is complex, the optical aperture is limited, and the spatial high-frequency light wave cannot be collected, so that the wavefront inversion has larger errors. In the wavefront-free detection method, in order to collect all diffraction order light spots of the whole far field, the light spots are often required to be irradiated to a scattering surface (white board), and then image data collection is carried out on the whole surface by using a CCD (charge coupled device) and a lens, but the scattering degree of the scattering surface cannot be guaranteed to be the same by large-area secondary scattering collection, and the scattering degree is different under the condition of different angles, so that the light power distribution of secondary scattering cannot be equivalent to the actual laser power distribution, and a great error is brought to the system; meanwhile, if a method of collecting diffracted light by using a direct lens is adopted, the direction angle of a beam which can be optimized is limited by the aperture of the lens.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a diffraction efficiency optimization system of a liquid crystal optical phased array.
The specific technical scheme of the invention is as follows: a diffraction efficiency optimization system of a liquid crystal optical phased array specifically comprises: the device comprises a laser, a polarization splitting prism, a Faraday polarimeter, a liquid crystal optical phased array, a triangular cone, a lens, a CCD and a control center; the control center includes: a controller and a wave controller;
the laser is connected to the polarization beam splitter prism, the direction of laser output by the laser is consistent with the direction of S light of the polarization beam splitter prism, the S polarized light is transmitted along a light path through the Faraday polarimeter, the polarization direction rotates by 45 degrees, the rotated light beam vertically enters the liquid crystal optical phased array, and the polarization direction of incident laser is consistent with the direction of an optical axis of the liquid crystal optical phased array;
the triangular cone is placed in the center of a main lobe light spot of a far field after deflection, laser light coming out of the liquid crystal optical phased array is reflected by the triangular cone and then returns to the liquid crystal phased array from the original path, and because the polarization state of the reflected light does not change after the polarization maintaining processing of the triangular cone, the reflected laser beam returns along the original path, the reflected light enters the Faraday polarimeter, and the Faraday polarimeter rotates the polarization direction of the reflected light by 45 degrees along the light transmission direction in an anticlockwise mode, so that the reflected light reaches the polarization splitting prism, is consistent with the P direction of the polarization splitting prism, completely passes through the Fourier lens, reaches the CCD detector at a focal plane, is converted into an electric signal, and is transmitted to a controller in the control center;
the main controller is used for processing the received electric signals to generate optimized voltage;
the wave controller is used for loading the voltage codes generated by the main controller into the liquid crystal array controller in a frame-by-frame mode, and the liquid crystal array controller converts the voltage codes into corresponding voltages, loads the voltages onto electrodes corresponding to the liquid crystal optical phased array and converts the voltages into laser signals to transmit the laser signals to the triangular cone.
Based on the diffraction efficiency optimization system of the liquid crystal optical phased array, the invention also provides a diffraction efficiency optimization method of the liquid crystal optical phased array, which specifically comprises the following steps:
s1, a laser is connected to a polarization beam splitter prism, the direction of laser output by the laser is consistent with the direction of S light of the polarization beam splitter prism, the S polarized light is transmitted along a light path through a Faraday polarimeter, the polarization direction rotates by 45 degrees, the rotated light beam vertically enters a liquid crystal optical phased array, and the polarization direction of incident laser is consistent with the direction of an optical axis of the liquid crystal optical phased array;
