热点跟踪中目标特性的仿真研究

主要对强激光武器系统中热点跟踪方式进行了分析，建立了真实边界的三维复合传热模型，通过控制容积法用Ｃ语言编制了分析软件，对几种典型靶材的目标特性进行了仿真分析，包括热辐射质心飘移情况和靶材在随机噪声影响下的热点稳定性等。探讨了热点闭环问题，最后给出了结论。     

一种全新的激光自动跟踪方法在激光移动通信中的应用

介绍了传统激光移动通信的特点及其不足，提出一种基于MOEMS(微光机电系统)技术的全新的激光自动跟踪方法。给出一个基于这种方法的激光移动通信系统实例，这种系统结构简单、体积小、重量轻、功耗低、控制简便，在一定的角度范围内能够自动跟踪目标实现移动通信。实验研究结果表明，这种系统能够很好地满足激光移动通信所要求的功能。     

激光跟踪测量系统的原理及在车身在线检测中的应用

激光跟踪测量系统是一种高精度的工业测量仪器，它具有测量精度高、实时快速、动态测量、便于移动等优点，但其原理实际上是一台单频激光干涉测距、又能自动跟踪目标的全站仪。激光跟踪仪在航空航天、汽车制造、电子工业、高能粒子加速器工程以及大尺寸计量等行业中，已有广泛应用，我国自90年代中期开始也已大量引进该类仪器，并已应用于生产实践和科研。本文主要介绍激光跟踪仪的原理，校准方法及在汽车工业的一个应用情况。     

激光跟踪仪的动态特性研究

设计制造出一种标准圆轨迹发生器，可为标准反射镜的运动提供高精度的规定轨迹。介绍了在此基础上对激光跟踪仪的动态特性进行的研究和试验结果，并据此提出了激光跟踪仪动态特性评定的参数和方法，用于评价激光跟踪仪对物体运动轨迹的跟踪和测量能力。     

激光跟踪测量系统校验及在三维测量中的应用

介绍了激光跟踪仪（LTS）原理，提供了一种校验激光跟踪测量系统的方法。通过与高精度三坐标测量机（CMM）比对测量，检验其精度，实验结果表明角向误差是影响LTS精度的主要因素。利用激光跟踪仪对汽车外形进行扫描，建立其三维模型，发现测量中存在的问题，并提出解决方法，结果表明，激光跟踪仪应用于汽车车身扫描有操作简单、精度较高等优点。     

基于激光跟踪仪和坐标测量臂的工业测量系统

针对激光跟踪仪测量大尺寸复杂结构目标时存在测量盲区的问题,将激光跟踪仪和坐标测量臂联合起来组成一种新型工业测量系统。以激光跟踪仪为系统的测量基准,采用基于bundle技术的多公共点作为坐标测量臂坐标系与激光跟踪仪坐标系的联系纽带,充分利用激光跟踪仪测量准确度高和坐标测量臂灵活的特点,可以有效完成复杂大型工业测量任务。     

大尺寸空间计量仪器的应用与校准

随着激光跟踪仪、激光扫描仪或激光雷达、室内GPS等新型大尺寸空间测量仪器在航空、船舶和风电等高新技术行业应用愈加广泛,大尺寸量值溯源问题成为各国计量机构研究的热点.本文综述了多种空间测量仪器的原理、应用,以及国内外进行的校准研究,并提出了我国建设完整的空间大尺寸测量仪器校准平台的重要意义.     

提升激光跟踪仪长度测量准确度的方法

提出了利用激光跟踪仪进行高准确度测量的方法.描述了激光跟踪仪测量时的特定设置,以获得具有激光干涉仪准确度的长度测量结果.通过几何推导,证明了这种方法不受激光跟踪仪角度测量的影响.列出了方法中主要的测量不确定度来源和不确定度合成的公式.     

