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 total optics,and the blackbody was taken as the inner reference source to calibrate the radiance responsivity of the partial optics. Finally, the transmittance of the front optics was calculated based on the inner and outer calibration results, and the radiance responsivity of the total optics was calibrated in pixel levels. Several experiments were performed to inverse the illuminance of the infrared stars. The results show that the maximum relative inversion error of the proposed method is 15.89% and that from infrared standard star calibration is 15.92%, which means that the proposed method keeps more accurate than that of the infrared standard star method. Moreover, the radiance responsivity of the total optics corresponding to each pixel is calibrated, and the results indicate that the proposed method overcomes the interference of system non-uniformity, improves the utilization ratio of the focal plane array and makes up the application defect of standard infrared stars.

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.

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 system was implemented. With finite element method, the influences of the lateral positioning system on the large aperture primary mirror system was analyzed in several aspects, such as system location, resonant frequency and mirror surface profile. As the results, it shows that the resonant frequency of the primary mirror reaches 13.6 Hz, the average displacement of the primary mirror is -355.863 nm along the Y-axis direction, and the primary mirror surface profile is uninfluenced. These parameters all meet the design requirements of this lateral positioning system. Experimental results verify the engineering signification of proposed lateral positioning system on the design of support and position systems of primary mirror in large aperture telescopes in the future.

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 platform was adopted to support the cube mirror to improve the accuracy to 0.01″. Moreover, hexapod platform errors induced from the test environment was estimated by the related principle of frequency response function. Finally, the normalized Point Source Sensitivity (PSSn) was deduced to evaluate the testing results. The simulation and experiment were performed. For mirror seeing, the slope power spectra and original power spectra in two different directions were calculated, and both PSSn in two directions are 0.999 based on the relation between power spectra and PSSn. This method can be used to quantitatively predict the mirror seeing of primary mirrors under actual working conditions of the telescopes.

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 was taken as a main chip to perform experimental verification, and the experiment results show that the algorithm reduces the hardware resources by 50%, and improves wave-front processing ability of the system. Furthermore, all of the wave-front processing operations can be implemented in the current frame before the processing end, which improves processing speeds and control bandwidths of the adaptive optic system. The new algorithm has carried on the correction experiment of the laser light source for a Shack-Hartmann in the room, and it shows a higher concentration ratio of light source.

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-based photo-electronic surveillance system was given by comparing the SNRs in different modes. In combined with target motion, observation conditions and other factors, an observation model of Geosynchronous Orbit (GEO) targets was designed. Finally, in view of faint target recognition, a new target recognition method for faint targets was presented based on optimization principle. According to the measured data, this method was validated and compared with that of the traditional difference frame method. The results show that the target can be identified when the target SNR is greater than 3.09. This research provides a high reference value for the design and application of photo-electronic surveillance equipment for faint targets in the mid-high orbit.

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.

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 measuring system with 6 Line Variable Differential Transformer(LVDT) was established. Under two cases with or without mage stabilizing technologies based on hydraulic support, the displacement between mirror and cell was measured, and the 5 freedom of mirror was computed by using the measured data from sensors. Experimental results indicate that the proposed technology based on hydraulic support has excellent stabilizing image ability. Under the case without the image stabilization technology, the mirror displacement of Z direction is about 150 μm and the angle around X axis is 2.5″ when the rotation angle of mirror is 40°. However, the X displacement has reduced to 3 μm and the angle reduced to 0.4″ when this technology is conducted. It concludes that the stabilizing image technology based on hydraulic support can implement the determination and control of primary mirror position in real time.

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.

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 used to test the designed support structure. The finite element analysis shows that the designed structure effected by gravity induces about 0.004 2λ coma while the telescope points to the horizon, and the first-order modal frequency is about 57.2 Hz. The modal analysis indicates that the first-order resonance frequency is up to 54.1 Hz, which is in agreement with that of finite element analysis. Experimental results and FEA results are compared, and it shows that it is difficult to extract the modal when the vibration magnitude on the vane is smaller and obtained results are little smaller than that of the FEA, in which the maximum relative error is less than 7%. In conclusion, this design is not only a fewer obstruction but also an excellent stiffness, meeting the requirement of telescopes.

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 induced into each step of backstepping approach to attenuate the influence of nonlinearity friction and external disturbance on the pointing precision and following precision of the large telescope. The effectiveness of the proposed method was verified by theoretical simulation and experimental test. The experimental results demonstrate that the system has a good dynamic performance and is insensitive to the uncertainty factors such as disturbance. The stable pointing error is 0.048 51″ when the position command is 4.6″, which decreases 21.4% than that of the traditional PI controller. The stable following error is 0.031 26″ when the ramp position command 5 (″)/s, which decreases 30.1% than that of the traditional PI controller. The proposed controller improves the pointing precision and following precision of large telescopes successfully.

