激光与现代医学

 本世纪科学技术的发明之一--激光,自1960年作为一种新光源初露锋芒之后,发展神速,深刻地影响着自然科学的各个领域,应用范围遍及国防军事、医疗卫生及国民经济诸多部门。激光诞生不久就与生命科学结下不解之缘,在医学研究、临床治病方面日益显示其优势、其潜能深受人们关注。 光是生命系统赖以生存、成长的基本能源。植物依靠光合作用为人类提供了丰富的食粮,光对人体的作用、对体内肌体组织产生的刺激,影响着组织细胞结构、形态及其功能。长期以来这些一直是科学家研究的重要课题。作为光的一种特殊形态--激光,用于生命科学的研究早就受到重视,激光医学就是由此应运而生的一门新学科,它包括激光技术用于基础医学的研究、疾病诊断、临床治疗、预防保健等方面。     

激光与生命科学

 激光器的发明开创了一个光学新时代.从第一台激光器诞生到现在不到40年,激光技术的发展和应用突飞猛进,它与生命科学的结合便是其中之一.     

激光技术在生命科学中的地位

激光技术在生命科学中的地位许松林（上海第二医科大学）激光技术已深入到生命科学的各个领域，尤其在医学方面取得了广泛的应用。如眼科，激光改变了传统的手术治疗方法，提高了疗效；激光内腔镜的使用免除了病人开刀手术的痛苦；激光革新了传统的显微成像术；激光技术促...     

第二讲光电子技术在保健医疗和生物学应用中的进展

文章论述了激光与光电子技术在人类保健、医疗以及生命科学应用中的作用和意义.综述了光活检技术、光美容医疗和生物光子技术等光电子技术在保健、医疗和生物学领域中的具体应用.重点介绍了：（1）用于组织病理诊断的光活检技术,其中包括光活检的发展历史、技术优点、研究现状,以及荧光光谱和成像技术等实用光活检技术的临床应用;（2）非消融性光疗的基本作用机制和研究进展;（3）扫描共焦显微术、多光子荧光显微术、近场光学扫描显微术和光镊等显微生物成像技术的工作原理和应用.最后,展望了激光与光电子技术在生命科学中的应用前景.     

激光全息技术的应用及发展趋势的研究

举例介绍了激光全息技术在几个学科和产业领域的应用现状,分析了几个应用实例中的突出优点和存在的问题,讨论了几个学科领域激光全息技术的发展趋势。结论表明:随着激光全息技术不断与其它学科技术,尤其是其它学科最新技术的交叉和综合运用,激光全息技术的应用前景是很大的。目的是明确激光全息技术的发展方向,不断推动激光全息技术的发展和应用。     

激光技术在引信中的应用

 激光就是对受激辐射的光源采取适当的措施后,获得光强度极高、光能量集中在某一方向上,而且相干性极好的传播光源。激光的特性可概括为:单色性、相干性、方向性和高亮度。激光测距是激光技术在军事方面的最早应用。当激光器和激光技术刚跨出实验室之时,激光在引信中的应用发展,与激光在测距中的应用发展一样受到各国的重视。一、激光引信工作原理激光引信目前大多采用主动式,发射部分由激光器和发射装置组成,激光朝着目标发射后,碰到目标而被漫发射,其中的一部分就沿着原路返回,进入激光接收系统。     

固体材料激光冷却的实验研究及其最新进展

近年来,基于反斯托克斯荧光制冷(Anti-StokesFluorescentCooling)的固体材料激光冷却技术得到了快速发展。本文首先简单介绍了固体材料激光冷却的基本原理及其技术;其次,详细介绍了各种固体激光冷却的新材料、新方案和新结果及其最新实验进展;最后,就固体激光冷却技术的应用前景及其未来发展方向等问题进行了简单讨论与展望。     

激光在农业中的若干应用

概述了激光的基本特性及其对生物体的作用过程，介绍了激光诱变，激光微束，激光荧光光谱，激光扫平等技术在现代农业中的一些应用。     

光镊技术在生命科学研究中的应用

介绍了光镊技术的工作原理和系统结构,论述了光镊技术工作特点,并结合具体的研究工作,阐述了光镊技术在单细胞、单分子等生命科学研究领域中的应用,最后给出了近年来光镊技术取得的进展和新的应用.     

激光在汽车工业中的发展现状与应用

介绍了近年来激光技术在汽车工业中的几项重要应用，详述了激光在诸如激光焊接、激光打标、激光热处理和激光切割等有关汽车工业技术中的应用状况，同时对汽车工业中所用激光类型进行了归类。最后综述了半导体激光器泵浦全固态激光器以及短脉冲和超短脉冲激光的应用前景。     

Inert gas cutting of titanium sheet with pulsed mode CO2 laser

The present work aimed at studying the dynamic behavior of melt ejection in laser cutting of 1 mm thick titanium sheet and to obtain dross-free cuts with minimum heat affected zone (HAZ). CO₂ laser cutting of titanium sheet was carried out with continuous wave (CW) and pulsed mode laser operation with different shear gases namely argon, helium and nitrogen. Laser cutting with high frequency and low-duty cycle pulse mode operation produced dross-free cuts with no noticeable HAZ. Helium, because of its high heat convection and ability to generate high shear stress, produced laser-cuts with narrow HAZ and low dross, as compared to those produced with argon as the shear gas. Microscopic features of laser cut surfaces were analyzed and correlated with dynamic mechanism involved in laser cutting process. Process parameters for laser piercing, required for the initiation of fusion cut within the sheet, were also studied. Laser piercing requires either CW or high-duty cycle (>80%) pulse mode operation.     

