Abstract. Phase shifting interferometry is an optical metrology with a high precision, but it usually requires the expensive high precision phase shifter. Therefore, low cost methods of extracting phase from a single shot interferogram were very valuable, but available algorithms are usually effective only in a limited conditions. To solve these problems, a novel method is presented in this work. Based on this method, the interference fringe is retrieved to a wrapped phase and divided into different regions and the index of the pixel is calculated. The pixels in the same region have the same parity and the PSF’s gravity center of part wavefront so as to solve the sign ambiguity. The theoretical simulation results indicate that the PV of wavefront error is 0.00054λ and the rms is 0.000125λ,which is much better than the results from the Fast Fourier Transformation method. The experimentally measured interferogram is also used to validate the method. It has the advantages of simplicity, high precision and effective for both open and closed interferometer fringes.

The deformable mirror is one of the core units of the Adaptive Optics (AO) System. This article proposes a new voice coil actuator structure based on the principle of minimum magnetoresistance. The soft magnetic material-Permalloy is added to the traditional voice coil structure design to reduce magnetic leakage and thus improve output force and efficiency. The model is established by ANSYS Maxwell for simulation and the structural dimensions of each component are optimized. The results show that the actuator structure can generate a force of 3.4 N, an efficiency of 9.05N X W-1/2, and a response time of 0.03 ms. At the same time, it is found that the working influence between adjacent actuators is very small, so it is established that the coupling of deformable mirror is 11.7% when the actuator spacing is 15 mm, which meets the system requirements. This work lays a solid foundation for the development of deformable mirrors with large travel, fast response, low power consumption and high actuator density, which have good application prospects.

影响大口径地基自适应光学望远镜成像的因素很多,为获得近衍射极限的高分辨力成像效果,需要对系统的关键参数进行优化.本文分析了影响地基光学望远镜成像的误差源,建立合理的误差评价模型.并利用仿真的方法对该模型进行了验证,并对湍流条件、望远镜口径、采样频率、变形镜驱动器间距、导星等关键参数进行了优化分析.与仿真结果对比表明:误差模型预测精度在较好的观测条件下能达到30 nm以内.该模型也为自适应光学系统在生物显微成像、眼底成像、激光大气通信等领域的应用提供了参考.

Traditional phase-shifting interferometry technique cannot be used to measure time-varying phase distributions. But single shot techniques could resolve the problem. Many efforts have been made on the phase retrieval methods from a single shot interferogram. In the paper, a simple and effective method is presented without complex computation. The interference fringe is transferred to a phase distribution with a look-up-table. And then it is divided into different regions according to the parity of every pixel. The pixels in the same region have the same parity, which determines the wrapped phase. Additionally, the light spot displacement of a local wavefront is obtained to solve the global sign ambiguity. The theoretical simulation results indicate that the PV of wavefront error is 0.00054(lambda) and the rms is 0.000125(lambda), which is much better than the results from the Fast Fourier Transformation method. We also use it in the experimentally measured interferogram. Our algorithm has the advantages of simplicity, high precision and effective for both open and closed interferometer fringes, which will be valuable for real time monitoring the optical elements shape during their processing.

The structure of 7 actuators VDM is designed, and the mechanical characteristics of its mirror are analyzed based on the finite element method with ANSYS software. The maximum deformation and stress of the VDM under different material and physical parameters are simulated and discussed. The results show that the designed VDM has an outstanding comprehensive performance, and basically meets the requirements of applications. Our simulation results can provide a reasonable reference for the application of VDM.

A liquid crystal spatial light modulator (LCSLM) has a wide range of applications in the non-display field. In this study, the phase modulation characteristics of LCSLM arc evaluated using a Shack-Hartmann wavefront detector. The results denote that the linear phase modulation range of the low-order Zernike mode is relatively large, and the diffraction efficiency significantly decreases as the modulation range increases. Furthermore, the possibility of using LCSLM for performing aspherical surface measurements is discussed, which provides a new approach for expanding the method of aspheric surface shape detection.

In this paper, based on deformable mirrors and the stochastic parallel-gradient-descent (SPGD) algorithm, an adaptive optics system (AOS) without wavefront detection is theoretically simulated. In order to improve the convergence speed of the AOS without reducing its accuracy, this paper optimizes the relationship between the amplitude of random perturbation and the gain coefficient in the SPGD algorithm. The experiment conducted in this study shows that the AOS has a parameter preference area, which is related to the initial distortion magnitude. Furthermore, the results of the theoretical verification and the comparison with that by the simulated annealing algorithm reveal that the convergence accuracy of the SPGD algorithm is 6.32% higher than that of the SA algorithm and the SPGD algorithm has a larger convergence speed.

The temperature variation can affect the phase modulation characteristics and response speed of the liquid crystal wavefront corrector of adaptive optics, thereby affect its phase modulation accuracy. To solve this problem, the influence of temperature on the LUT (look-up table) of a 512 X 512 pixel silicon-based liquid crystal wavefront corrector (LCOS) was measured experimentally and analyzed. It is due to the change of the LUT induced by temperature that changed the phase modulation characteristics of the LCOS. The experimental measurements of temperal and phase response of the LCOS were conducted at different temperatures. And the corresponding LUTs were calculated. We used the method of least squares fitting to fit the obtained results and obtained an expression for LUTs in the range of 16 to 26 degrees C. As a result, we can get a reasonable LUT at arbitrary temperature ranged from temperature range. We use the blazed grating generated by liquid crystal to verify the diffraction efficiency of the incident beam. The results indicate that our method can overcome the effects of temperature variations and improve the phase modulation capability of the LCOS by using the LUT at the corresponding temperature instead of a fixed one. Our results are valuable for fields, such as liquid crystal adaptive optics, display and so on.

The study on alcohol fermentation by uncooked corn flour with selected glucoamylase as saccharifying agent was illustrated in this paper. The experimen t process was as follows: the optimal addition quantity of glucoamylase as 100 u/g, the ratio of material to water as 1∶2 with natural pH value, corn flour as raw materials (filtered by 40 screen mesh) and 0.3 % addition of active dry ye ast, then 60～70 h fermentation under stable temperature at 30 ℃, alcoholicity of fermented mash was 15 %(v/v), addition of nitrogen source or acid protease c ould advance fermentation and enhance alcoholicity to 16 %(v/v), the utilization rate of amylum reached about 88, and the scaled-up test (15l big fermentation p ot)also showed a good result, in the fermentation course, reducing sugar kept in low level all the time which could effectively inhibit sundry bacteria and ensu re fluent fermentation. Such technique could greatly reduce energy consumption i n ethanol production and had significant influence on alcohol status in energy s tructure in China. (Tran. by YUE Yang)

In the alcoholic fermentation with external circumfluent fermentor,the sediment of raw corn flour was studied. The results indicated that the initial settling velocity decreased with the increase of initial concentration. It also proved that a smallest circulation flux existed for corn flour suspension to fulfill compulsory circulation. Compulsory circulating fermentation promoted the process of transferring mass, the multiplication rate of the yeast cell was increased by 84. 8% ,the death rate of that was decreased by 100% after 20 hours' fermentation,and the ethanol concentration at 70 h was increased by 11. 5% compared with none circulating fermentation. Additionally, the fermentor with the bigger ratio of height to diameter contributed to alcoholic fermentation with uncooked corn flour.