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 disturbances, and the estimated disturbance is fed into the control system to form a composite correction system. To solve the problem of controller saturation caused by the large dynamic input, an anti-windup control algorithm was induced the input of the extended state observer to guarantee the stability and good dynamic characteristics of the system. The simulation and experimental results show that linear active disturbance rejection controller with anti-windup achieves fast response without overshoot at both high or low speeds as compared with the PI controller. In a low speed smoothing experiment, the algorithm improves the RMS value of speed error from 0.000 68(°)/s to 0.000 32(°)/s. Experimental results demonstrate that the proposed algorithm effectively reduces the velocity fluctuation of the servo system caused by the motor torque ripple and improves its speed smooth.

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 estimate the low-acceleration based on encoder feedback data by using the double integration and PD control method. Finally, based on the inertia identification and acceleration estimation, a disturbance observer was designed to estimate the external torque according to the motor current and turntable acceleration. Furthermore, the estimated disturbance torque was used to compensate the current input to correct reference currents . Experiment results demonstrate that after the observer is added, the following error RMS is reduced from 0.012 7″ to 0.0073″ at the sloop position of servo system to be 0.36 (″)/s. Compared with that without the disturbance torque observer, the following tracking jitter is reduced and the tracking accuracy is improved.

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 ability of the system. Verification experiments were carried out, and the results demonstrate that when the motor is operating at a speed of 900 r/min, the robust ILC reduces the 6th harmonics amplitude from 0.89 to 0.56. When a sudden load 0.5 N·m is added to the system, the robust ILC gives a maximum speed fluctuation of 22 r/min. Compared with PI-ILC, the speed fluctuation is reduced by 1.4%. When the motor is operating at a speed of 60 r/min, the robust ILC reduces the 6th harmonics amplitude from 4.87 to 0.45. When a sudden load 0.5 N·m is added to the system, the robust ILC gives a maximum speed fluctuation of 24 r/min. Compared with that of a PI-ILC, the speed fluctuation is reduced by 23%. The experimental results indicate that the proposed robust ILC method improves the dynamic and robust performance of the speed servo system and suppresses the periodic torque ripples effectively.

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 lasers were realized by the beam shaping of image propagation and the precise control of trigger delay. The laser outputs were researched ,and the results show that the 589 nm laser outputs with the powers of 53, 42.6, 27 and 22 W are obtained under the conditions of 500, 600, 800 and 1000 Hz, and the corresponding sum-frequency efficiencies are 21.8%, 20.3%, 16.9 % and 16.3%, respectively. Moreover, the beam quality factor of M2 is 1.32 and the pulse width is 100 μs at the maximum power of yellow light. A control system compound by a PZT and a stepper motor was used to stabilize the frequency, and results indicate that the frequency fluctuation is in the range of ±0.2 GHz, which ensures that the wavelength of yellow light is within the D2a absorption spectrum of sodium atom. The research results iprovide a technologic support for generating 50 W high-power quasi-continuous microsecond pulse sodium guide lasers.

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 installation structure with a handle was adopted. When machining blade processing was switched into the on-machine measurement, the system could operate a tool change program, and the system might be taken out from the tool magazine to on-machine measuring mode. For the electronic control part of the measuring system, a data acquisition system of wireless transmission was developed. To verify the practicability and effectiveness of the on-machine measuring system, the experiment of scanning and measuring the blade section was executed on a 5-axis blade machining center. The experimental results show that the measuring precision is 20 μm and the measuring time is 10 min. As the results, it indicates that laser on-machine measuring system established in the paper realizes the measuring assignment of blade surfaces in a rapid and accurate manner.

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 performance changes caused by irradiation are intuitively obtained. An experimental test is performed with the proposed method, and the results show that the switching gain caused by irradiation is reduced by 7.82% . On the basis of the results, the degradation mechanism of photon transfer curve and conversion gain of the CMOS caused by irradiation is analyzed. The results point out that conversion gain degradation comes from the increses of dark current and the non-uniform noise of dark current caused by the proton radiation ionization effect and displacement effect. The paper provides a theoretical basis for mastering the spatial radiation effect of CMOS image sensors.

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 displacement deviation for the motion stage was proposed. By which, zero fringe of each subaperture was realized, and the cumulative error of subaperture stitching was controlled finally. A 450mm×60mm flat mirror was measured by subaperture stitching interferometry, the experiment result shows that the surface distributions of automatic stitching measurement results are more consistent with that of the zero fringe measurement by manual adjustment , the measuring speed and measuring efficiency are improved and the measuring time is reduced by 5 min on average. As compared with zero fringe measurement by manual adjustment. The proposed method not only completes the automatic positioning and automatic adjustment of the interference stitching measurement apparatus, but also improves the measuring repeatability and detection efficiency.

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, and its microstructure and composition were analyzed. By measuring the surface roughness, surface microstructure and the surface/subsurface damage, the grinding performance of the SAGW was further explored. In the end, fabricated silicon wafer with the same particle size by the SAGW, Chemical Mechanical Polishing (CMP) and diamond grinding wheel was compared and analyzed. The results show that the surface roughness of the silicon wafer by the SAGW is less than 1 nm and its subsurface damage layer is about 30 nm in thickness , which is comparable to that produced by the CMG and much better than that of the diamond wheel. This study demonstrates that the developed SAGW achieves the low-damage grinding of silicon wafers.

