结合高位深相位光栅图的LC-SLM标定

为了提高对液晶空间光调制器（LC-SLM）的校准精度,采用高位深相位光栅图对LC-SLM进行了标定。在LC-SLM上加载16位深度相位光栅图,并使光束经LC-SLM调制后生成衍射光斑;测量衍射光斑中心光强,经过计算分析得出计算机灰度信号与相位调制量之间的映射关系,最终得出针对488nm激光的LC-SLM标定LUT文件（LUT16）。结果表明,在LC-SLM上加载0~2π涡旋相位,并结合LUT16文件调制光束可以得到光斑质量很好的中空光斑,这与结合LUT8文件调制的中空光斑相比,光斑质量从0.53提高到0.76,提高了1.43倍。针对特定波长,利用高位深相位光栅图标定LC-SLM得到的LUT文件可以使LC-SLM根据加载相位对光束进行有效调制,且调制效果优于结合LUT8对光束进行调制的结果,对LC-SLM的校准精度得到提高。     

基于液晶空间光调制器的涡旋相位恢复检测系统像差

提出一种基于液晶空间光调制器对涡旋相位进行相位恢复的方法,这有别于传统相位恢复算法。实验中利用液晶空间光调制器产生光学涡旋,再利用CMOS摄像头来捕捉涡旋光斑。采用改进的GS算法对系统相位进行恢复,算法中入射液晶面光振幅与随机输入相位结合进行迭代计算恢复液晶波阵面。因为程序经过多次迭代计算均恢复出涡旋相位,故证实该方法可进行相位恢复。通过计算得出系统的像差,同时利用泽尼克多项式对系统像差进行了定量分析。     

基于液晶空间光调制器相位调制的波面转换

本文介绍了一种基于液晶空间光调制器（LCSLM）相位调制特性的波面转换方法,可将入射光变换成任意波面。测量了液晶空间光调制器相位调制特性,得到相位和灰度的对应关系;分别以几何理论和G-S算法为基础计算出衍射光学元件（DOE）的表面相位分布;将DOE表面的相位分布转换为灰度分布显示在LCSLM上,使得LCSLM具有波面实时转换功能;并以高斯激光为入射光对其进行波面转换实验,实验结果证明了设计方法的准确性及可行性。     

相位型空间光调制器的自参考标定方法

相位型空间光调制器(SLM)是一种对光的相位信息进行定量调控的器件.由于制造和使用过程中的一些不确定因素,需要标定SLM的相位调制,即输入灰度和输出相位的响应(LUT).本文介绍了基于自参考光路的SLM相位调制标定方法.通过在SLM上产生光栅相位,光栅的衍射级次作为参考光,与标定区域的光干涉、形成干涉图.利用傅立叶频谱...     

共路外差干涉测量液晶空间光调制器相位特性

为了对液晶空间光调制器进行高精度的校准, 使其满足线性相位调制的应用需求, 采用共路外差干涉法测量了液晶空间光调制器的相位调制特性, 分析了实验系统的测量原理, 取得了液晶空间光调制器相位调制量随输入灰度值变化的实验数据, 并进行了线性校准。结果表明, 实验中所用的液晶空间光调制器的最大相位调制量为2.55π, 利用反插值法对20~240灰度范围内的相位调制曲线进行线性校正后的理论相位调制曲线非常接近理想线性曲线, 相位调制曲线与理想线性调制曲线的相关系数可达0.9996;该测量方法可克服传统测量方法对图像处理的依赖性, 具有较高的测量精度, 相位调制量直接通过锁相放大器就可获得。该研究为基于液晶空间光调制器的高精度波前校正和精密测量提供了参考。     

铁电液晶空间光调制器

铁电液晶空间光调制器具有响应快、开关功耗低以及双稳态开关特性等优点，在光学信息处理、光计算和神经网络等中有特点诱人的优势。本文介绍了表面稳定型铁电液晶器件的特点及研究进展，并着重描述了光寻址铁电液晶／氢化非晶硅器件的结构、工作原理、主要研制技术关键及共应用。     

液晶空间光调制器的研究

空间光调制器的品种繁多,涉及到的学科范围、理论基础以及工艺技术都十分广泛。文中把空间光调制器归纳为4种类型,对每种类型的基本原理、工作方式和优缺点均进行了讨论,并列举了几种典型常见的空间光调制器,分析了它们的结构、工作原理和方式。     

基于偏振显示的液晶空间光调制器相位特性研究

为了校准液晶空间光调制器,基于偏振显示原理提出一种测量液晶空间光调制器相位调制特性的方法.首先分析液晶空间光调制器对入射线偏振光偏振态的调制特性,然后建立椭圆偏振光经过角向偏振显示器后的长轴方向与液晶空间光调制器相位调制量的理论关系,并搭建测量液晶空间光调制器相位特性的光学系统.结果表明,所用的空间光调制器的最大相位调...     