s2, the triangular cone is placed in the center of a main lobe light spot of a far field after deflection, laser light coming out of the liquid crystal optical phased array is reflected by the triangular cone and then returns to the liquid crystal phased array from the original path, and the polarization state of the reflected light does not change after the triangular cone is subjected to polarization maintaining processing, the reflected laser beam returns along the original path, the reflected light enters the Faraday polarimeter, and the Faraday polarimeter rotates the polarization direction of the reflected light by 45 degrees along the light transmission direction in an anticlockwise mode, so that the reflected light is consistent with the P direction of the polarization beam splitter prism, completely passes through the polarization beam splitter, enters the Fourier lens, reaches the CCD detector at the focal plane, is converted into an electric signal, and is transmitted to a controller in the control center;
s3, the main controller processes the received electric signals and generates optimized voltage;
and S4, the wave controller loads the voltage codes generated by the main controller into the liquid crystal array controller in a frame-by-frame manner, and the liquid crystal array controller converts the voltage codes into corresponding voltages, loads the voltages onto electrodes corresponding to the liquid crystal optical phased array, converts the voltages into laser signals, transmits the laser signals to the triangular cone, reflects the laser signals by the triangular cone and returns the laser signals to the liquid crystal phased array through an original path.
Further, the specific process of processing the received electrical signal in step S3 is as follows: the main controller converts acquired image data into a gray scale image, Kalman filtering is performed, median filtering is performed, air disturbance and CCD acquired noise are filtered through filtering, a filtered result is subjected to self-adaptive binarization to obtain a binary image, canny edge detection is performed on the binary image, connected bodies are calculated, the number of the connected bodies is the number of light spots acquired by the CCD, the sum of gray scale values of each pixel in each light spot is calculated to serve as the energy of each light spot, the largest energy is a main-lobe light spot, and the rest of the energy is a grating lobe;
the diffraction efficiency is obtained by calculating the ratio of the main lobe energy to all the energies, and the formula is as follows:
Figure BDA0001110259480000031
wherein E ismainEnergy of the main lobe, EtotalThe sum of the main lobe and all acquired side lobes:
Figure BDA0001110259480000032
Figure BDA0001110259480000033
wherein S is the region where the main lobe is located, S is the whole image, grayi,jIs the gray value corresponding to the pixel coordinate.
Further, the specific process of generating the optimized voltage in step S3 is as follows:
s30. initializing, current electrode z is 1, n is 1, electrode voltage is μz (n)；
S31, calculating a voltage value mu according to an angle to be deflectedz (1)While generating a random voltage Δ μz (1)；
S32, converting the voltage value muz (1)+Δμz (1)Converting the voltage code into a voltage code and sending the voltage code to the liquid crystal optical phased array;
s33, collecting images by using CCD, filtering and calculating Jz+ (1)；
S34, converting the voltage value muz (1)-Δμz (1)Converting the voltage code into a voltage code and sending the voltage code to the liquid crystal optical phased array;
s35, collecting images by using CCD, filtering and calculating Jz- (1)；
S36, calculating the difference value delta J of the two evaluation resultsz (1)＝Jz+ (1)-Jz- (1)；
S37, calculating the voltage muz (2)＝μz (1)+γ·μz (1)·ΔJz (1)Converting the voltage value into a voltage code and transmitting the voltage code until delta Jz (n)And stopping iterating the voltage value of the electrode when the voltage value is 0, finishing the current optimization of the electrode, and entering the iteration optimization of the next electrode.
The invention has the beneficial effects that: the diffraction efficiency optimization system and method of the liquid crystal optical phased array are based on the collection of reflected light of the triangular cone, and the position of a main lobe light spot of the reflected light in a CCD array surface can be kept unchanged no matter how the angle of the liquid crystal phased array is adjusted, so that additional errors caused by readjustment of a light path can be omitted, and most of grating lobe energy can be collected at the same time; and the diffraction efficiency of the liquid crystal phased array can be calculated by calculating the ratio of the main spot to all main lobes and the deleting lobes in the image collected by the CCD, the SPGD algorithm iteration is carried out until the loading voltage of all the electrodes meets the condition that the diffraction efficiency reaches the maximum value, the high efficiency of the diffraction efficiency of the liquid crystal phased array can be realized, the optimization can be carried out quickly, and the problem of the existing wavefront-free detection system is solved.
