高精度激光微能量校准技术研究

利用斩波器将连续激光斩波成为脉冲宽度s量级重频脉冲激光,利用选单器将重频脉冲激光转变成单脉冲激光,从而实现变连续激光为单脉冲激光。由陷阱探测器测量连续激光的输出功率,高速APD、高增益PIN探测器作为波形探测器测量脉冲激光波形,并通过示波器对脉冲宽度进行测量。依据测量得到的功率和波形就可得到脉冲激光能量,从而实现了0.2 pJ激光微能量的测量和校准,通过不确定度分析,该装置的pJ激光能量测量不确定度达到了0.42%。     

太瓦飞秒脉冲激光峰值功率测量装置及测量不确定度分析

超短超强脉冲激光（飞秒强激光）具有极高的峰值功率,在激光惯性约束聚变、高能物理、激光微加工等领域具有广阔的应用前景。飞秒脉冲激光峰值功率是评价超短超强脉冲激光系统性能的重要参数。介绍了基于光谱相位相干直接电场重构法的太瓦量级飞秒脉冲激光峰值功率测量方法、测量装置组成和工作原理,搭建了一套太瓦量级的飞秒脉冲激光峰值功率测量装置,分析和讨论了影响太瓦激光峰值功率测量结果的测量不确定度分量来源和主要因素。测量峰值功率的重复性为2.9%,测量不确定度达到17.6%(k=2),有效解决了太瓦量级飞秒激光峰值功率测量问题。     

355 nm紫外激光损伤阈值自动测量装置及实验

介绍了一套355nm紫外激光损伤阈值自动测量装置。该测量装置由一台Nd：YAG激光器产生紫外355nm激光,经过紫外激光传输系统,紫外激光聚焦形成测试激光。脉冲激光能量由激光能量计监测,Normaski显微镜判断样片的激光损伤。另外,整个测量装置和测量过程由计算机集成控制,具有良好的操作性和运行参数控制能力,可实现1—on-1,n-on-1,s—on—1,R-on-1等多种激光损伤测试。     

光学在大型几何尺寸测量中的应用

介绍了几种光学原理在大型几何尺寸测量中的应用．讨论的内容包括：多波长、双波长合成波长绝对距离干涉测量；激光频率分裂干涉测量；线性调频绝对距离干涉测量；相位板激光准直；旋光激光准直；半导体激光动态定位等．文章介绍了测量系统的工作原理，并讨论了测量精度和应用前景     

强激光远场光斑强度分布测量技术

准确测量激光远场光斑强度时空分布是分析强激光大气传输效应和评价激光系统性能的有效手段。概述了测量激光光斑强度分布的几种方法及其适用性,重点叙述了基于阵列探测法的强激光远场光斑强度分布测量技术,总结分析了量热阵列法、光电阵列法和量热/光电复合法等三类阵列探测系统应用特点。最后介绍了两种分别用于测量连续波高能激光和重频脉冲激光的光电阵列靶斑仪,系统具有结构紧凑的特点,能够满足运动靶目标上强激光参数测量要求。     

一种实时测量入射激光波长及方位的新方法

提出了一种利用CCD和光栅实时测量入射激光波长及方位的新方法。该方法利用成像CCD,通过测量入射激光成像点在电视成像坐标系中的位置来确定激光的入射方位;根据光学系统中成像点位置与光栅入射角和衍射角的几何关系,利用光栅测量入射激光的波长。介绍了该方法的测量原理及光学系统结构,给出了测量入射激光波长及方位的计算表达式,分析了测量误差,并在室内通过测量实验对该方法进行了验证。     

飞焦级脉冲激光能量测量方法研究

为解决1 fJ～1 pJ脉冲激光能量的测量问题,提出了一种基于时域波形积分的飞焦级脉冲激光能量测量方法。该方法采用光电倍增管（PMT）获得飞焦级脉冲激光的响应信号,该微弱响应信号经放大、校准与激光脉冲时域波形积分后实现飞焦级脉冲激光能量测量。根据该方法设计了飞焦级脉冲激光能量测量装置,并分析了该装置的测量不确定度。实验表明,该装置实现了波长1 064 nm、脉冲宽度5 ns～1 s、能量范围1 fJ～1 pJ的脉冲激光光源的能量测量,测量不确定度为15.8%。     

准分子激光的光束波面测量技术

 准分子激光在激光光刻和微细加工中有广泛的应用，要求激光具有好的稳定性和光束波面均匀性。介绍了准分子激光的波面特性以及波面分析测量技术。用波面分析仪对XeCl和ArF激光特性进行全面的测量和评估，给出了主要参数的测量结果，重点分析了光束均匀性。     

便携式激光辐照度测量系统

激光驾束制导中,制导激光的辐照度是一个重要的性能参数。为了实现制导激光辐照度的野外快速、准确测量,研制了小型、便携式激光辐照度测量系统。系统利用微处理器进行控制和数据采集处理,实现了测试数据的自动修正,提高了测量结果的准确性。同时可选择测量0.92μm、0.98μm和1.06μm三种波长的激光辐照度。经实验验证,该系统测量准确、结构简单、使用方便,适合室内以及野外测试。     

斩波法在激光微能量计标定中的应用

针对激光微能量测量的问题,提出一种激光微能量计标定新方法与装置。研究内容包括使用稳功率连续激光作为光源,通过基于斩波的脉冲发生器组件产生微能量的脉冲激光,分别使用脉冲宽度测量组件与功率测量组件进行采集、软件分析,计算微能量值及通过比对给出待标定能量计的修正系数,计算机自动控制。结果表明,该方法获得的脉冲激光波形稳定,脉冲宽度测量不确定度为0.08%,激光功率测量不确定度为0.25%,实现了对0.1 pJ～1 mJ的激光能量进行准确复现和传递。     

Photothermal techniques with a top-hat beam excitation

A flatly topped circular beam (“top-hat beam”) is employed as the excitation beam for photothermal deflection and surface thermal lens techniques. The Fresnel diffraction model is applied to describe the photothermal signals. The theoretical comparison between a Gaussian beam and a top-hat beam excited photothermal signal amplitudes shows that the use of the top-hat beam excitation improves the measurement sensitivity of the photothermal techniques. Experimental results for both photothermal deflection and surface thermal lens are presented. The potential applications of the top-hat beam excited photothermal techniques are highlighted.     

