测试激光Raman分光计中超低杂散光的一种新方法

本文提出了一种利用高灵敏度的光子计数技术及中性滤光片分段减光方法去测试激光Raman分光计中超低杂散光的新方法。它不仅省去了大量级范围内光电检测系统线性检测与中性滤光片透过率标定的麻烦,提高了测试精度,而且实现了光强变化任意量级的杂散光测试,其测量限最终仪受激光功率大小的限制,获得了10~(-14)量级的杂散光测量限。     

整体快速擦除式激光选址液晶光阀

本文介绍一种改进的激光选址液晶光阀。它以液晶的光散射态(暗态)为显示背景,减少了对观察者眼睛的刺激;它的整体擦除时间大约0.5～1s.采用以暗态为背景的方案,必须对光阀施加高电压才能进行整体擦除,高电压容易使光阀击穿。本文采用在导电层与吸收层之间镀隔离层,就可避免因加大液晶层厚度使写入光灵敏度降低,又增加了高电压与大电流的承受能力。     

聚噻吩/季铵盐聚离子液体双层体系的电存储性能研究

合成了一种基于季铵盐的聚离子液体q-PVBC,以其作为固体电解质层,制备基于聚[3-(6-羧基)己基]噻吩(P3CPT)的OFET型微电子器件。器件的电流-时间关系曲线揭示了双层体系具有双稳态的存储特性,在+3V的电压下写入信号,在-3V的电压下擦除信号,写入/擦除操作之后可用0.5V的电压读取信号。两种导电态的电流比达到104,"写入-读取-擦除-读取"循环操作可以达到上百次。由双脉冲测试观察到瞬时的响应和较快的开启速度,信号写入时间约为0.39s。尽管写入电信号随时间出现一定的衰减,在保持大约2000s后体系仍然可以进行擦除操作。     

掺铜铌酸钾锂晶体光析变效应的研究

在铌酸钾锂 (KLN)晶体中掺进CuO ,采用Czochralski法生长Cu∶KLN晶体。测试Cu∶KLN晶体红外透射谱 ,研究OH- 吸收峰发生红移的原因。以二波耦合光路测量Cu∶KLN晶体的光析变擦除曲线 ,计算擦除时间和光电导 ,研究Cu∶KLN晶体的光折变性能     

双向行波式声光驻波调制器

提出了一种新型的声光驻波调制器，即双向行波式声光驻波调制器，建立了数学模型，进行了模拟计算，并从理论上证明了其衍射光的振幅和光强的表达式安全等效于反射式的声光驻波调制器，利用中心频率为５０ＭＨｚ的器件，测得其对衍射光强的调制频率两倍于声频，并随时间做周期的变化，其带宽Δω＝７ＭＨｚ，远远大于驻波器件；而且从对调制光的调制度的测试结果来看，较易获得对光强具有大的调制度的调制器件。     

一种基于TN型液晶的自控光阀

对TN(扭曲向列)型液晶的透光率测量实验表明,在外加电压的作用下TN型液晶可以吸收入射光线,并且在外加电压连续改变时,对入射光的透光率将呈现连续非线性变化。根据此特性,利用数字电路来控制加到液晶电极上的电压,就得到了一种空间光调制器──自控光阀。自控光阀能控制通过光阀的光强,使之趋于设定值。     

M_(1—β)(TCNQ):用于可擦式高密度存贮器的信息薄膜材料

利用我们自己开发的新型分子电子材料的光致变色性能可制成可擦写的光盘,它的特点是可用任意波长的激光写入,用热、电或光擦除。已经做到Ag_(1-β)(TCNQ)的写擦循环次数N>1000,反差系数K>50%。利用它的电开关性能则预计可在cm~2的基片上用“5μm平面工艺”制成两种1兆位(MB)存贮器。第一种称为“金属有机存贮器(OMM)”,是全固态的电擦除可编程只读存贮器(E~2 PROM),可做在硅片上并与硅器件兼容;另一种称为“可擦式存取存贮管(EAST)”,是一个特殊的电子管,可用作随机存取存贮器(RAM),用电子束进行信息的写入、读出、擦除。这两种存贮器的存贮密度都可接近于光盘存贮器而存取时间相当于半导体存贮器。它们都不用半导体单晶,没有p-n结;器件面积小、工艺简单。可以认为是分子电子学方面真正有实用价值的一些工作的开端。     

