显示反射全息图单光束相干复制技术

描述用单光束激光复活制银盐白光显示反射全息图的技术，本技术的关键：１）母全息图的颜色必须恢复到满足其布拉格条件；２）复制所用的光波与记录母全息图时的参考的相同；（３）复制所用的激光采用平行偏振，以减少界面反射；９４）采用白糖溶液作为折射率匹配液，取得极佳效果。     

Direct amplitude detection of Zernike modes by computer-generated holographic wavefront sensor: Modeling and simulation

A fast holographic wavefront sensor is proposed using a computer-generated hologram (CGH). This CGH is a multiplexed hologram of different Zernike mode–amplitude combinations, and is designed in such a manner as to get the corresponding spots on the detector according to the presence and strength of a particular aberration. Interference between the aberrated wavefront (with a single mode–amplitude combination) and the Fourier transform of an image with single bright pixel (defined as dot image) is numerically calculated for one hologram. Different mode–amplitude combination and corresponding different positions of bright pixels (dots) are taken to compute various holograms and then all the holograms are multiplexed to get the final hologram. When the aberrated wavefront with a particular mode–amplitude combination is incident onto the multiplexed hologram, the corresponding dot is generated in the Fourier plane. A lens performs the Fourier transform in optical domain and provides the instant detection of amplitude of the respective Zernike mode. The main advantage of the scheme is to avoid the need of any computations, which makes it really fast. The simulation results are presented with the cross-talk analysis for few Zernike terms.     

Double Hopf bifurcation for van der Pol-Duffing oscillator with parametric delay feedback control

The stability and bifurcation of a van der Pol-Duffing oscillator with the delay feedback are investigated, in which the strength of feedback control is a nonlinear function of delay. A geometrical method in conjunction with an analytical method is developed to identify the critical values for stability switches and Hopf bifurcations. The Hopf bifurcation curves and multi-stable regions are obtained as two parameters vary. Some weak resonant and non-resonant double Hopf bifurcation phenomena are observed due to the vanishing of the real parts of two pairs of characteristic roots on the margins of the “death island” regions simultaneously. By applying the center manifold theory, the normal forms near the double Hopf bifurcation points, as well as classifications of local dynamics are analyzed. Furthermore, some quasi-periodic and chaotic motions are verified in both theoretical and numerical ways.     

计算全息补偿法制作全息凹面光栅的改进

鉴于计算全息图可以产生一个任意形状的波面,用它作为位相补偿板来制作全息凹面光栅以适应消象差的要求比普通光学全息法更具灵活性,而且消象差波长的选择也不受制作时所用的光源光波波长所限制。本文中采用了离轴滤波及改变参考波面特性等措施,大大提高了计算全息图的空间带宽积,扩大了这一方法的使用范围。对1200l/mm的Ⅲ型及Ⅳ型凹面全息光栅进行了设计,制作及实验验证。     

浅谈全息图的复制

简要介绍了将原全息图再现和接触复制法两种全息图复制的原理与方法.进一步采用接触复制法的方法,利用激光作为光源进行了全息图的复制实验研究.实验结果表明复制的全息图再现像图像比较清晰,层次分明.     

Real-time optical reconstruction of the diffused 3D object using phase information calculated by Continuous Wavelet Transform

We propose the real time optical reconstruction of a three-dimensional (3D) object from a digitally recorded hologram. Phase distribution of the recorded hologram is numerically calculated by 1-dimensional Continuous Wavelet Transform (1D-CWT) for digital reconstruction with phase only information. Also, the phase distribution of 1D-CWT transferred to the spatial light modulator (SLM) is used to obtain optically reconstructed image. It is observed that an efficient real-time analysis can be achieved, if phase of 1D-CWT is used. In the same time, optically reconstructed 3D objects obtained by only phase information are about three times brighter than bleached hologram intensity's. So the minimum power loss can be obtained. Numerical and experimental results are presented.     

一种离轴计算全息图在凹非球面检测中的应用

为了精确检测大口径非球面面型质量,将CGH作为补偿器应用于凹非球面的离轴全息检测系统中.根据计算全息图的离轴全息检测系统检测凹非球面的基本原理,分析了离轴CGH的计算、制作过程,实现了对口径为150 mm,近轴半径为1499.7 mm,非球面系数为-1的凹非球面镜的检测.实验结果与轮廓仪检测结果吻合得很好.     

全息声压场的加权范数外推方法

全息声压外推是Patch近场声全息技术的关键步骤.本文提出了全息声压的加权范数外推方法,该方法首先通过实测声压数据的功率谱信息构造频域加权范数,然后通过极小化频域加权范数实现全息声压外推.由于外推过程中同时利用了声压信号的波数域带宽和波数谱形状信息,因此其外推结果优于传统带限外推方法.数值仿真结果表明,该方法无论在外推精度还是计算效率上都明显优于经典的全息声压波数域外推方法.刚性箱体上的声激励固支板声压外推实验进一步验证了该方法的有效性和实用性. 关键词： 近场声全息 全息声压外推 加权范数     

Application of Surface Relief Hologram Using Azobenzene Containing Polymer Film

Surface relief holograms are fabricated by irradiation of laser interference patterns on an azobenzene polymer film. The hologram needs no post-treatment, and can be erased by heating the films to above its glass transition temperature. Rewritable Fresnel holograms are fabricated on azo-polymer film. Replication of the surface relief hologram is also demonstrated. An application for business cards is considered.