激光跟踪计测系统简介

三坐标测量机在世界上发展了近20年，目前已有多种型号，但其基本形式为桥式移动型，在构造上趋于成熟，近年来变化较小，研究的主攻方向是为了提高精度而制造出能够快速移动、轻且稳定的构件。但是轻和高精度是相互矛盾的2方面，追求刚性高而轻的构件困难很大，不仅成本昂贵，还给精度的进一步提高带来限制，因此，现有三坐标测量机在原理上，阻碍了精度的进一步提高。为此，约在5年之前，日本东京精密（株）与计量研究所共同协作，在利用光导纤维的激光干涉仪研究成果基础上，进行了激光跟踪计测系统的构思，日前终于完成了使用激光干涉仪…     

焊缝激光跟踪图像处理中关键技术的研究

在焊缝激光跟踪实时图像处理中,采用卷积滤波和中值滤波相结合的方法,提高了中值滤 波能力和处理速度;采用Robert算子,较好地保留了激光光带的边缘;采用左右边界平均值来抽取激光带中心线简单易行;用斜率分析法来检测特征点方便可靠。该图像处理技术效果好能够满足跟踪系统的实时性要求。     

自由振荡激光引爆机理的初步研究

自由振荡激光广泛运用于科研与生产 ,研究自由振荡激光引爆机理是相当有意义的。炸药体在激光的照射下 ,由于温度场发生骤变 ,在炸药体未发生相变前 ,炸药表面将出现一热应力场。本文用一维激光热熔条件计算了与时间效应有关及无关的热应力值 ,从理论上证明自由振荡激光引爆机理是热起爆 ;按照热起爆机理给出了激光起爆方程 ,用热起爆机理中的瞬时加热热点理论推导出激光引爆炸药的延滞期公式     

自由振荡激光引爆机理的初步研究

自由振荡激光广泛运用于科研与生产 ,研究自由振荡激光引爆机理是相当有意义的。炸药体在激光的照射下 ,由于温度场发生骤变 ,在炸药体未发生相变前 ,炸药表面将出现一热应力场。本文用一维激光热熔条件计算了与时间效应有关及无关的热应力值 ,从理论上证明自由振荡激光引爆机理是热起爆 ;按照热起爆机理给出了激光起爆方程 ,用热起爆机理中的瞬时加热热点理论推导出激光引爆炸药的延滞期公式     

Infrared laser ablation sample transfer for MALDI imaging

An infrared laser was used to ablate material from tissue sections under ambient conditions for direct collection on a matrix assisted laser desorption ionization (MALDI) target. A 10 μm thick tissue sample was placed on a microscope slide and was mounted tissue-side down between 70 and 450 μm from a second microscope slide. The two slides were mounted on a translation stage, and the tissue was scanned in two dimensions under a focused mid-infrared (IR) laser beam to transfer material to the target slide via ablation. After the material was transferred to the target slide, it was analyzed using MALDI imaging using a tandem time-of-flight mass spectrometer. Images were obtained from peptide standards for initial optimization of the system and from mouse brain tissue sections using deposition either onto a matrix precoated target or with matrix addition after sample transfer and compared with those from standard MALDI mass spectrometry imaging. The spatial resolution of the transferred material is approximately 400 μm. Laser ablation sample transfer provides several new capabilities not possible with conventional MALDI imaging including (1) ambient sampling for MALDI imaging, (2) area to spot concentration of ablated material, (3) collection of material for multiple imaging analyses, and (4) direct collection onto nanostructure assisted laser desorption ionization (NALDI) targets without blotting or ultrathin sections.     

IR thermographic investigation of nucleate pool boiling at high heat flux

Nucleate water pool boiling at high heat flux was investigated on the 25 µm titanium and stainless-steel heaters at atmospheric pressure. A high-speed IR thermographic camera was applied to measure the rapidly changing transient temperature field, which served as input data for calculating the transient local heat flux distributions by solving a 3-dimensional (3-D) inverse heat conduction problem (IHCP). A phenomenon of hot spot was observed at the irregular active bubble site characterized by a longer waiting time and a higher activation temperature compared to a regular active nucleation site. The results show that the temperature of the hot spot can significantly exceed the temperature of the heater in its surroundings and remains present on the boiling surface even after the bubble departure. The calculations have shown a strong reduction of the local heat flux at the spot, which represented a potential for the beginning of the boiling crisis.     

