激光粒子图像速度场仪的开发

激光粒子图像速度场仪（LPIV）是近年发展起来的一种流速测量新技术。本文开发了一套激光粒子图像速度场仪系统,其中包括成像及查询系统两大部分的开发。该系统利用灰度判别法来判别粒子图像的运动方向。实际应用证明系统的开发是成功的。     

基于声光调制的粒子图像速度粒度场成像系统开发

本文开发了一套基于声光调制的粒子图像速度粒度场仪成像系统,其中包括双脉冲激光系统和光强调整两部分.该系统选用连续激光器,利用声光调制器对激光束的外调制作用,产生不同光强不同频率的激光脉冲,简化了激光系统,实现了基于灰度统计判别的查询方法;采用数字摄像机记录图像,省略了图像采集卡.光强调整减小了光强的高斯分布对成像质量的不利影响.采用像增强技术,使小功率激光器能够达到与大功率激光器相同的效果,降低了激光器功率的要求.利用该系统对循环水槽模拟水涡流开展了测量,并分析了相应的试验结果.     

一种用于粒子场全息图像的目标检测新方法

文章介绍了一种全新检测尺寸跨度较大的粒子场全息图像的目标检测和提取方法。用双窗口法分别增强大、小尺寸粒子目标;用二值图像形态运算的有关算法,较好地解决了粒子目标的识别检测问题。     

基于灰度统计的粒子图像速度粒度实时测量新技术

本文提出了一种基于灰度统计判别原理,可以对粒子图像实现速度和粒径实时同时测量的新技术--粒子图像速度粒度场仪.粒子图像速度粒度场仪通过灰度判别解决了DPIV粒子图像中方向二义性问题,简化了DPIV系统,利用图像处理技术实现了对粒子图像粒径的同时测量.以DPIV粒子图像为研究对象,结合图像处理技术,开发了相应的查询算法,实现了速度粒度的同场测量,并利用模拟粒子图像对查询算法进行了分析检验.通过算法检验表明,速度粒度同场测量算法能够很好地处理各种模拟粒子图像,满足未来实际应用对计算精度及测量时间的要求.     

用于医疗的新型光源

1.前言激光用于治疗仪投入使用有以下几方面必须明确或具体化:1)激光与生物体的相互作用;2)新激光器的问世;3)作为治疗仪的实用性.2.激光与生物体的相互作用激光与生物体的相互作用可分为:1)光波长与生物体的关系,2)光能与生物体的关系.     

粒子场全息图的再现分析

采取移动全息图的方法对再现粒子场全息图进行了分析,同时对非平行光记录和再现粒子场全息图及固定观察平面进行了讨论,对粒子场的量化导出了横向放大倍数的关系式。     

粒子场全息中的定标方法分析及改进

在粒子场的定量分析中.通常采用外加标准丝作为粒子尺寸测量的定标尺度.为了解一定景深范围内存在的标准丝再现像实验测量结果的影响,从理论和实验上详细分析了标准丝再现像在不同位置处的强度分布及变化,指出了常规定标方法对粒子场图像数据所带来的影响,同时提出了一种新的定标方法--非实时定标方法.实验结果表明,非实时定标方法在保持空间定化精度的基础上,测量得到的标准粒子尺寸的不确定在4%左右.该方法有效地解决了标准丝再现像对粒子尺度测量精度影响问题,可以用于粒子场实际测量工作中.     

基于细胞分裂的粒子图像运动分析

针对粒子追踪技术中的粒子误对应问题与粒子相关法对粒子区域平均化处理所带来的误差问题,制定了用于粒子图像测速的细胞分裂准则,并提出了基于细胞分裂的粒子追踪匹配算法模型:将兴趣区域作为细胞体并以细胞体内单点匹配相关程度与粒子的近邻程度作为判断准则对分析窗口内的点进行分裂;分裂形成的子团之间进行竞争并将优胜团代表本分析区域参与其他区域优胜团的竞争;根据优胜团先后位置变化得到矢量位移场.最后,使用人工合成的粒子图进行了算法验证及误差分析.结果表明:所提算法在分析精度方面有了较大的提高.     

Measurement of Deep Energy Level in InP：Fe by the Method of OTCS

We have measured the deep energy level of the InP:Fe which is semi -insulator through the method of OTCS.The effect of light intensity on OTCS measurement is mainly discussed. There are electron trap of ET=0.034 eV and hole trap of ET=1.13 eVin InP:Fe under the strong light and low temperature .The location of the OTCS peak of electron trap(ET=0.34 eV)moves towards the direction of high temperaturer,when the light intensity was increased,ET is different under different light intensity .It is corrected in terms of theory that the stuff ratio of the deep energy level is affected by the light intensity. The experiments show that the error is decreased greatly with the correction.     

