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Issue 10 ， 2017
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Combined radiometric calibration of ground-based large-aperture infrared photoelectric systems
Abstract：When infrared standard stars are used in radiation calibration for a ground-based large-aperture infrared photoelectric system, it can not determine the radiance responsivity of each pixel and shows a poor adaptability for non-uniformity of the system. To solve this problems, a combined radiometric calibration method based on infrared standard stars and the small-aperture blackbody was proposed. The infrared standard stars were taken as an outer reference source to calibrate the radiance responsivity of the Keywords：infrared photoelectric system;combined radiometric calibration;infrared standard stars;small-aperture blackbody;infrared radiation feature- 122
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Published：2020-08-13 -
Active correction of 1.23 m SiC mirror using bending mode
Abstract：As active correction of a large aperture SiC mirror with high stiffness is vulnerable to many calculation errors by direction least square method or free resonance method, this paper proposes a primary surface correction algorithm using bending mode to calculate and optimize the active force and to improve the correction capability. Firstly, a series of mathematical transformations were performed on the influence matrix of the primary mirror, and a set of orthogonal bending modes of primary mirror were obta Keywords：active optics;SiC mirror;aberration correction;bending mode;S-H sensor- 114
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Published：2020-08-13 -
Lateral positioning system for large aperture primary mirror
Abstract：To locate accurately a large aperture primary mirror with balance weight support and Whiffletree support in the primary mirror cell, a lateral positioning method for the large aperture primary mirror was proposed based on the kinematic constraint. The principle of kinematic constraint was introduced, a design scheme of lateral positioning system for the primary mirror was proposed including the selection of location points and the design of flexure hinges and location bases, and then a lateral positioning s Keywords：large aperture primary mirror;positioning;kinematic constraint;resonant frequency;surface profile- 88
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Published：2020-08-13 -
Seeing metrology of large aperture mirror of telescope
Abstract：To ensure the quality and efficiency of manufacturing and detecting large aperture optical systems, a method to improve the seeing metrological accuracy was proposed. By determining the wavefront slope with electronic autocollimators and a flat mirror, the relationship between slope information and mirror seeing was deduced. With the purpose to enhance the accuracy and to exceed the limit of only one autocollimator, three autocollimators were used to calibrate each other. To decrease errors, a hexapod platf Keywords：optical test;mirror seeing;large aperture optical system;Power Spectral Density(PSD);autocollimator- 103
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Published：2020-08-13 -
Adaptive optical wave-front processing algorithm based on FPGA
Abstract：A wave-front processing algorithm was proposed based on Field Programming Gate Array(FPGA) for improving computational complexity and real-time ability of adaptive optical systems. The reuse of core processing module was used to calculate a wave-front slope, and the decomposition of matrix and vector was used to calculate the wave-front restoration. Under the synchronization of pixel clock, the whole wave front was processed and the momentum required by an actuator was given. A piece of Virtex-4 LX80 FPGA w Keywords：adaptive optics;wave-front processing;wavefron sensor;Field Programmable Gate Array(FPGA)- 89
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Published：2020-08-13 -
Ground-based photoelectric surveillance for mid-high orbit target
Abstract：A ground-based photo-electronic surveillance system based on passive optical systems was investigated for improving its recognition ability and recognition efficiency for faint targets in mid-high orbits. Meanwhile, an optimized processing method for original images was presented to enhance the Signal to Noise Ratios(SNRs)of the faint targets and improve the system recognition efficiency. The optical reflection characteristics of orbital targets were analyzed and a optimized design scheme for the ground-bas Keywords：Geosynchronous Orbit (GEO);mid-high orbit;target recognition;photoelectric surveillance;Signal to Noise Ratio(SNR);image process- 108
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- 17
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Published：2020-08-13 -
Flexible passive support system for 2 m SiC reflective mirror
Abstract：To apply SiC mirror in a ground-based telescope, a flexible passive support system was designed on its high thermal expansion coefficient and high rigidity. In this system, a thin and long flexible rod was used in the axial support whiffletree structure and a flexure joint rod wad used in the lateral support structure. By which, the axial support structure and the lateral support structure could support the system respectively. This structure not only allows the primary mirror to be a good position and a sh Keywords：SiC reflective mirror;flexible;passive support system;whiffletree;A-frame- 121