Drawings
FIG. 1 is a structural block diagram of a liquid crystal optical phased array diffraction efficiency optimization system.
FIG. 2 is a schematic diagram of light spots collected by a CCD of the liquid crystal optical phased array efficiency optimization system.
FIG. 3 is a flow chart of image processing for a liquid crystal optical phased array efficiency optimization system.
FIG. 4 is a SPGD algorithm processing flow chart of the liquid crystal optical phased array efficiency optimization system.
Detailed Description
The embodiments of the present invention will be further described with reference to the accompanying drawings.
As shown in fig. 1, the present invention provides a system for optimizing efficiency of a liquid crystal optical phased array, which specifically includes: the device comprises a laser, a polarization splitting prism, a Faraday polarimeter, a liquid crystal optical phased array, a triangular cone, a lens, a CCD and a control center; the control center includes: a controller and a wave controller;
the laser is connected to the polarization beam splitter prism, the laser of laser output is unanimous with the S light direction of polarization beam splitter prism, and S polarisation passes through Faraday polarimeter, along the light path transmission, and the polarization direction takes place 45 degrees rotations, and the light beam after the rotation perpendicularly gets into liquid crystal optics phased array to the polarization direction of incident laser is unanimous with the optical axis direction of liquid crystal optics phased array.
The laser wavelength is chosen here depending on the operating wavelength of the liquid crystal phased array to be tested.
The triangular cone is placed at the center of a main lobe light spot of a far field after deflection, the liquid crystal optical phased array is returned from the original path after laser coming out of the liquid crystal optical phased array is reflected by the triangular cone, and because the triangular cone is subjected to polarization maintaining processing, the polarization state of reflected light does not change, the reflected laser beam returns along the original path, reflected light enters the Faraday polarimeter, the Faraday polarimeter rotates the polarization direction of the reflected light along the light transmission direction by 45 degrees anticlockwise, and therefore when the reflected light reaches the polarization splitting prism, the reflected light is consistent with the P direction of the polarization splitting prism, completely passes through the polarization splitting prism, enters the Fourier lens, reaches a CCD detector (see figure 2) at a focal plane, is converted into an electric signal, and is transmitted to a controller in the control center. The CCD can adopt a universal CCD image sensor, and has no particularly strict requirements on caliber and resolution.
The main controller is used for processing the received electric signals to generate optimized voltage;
the wave controller is used for loading the voltage codes generated by the main controller into the liquid crystal array controller in a frame-by-frame mode, and the liquid crystal array controller converts the voltage codes into corresponding voltages, loads the voltages onto electrodes corresponding to the liquid crystal optical phased array and converts the voltages into laser signals to transmit the laser signals to the triangular cone.
It can be seen that the optimized data is derived from the image acquired by the CCD, and the diffraction efficiency of the liquid crystal optical phased array is calculated through the image, so that an evaluation basis of the performance is provided for the optimization of the SPGD algorithm. The SPGD algorithm converts the optimized voltage into a voltage code that can be recognized by the liquid crystal optical phased array controller.
The invention provides a method for optimizing diffraction efficiency of a liquid crystal optical phased array, which specifically comprises the following steps:
the method comprises the following steps that S1, a laser is connected to a polarization beam splitter prism, the direction of laser output by the laser is consistent with the direction of S light of the polarization beam splitter prism, the S polarized light is transmitted along a light path through a Faraday polarimeter, the polarization direction rotates by 45 degrees, a rotated light beam vertically enters a liquid crystal optical phased array, and the polarization direction of incident laser is consistent with the direction of an optical axis of the liquid crystal optical phased array.
After passing through the liquid crystal optical phased array, the light beam transmission direction is angularly deflected, wherein the deflection angle is determined by wave control data of the liquid crystal optical phased array, and the wave control data is a physical quantity to be optimized by the system.
And S2, the triangular cone is placed in the center of a main lobe light spot of a far field after deflection, laser light coming out of the liquid crystal optical phased array is reflected by the triangular cone and then returns to the liquid crystal phased array from the original path, and the polarization state of the reflected light does not change after the triangular cone is subjected to polarization maintaining treatment, the reflected laser beam returns along the original path, the reflected light enters the Faraday polarimeter, and the Faraday polarimeter rotates the polarization direction of the reflected light by 45 degrees along the light transmission direction in an anticlockwise mode, so that the reflected light is consistent with the P direction of the polarization beam splitter prism when reaching the polarization beam splitter prism, completely passes through the polarization beam splitter, enters the Fourier lens, reaches the CCD detector at the focal plane, is converted into an electric signal and is transmitted to a controller in the control center.
Due to the process defects of the liquid crystal optical phased array and the existence of a return stroke area, the phase shift distribution is not ideal, and grating lobes exist in other periodic positions besides a main lobe in a far field area. Due to the reversible characteristic of the phase shift characteristic of the phased array, after the reflected light passes through the liquid crystal optical phased array, the main lobe direction is the angle vertical to the liquid crystal optical phased array, namely: the 0 ° direction of the optical axis of the system, as shown in fig. 1; and the optical characteristic is independent of the angle at which the liquid crystal optical phased array is loaded.
When the liquid crystal optical phased array loads wave control data with different pointing angles, the main lobe of a reflected light beam is always positioned at the center of the CCD, the distance between grating lobes is the wave control angle, and the optimization system does not need to perform complex light path readjustment under the condition that the device is pointed by different wave beams.
S3, the main controller processes the received electric signals and generates optimized voltage;
and S4, the wave controller loads the voltage codes generated by the main controller into the liquid crystal array controller in a frame-by-frame manner, and the liquid crystal array controller converts the voltage codes into corresponding voltages, loads the voltages onto electrodes corresponding to the liquid crystal optical phased array, converts the voltages into laser signals, transmits the laser signals to the triangular cone, reflects the laser signals by the triangular cone and returns the laser signals to the liquid crystal phased array through an original path.
Here, the specific process of processing the received electrical signal in step S3 is as follows: the main controller converts acquired image data into a gray scale image, Kalman filtering is performed, median filtering is performed, air disturbance and CCD acquired noise are filtered through filtering, a filtered result is subjected to self-adaptive binarization to obtain a binary image, canny edge detection is performed on the binary image, connected bodies are calculated, the number of the connected bodies is the number of light spots acquired by the CCD, the sum of gray scale values of each pixel in each light spot is calculated to serve as the energy of each light spot, the largest energy is a main-lobe light spot, and the rest of the energy is a grating lobe; and collecting diffraction light spots through a CCD (charge coupled device), wherein the ratio of the collected main lobe light spots to all main lobes and deleting lobes is used as an evaluation function of the SPGD algorithm. As shown in fig. 3:
the diffraction efficiency is obtained by calculating the ratio of the main lobe energy to all the energies, and the formula is as follows:
Figure BDA0001110259480000061
wherein E ismainEnergy of the main lobe, EtotalIs the sum of the main lobe and all the acquired side lobes.
Figure BDA0001110259480000062
Wherein s is the region gray where the light lobe is locatedi,jIs the gray value corresponding to the pixel coordinate。
The process of generating the optimized voltage specifically uses an SPGD (random parallel gradient descent) algorithm, specifically, wave control data of each electrode are subjected to one-by-one iterative optimization, and the SPGD algorithm has a theoretical formula:
Figure BDA0001110259480000063
Jz (n)＝η(n)(4)
ΔJz n＝Jz+ (n)-Jz (n)(5)
in the formula: z is the antenna number, mu, of the liquid crystal phased array elementz (n)＝{μz1 (n),...,μzj (n)，μzN (n)And muz (n+1)＝{μz1 (n+1),...,μzj (n+1),μzN (n+1)N and N +1 times of closed loop iterations, respectively, are the correction voltage vectors applied to the N drivers of the liquid crystal optical phased array, where μzk (n)Representing the voltage applied to the kth electrode at the nth time; gamma is a gain constant; Δ μz (n)＝{Δμz1 (n),...,Δμzj (n),ΔμzN (n)Is the random perturbation voltage vector applied on each electrode at the nth iteration, wherein, the value of the random perturbation voltage vector is delta muzk (n)Representing the amount of change of the voltage loaded to the kth electrode at the nth time compared with the previous time, which are independent of each other and have the same Bernoulli distribution, i.e. the amplitudes of the components are equal to | muzj|＝σPr(Δμzj± σ ═ 0.5, where Δ μzkAs a function of the distribution of the voltage applied to the kth electrode.
System performance evaluation function:
Figure BDA0001110259480000064
wherein the content of the first and second substances,
Figure BDA0001110259480000065
the voltage applied to the liquid crystal optical phased array is muz (n)+Δμz (n)The efficiency of the diffraction at the time of diffraction,
Figure BDA0001110259480000066
the voltage applied to the liquid crystal optical phased array is muz (n)-Δμz (n)Diffraction efficiency of the light beam.
Fig. 4 is an execution flow chart of the SPGD algorithm of the liquid crystal optical phased array efficiency optimization system according to the embodiment of the present invention, where the execution flow of the SPGD algorithm is as follows:
the specific process is as follows:
s30. initializing, current electrode z is 1, n is 1, electrode voltage is μz (n)；
S31, calculating a voltage value mu according to an angle to be deflectedz (1)While generating a random voltage Δ μz (1)；
S32, converting the voltage value muz (1)+Δμz (1)Converting the voltage code into a voltage code and sending the voltage code to the liquid crystal optical phased array;
s33, collecting images by using CCD, filtering and calculating Jz+ (1)；
S34, converting the voltage value muz (1)-Δμz (1)Converting the voltage code into a voltage code and sending the voltage code to the liquid crystal optical phased array;
s35, collecting images by using CCD, filtering and calculating Jz- (1)；
S36, calculating the difference value delta J of the two evaluation resultsz (1)＝Jz+ (1)-Jz- (1)；
S37, calculating the voltage muz (2)＝μz (1)+γ·μz (1)·ΔJz (1)Converting the voltage value into a voltage code and transmitting the voltage code until delta Jz (n)And stopping iterating the voltage value of the electrode when the voltage value is 0, finishing the current optimization of the electrode, and entering the iteration optimization of the next electrode. The advantages of each electrodeThe procedure is as above until all electrode optimization is completed.
It can be seen that, in the system and method provided by this embodiment, after a laser beam emitted by a laser is deflected by a liquid crystal phased array, the laser is reflected by a triangular cone along an original path, and then the angle is deflected back by the liquid crystal phased array, so that it is ensured that no matter how the liquid crystal phased array is deflected, the position of a main lobe light spot of the reflected light in a CCD remains unchanged, and meanwhile, efficiency iterative calculation is performed on the collected light beam through an SPGD algorithm until the loading voltages of all electrodes meet the maximum diffraction efficiency, and therefore, the high efficiency of the diffraction efficiency of the liquid crystal phased array can be realized, and the rapid optimization can be realized.