MEMS光栅光调制器阵列的控制系统设计

针对光栅光调制器阵列的显示控制,提出了一种控制系统设计方案。设计应用软件,产生显示数据源,由USB数据线发送到FPGA芯片,在FPGA芯片上实现格式转换、乒乓操作、脉宽调制等模块电路。实验结果表明,该控制系统操作灵活方便,为测试光栅光调制器的显示参数提供了有力的技术支持。     

新型三维存储材料及应用

通过实施双掺杂工程,既控制光折变晶体中的光折变敏感中心(即施主中心),又控制其中的电子陷阱中心,优化双掺LN晶体的光折变存储特性,得到了优良的光存储材料,同时,利用光折变全息记录以及全光固定光栅技术,研制成三维全息存储器原型。具体研究成果如下: (1)首次在国际上发现光强阈值效应,打破了国际上传统的“与光强无关”的概念,同时,首次提出最佳写入光强的概念;首次发现高掺镁晶体的紫外光折变增强效应,打破了国际上的“掺镁抗光折变”的概念的绝对化;建立了国际上较为完善的晶体缺     

丝网印刷法制备染料敏化太阳能电池光电性能的研究

采用水热法制备TiO2纳米颗粒,将获得的TiO2纳米颗粒制备成胶体,采用丝网印刷法在FTO表面刷涂制备染料敏化太阳能电池（DSSC）光阳极,通过扫描电子显微镜对电极表征和电池光电性能测试,探讨印刷层数及入射光强对DSSC光电性能的影响,实验结果表明,将制备的光阳极组装成电池后具有较好的光电性能,当印刷层数为8层、光强为80W／m2时,电池取得最好的光电性能。     

Real-time phase-difference amplification with a liquid-crystal spatial light modulator

We describe a simple system for achieving real-time phase-difference amplification of interferograms. We arrange the interferogram such that it contains high-spatial-frequency carrier fringes and project it onto the write side of an optically addressed phase-only spatial light modulator. The resultant phase pattern on the modulator is read out by two readout beams, and diffraction by the carrier fringes provides the spatial heterodyning that is necessary for achieving phase-difference amplification. We present results that demonstrate real-time phase-difference amplification by as much as a factor of 10.     

Programmable spatial filtering with bacteriorhodopsin

We describe a programmable spatial-filtering system using bacteriorhodopsin (BR) film as a programmable, optically addressed spatial light modulator illuminated by a single wavelength of light. We use a computer-controlled mirror scanning system to write time-varying filter functions to the BR film and present proof-of-principle experimental results that demonstrate several elementary filtering operations.     

Frequency-multiplexed logic circuit based on a coherent optical neural network

We propose an adaptive logic circuit whose function can be controlled by optical carrier frequency modulation. The circuit learns the desired functions by adjusting the delay time at a spatial light modulator with a complex-valued Hebbian learning rule. After the learning, the circuit can switch its function all at once. A high degree of mechanical stability is achieved by spatial phase-difference coding. Two orthogonal phase components are detected in parallel spatially. Experiments demonstrate that the system works as an AND circuit at a certain frequency and as an XOR at another. The proposal will enhance the design of optical plastic cell architectures.     

Phase-difference amplification in near-real-time phase-stepping interferometers

We present results from two interferometer systems incorporating phase amplification and phase stepping that operate in near real time. Each system contains two interferometers. The first interferometer projects an interferogram of the test object onto the write side of an optically addressed phase-only liquid-crystal spatial light modulator (LCSLM). The read side of the LCSLM is illuminated by two beams from the second interferometer that are adjusted so that their +n- and -n-order beams are diffracted back along the optic axis. These produce an output interferogram that is phase amplified by a factor 2n. This phase distribution is retrieved by phase stepping.     