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Published：2020-08-13 -
Position control technology of large aperture mirror based on hydraulic support
Abstract：The pitching rotation of a telescope will cause the relative displacement between a primary mirror and its cell, and the displacement will influence on the stabilizing image of a telescope. To correct the relative displacement of the primary mirror, a method for stabilizing images of the primary mirror was proposed based on a hydraulic support to control the displacement between primary mirror and cell. A 1.23 m SiC mirror in our lab was used to complete the online measuring experiment and a mirror position Keywords：large aperture telescope;primary mirror;image stabilization technology;hydraulic support- 87
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Published：2020-08-13 -
Hydrostatic support system for in-situ optical testing of a 4 m aperture SiC mirror
Abstract：A set of hydrostatic support system for a 4 m SiC mirror in-situ testing was designed to reduce the risk of ultra-large mirror off-line testing and to improve fabrication efficiency. Firstly, the analytical formula for calculating support stiffness was derived, and its main factor was found. Then, some support samples were tested, and the support stiffness of a single support unit in different groups was predicted by combining the sample results and analytical formula. Finally, the stability of the support Keywords：ultra-large SiC mirror;in-situ optical testing;hydrostatic support system;stiffness difference;figure accuracy- 111
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Published：2020-08-13 -
Secondary mirror supporting structure for 1.2 m telescope
Abstract：A reasonable supporting structure between primary mirror and secondary mirror for a 1.2 m telescope was fabricated to meet its requirement for stiffness and the bandwidth of servo system. A four-vane spider effecting on the primary obstruction and secondary mirror stiffness was explored. The key parameters for the four-vane spider were selected by dynamic molding. Then, a finite element model was established in the ANSYS to perform static analysis and modal analysis. Finally, the modal analysis method was u Keywords：telescope;supporting structure;secondary mirror;impact testing;FEM;structural analysis and testing- 100
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- 18
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Published：2020-08-13 -
Backstepping sliding mode control of large telescope based on friction model
Abstract：According to the requirement of a large telescope driven by a permanent magnet synchronous motor(PMSM) for pointing precision and following precision, a sliding mode position controller was designed based on a friction model with backstepping approach. Firstly, the system model was established based on LuGre friction model and external disturbance. Then, a subsystem which is the furthest away from the control input was designed by inversion method. In the design process, the sliding mode control law was ind Keywords：friction model;backstepping with sliding mode control;Permanent Magnet Sychronous Motor(PMSM);large telescope- 89
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Published：2020-08-13 -
Disturbance rejection control for large ground-based telescope
Abstract：An improved disturbance rejection control algorithm was proposed to overcome the velocity fluctuation caused by the disturbance torque in a large ground-based telescope. The algorithm consists of two closed-loop structures, an inner high-bandwidth current loop and an outer speed loop. The inner current loop is a PI controller. The outer loop is a speed controller adopting the linear active disturbance rejection controller. For the speed loop, an extended state observer is used to estimate the system disturb Keywords：ground-based telescope;disturbance rejection;linear active disturbance rejection control;permanent magnet synchronous motor;anti-windup;low-speed performance- 89
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Published：2020-08-13 -
Low-speed control of large telescope based on disturbance torque observer
Abstract：To improve the anti-disturbance performance and following tracking accuracy for the servo system in a large telescope, a torque compensation method based on a disturbance observer was proposed. With the method, the revised acceleration/deceleration control method was adopt to guide the telescope turntable oscillating in a little angle. Through measuring the velocity and current of a motor, the rotation inertia of the telescope turntable was indentified. Then, an acceleration estimator was designed to estima Keywords：large telescope;low-speed tracking;inertia identification;acceleration estimation;disturbance torque observer- 107
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- 26
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Published：2020-08-13 -
Torque ripple minimization of PMSM based on robust iterative learning control
Abstract：A Robust Iterative Learning Control (RILC) method by combining sliding mode control with Iterative Learning Control (ILC) was proposed to suppress the effect of torque ripples on control system and to improve the performance of speed servo system in a Permanent Magnet synchronous Motor(PMSM). An iterative learning controller was designed to reduce the periodic torque ripples and a sliding mode controller was used to guarantee the fast response and strong robustness to further enhance the anti-disturbance ab Keywords：Permanent Magnet Synchronous Motor(PMSM);Iterative Learning Control(ILC);sliding mode control;torque ripple suppression;speed control- 131