Claims (4)

1. A diffraction efficiency optimization system of a liquid crystal optical phased array specifically comprises: the device comprises a laser, a polarization splitting prism, a Faraday polarimeter, a liquid crystal optical phased array, a triangular cone, a lens, a CCD and a control center; the control center includes: a controller and a wave controller;
the laser is connected to the polarization beam splitter prism, the direction of laser output by the laser is consistent with the direction of S light of the polarization beam splitter prism, the S polarized light is transmitted along a light path through the Faraday polarimeter, the polarization direction rotates by 45 degrees, the rotated light beam vertically enters the liquid crystal optical phased array, and the polarization direction of incident laser is consistent with the direction of an optical axis of the liquid crystal optical phased array;
the triangular cone is placed in the center of a main lobe light spot of a far field after deflection, laser light coming out of the liquid crystal optical phased array is reflected by the triangular cone and then returns to the liquid crystal phased array from the original path, and because the polarization state of the reflected light does not change after the polarization maintaining processing of the triangular cone, the reflected laser beam returns along the original path, the reflected light enters the Faraday polarimeter, and the Faraday polarimeter rotates the polarization direction of the reflected light by 45 degrees along the light transmission direction in an anticlockwise mode, so that the reflected light reaches the polarization splitting prism, is consistent with the P direction of the polarization splitting prism, completely passes through the Fourier lens, reaches the CCD detector at a focal plane, is converted into an electric signal, and is transmitted to a controller in the control center;
the controller is used for processing the received electric signals to generate optimized voltage;
the wave controller is used for loading the voltage codes generated by the main controller into the liquid crystal array controller in a frame-by-frame mode, and the liquid crystal array controller converts the voltage codes into corresponding voltages, loads the voltages onto electrodes corresponding to the liquid crystal optical phased array and converts the voltages into laser signals to transmit the laser signals to the triangular cone.
2. A diffraction efficiency optimization method of a liquid crystal optical phased array based on the system of claim 1 specifically comprises the following steps:
s1, a laser is connected to a polarization beam splitter prism, the direction of laser output by the laser is consistent with the direction of S light of the polarization beam splitter prism, the S polarized light is transmitted along a light path through a Faraday polarimeter, the polarization direction rotates by 45 degrees, the rotated light beam vertically enters a liquid crystal optical phased array, and the polarization direction of incident laser is consistent with the direction of an optical axis of the liquid crystal optical phased array;
s2, the triangular cone is placed in the center of a main lobe light spot of a far field after deflection, laser light coming out of the liquid crystal optical phased array is reflected by the triangular cone and then returns to the liquid crystal phased array from the original path, and the polarization state of the reflected light does not change after the triangular cone is subjected to polarization maintaining processing, the reflected laser beam returns along the original path, the reflected light enters the Faraday polarimeter, and the Faraday polarimeter rotates the polarization direction of the reflected light by 45 degrees along the light transmission direction in an anticlockwise mode, so that the reflected light is consistent with the P direction of the polarization beam splitter prism, completely passes through the polarization beam splitter, enters the Fourier lens, reaches the CCD detector at the focal plane, is converted into an electric signal, and is transmitted to a controller in the control center;
s3, the main controller processes the received electric signals and generates optimized voltage;
and S4, the wave controller loads the voltage codes generated by the main controller into the liquid crystal array controller in a frame-by-frame manner, and the liquid crystal array controller converts the voltage codes into corresponding voltages, loads the voltages onto electrodes corresponding to the liquid crystal optical phased array, converts the voltages into laser signals, transmits the laser signals to the triangular cone, reflects the laser signals by the triangular cone and returns the laser signals to the liquid crystal phased array through an original path.
3. The method for optimizing the diffraction efficiency of the liquid crystal optical phased array as claimed in claim 2, wherein the step S3 is to process the received electrical signal by: the main controller converts acquired image data into a gray scale image, Kalman filtering is performed, median filtering is performed, air disturbance and CCD acquired noise are filtered through filtering, a filtered result is subjected to self-adaptive binarization to obtain a binary image, canny edge detection is performed on the binary image, connected bodies are calculated, the number of the connected bodies is the number of light spots acquired by the CCD, the sum of gray scale values of each pixel in each light spot is calculated to serve as the energy of each light spot, the largest energy is a main-lobe light spot, and the rest of the energy is a grating lobe;
the diffraction efficiency is obtained by calculating the ratio of the main lobe energy to all the energies, and the formula is as follows:
Figure FDA0002349686710000021
wherein E ismainEnergy of the main lobe, EtotalThe sum of the main lobe and all acquired side lobes:
Figure FDA0002349686710000022
Figure FDA0002349686710000023
wherein S is the region where the main lobe is located, S is the whole image, grayi,jIs the gray value corresponding to the pixel coordinate.
4. The method of claim 3, wherein the diffraction efficiency of the liquid crystal optical phased array is optimized,
the specific process of generating the optimized voltage in step S3 is as follows:
s30, initializationWhen the current electrode z is 1, n is 1, and the electrode voltage is μz (n)；
S31, calculating a voltage value mu according to an angle to be deflectedz (1)While generating a random voltage Δ μz (1)；
S32, converting the voltage value muz (1)+Δμz (1)Converting the voltage code into a voltage code and sending the voltage code to the liquid crystal optical phased array;
s33, collecting images by using CCD, filtering and calculating Jz+ (1)；
S34, converting the voltage value muz (1)-Δμz (1)Converting the voltage code into a voltage code and sending the voltage code to the liquid crystal optical phased array;
s35, collecting images by using CCD, filtering and calculating Jz- (1)；
S36, calculating the difference value delta J of the two evaluation resultsz (1)＝Jz+ (1)-Jz- (1)；
S37, calculating the voltage muz (2)＝μz (1)+γ·μz (1)·ΔJz (1)Gamma is a gain constant, converts the voltage value into a voltage code, and transmits,
up to Δ Jz (n)And stopping iterating the voltage value of the electrode when the voltage value is 0, finishing the current optimization of the electrode, and entering the iteration optimization of the next electrode.
CN201610804695.8A 2016-09-06 2016-09-06 Liquid crystal optical phased array diffraction efficiency optimization system and method Expired - Fee Related CN106125445B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201610804695.8A CN106125445B (en) 2016-09-06 2016-09-06 Liquid crystal optical phased array diffraction efficiency optimization system and method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201610804695.8A CN106125445B (en) 2016-09-06 2016-09-06 Liquid crystal optical phased array diffraction efficiency optimization system and method

