透射漫反射混合型物体的全息图拍摄

用物体的透射光做物光波,分时分区照明,并采用二次曝光,拍摄了透射漫反射混合型物体的全息图.     

二维多色阵列辐射的产生及其弱光控制

在二阶非线性介质中观察到二维多色阵列辐射. 空间分布为椭圆状的飞秒光束在二阶非线性介质中空间分裂成二阶空间孤子，与另一飞秒光束交叉重叠发生非共线级联二阶非线性耦合后产生了二维多色阵列辐射. 同时，交叉耦合的光束在介质中形成了瞬态光栅，同步注入的超连续白光被此瞬态光栅衍射，获得相同相位的上转换二维多色阵列放大. 注入少量二次谐波，抑制了二阶空间孤子的产生，从而导致二维多色阵列辐射及其上转换放大被抑制. 关键词： 二维多色阵列 级联非共线二阶非线性 弱光控制     

多色量子阱红外探测器的发展（上）

军用红外探测器需要使用工作在各种红外波段的大规格,高均匀性多色焦平面阵列器件。满足这些要求的一个候选者就是量子阱红外（光电）探测器（QuantumWell Infrared Photodetector,QWIP）。作为新一代红外探测器,QWIP基于极薄半导体异质结构中的载流子束缚效应。GaAs／A1GaAs／QWIP的主要优点包括标准的III—V族衬底材料和技术、良好的热稳定性、大面积、低研发成本以及抗辐射性。QWIP的另一个重要优点是具有带隙工程能力。可以通过调节量子阱宽度和势垒组分设计出满足特殊要求（例如多色焦平面列阵应用）的器件结构。介绍了对QwIP探测物理机制的理解以及近年来多色QwIP技术的发展状况。     

三维物场多重分数傅里叶变换全息图光电再现实验研究

对基于多重分数傅里叶变换(FrFT)的三维(3D)物场计算全息图进行光电再现实验研究.根据分数阶与衍射距离的关系,对不同物面分别设置不同的分数阶,分别计算得到各层物面在全息面的复振幅并进行叠加,对其进行编码分别得到分数傅里叶变换振幅型全息图和相息图.同时在计算3D物场的全息图时,在物波面加入不同的随机相位因子,得到3D...     

灰度调整与数字全息图像质的关系

如何在有限的灰度级别下输出高质量全息图是人们关注的问题之一,文章从数字全息图(计算机制全息图)的灰度直方图出发,研究灰度调整对全息图再现像质的影响.首先通过理论推导研究了压缩计算机制全息图中占比例少的灰度,展宽占比例多的灰度后全息图衍射效率的变化,发现处理后的计算机制全息图经灰度压缩的阈值越大,衍射效率越高.然后研究了...     

Improvement of speckle noise suppression in digital holography by rotating linear polarization state

An improved polarization recording approach to reduce speckle noise in digital holography is proposed. Multiple off-axis holograms are obtained by rotating the linear polarization state of both illumination and reference wave simultaneously. By averaging the intensity fields, the speckle noise in the reconstructed images is well suppressed. Statistical evaluation of the experimental results shows the effectiveness and improvement of the proposed method.     

Optimization of computer-generated holograms for dynamic optical manipulation with uniform structured light spots

An optimized iterative technique combining the merits of conventional Gerchber-Saxton (G-S) and adaptive-additive (A-A) algorithms to design multilevel computer-generated holograms for the creation of a desirable structured intensity pattern for multiple optical manipulation is theoretically adopted. Optical trap arrays are demonstrated with the help of liquid crystal spatial light modulator and a microscopic optical tweezer system. Additionally, continuous locked-in transport and deflection of microparticles with the generated optical lattice is proven experimentally. The proposed method possesses apparent high efficiency, high uniformity, and dynamic and reconfigurable advantages.     

参考光照射下的数字全息图频谱特点及应用

提出了一种在离轴数字全息再现过程中确定参考光角度和简化滤波器设计过程的方法。分析了模拟参考光照射下的离轴数字全息图的频谱特点。首先将数字全息图与计算机模拟的原参考光波相乘,然后做傅里叶变换,得到其频谱图。结果发现,含有被记录物体信息的物光波频谱始终处在频谱面的中央位置。依据这一特点,不仅可以实现模拟再现时最佳参考光的角度参数测定,而且还可以使滤波器的结构设计过程简化。借助于滤波技术,数字全息再现像中零级像和共轭像得到了有效的去除,再现物体实像质量得到了有效的改善。     

Bounding box extraction from spherical hologram of elementary object to synthesize hologram of arbitrary three-dimensional scene with occlusion consideration (Invited Paper)

A novel method to extract a bounding box that contains the three-dimensional object from its spherical hologram is proposed. The proposed method uses the windowed Fourier transform to obtain the angular distribution of the quasi-collimated beams at each position in the spherical hologram and estimates the bounding box by accumulating the quasi-collimated beams in the volume inside the spherical hologram. The estimated bounding box is then used to realize occlusion effect between the objects in the synthesis of the three-dimensional scene hologram.     

Fresnel hologram reconstruction of complex three-dimensional object based on compressive sensing

Reconstruction the computer generated Fresnel hologram of complex 3D object based on compressive sensing （CS） is presented. The hologram is synthesized from a color image and the depth map of the 3D object. With the depth map, the intensity of the color image can be divided into multiple slices, which satisfy the condition of the sparsity of CS. Thus, the hologram can be reconstructed at different distances with corresponding scene focused using the CS method. The quality of the recovered images can be greatly improved compared with that from the back-propagation method. What＇s more, with the sub-sampled hologram, the image can be ideally reconstructed by the CS method, which can reduce the data-rate for transmission or storage.