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- 26
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Published：2020-08-13
Ground-based Large-aperture Optical Engineering
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Active correction of 1.23 m SiC mirror using bending mode
Abstract：As active correction of a large aperture SiC mirror with high stiffness is vulnerable to many calculation errors by direction least square method or free resonance method, this paper proposes a primary surface correction algorithm using bending mode to calculate and optimize the active force and to improve the correction capability. Firstly, a series of mathematical transformations were performed on the influence matrix of the primary mirror, and a set of orthogonal bending modes of primary mirror were obtained. Then, correction targets were fitted in bending modes to calculate the correction force. An 1.23 m SiC mirror and a support system were modeled by finite element analysis and the algorithm was verified by simulation experiments. Moreover, an active support system for the 1.23 m SiC mirror was set up to correct primary surface and a further optimization for the algorithm was conducted based on this system. The experiments show that the surface error is corrected from 0.23λ RMS to 0.048λ RMS by the proposed bending mode. Results of analysis and experiment demonstrate that the algorithm by bending mode efficiently reduces active force ranges and improves correction capability. It is significant for the active correction of large aperture SiC mirrors with high stiffness.Keywords：active optics;SiC mirror;aberration correction;bending mode;S-H sensor- 65
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- 16
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Published：2020-08-13 -
Flexible passive support system for 2 m SiC reflective mirror
Abstract：To apply SiC mirror in a ground-based telescope, a flexible passive support system was designed on its high thermal expansion coefficient and high rigidity. In this system, a thin and long flexible rod was used in the axial support whiffletree structure and a flexure joint rod wad used in the lateral support structure. By which, the axial support structure and the lateral support structure could support the system respectively. This structure not only allows the primary mirror to be a good position and a shape but also easily eliminate assemble stress and thermal stress. The static analysis, thermal analysis and modal analysis for the mirror were performed under the support system, and then the analytical results were verified by a surface test, mirror inclination test and a displacement test. The test result of the primary mirror shows that the surface error(RMS) is λ/40(the optical axis is vertical) and that (RMS ) is λ/16 (the optical axis is horizontal), the maximum inclination change of the primary mirror at different pitch angles is 8 "and the displacement is 0.070 7 mm.The test results are basically consistent with the analysis results, meeting the design requirements. It shows that this flexible passive support system has good engineering feasibility.Keywords：SiC reflective mirror;flexible;passive support system;whiffletree;A-frame- 68
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Published：2020-08-13 -
Hydrostatic support system for in-situ optical testing of a 4 m aperture SiC mirror
Abstract：A set of hydrostatic support system for a 4 m SiC mirror in-situ testing was designed to reduce the risk of ultra-large mirror off-line testing and to improve fabrication efficiency. Firstly, the analytical formula for calculating support stiffness was derived, and its main factor was found. Then, some support samples were tested, and the support stiffness of a single support unit in different groups was predicted by combining the sample results and analytical formula. Finally, the stability of the support system was evaluated by pressurization test and in-situ testing, and the mirror surface precision with its gravity offloaded by the support system was calculated by finite element simulation. Results show that the average stiffness is about 1.9 kN/mm with a relative difference among support units about 3% when 5 units are linked together, the stiffness for a single unit isolated is as high as 15 kN/mm,and 3 kinds of unit stiffness in the support system are 1.7, 1.1 and 0.8 kN/mm respectively. Moreover, pressurization test shows a slow pressure change, which indicates that the system is well sealed. When the hydrostatic system was used for a 4 m mirror, the height changes rise up and down within 50 μm in 11 days, and the relative change is less than 20 μm. When the mirror is supported on 54 units with stiffness difference by 3% randomly, the surface RMS is less than 20 nm. The proposed system meets the requirement of in-situ optical testing for precision and stability.Keywords：ultra-large SiC mirror;in-situ optical testing;hydrostatic support system;stiffness difference;figure accuracy- 56
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Published：2020-08-13
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High-power quasi-continuous microsecond pulse sodium guide star laser
