The design of a controllable imaging device with the cold atomic medium

Under the circumstance of a Gaussian control field, the cold atomic medium with electromagnetically induced transparency (EIT) turns out to be the special medium with the quadratic index distribution which is controllable online. In our study, the optical system occupies a portion of the EIT medium which acts as an imaging device. With the help of the Collins formula, the analytic expression for the spatial distribution of the probe field in the cold atomic medium is obtained as well as the location of the imaging. The methods for improving the visibility of the imaging are proposed in this paper. Moreover, we also show that the shapes of the images on the output are strongly influenced by the intensity of the control field, which provides a potential optical processing method.

矩阵理论在半导体激光器耦合中的应用

傍轴近似下的光学矩阵理论，可以简化光束传输计算过程，使光学系统设计更为方便。将ABCD变换矩阵方法引入到耦合光学系统的设计中，运用高斯光束的ABCD法则，详尽地给出了某一耦合方式下的半导体激光器耦合入单模光纤系统的设计；另一方面，对系统的耦合损耗与耦合距离的关系进行了理论计算，并把计算结果与最近的实验报道做了比较，它们基本相吻合，说明此方法是可行的、合理的。从整个设计及理论计算来看，ABCD矩阵方法减少了复杂的计算，从而简化了设计过程，与通常的衍射计算相比，它不失为一种方便、有效的方法，同时它对生产半导体

星间激光通讯中的精跟踪研究

星间激光通讯中，精跟踪起着十分重要的作用，而精密偏转镜（FSM）是精跟踪系统中最为关键的部件．基于光学矢量反射定律，推导得到了FSM的精确光学特性，这一特性为精跟踪控制系统提供了精确的理论依据．设计了基于FSM精确光学特性的精跟踪控制系统，对系统整定所用的单纯形法进行了两点重要改进，并对所设计的精跟踪系统进行了数字模拟，由此实现了对FSM的精确控制，提高了精跟踪系统的精确性；将光学衍射超分辨原理应用到星间激光通讯中．利用三区位相光瞳滤波器的超分辨性能，改变光学系统的点扩散函数，从而改变接收端焦平面上的光强

Two-step digit-set-restricted modified signed-digit addition-subtraction algorithm and its optoelectronic implementation

A novel, to our knowledge, two-step digit-set-restricted modified signed-digit (MSD) addition-subtraction algorithm is proposed. With the introduction of the reference digits, the operand words are mapped into an intermediate carry word with all digits restricted to the set {(1) over bar, 0} and an intermediate sum word with all digits restricted to the set {0, 1}, which can be summed to form the final result without carry generation. The operation can be performed in parallel by use of binary logic. An optical system that utilizes an electron-trapping device is suggested for accomplishing the required binary logic operations. By programming of the illumination of data arrays, any complex logic operations of multiple variables can be realized without additional temporal latency of the intermediate results. This technique has a high space-bandwidth product and signal-to-noise ratio. The main structure can be stacked to construct a compact optoelectronic MSD adder-subtracter. (C) 1999 Optical Society of America.

Enlarging the depth of focus by filtering in the phase-space domain

The ambiguity function was employed as a merit function to design an optical system with a high depth of focus. The ambiguity function with the desired enlarged-depth-of-focus characteristics was obtained by using a properly designed joint filter to modify the ambiguity function of the original pupil in the phase-space domain. From the viewpoint of the filter theory, we roughly propose that the constraints of the spatial filters that are used to enlarge the focal depth must be satisfied. These constraints coincide with those that appeared in the previous literature on this topic. Following our design procedure, several sets of apodizers were synthesized, and their performances in the defocused imagery were compared with each other and with other previous designs. (c) 2005 Optical Society of America.

图像深度估计的光学微分方法

讨论了光学微分方法在图像深度估计问题中的应用。基于线性成像理论对Farid提出的光学微分模型进行了推广，即用于图像深度估计的两幅图像在成像过程中可以满足任意阶的线性微分关系。此模型拓宽了光学微分的概念，使两次成像之间关系有了更多的光学微分形式。围绕如何选择合适的光学微分关系以使系统的整体性能达到最优，分析了光学成像系统的参量对于图像深度估计的精度以及纵向分辨力的影响，并且对光学微分方法中的关键光学元件—光学掩模板的构建方法及优化问题也作了初步的探讨。

基于光栅成像投影的微位移检测方法

提出了一种基于光栅成像投影的微位移检测方法，利用光学傅里叶变换原理给出了具体的理论分析。准直激光束照明的光栅通过一个4f系统成像投影在被测物体表面上，光栅投影经过被测物体表面反射后由另一个4f系统成像在探测光栅上。探测光栅由一个透镜组成像在光电探测器上，其中采用由起偏器、光弹调制器和检偏器组成的偏振调制单元对探测光强进行调制。通过在4f系统的频谱面上设置滤波光阑，在光电探测器上获得了与被测物体的微位移成正弦关系的光强变化，检测出光电探测器上的光强变化即可以获得被测物体的位移量。实验验证了该检测方法的可行性