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 evaluation for radial rotation errors of the ultra-precision spindle were discussed, the control for mounting errors of eccentric and declination angles and the calibration for nonlinear error of atomic force scan system were described. Finally, the tip arc waviness of a diamond tool was measured by self-developed ultra-precision profile measurement system, and the measurement accuracy and uncertainty were analyzed. Experimental results show that the tip arc waviness of diamond tools can be accurately described by proposed method, the waviness is 0.106 μm,and the uncertainty is 23.8 nm. These results satisfy the system requirements for higher precision and stabilization.

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 proposed method．The proposed method was used to derive polishing removal functions of different polishing heads．By computer simulation, it shows that type Ⅱ petal polishing head gets a better removal function curve when the eccentricity ratio is 0.4．Finally, the type Ⅱ petal polishing head was polished, and the results indicate that when the eccentricity ratio was 0.4 and the speed ratio is 10, the test and simulation results are consistent with each other and they are all close to the Gaussian curve．These test result verifies the correctness of the proposed method again．

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-SiC in the RUG tested by the two methods mentioned above. The results show that the evaluation indexes from cross-sectional polishing method (the silicon as foil) are 3.30 μm, 6.59 μm, 8.64 μm, and 17.44 μm, those from the cross-sectional polishing method (the polyester as foil) are 5.71 μm, 14.33 μm, 15.36 μm, and 54.82 μm, and those from the bonded interface sectioning method are 9.19 μm, 19.45 μm, 13.04 μm, and 32.20 μm. It demonstrates that the cross-sectional polishing method (the silicon as foil) has the higher test accuracy, and the detection result is more in line with the actual situation. Finally, the paper summarizes subsurface damage characteristics of RB-SiC in the RUG.

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 used to accurately establish the sample image database and their relation. Then, a multi-angle synchronous real-time detection algorithm was proposed to quickly complete the real-time visual detection of the targets, meanwhile recording key images instantaneously. To confirm the validity and stability of algorithms, the two-angle-view high-speed vision monitor system was built in laboratory, and real mechanical parts were detected in experiments. The experimental results show that the vision monitor system achieves a high-speed synchronous detection of 500fps, the validity judgment of abnormal motion happened in 0.1 s, and the recording instantaneously for key images. The research working provide a higher speed visual detection method for the noncontact detection of mechanical systems.

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 coherent detectors can be used for high-speed coherent detection, while the detection sensitivity and anti-noise performance from the double TIA voltage synthesis balanced detector are better than those from the resistance sampling type detector. When the communication rate is 5Gbps and the bit error rate is 10-8, the optimal detection sensitivity of resistance sampling type balanced detector is -33.51 dBm, and that of the double TIA synthesis balanced detector is -43.4 dBm, higher nearly 8dB than that of the Discovery's 5Gbps balanced detector. The research on the structure of high-speed spatial coherent photodetector provides a theoretical basis for the establishment of a high-sensitivity and high-speed spatial coherent optical communication system.

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 the measuring procedure, five transversals at the leading and trailing edges were selected and their contour information was measured to determine the geometric dimensions and machining allowance of the measured blade edges. The system could be used as a component of the manufacturing system to link the segments of designing, manufacturing and measuring of blades together. Finally, the leading and trailing edges of three sections of a blade after precision forging are measured by the system. The measuring results verify the effectiveness and practicability of the optical measuring system and show that the repeatability of the system meets the requirements for design and measuring of blade edges. In conclusion, the system could serve as an evaluating means for the machining quality of the leading and trailing edges of blades.

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 characteristics of laser trackers, the geometrical constraints of the method were constructed by motion characteristics of the probes in trackers. So, if the instruments to be measured were visible each other, they will be orientated by the smaller public view field. The mathematical modeling and optimization of this method were elaborated. Then, the experimental verification was performed on an establishment processing of circular measuring control network in Shanghai Synchrotron Radiation Facility(SSRF). The results indicate that the precision of the proposed method is within 0.12 mm and the orientation rotation angle error is less than 1.5″when the two laser trackers are 5m away from each other. As compared to that of traditional orientation method, the measuring efficiency of the method has been obviously promoted with almost the same precision level in a limited space. The method can also be applied to other single station coordinate measuring systems.

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 computational complexity. The results show that the proposed method effectively eliminates the influence of DC offset. on the system performance. Compared to the traditional method, the mean square error is reduced by about 1/2 and the bit error rate is significantly improved. Under the optimal power distribution conditions, when the bit error rate is 4×10-3, the SNRs of 0.2 and 0.4 DC offset scenarios are improved by about 2 dB and 6d B, respectively, while the computational complexity is only increased by 14.2%.

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 information. The simulation and experiment were performed. The internal and external parameters of the camera were calibrated by proposed method and traditional checkerboard interior angle method, and the calibration results were compared. The results only by using edge information show that the proposed method have the almost the same accuracy with the traditional method and the reprojection error(RMS) is 0.6 pixel. In conclusion, the proposed calibration method can implement the estimation of internal and external parameters only by using the object with a standard size and can obtain the same calibration precision as that of traditional method without preparation of the plane calibration object. It is more flexible and practical.