Abstract：A high-power quasi-continuous microsecond pulse sodium guide laser was generated by extra-cavity sum frequency of Nd:YAG 1064 and 1319 nm spectral line lasers in a Lithium Borate (LBO) crystal. The three wave coupling equations of the sum-frequency process were simulated by the improved Euler method, and the waist size of fundamental light and the length of LBO crystal were optimized. To improve the sum frequency efficiency, the spatial mode matching and time domain pulse synchronization of two fundamental Keywords：sodium guide star laser;high-power laser;Lithium Borate(LBO) crystal;sum-frequency generation;frequency stabilization- 69
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Published：2020-08-13 -
Implementation of laser on-machine measuring system
Abstract：A non-contact laser on-machine measuring system was developed to realize rapid on-machine measurement of complex curving parts such as blades in an aircraft engine. The mechanical structures and electronic controlling systems of the measuring system were introduced in detail. The laser on-machine measuring system is composed of laser sensors, wireless transmission circuits, a rechargeable lithium battery, transit bases, a handle and a shell etc. To rapidly switch the machining mode and measuring mode, the i Keywords：on-machine measurement;laser measurement;laser sensor;blade;numerical control machine- 83
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Published：2020-08-13 -
Degradation mechanism for photon transfer curve of CMOS image sensor after irradiation
Abstract：As application scopes of photon transfer curve and conversion gain of a CMOS (Complementary Metal-oxide-Semiconductor)image sensor are limited after irradiated by EMVA 1288 standard testing, an improved testing method of photon transfer curve and conversion gain of CMOS image sensor is presented. By adjusting test conditions, the method limits the dark current and the non-uniform noise of dark current from the CMOS image sensor after irradiation to solve the correct device parameters. By which the device pe Keywords：CMOS image sensor;irradiation;photon transfer curve;conversion gain- 85
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Published：2020-08-13 -
Rapid adjustment and measurement for subaperture stitching interferometry
Abstract：An automatic and quick adjustment method for zero interference fringes was proposed to meet the requirement of high precision subaperture stitching interferometry. The influence of interference fringe numbers on stitching errors was analyzed, and the analyzed results show that the interferometer return error is less than λ/50(PV value) when the interference fringe numbers of subaperture are less than 5. A subaperture stitching measurement apparatus was optimized, and an auto-compensation method of angular d Keywords：interferometry;automatic measurement;subaperture stitching;stitching error- 89
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Published：2020-08-13
Modern Applied Optics
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Grinding wheel for low-damage grinding of silicon wafers and its grinding performance
Abstract：A new Soft Abrasive Grinding Wheel (SAGW) was developed for Chemo-mechanical Grinding (CMG) of silicon wafers to overcome the surface/subsurface damage of the silicon wafer machined by traditional ultra-precision grinding. According to the principle of the CMG and the material characteristics of monocrystalline silicon, the SAGW took the cerium oxide (CeO2) as abrasive, silicon dioxide (SiO2)as additive, and the chlorine oxide magnesium as binding agent. The preparation process of the SAGW was investigated, Keywords：monocrystalline silicon;soft abrasive grinding wheel;chemo-mechanical grinding;surface roughness;surface/subsurface damage- 115
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Published：2020-08-13 -
Measurement and evaluation of tool tip arc waviness of diamond tool
Abstract：To realize the ultra-precision measurement for tip arc waviness of diamond tools, an arc profile measurement system based on an atomic force microscopy and an ultra-precision spindle was established. The evaluation method of tool tip arc waviness and the scheme to control measuring error were investigated. Firstly, the selection principle of waviness cut-off wavelength was proposed in the arc waviness evaluation and the flowchart of tool tip arc waviness measurement was presented. Then, the measurement and Keywords：diamond tool;tip arc waviness;radial rotation error;eccentric and declination angle error;nonlinear error- 161
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Published：2020-08-13 -
Removal functions of different polishing heads worked in planet motion model
Abstract：To obtain Gaussian-like removal function in optical manufacturing process, a convenient method to derive the removal functions of various complicated polishing heads by integrating the rotation removal function along the revolution trajectory was proposed based on the traditional planet polising theory. When the speed ratio was greater than 10, the removal function curve of a solid disk by the proposed method was very close to the result by the traditional method, which verifies the correctness of the propo Keywords：planet polishing;polishing head;Gaussian-like removal function;rotation removal function- 76
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Published：2020-08-13 -
Subsurface damage detection of RB-SiC and its subsurface damage characteristics in rotating ultrasonic grinding