Bessel function output from an optical correlator

We introduce a new filter for an optical correlator that produces a Bessel function correlation output. The advantage of this type of output is that the width of the central dark spot at the center of the correlator output is narrower than the width of the usual correlation spot. In addition, the dark spot is insensitive to changes in illumination intensity. We present experimental results with which we write the new filter onto a programmable magneto-optic spatial light modulator.     

Erase profiles of floppy disk heads

An experimental method is described to measure the amplitude profiles across written tracks used in rigid and floppy disk drives. This method allows determination not only of read, write, and side-erasure widths associated with the heads, but also of the detailed shape of the written profiles. These profiles may be obtained for tracks in the as-written condition, or after modification by the write or erase functions of the head. This method was applied to floppy disk heads in order to determine the trim erase characteristics of straddle erase, tunnel erase, and the implicit side erase characteristic of the read/write core itself. A number of typical track profiles are shown, demonstrating the usefulness of this technique. It was found that the straddle erase elements exhibit erasure both under the air gap and under the poles straddling the read/write core; the tunnel erase elements exhibit uniform erasure across their erase gaps but are subject to azimuthal misalignment effects; and the read/write cores themselves exhibit an implicit erase function during normal writing which, in the case studied, extended about 360 μm (9 μm) to each side of the core. Applications of this method to evaluate heads for use at high track densities are also outlined.     

Real-time optical image subtraction and edge enhancement using ferroelectric liquid-crystal devices based on speckle modulation

We carried out real-time optical image subtraction and edge enhancement based on a speckle modulation technique by using ferroelectric liquid-crystal polarization switches and a ferroelectric liquid-crystal spatial light modulator. A ferroelectric liquid-crystal spatial light modulator is employed as a real-time and multiple-exposure optical device, and successful results are obtained from three-exposure images modulated by speckles. Thus, image subtraction and edge enhancement are realized in real time. The whole operation is performed within several milliseconds with modest operating conditions. Because the spatial light modulator has a high resolution of greater than 100 line pairs/mm and can store fine speckle patterns, the image qualities we obtained are quite satisfactory.     

Incoherent-to-coherent conversion and square-law transmission based on photoinduced birefringence in bacteriorhodopsin films

We review the main optical properties of bacteriorhodopsin that are relevant to its use as a spatial light modulator. A model is described for the transmittance of a film placed between crossed polarizers in which photoinduced birefringence occurs. We show when the transmittance is proportional to the write intensity. We use this property in a joint transform correlator for incoherent-to-coherent conversion and effective square-law modulation in the Fourier plane.     

Optical rotatory-dispersion-type spatial light modulator and characteristics of the modulated light

Among known temporal-spatial light modulation methods, there is no realistic method that can precisely control a light pulse simultaneously in the temporal and spatial domains. By careful consideration of the symmetries and topological properties of electromagnetic waves, a novel spatial light modulator has been developed to create different far-field patterns for each wavelength of linearly polarized light composed of various wavelength components. The system consists of an optical rotatory dispersion device, which is like a Faraday rotator, and a spatial light modulator with parallel-alignment nematic liquid-crystal cells. Numerical simulation results show the effectiveness of this new spatial light modulation method.     

Effects of magnetic fields on flexible disk drive performance

The read/write heads in flexible disk drives operate in the presence of AC and DC magnetic fields generated by solenoids, motors, recording head erase structures, circuit board components, and external sources such as CRT flyback transformers present in "smart terminals and word processors. Time varying magnetic fields induce signal on the read/write coil and introduce interference. This interfering signal increases the error rate and can cause "extra bits". Steady state fields cause shifts in the location of transitions, which also translates into higher error rates. The benefits derived from various shield configurations in and external to the flexible disk drive are presented.