Performance analysis of multi-stage thermoelectric coolers

Multi-stage thermoelectric coolers offer larger temperature differences between heat source and heat sink than single-stage thermoelectric coolers. In this paper, a pyramid-type multi-stage cooler is analyzed, focusing on the importance of maximum attainable target heat flux and overall coefficient of performance, COP. Having considered the COP and the thermal resistance of a heat sink as key parameters in the design of a multi-stage thermoelectric cooler, analytical formulas for COP and heat sink thermal resistance versus working electrical current are derived. For a fixed cooling target heat flux, the ratio of the heat sink thermal resistance to the respective single-stage value and the attainable COP in a cascaded cooler are determined as a function of the number of stages. Numerical simulations clearly indicate that the thermal resistance of the hot side heat sink is the controlling factor in determining the overall performance of a multi-stage thermoelectric cooler.     

用于高空动靶饱和损伤的地面激光的最低稳速跟踪分析

由地面激光束凝视高空动靶使其饱和或损伤的凝视时间，讨论并计算出地面伺服系统方位跟踪精度及最低稳定运动速度。 给出了地面伺服系统方位跟踪速度与高空激光束移动距离之间的关系，由此得出相应结论。     

不锈钢激光点焊接头组织和力学性能研究

目的 改善SUS301L–HT不锈钢激光点焊焊接性能。方法 以2 mm SUS301L–HT不锈钢为母材进行激光点焊试验,并分析焊接接头的金相组织、硬度、拉伸性能以及断口形貌等。结果 焊点表面无损坏、压痕均匀、无较大焊接变形,表面无飞溅、母材颜色无明显变化。焊核区的微观组织主要是柱状晶,柱状晶依附于未熔化母材晶粒向焊核中心生长。母材硬度最高,约为309HV;焊核中心附近区域硬度适中,约为255HV,热影响区硬度最小,不到220HV。点焊接头断裂形式多为纽扣式断裂且发生在热影响区。结论 不锈钢激光点焊整体质量较好,可用于轨道列车车体加工。     

A Semi-analytic Approach for Coherent Laser Radar System Efficiency

Abstract

A nearest Gaussian approximation (NGA) is proposed to approximate any shape for a single mode laser beam by a Gaussian shape. The application considered is a determination of the system efficiency in heterodyne coherent laser radar (HCLR). For an actual beam its NGA is defined by three parameters: the waist spot size and location, and an amplitude coefficient. These parameters are computed by a maximization of the norm of the scalar product written for the actual and Gaussian beams. In the case of the truncated Gaussian beam, particularly relevant to HCLR, the waist location can be analytically calculated, and only two parameters remain unknown: the waist spot size and amplitude coefficient. Using numerical applications, it is shown the NGA is in good agreement with Fresnel integral solution. The NGA combines a good accuracy and capability of analytical solutions. It can treat a variation in system efficiency owing to a misalignment angle between the transmitter and local oscillator.     

A finite element model to predict the ablation depth in pulsed laser ablation

This work presents development of a two-dimensional finite element model to predict temperature distribution and ablation depth in a laser ablation process. The model considers a number of aspects of the process, which hitherto have been considered independently in the literature. The aspects considered include: temperature dependent material properties of the target material, effect of plasma shielding on the incident laser flux, and temperature dependent absorptivity and absorption coefficient of the target. It was evident that these considerations have resulted in a significant improvement in the ability of the model to predict the ablation depth. Finally, the predicted ablation depth was found to match extremely well with experimental results at lower laser fluences, though at higher fluences there is a marginal overestimation.