Abstract：A cross-sectional polishing method(taking a silicon as foil or taking a polyester as foil) and a bonded interface sectioning method were used to test the subsurface damage of RB-SiC (reaction bonded SiC)in rotary ultrasonic grinding(RUG) respectively. To determine the optimal test form, four kinds of subsurface damage evaluation indexes, namely average chipping layer depth, maximum chipping layer depth, average crack depth and maximum crack depth were used to analyze and compare the subsurface damages of RB Keywords：rotary ultrasonic grinding;reaction Bonded SiC(RB-SiC);subsurface damage;cross-sectional polishing;bonded interface sectioning- 129
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Published：2020-08-13
Micro/Nano Technology and Fine Mechanics
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Two-view high speed vision system for instant object detection in mechanical system
Abstract：A two-view high-speed synchronous vision system was developed based on high-speed cameras. It was used to monitor synchronously periodic mechanical motion in non-contact and long term modes from different views. It could automatically judge the abnormal motion and could record high-speed vision images at a moment. On the basis of extraction of motion characteristics of a mechanical system, an offline processing algorithm of multi-view high frame rate video image was proposed. Two high-speed cameras were use Keywords：computer vision;high-speed vision;image processing;object detection;mechanical system- 111
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Published：2020-08-13 -
Structure optimization of high speed space coherent optical balance detectors
Abstract：The circuit structure and noise characteristics of a high-speed spatial coherent balanced detector were analyzed, and the dependence of key technical parameters on the circuit structure of the balanced detector was clarified. Two kinds of high-speed spatial balanced photoelectric detectors were designed by using resistance sampling and double TIA (Transimpedance Amplifier) synthesis, and their performance parameters were verified by experiments. The experiments indicate that both kinds of high-speed coheren Keywords：balanced detector;coherent optical communication;local-oscillator power;structure optimization;noise power- 65
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Published：2020-08-13 -
Establishment of optical measuring system for blades edges
Abstract：For the low accuracy and bad consistency of blade edges in aero engines, a non-contact optical measuring system was established to measure the geometric dimensions and contour shapes of blade edges in a rapid and accurate way. In the system, a traditional coordinate measuring machine was taken as a platform, a special sensing device composed of two laser scanning sensors fixed at a certain angle to each other was taken as the front-end sensor and several data post-processing algorithms were integrated. In t Keywords：aero-engine;blade edge;non-contact measurement;optical sensor- 92
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Published：2020-08-13 -
Two-face reciprocal orientation for laser tracker
Abstract：As traditional orientation method depends heavily on measurement spaces and it is great difficult to implement the orientation of large dimension instruments in a limited space. Therefore, a two-face reciprocal orientation method was proposed to implement the orientation of a spherical coordinate measurement system in the limited space, and the theory analysis and experiment verification were performed by taking two laser trackers for example. With combination of measuring principle and working characterist Keywords：large-scale metrologic instrument;laser tracker;limited space;orientation;two-face reciprocal measurement- 90
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Published：2020-08-13 -
DC offset elimination in wireless optical channel estimation by employing implicit sequence
Abstract：For the DC offsets caused by traditional implicit sequence based channel estimation in wireless optical communication links, a novel implicit sequence based channel estimation method was proposed to eliminate the DC offsets. Some key factors affecting the system performance were investigated. The maximum output Signal-to-Noise Ratio (SNR) criterion was used to derive the optimal power allocation factor. Then, a simulation experiment was performed to evaluate its mean square error, bit error rate and computa Keywords：wireless optical communication;implicit training sequence channel estimation;DC offset;power allocation factor- 80
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Published：2020-08-13 -
Optimization of camera parameters based on linear model
Abstract：A camera in-line calibration method based on a line model was proposed. By automatically tracking the edge of an object, the internal and external parameters of the camera were solved linearly while the corresponding relationship between object edge and image edge was established. On the basis of the relationship and the initial values of internal and external parameters, the camera parameters were estimated optimally by developing a new error model between the model line and image line with the endpoint in Keywords：vision metrology;online calibration;linear model;camera parameter- 59
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Published：2020-08-13
Information Sciences
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