Investigation of laser via formation technology for the manufacturing of high density substrates

Fabrication of micro-vias is one of the critical processes in manufacturing high-density printed circuit boards. The conventional mechanical drilling technique becomes expensive for vias smaller than 200 μm in diameter due to the frequent breakage of the drill bits and machine downtime. The inability to produce blind vias renders the mechanical drilling method of limited use in providing vertical interconnections needed for multi-layer boards. Laser micro-drilling has emerged as one of the most feasible technologies for forming micro-vias. It offers greater resolution over the mechanical technique and is capable of producing vias well below 70 μm, consistently. The feasibility of being able to laser drill depends on the laser characteristics such as wavelength, energy density and pulse shape of the laser beam on the one hand, and on the type, structure configuration and thickness of the PCB substrate on the other hand. As most of the PCB materials have finite absorption characteristics with respect to the laser wavelength, only certain laser types are compatible with the common substrate materials. Laser via-drilling can either be a serial process with one via drilled at a time, or a mask imaging process with many vias drilled simultaneously. In this paper, the issues involved in the laser micro-drilling of PCB vias, including beam characteristics and processing mechanisms, for different substrates are investigated. A brief comparison with the other two emerging technologies, i.e. photo-vias and plasma etching is also discussed.     

肖克莱与半导体科学技术的发展

文章介绍了肖克莱的生平事迹及其在物理学上取得的成就,着重论述了他提出的晶体管理论以及据此发明的晶体管对后世的影响,指出肖克莱提出的晶体管理论奠定了今天半导体科学技术发展的基础。     

物理学与材料科学结合的机遇与挑战

物理学，特别是凝聚态物理学与材料科学的交叉在近几十年已取得丰硕的研究成果，文章分四部分：（1）简要介绍了材料与材料科学的基本概念；（2）回顾近代历史上物理学与材料科学交叉的一些典型例子；（3）介绍在表面和界面、缺陷、理论和模型、微结构表征、新材料以及新工艺等领域物理学与材料科学交叉的简况及材料研究的一些前沿问题；（4）讨论物理学在纳米材料发展中的作用。     

激光推进器概念设计研究现状及发展趋势

 激光推进器技术是激光推进技术的关键技术之一，也是其核心技术，而激光推进器概念设计是开展激光推进器技术研究的首要任务。在对国内外文献综合调研的基础上，总结给出了激光推进器概念设计的研究现状。通过对比分析给出了各种激光推进器构形的优缺点，并就激光推进器概念设计的发展趋势进行了分析讨论。     

Laser conditioning of high-reflective and anti-reflective coatings in vacuum environments

Laser conditioning effects of the dielectric mirror coatings in vacuum environments were investigated. The laser-induced damage thresholds (LIDT) in vacuum environments before and after laser conditioning were compared. It is found that laser conditioning in vacuum environments decrease the LIDT of the component. Laser conditioning effects in vacuum and atmosphere environments were also compared and investigated. The negative effects of laser conditioning in vacuum environments were discussed and analyzed with defect statistical model, energy dispersive X-ray analysis and absorption measurements.     

Elastic characterization of platinum/rhodium alloy at high temperature by combined laser heating and laser ultrasonic techniques

We demonstrate an innovative pump–probe technique combined with laser heating to determine the velocity of a surface Rayleigh wave at high temperature. Laser ultrasonics in a point-source–point-receiver configuration was combined with laser heating to evaluate the elastic properties of micron size specimens. The measurements of the velocity of the surface Rayleigh wave (SRW) were conducted at 1070 K.     

光学课程和高、新科技结合探索

对光学课程教学现代化问题进行了探索和实践,一是光学基本原理与科技前沿典型实例结合,二是从激光新技术讲授光学基本概念,三是从光电技术发展探讨光学课程中的新仪器,新器件。     

Cemented carbide cutting tool: Laser processing and thermal stress analysis

Laser treatment of cemented carbide tool surface consisting of W, C, TiC, TaC is examined and thermal stress developed due to temperature gradients in the laser treated region is predicted numerically. Temperature rise in the substrate material is computed numerically using the Fourier heating model. Experiment is carried out to treat the tool surfaces using a CO₂ laser while SEM, XRD and EDS are carried out for morphological and structural characterization of the treated surface. Laser parameters were selected include the laser output power, duty cycle, assisting gas pressure, scanning speed, and nominal focus setting of the focusing lens. It is found that temperature gradient attains significantly high values below the surface particularly for titanium and tantalum carbides, which in turn, results in high thermal stress generation in this region. SEM examination of laser treated surface and its cross section reveals that crack initiation below the surface occurs and crack extends over the depth of the laser treated region.     

用1064nm激光增强HfO2/SiO2薄膜的抗激光损伤能力的实验研究

 用1 064nm激光实验研究了HfO₂/SiO₂薄膜的激光损伤增强效应，实验以薄膜激光损伤阈值70%的激光能量开始，采用N-ON-1方式处理薄膜，激光脉冲的能量增量为5J/cm²。实验结果表明，激光处理薄膜表面能使激光损伤阈值平均提高到3倍左右，并且薄膜的损伤尺度也明显减小。对有缺陷的薄膜，其缺陷经低能量激光后熔和消除，其抗激光损伤能力得到增强，但增强得并不显著，而薄膜本身的激光预处理，可以使其激光损伤阈值大大提高。