In0.53Ga0.47As／InP异质结光电二极管的深能级

采用深能级瞬态谱仪（ＤＬＴＳ）测定了Ｉｎ０．５３Ｇａ０．４７Ａｓ／ＩｎＰ异质结光电二极管的ＤＬＴＳ谱。发现存在一电子陷阱，该陷阱能级位于导带底以下０．４４ｅＶ处，能级密度为３．１０×１０１３ｃｍ－３，电子俘获截面为１．７２×１０－１２ｃｍ－２。由于深能级的存在，导致了该器件存在一种新的“暗电流”──“深能级协助隧穿电流”。     

New dark current component of InGaAs／InP HPDs confirmed by DLTS

The dark current of In_(0.47) Ga_(0.53) As/InP heterojunction photodiodes (HPDs) was analysed. We found that there exists a new dark current component-deep level-assisted tunnelling current.DLTS was used to measure the In_(0.47)Ga_(0.53)As/InP HPDs. An electronic trap which has a thermal activation energy of O.44 eV, level concentration of 3.10×10^(13)cm^(-3) and electronic capture cross section of 1.72×10^(12)cm^2 has been found.It s existence results in the new tunnelling current.     

New dark current component of InGaAs/InP HPDs confirmed by DLTS

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用调制光谱研究半导体体材料及微结构的非线性极化率

提出了用调制光谱信号强度表征半导体体材料及微结构的非线性极化率,研究了测量的原理和方法．对玻璃中量子点电反射调制光谱信号强度随团簇颗粒尺寸的不同而产生几个数量级变化的原因作出了解释     

InP表面等离子体CVD淀积SiO2膜的界面结构及C—V特性

报道了以正硅酸乙酯（ＴＥＯＳ）为源，采用等离子体增强化学汽相淀积（ＰＥＣＶＤ）技术在ＩｎＰ表面低温生长ＳｉＯ２钝化膜。对ＳｉＯ２／ＩｎＰ界面态进行了Ｘ射线光谱（ＸＰＳ）分析和Ｃ－Ｖ特性研究。     

MOS结构深能级瞬态谱的测试与分析

叙述了一种采用MOS结构研究半导体深能级陷阱的深能级瞬态谱(DLTS)测试与分析方法。该方法简便易行,适用范围广。通过对n-Al_(0.2)Ga_(0.8)As中深能级的研究表明,MOS结构和p~+-n结构的DLTS结果相同。     

Semi-insulating InP: Fe regrowth by the hydride VPE technique aroundp-InP substrate laser mesas fabricated by reactive ion etching

Successful regrowth of semi-insulating (SI) InP: Fe by the hydride vapour phase epitaxy technique around reactive ion etched vertical mesas of laser grown on Zn dopedp-InP substrate is demonstrated. The device performance of the buried heterostructure laser is presented. The current confining property of the regrown SI-InP: Fe are good although it lies adjacent to InP: Zn.     

Studies on structural,morphological, magnetic and optical properties of chromium sesquioxide (Cr2O3) nanoparticles: Synthesized via facile solvothermal process by different solvents

Chromium sesquioxide (Cr₂O₃) nanoparticles have been successfully synthesized via the facile solvothermal process, by using CrO₃ in different solvents. The as-synthesized nanoparticle sizes are calculated and confirmed to be 25–45 nm, by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The functional groups of the samples were tested by the Fourier transform infrared (FTIR) spectroscopy. Fine and spherical-like morphologies and compositional elements of the products were observed by the scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. A weak ferromagnetic (WFM) property was observed for sample by the vibrating sample magnetometer (VSM). The observed band gap values (E_g=4.33–3.54 eV) higher than that of bulk Cr₂O₃ (~3.4 eV) indicated that the particles had been successfully synthesized in the nano region, and measured by ultra-violet visible (UV–vis) absorption spectroscopy. The broad visible emission at ~399 nm, in the photoluminescence spectroscopy revealed the high purity and perfect crystallinity of the samples.     

Evaluation of InP:Fe parameters by measurement of two wave mixing photorefractive and absorptive gain

In this paper, we present two-wave mixing absorption gain measurements in InP:Fe in the 960–1035 nm wavelength range. The measured absorption gain is shown to be positive for long wavelength but changes sign for shorter wavelength. By simultaneously measuring the photorefractive gain and the absorption gain, we deduce the values of the photo-ionization cross sections related to the iron deep level trap. Finally, the study of the temperature dependence of the absorption gain allows us to evaluate a temperature shift of the iron level with respect to the conduction band of −4×10⁻⁴ eV/K.