4f光学系统中滤波函数角位移补偿的研究

实验中4f光学系统的输入函数载体与滤波函数载体往往存在着一定的角位移,而这个角位移的存在影响了4f光学系统的精确滤波。将空间光调制器(SLM)作为4f光学系统的输入和滤波函数的载体,利用光栅衍射理论和傅里叶变换理论,提出了一种测量该角位移的方法。滤波函数旋转角位移值的大小可以补偿输入和滤波函数载体间存在的角位移。滤波实验证明了方法的有效性和必要性。     

Spatial and Temporal Properties of a Nonlinear Optical Feedback System

We experimentally investigate the spatial and temporal properties of a nonlinear optical system composed of an optically addressed spatial light modulator and a two-dimensional optical feedback. The system property is examined using fringes with only one spatial wave vector. The fringes are spontaneously generated using a spatial frequency filter in the optical feedback. We also experimentally investigate the properties of the spatial light modulator in the system using ordinary interference fringes in order to compare with the system property. We demonstrate that the spatial frequency response of the nonlinear optical system is identical to that of the spatial light modulator. We also demonstrate the distinctive temporal behavior of diffraction lights from the fringes generated in the system.     

利用空间光调制器的偏振特性实现图像边缘增强

讨论了光电混合型范德卢格特相关器中起偏器和检偏器对场景空间光调制器的影响。提出了一种通过设置起偏器和检偏器相对于场景空间光调制器入射表面液晶指向矢方向的角度来实现图像边缘增强的预处理方法。通过对XGA2L11型电寻址薄膜晶体管驱动透射式液晶空间光调制器的实验测试表明,该方法减少了计算机图像预处理的运算量,有效地提高了目标识别的速度,实现了场景图像边缘增强的实时预处理。     

基于液晶纯相位光调制器的4f系统去噪方法

分析了4f系统的噪声来源,提出使用液晶空间光调制器实时去除系统噪声.通过使用Zemike多项式拟合透镜等光学器件引入的像差,根据液晶纯相位光调制器利用位相共轭波进行静态波面校正的工作原理,提出了一种新的相位校正算法,模拟仿真美国BNS公司反射式256×256纯相位液晶空间光调制器,通过重构并逼近畸变波面,产生相位共轭波...     

利用光束整形器件阵列消除电寻址空间光调制器的"黑栅"效应

研究了电寻址空间光调制器中由于低开口率所引起的"黑栅"效应对图像质量的影响。提出了一种基于纯相位型光束整形器件阵列的"黑栅"消除方法,并分析了该方法的基本原理。介绍了用Gerchberg Saxton相位恢复算法来设计光束整形器件的基本思路,给出了光束整形的结果。理论分析及仿真计算表明,该方法能有效地消除电寻址空间光调制器相邻像素之间的黑带。     

在光学相关器中测试滤波空间光调制器的相位调制特性

研究了在范德卢格特型光电混合相关器中,利用朗奇光栅图像替代实物光栅测试滤波空间光调制器相位调制特性的原理和方法.对XGA2L11型空间光调制器的相位调制特性进行了现场测试,并对测试结果进行了误差分析和光学相关实验验证.结果表明,该方法不需要单独构建测量装置而是完全在相关器的工作状态下测试,保证了空间光调制器的特性测试结果和实际工作性能的一致性.     

A single-shot pixellated phase-shifting interferometer utilizing a liquid-crystal spatial light modulator

We introduce a novel phase-shifting pixellated interferometer based on a liquid-crystal spatial light modulator and simulate the expected performance. The phase-shifted frames are captured simultaneously, which reduces problems arising from vibrations and air turbulence. The liquid-crystal spatial light modulator is flexible and can be configured to provide a large number of phase-shift levels and geometries to reduce measurement error.     

液晶空间光调制器相位调制测量及波前校正

提供了一种简单且精度较好的测量液晶空间光调制器相位调制特性的方法,即相位与电压(灰度)之间的关系。采用数字波面移相干涉仪,由干涉仪直接给出不同灰度对应的相位差,从而得到液晶空间光调制器的相位调制曲线。利用液晶空间光调制器实现了波前校正。由干涉仪作波前测试,对待校正的畸变波前进行泽尼克多项式描述,根据液晶空间光调制器的相位与灰度的关系,产生相应的灰度图,获得畸变波前的共轭波前,从而完成静态波前的校正,使相关参数如PV值、RMS值和Strehl比值得到了改善。     

Programmable fractal zone plates (FraZPs) with foci finely tuned

We examined the focusing properties of fractal zone plates (FraZPs) in detail based on a liquid crystal on silicon (LCOS) spatial light modulator (SLM). It was shown that the focal length shifted linearly when the lacunarity of first order FraZPs experienced a linear displacement. From the theoretical analysis and the experimental results, we showed the potential to use the FraZPs as a focusing element whose focal length can be tuned finely. In addition, some side effects of this element were also discussed.     

Development of spatial light modulators with nonlinear organic materials

An electrically addressable spatial light modulator is designed using nonlinear organic materials for optical information processing and display. One candidates for spatial light modulator (SLM) material is a nonlinear organic polymer of poly-methyl-methacrylate doped with disperse red 1. The measured electrooptic coefficient r₃₃ is 2.9 pm/V at the wavelength of 633 nm. Resonator structure for a material is discussed with the goal of increasing electrooptic effects for SLM applications.     