精确标定光弹调制器的新方法

针对现有光弹调制器标定方法的不足，提出了一种精确标定光弹调制器的新方法。首先利用起偏器、波片、光弹调制器和检偏器构成标定光路．通过寻找探测信号基频分量的极大值进行粗略标定，使光弹调制器的峰值延迟量处在1．841rad附近。然后撤走波片形成光弹凋制器的精确标定光路．在检偏器旋转90°前后获得探测信号的直流分量和二次谐波分量。最后利用这两种探测信号的直流分量和二次谐波分量精确地计算出光弹调制器的峰值延迟量。实验验让了此光掸调制器标定方法，实验结果表明其标定误差仅为0．7％。在此光掸凋制器标定方法中．光弹调制器

Phase-space analysis of wavefront coding imaging systems

We explore the use of the Radon-Wigner transform, which is associated with the fractional Fourier transform of the pupil function, for determining the point spread function (PSF) of an incoherant defocused optical system. Then we introduce these phase-space tools to analyse the wavefront coding imaging system. It is shown that the shape of the PSF for such a system is highly invarient to the defocous-related aberrations except for a lateral shift. The optical transfer function of this system is also investigated briefly from a new understanding of ambiguity function.

“神光-Ⅱ”第九路终端光学系统稳定性分析

在“神光-Ⅱ”装置上进行先进高能多功能激光束系统（简称第九路）研制工程中,由于在原ICF靶室上又增加了输入“汤姆逊探针光”和“X光背光照明探针光”的锥形真空套筒及其终端光学元件,导致原有靶室结构的变化,可能会引入新的不稳定因素.通过有限元分析方法,建立有限元分析模型,进行优化设计.通过位移传感器测量结果可知,第九路终端光学元件径向窜动所引起的打靶误差最大值为2.110 μm,小于“神光-Ⅱ”靶场终端光学系统的最大允许误差值7.785 μm.

New approach to superresolution

We propose a new method to increase the resolution of an optical system by modifying part of the spatial-frequency spectrum, viz., displacing the lower-frequency light to a high-frequency band, which makes the central maximum in the diffraction pattern narrower and increases the depth of focus. Simulation results show that this kind of apodizer (the term apodization was originally used to describe ways to reduce the sidelobes of the PSF, but in this paper, we use it in a wider sense) is superior to the phase-shifting ones. (C) 2001 Society of Photo-Optical Instrumentation Engineers.

Phase-shifting apodizer for next-generation digital versatile disk

The next generation digital versatile disk (DVD) using blue lasers will have a capacity of 13 to 15 Gbytes. Compared with current DVD, the wavelength will be shorter and the numerical aperture (NA) will be higher. But with the increase of NA and decrease of wave length, the depth of focus (DOF) decrease rapidly, which makes it hard for the servo-system to track. We propose an optimized three-portion phase-shifting apodizer to increase the depth of focus and at the same time minimize the spot size, which makes the DOF of next generation DVD comparable to current DVD. The simulation result shows that an optical system with this apodizer also has a good defocus characteristic. (C) 2001 Society of Photo-Optical Instrumentation Engineers.

激光二极管阵列的窄线宽、可调谐输出

外腔反馈的激光二极管阵列(LDA)可获得窄线宽、可调谐的光谱输出。外腔由快轴准直镜、准直光学系统和闪耀光栅组成。由于阵列中各发光单元的排列弯曲导致不同波长的光原路返回,引起谱线展宽,在输出光路中加入光谱滤波器,使激光二极管阵列的线宽进一步窄化。这样,激光二极管阵列的输出光谱由自由运转时的2 nm压缩到0.12 nm,在恒定温度23 ℃时,实现了激光在806～818 nm的调谐,调谐范围达12 nm。

Propagation of flat-topped beams

The propagation of flat-topped beams passing through paraxial ABCD optical system is investigated based on the propagation formulas of Gaussian beam. The focal shift of focused coherent flat-topped beam is also studied in detail. Analytical expressions of the M-2 factor and the far-field intensity distribution for flat-topped beams are derived on the basis of second-order moments. (C) 2007 Elsevier Ltd. All rights reserved.

激光尘埃粒子计数器微型光学传感器的研究

研制成功便携式激光尘埃粒子计数器的核心部件——微型光学传感器。该传感器采用直角散射光收集形式。以高功率半导体激光器作为光源，同时采用高性能的PIN型光电二极管作为光电探测器。散射光收集系统为单一大数值孔径的球面反射镜，其对粒子散射光的收集角范围从20°到160°。粒子散射光信号是脉冲信号，其频谱成份主要在高频段，所以在PIN型光电二极管后用一个带通式前置放大器来消除外界的低频噪声．根据米氏散射理论计算了该光学传感器的光散射响应特性，并用聚苯乙烯标准粒子实测了该光学传感器的性能。结果表明，该系统具有高的信噪