Publications (2)

Publication Number Publication Date
CN106125445A CN106125445A (en) 2016-11-16
CN106125445B true CN106125445B (en) 2020-03-17

Family

ID=57271224

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201610804695.8A Expired - Fee Related CN106125445B (en) 2016-09-06 2016-09-06 Liquid crystal optical phased array diffraction efficiency optimization system and method

Country Status (1)

Country Link
CN (1) CN106125445B (en)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108050937B (en) * 2018-01-08 2019-07-16 浙江大学 The detection method and device of optical elements of large caliber intermediate frequency error
CN110068446B (en) * 2018-01-23 2020-11-13 舜宇光学（浙江）研究院有限公司 Diffraction efficiency testing method of image-based diffractive optical element
CN108363051B (en) * 2018-01-26 2021-09-21 北京航空航天大学 Self-adaptive calibration system for optical phased array light beam scanning
US11698445B2 (en) * 2018-09-04 2023-07-11 GM Global Technology Operations LLC Automotive Lidar with multi-spectral depth imaging and discrete scanning mechanism
CN109085558B (en) * 2018-09-21 2023-12-29 深圳市速腾聚创科技有限公司 Phased array laser radar and control method thereof
CN111612121B (en) * 2020-06-02 2023-04-18 电子科技大学 Optimization method for dynamic gain of liquid crystal microwave phased array antenna
CN113446963B (en) * 2021-06-08 2022-06-21 同济大学 Angle measuring system based on phased array and measuring method thereof
CN114815436B (en) * 2022-04-21 2023-05-19 电子科技大学 Optical phased array element mutual coupling compensation method based on neighborhood sampling principal component analysis

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5191339A (en) * 1992-03-05 1993-03-02 General Electric Company Phased-array antenna controller
CN102122096A (en) * 2010-12-21 2011-07-13 哈尔滨工业大学 Large-angle light beam deflection implementation device and deflection method thereof based on liquid crystal optical phased array
CN102122089A (en) * 2010-12-29 2011-07-13 哈尔滨工业大学 Liquid-crystal-optical-phased-array-based three-dimensional independent control methods for light beam focal points
CN103019258A (en) * 2012-11-28 2013-04-03 中国人民解放军装甲兵工程学院 Multi-target tracking indicating technology based on optical phased array and reverse optics
CN104865770A (en) * 2015-05-11 2015-08-26 电子科技大学 Method for achieving one-dimensional deflection and beam divergence angle scaling of laser beam based on optical phased array

