二次光栅在波前测量中的应用

采用一种特殊的二次光栅用于激光波前测量, 它对非零级衍射光束具有不同的聚焦效应, 其光栅线为圆弧型而非直线。导出了在会聚光束情况下的两平面成像在单一像平面上的距离关系, 实验上实现了二次光栅用于会聚光束的波前测量, 测量得到会聚光束具有较大的散焦(-2.93λ)和球差(1.34λ), 与该透镜引起波前的离焦像差理论理想值(-2.695λ)基本符合。该技术可以实现波前的高空间分辨力和高精度实时测量, 大大减少光学元件数量, 降低装置成本。由于大功率激光束的不稳定性, 其波前变化非常快, 所以该方法的实时性非

高精度微结构聚合物光栅的复制技术

光栅复制是降低光栅制造成本,提高产量的一条有效途径。研究了利用紫外压印技术复制微结构光栅的方法。使用玻璃基底矩形浮雕结构的微结构光栅作为母光栅,给出了利用聚二甲基硅氧烷(PDMS)制作光栅模具和在光敏聚合物材料上复制微结构光栅的详细过程。经过优化工艺条件,成功地复制了一系列不同周期和开口比的微结构光栅,测试了复制光栅和母光栅的衍射图像和0级与±1级的衍射强度,结果表明,复制光栅和母光栅的衍射图像与光强分布基本一致。

Fiber Bragg grating temperature sensor for multiplexed measurement with high resolution

A novel fiber Bragg grating temperature sensor is proposed and experimentally demonstrated with a long-period grating as a linear response edge filter to convert wavelength into intensity-encoded information for interrogation. The sensor is embedded into an aluminum substrate with a larger coefficient of thermal expansion to enhance its temperature sensitivity. A large dynamic range of 110 degreesC and a high resolution of 0.02 degreesC are obtained in the experiments. The technique can be used for multiplexed measurements with one broadband source and one long-period grating, and therefore is low Cost. (C) 2004 Society of PhotoOptical Instrumentation Engineers.

Wave-front analysis method of circular aperture sampling for collimation testing

A new type of wave-front analysis method for the collimation testing of laser beams is proposed. A concept of wave-front height is defined, and, on this basis, the wave-front analysis method of circular aperture sampling is introduced. The wave-front height of the tested noncollimated wave can be estimated from the distance between two identical fiducial diffraction planes of the sampled wave, and then the divergence is determined. The design is detailed, and the experiment is demonstrated. The principle and experiment results of the method are presented. Owing to the simplicity of the method and its low cost, it is a promising method for checking the collimation of a laser beam with a large divergence. © 2005 Optical Society of America.

径向双折射滤波器的超分辨性能研究

超分辨技术因其可以超越经典的衍射极限而为人们所熟知．并且．在光存储和共焦扫描成像系统中有着广泛的应用。把由两个偏振器和一个圆对称的双折射元件组成的径向双折射滤波器引入超分辨技术，借助琼斯算法推导出其光瞳函数的表达式。由分析得出通过改变径向双折射滤波器中偏振器的偏振方向和双折射元件的主轴之间的夹角，即可实现光学系统的横向超分辨或轴向超分辨。同时对评价该器件超分辨性能的参量第一零点比、斯特尔比和旁瓣强度抑制比做了详细的讨论。该滤波器用于超分辨技术的优点在于其制作不涉及相位的变化而比较简单，且费用比较低。缺点是

Novel Mach-Zehnder interferometer structure for tunable optical interleaver

A novel optical interleaver scheme based on nested optical glass pairs is proposed. The assembly of pairs behaves as a cascaded Mach-Zehnder interferometer. The interleaver, with simple structure, low cost, and compact size, can be easily implemented with inexpensive material and mature preparation technology. Small channel spacing (<= 50 GHz), high isolation (<-30 dB), a wide, flat passband and stop band (> 2/11 period), and center-frequency tunability can be obtained simultaneously. An optimum design of a 50-GHz tunable interleaver based on this structure is given as an example. Its environmental temperature sensitivity and fabrication tolerance are also analyzed. (c) 2006 Society of Photo-Optical Instrumentation Engineers.

Collimation testing using axial intensity

We proposed a new method of measuring the degree of collimation of laser beam using axial intensity information near paraxial focus. Preceding methods for collimation testing are mainly either based on self-imaging or interferometric techniques. The new method is to employ the diffraction behavior of noncollimated wave in circular aperture diaphragm. The principle of the proposed method and experiment results are presented. Due to simplicity of the method and its low cost, it is a promising method for checking the collimation of laser beam. (c) 2005 Published by Elsevier GmbH.

Fiber grating sensors for high-temperature measurement

Two fiber grating sensors for high-temperature measurements are proposed and experimentally demonstrated. The interrogation technologies of the sensor systems are all simple, low cost but effective. In the first sensor system, the sensor head is comprised of one fiber Bragg grating (FBG) and two metal rods. The lengths of the rods are different from each other. The coefficients of thermal expansion of the rods are also different from each other. The FBG will be strained by the sensor head when the temperature to be measured changes. The temperature is measured based on the wavelength-shifts of the FBG induced by the strain. In the second sensor system, a long-period fiber grating (LPG) is used as the high-temperature sensor head. The LPG is very-high-temperature stable CO2-Aaser-induced grating and has a linear function of wavelength-temperature in the range of 0 - 800 degrees C. A dynamic range of 0 - 800 degrees C and a resolution of 1 degrees C have been obtained by either the first or the second sensor system. The experimental results agree with theoretical analyses. (c) 2007 Elsevier Ltd. All rights reserved.

A novel fiber Bragg grating high-temperature sensor

A novel fiber Bragg grating (FBG) sensor for the measurement of high temperature is proposed and experimentally demonstrated. The interrogation system of the sensor system is simple, low cost but effective. The sensor head is comprised of one FBG and two metal rods. The lengths of the rods are different from each other. The coefficients of thermal expansion of the rods are also different from each other. The FBG will be strained by the sensor head when the temperature to be measured changes. The temperature is measured basis of the wavelength shifts of the FBG induced by strain. A dynamic range of 0-800 degrees C and a resolution of 1 degrees C have been obtained by the sensor system. The experiment results agree with theoretical analyses. (c) 2007 Elsevier GmbH. All rights reserved.

High-fidelity replication of Dammann gratings using soft lithography

We report the experimental results of using the soft lithography method for replication of Dammann gratings. By using an elastomeric stamp, uniform grating structures were transferred to the LTV-curable polymer. To evaluate the quality of the replication, diffraction images and light intensity were measured. Compared with the master devices, the replicas of Dammann gratings show a slight deviation in both surface relief profile and optical performance. Experimental results demonstrated that high-fidelity replication of Dammann gratings is realized by using soft lithography with low cost and high throughput. (C) 2008 Optical Society of America.

柱状ZnO阵列薄膜的生长及其发光特性

采用一种设备简单、原料低廉的新型方法，在镀有ZnO先驱薄膜的（0001）蓝宝石上利用水热法制备出了柱状ZnO阵列薄膜．用扫描电镜（SEM），X射线衍射（XRD）对样品的形貌和结构进行了表征，结果显示ZnO薄膜为柱状阵列，基于蓝宝石衬底沿c轴择优生长，且（0004）摇摆曲线半高宽度（FWHM）约为1.8°。此ZnO阵列薄膜具有很强的紫外发射光谱（PL）．