Digital phase-shifting interferometer with an electrically addressed liquid-crystal spatial light modulator

A digital phase-shifting interferometer with a liquid-crystal-display coupled, parallel aligned, nematic liquid-crystal spatial light modulator is developed. The optical phase shift in the Michelson-type polarization interferometer is achieved by a digital phase shift of a grating displayed on the spatial light modulator. Accurate experimental results of using the heterodyne system for pi/2 phase steps were demonstrated. A phase-shifting interferometer with no moving parts and no requirement for calibration of the value of the phase shift was achieved.     

激光显示中光学系统研究

为了满足机械转镜扫描要求(转镜转速每分钟不少于3万转)及光束与水平信号的行场同步要求，提出采用面阵空间光调制器及多像素并行扫描方式。采用“面阵空间光调制器”对激光束进行选通和光强调制，使覆盖多像素的激光束在高速扫过面阵空间光调制器时，光强按视频图像的强弱进行调制，从而形成激光视频图像。由于采用了多像素并行扫描、新型二维扫描转镜和积分器光路，扫描速度大大降低，由每分钟几万转降低到3000转，解决了扫描式激光显示的技术瓶颈和激光干涉条纹问题，获得了很好的显示效果。     

利用相关分析法测量空间光调制器的相位调制特性

基于一维干涉条纹图像的相关分析法可实现液晶空间光调制器相位调制特性的测试。给出了XGA2L11型电寻址液晶空间光调制器的相位现场测试原理、测试装置和测试步骤。利用范德卢格特型光电混合相关器对测试结果进行了实验验证。结果表明,该方法具有原理简单、适应性强和精度高等优点。     

Spatial Temporal Analysis of Electrically-Addressable Phase-Only Spatial Light Modulator

An optically addressed parallel-aligned nematic-liquid-crystal spatial light modulator (PAL-SLM) has been studied as a dynamic phase-only modulation device. A computer control feature of the spatial light modulator is strongly desired for practical applications. For those demands, an electrically-addressable phase-only spatial light modulator has been developed to combine a liquid crystal display (LCD) with a PAL-SLM (LCD-coupled PAL-SLM) and its performance has been reported. However, a temporal characteristic especially two-dimensional (2D) response has not been discussed before. In this paper, 2D response analysis system has been constructed by using a high-speed complementary Metal-Oxide-Semiconductor (CMOS) camera (1000 frames/sec) and the 2D-modulation characteristic of the LCD-coupled PAL-SLM has been observed. As a result, the LCD has a spatially non-uniform modulation characteristic due to a scanning addressing. It has the potential to cause problems in high speed switching for a computer generated hologram. On the other hand, the spatial non-uniformity has not been observed with the LCD-coupled PAL-SLM.     

高阶涡旋光束生成技术研究

应用液晶空间光调制器加载螺旋相位片的方法可以高效地生成涡旋光束,但由于液晶空间光调制器分辨率有限,在加载高阶螺旋相位片时其中心会出现相位失真,造成涡旋光束质量不高。通过在螺线相位片中心区域引入闪耀光栅的方法,得到了光束质量较高的高阶单模涡旋光束和多模涡旋光束,为生成高阶涡旋光束提供了一种很好的方法。     

基于液晶空间光调制器的空间滤波实验

空间滤波实验可以实现对输入物体的频谱分析及图像的边缘增强、噪声消除等各种图像处理。液晶空间光调制器可以作为衍射波面变换器件来使用。在空间滤波实验系统的滤波面上放置了液晶空间光调制器,并用CCD数码相机进行输出图像的观察和记录,分别给出了低通滤波、高通滤波、方向滤波等的仿真实验结果。该实验实现了输入数字物体的实时改变,并能够实时观察采用不同空间滤波器对输出像的影响。     

Addressable discrete-line-scanning multiphoton microscopy based on a spatial light modulator

We developed a novel addressable discrete-line-scanning multiphoton microscope with high lateral and axial resolutions based on a spatial light modulator. Our discrete-line-focus design eliminates the cross talk that occurs in conventional one-dimensional line-scanning multiphoton microscopies. Additionally, a phase-only spatial light modulator is able to scan only a sample's target area by generating a specific discrete line focus according to the shape and location of the target area. Compared with other multiphoton microscopies, this technique shortens scanning time and minimizes photodamage by concentrating scanning energy and dwell time on the area of interest.     

Performance of a phase-conjugate engine implementing a finite-bit phase correction

The achievable Strehl ratio when a finite-bit correction to an aberrated wave front is implemented is examined. The phase-conjugate engine used to measure the aberrated wave front consists of a quadrature interferometric wave-front sensor, a liquid-crystal spatial light modulator, and computer hardware-software to calculate and apply the correction. A finite-bit approximation to the conjugate phase is calculated and applied to the spatial light modulator to remove the aberrations from the optical beam. The experimentally determined Strehl ratio of the corrected beam is compared with analytical expressions for the expected Strehl ratio and shown to be in good agreement with those predictions.     

Multistability in optical transmittance of spatial light modulators with internal feedback

A multistable spatial optical device has been developed on the basis of a spatial light modulator which contains photosensitive and electrooptical liquid crystal layers where an internal feedback loop is established.     

Bistable properties of spatial light modulator with internal feedback

A bistable spatial optical device has been developed on the basis of a spatial light modulator which contains photosensitive and electrooptical liquid crystal layers, where an internal feedback loop is established.