EM-wave scattering by an inclined strip grating

The characteristic spectral response of an inclined strip grating, either free-standing or embedded in a dielectric slab, is quite sensitive to variations of the cant angle. It is an attractive frequency-selective surface which allows considerable design flexibility through the cant angle and/or the refractive index of the host dielectric. The inclined strip grating is analyzed through an indirect mode-matching technique based on Green's second theorem. The analytical approach is simple and numerically efficient. Calculations focus on the effect of cant angle on the magnitude of all propagating Floquet harmonics on both sides of the structure. Interesting features of the scattering behavior are discussed     

Wideband trapezoidal strip grating for elimination of specularreflection

A trapezoidal strip grating surface that eliminates specular reflections almost over the entire X-band frequency range for TM polarisation is reported. This new grating structure overcomes the bandwidth limitation of conventional rectangular strip grating surfaces     

Wavefront curvature sensor with phase defocus grating

The proposed optimum phase defocus grating for wavefront curvature sensing features an equidistantly quantized two-phase-step and a phase step height of π. The optimum phase defocus grating suppresses the influence of zero-order diffraction. The high diffractive efficiencies of the ±1 diffraction orders are verified experimentally, showing average values of 38.08% and 40.36% respectively. The phase plate introduces the wavefront deformation, which are measured by wavefront curvature sensing and reconstructed via the Green's Function algorithm. The reconstructed wavefront is compared with the measurement result of a Veeco interferometer. It is verified that the measurement of the self-designed curvature sensor is correct. The error percent of peak-valley value (PV) is 10%, and the error percent of root mean square (RMS) is 2%.     

Field-controllable liquid-crystal phase grating

A new liquid-crystal phase-grating mode has been found. The grating is formed by the application of a spatially periodic electric field to a uniformly aligned liquid-crystal layer with dielectric and optical anisotropy. The fundamental diffraction characteristics of this liquid-crystal phase grating were measured by using a Schlieren optical system, and analyzed based on Fraunhofer diffraction theory with the assumption that the refractive indices vary periodically in the liquid-crystal layer. The incident light is diffracted under the electric field in particular directions determined by the spatial frequency of the periodic electrode, and the intensity of the diffracted light increases abruptly or gradually above the threshold depending on the cell thickness. The applicability of this liquid-crystal phase grating to a light valve in a projection display system is also considered.     

Diffraction of a plane wave by a thick strip grating

The diffraction of a plane electromagnetic wave by a thick strip grating is solved rigorously by the Wiener-Hopf technique. The solution contains an infinite number of unknowns, which are shown to satisfy a certain infinite set of equations. By applying the modified residue calculus technique, this set of equations is solved and the approximate solution is derived. Representative numerical examples are given and the transmission characteristics of the grating are discussed     

用相位光栅实现多重成象

提出一种用扫描曝光来制备相位光栅的方法,过程简单,易于控制。文中给出了原理及利用制备的三角相位光栅所获得的实验结果。     

用位相光栅进行图象相减

置一位相光栅于相干光学处理系统频谱平面,利用其零级与一级衍射光的相干迭加实现图象相减.通过控制光栅的位相调制量使零级与一级衍射光强相等,调节光栅位置获得π位相差.选择适当的光栅,还可同时得到图象的相加和相减信号.     

On the edge mode in the theory of TM scattering by a strip or strip grating

Consider a plane wave incident on a perfectly conducting strip (or strip grating), and let the incident electric vector be parallel with the edges of the strip. If the edge mode is included among the basis functions, it is found this greatly improves the convergence of the moment-method solution. Numerical data are included for the reflection coefficient of the strip grating. To correct an error in the previous literature, the rigorous solution is tabulated for broadside backscatter from a single strip.     

Off-Bragg TE blazing of a periodic strip grating on a groundeddielectric

Both off-Bragg and Bragg blazing phenomena, observed in a periodic strip grating over a grounded dielectric, are described, along with some discussion of the differences of the blazing phenomena in this geometry in comparison with those of the previous rectangular groove geometry