Photothermal deflection studies on heat transport in intrinsic and extrinsic InP

Laser induced transverse photothermal deflection technique has been employed to determine the thermal parameters of InP doped with Sn, S and Fe as well as intrinsic InP. The thermal diffusivity values of these various samples are evaluated from the slope of the curve plotted between the phase of photothermal deflection signal and pump-probe offset. Analysis of the data shows that heat transport and hence the thermal diffusivity value, is greatly affected by the introduction of dopant. It is also seen that the direction of heat flow with respect to the plane of cleavage of semiconductor wafers influences the thermal diffusivity value. The results are explained in terms of dominating phonon assisted heat transfer mechanism in semiconductors . PACS 78.20.Nv; 66.30.Xj; 61.72.Vv     

用共线光热偏转技术测量光学薄膜的微弱吸收

用具有高灵敏的共线光热偏转技术研究SiO_2、ZrO_2、MgF_2、ZnS等单层光学薄膜的吸收特性,测得它们的吸收率.实验结果与激光量热法及横向光热偏转技术符合良好,表明共线光热偏转技术是测量光学薄膜弱吸收的较理想方法.     

Study of thermal and optical properties of SiO2/GaN opals by photothermal deflection technique

In this paper the thermal and optical properties of the SiO₂/GaN synthetic opals are studied by photothermal deflection technique. This technique, used in different configurations, allows to determine the effective thermal diffusivity and the absorption spectra.     

微型光热驱动机构的光热膨胀理论模型与实验研究

提出和发展了一种基于微尺度光热膨胀效应的微型光热驱动机构.建立了膨胀臂的微尺度光热传导与膨胀的物理模型,利用有限元分析和数学物理方法,推导出膨胀臂的一维温度分布表达式及光热膨胀量和偏转量的计算公式.利用准分子激光微加工系统设计制作了一个长度为1200?μm 的微型光热驱动样机,根据激光和样机的相关参数,计算得到光热膨胀量与激光功率之间的理论关系曲线.实验结果表明,微型光热驱动机构的光热偏转量（对应于膨胀量）与照射到膨胀臂上的激光功率近似成线性关系,实验曲线与理论模型及计算结果符合良好.在理论和实验研究基础上,作为光热微驱动的应用实例,设计并加工制作了一个双向微开关型光热驱动机构,并通过实验实现了双向微开关功能. 关键词： 光热膨胀臂 微驱动机构 光热传导模型 激光     

基于LabVIEW的光热偏转检测系统的设计

将虚拟仪器技术和光热偏转检测技术相结合,在LabVIEW平台上设计开发了一套材料热扩散率测量的自动扫描和数据处理系统。整个系统在仪器控制、数据采集和数据显示等方面实现了自动化测量,并且集成了光热偏转检测技术的数据处理功能。实验结果表明系统运行稳定,操作简单快捷,具有很好的实时性和直观性。     

Photothermal investigation Study of ZnO thin films: effects of Zn and O polar substrate

ZnO thin films were grown by metal-organic chemical vapor deposition on Zn- and O-polar surfaces of ZnO substrate. The effect of Zn- and O-polar substrate on the surface morphology and opto-thermal proprieties has been studied. Hall-measurements were used to determine the carrier concentration of the deposited films. Photothermal deflection spectroscopy (PDS) was used to determine the optical absorption spectrum and the gap energy by comparing experimental amplitude of the photothermal signal to the corresponding theoretical one. Thermal conductivity and diffusivity were also deduced from the photothermal deflection measurements. The found values were very low due to the thermal resistivity of the layer–substrate interface.     

Fibre optic position sensitive detection of photothermal deflection

The use of an optical fibre as a position-sensitive detector in the photothermal deflection technique for thermal characterisation of solids is demonstrated. To validate the sensitivity and accuracy of the set-up, the thermal diffusivity of an n-type indium phosphide wafer is measured and compared with the literature values. The results are very promising. PACS 78.20.Nv; 66.30.Xj; 81.70.-q     

Photothermal probe beam deflection measurement of thermal diffusivity of atmospheric air

We have used a modified photothermal probe beam deflection system with a back pumping configuration for the measurements of the temperature-dependent thermal diffusivity of atmospheric air. The results are consistent and reasonably well agree with the literature values. The measured thermal diffusivity values are the same for the same measuring temperature regardless of the beam offsets and the deflecting surface temperatures. For the gas with known temperature-dependent thermal diffusivity, this method can be used to deduce the temperature of a gas from the measured thermal diffusivity value.     

A contactless method for investigating the thermal properties of thin films

The photothermal deflection technique has been extended as a contactless method to investigate thermal transport in thin films. A theoretical model is developed which quantitatively describes the transport behavior, and is shown to be in excellent agreement with experimental results. This approach yields the thermal diffusivity directly and in a spatially-resolved manner.