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5191339A (en) * 1992-03-05 1993-03-02 General Electric Company Phased-array antenna controller
CN102122096A (en) * 2010-12-21 2011-07-13 哈尔滨工业大学 Large-angle light beam deflection implementation device and deflection method thereof based on liquid crystal optical phased array
CN102122089A (en) * 2010-12-29 2011-07-13 哈尔滨工业大学 Liquid-crystal-optical-phased-array-based three-dimensional independent control methods for light beam focal points
CN103019258A (en) * 2012-11-28 2013-04-03 中国人民解放军装甲兵工程学院 Multi-target tracking indicating technology based on optical phased array and reverse optics
CN104865770A (en) * 2015-05-11 2015-08-26 电子科技大学 Method for achieving one-dimensional deflection and beam divergence angle scaling of laser beam based on optical phased array

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
Liquid crystal optical phased array device with a fine steering precision of a few micro-radians;Xiangru Wang等;《Optics Communications》;20131101;全文 *
Modeling and design of an optimized liquid-crystal optical phased array;Xinghua Wang等;《JOURNAL OF APPLIED PHYSICS》;20051010;全文 *
Numerical optimization of the performance of nematic liquid crystal optical phased arrays;Scott R. Harris等;《PROCEEDINGS OF SPIE》;20031231;全文 *
液晶相控阵衍射效率的优化分析;赵祥杰等;《光学学报》;20131130;全文 *

Also Published As

Publication number Publication date
CN106125445A (en) 2016-11-16

Similar Documents

Publication Publication Date Title
CN106125445B (en) Liquid crystal optical phased array diffraction efficiency optimization system and method
CN109164662B (en) Beam deflection control method based on liquid crystal optical phased array
CA2802790C (en) Method and apparatus for determining a doppler centroid in a synthetic aperture imaging system
CN106371102B (en) Inverse Synthetic Aperture Laser Radar receiving system based on adaptive optics
CN109596227B (en) A kind of phase recovery detection system of the optical element intermediate frequency error of convolutional neural networks priori enhancing
CN111504953B (en) Terahertz time-domain spectrum target three-dimensional scattering imaging measurement method
CN103398777B (en) Method for modulating terahertz wave by utilizing light-operated dynamic optical element
CN104062098B (en) A kind of device and method of twin-line array CCD scanning imagery measuring beam quality
CN105954734B (en) Large-caliber laser radar optical axis monitoring device
CN107942338B (en) Multi-wavelength associated imaging system based on digital micromirror device
CN101614593A (en) A kind of reflecting pyramid wave-front sensor
CN102735349A (en) Apparatus for measuring multiple parameters of laser
CN104537656A (en) Detection method for decentered Gaussian beams emitted by fiber beam expanding collimating lens barrel
CN111141701A (en) Rapid super-resolution imaging method and system based on terahertz single pulse
WO2019159334A1 (en) Defect inspection device
CN111272284A (en) Large-caliber laser polarization characteristic measuring instrument
CN102243098A (en) In-situ test system of strong laser beam quality
CN1769855A (en) Cavity mirror misalignment monitoring system based on positive-branch confocal unstable resonator and monitoring method thereof
CN114322829B (en) Splicing main mirror common-phase error detection system based on dual-wavelength vortex light beam phase shift interference and working method thereof
CN112930475B (en) Method for determining the relative reflectivity of a measuring surface
CN110455418B (en) Super-structure lens array and method for correcting non-uniformity of infrared detector
WO2017208270A1 (en) Compact optical apparatus for laser radar sensors m hostile environments
CN111207910A (en) Spliced mirror common-phase error correction method based on dispersion fringe slope analysis
CN207923419U (en) A kind of parallel optical detection device and system
CN116047748A (en) Adaptive optical telescope wavefront control device based on variable resolution Hartmann

Legal Events

Date Code Title Description
C06 Publication
PB01 Publication
C10 Entry into substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant
CF01 Termination of patent right due to non-payment of annual fee
CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20200317

Termination date: 20210906