Instrumentation for urologic laser surgery

Carbon dioxide, neodymium:yttrium-aluminum-garnet, ruby, and argon lasers are the only commercially available lasers with wavelengths suitable for laser surgery. Consequently, researchers have attempted to make the tool fit the clinical need. A pediatric #6 bronchoscope was fitted to a carbon dioxide laser endoscopic coupler to form a modified cystoscopic laser delivery system. This instrument was able to vaporize small condylomata of the distal male urethra. However, the restricted visibility of this crude adaptation represents an inferior solution compared with the endless possibilities of sophisticated fiberoptic technology. Future prospects in infrared optical fiber technology portend a breakthrough for transurethral carbon dioxide laser surgery. Adapting the Nd:YAG laser for urologic surgery is attractive because it can be easily incorporated into conventional cystoscopes. The argon laser's capacity to absorb blood and traverse water suggests future importance for transurethral surgery. Investigation is needed to develop a surgical laser adaptable to both open and transurethral urologic surgery.     

实实在在的节能

长期以来，节能一直是个宣传得较热，但实际操作上却流于口号和形式的概念。但是近些年随着经济的快速发展，不论是工业用电还是生活用电，都面临着能源紧张的尴尬境地。“拉闸限电”、“电荒”、“轮休放假”等词汇，频频出现在各种媒体上。能源紧张已经严重影响工业经济的良性发展和人民的正常生活，节约能源已成为全社会的共识，现在我们需要的就是如何将这个共识付之行动，我们需要的是实实在在的节能。     

准分子激光眼屈光手术中的一种过渡区模型

提出了一种在准分子激光眼屈光手术中过渡区模型的构造方法.首先设计一种修边函数,然后提取光学区边界的切削深度,并将其扩展到整个过渡区,最后通过修边函数和过渡区上扩展切削深度的乘积得到过渡区模型.再将该模型进行计算机仿真研究和临床研究.临床上统计了8名患者16只眼睛接受该模型指导的激光手术情况:术前平均裸眼视力为0.09±0.04,术后第1天平均裸眼视力为1.06±0.24,之后视力逐渐升高,在术后一个月时平均裸眼视力为1.42±0.36,裸眼视力最小值为1.0.仿真结果,特别是临床结果表明:过渡区模型实现了光学区与非切削区之间光滑平坦地过渡.采用参数化控制的模型,特别适用于光学区直径和过渡区宽度经常调整的情况,对各种眼屈光不正情况均适用;在光学区直径确定后,过渡区宽度的改变不影响光学区的切削深度;模型有较强的通用性,适用于传统仅矫正屈光不正(近视、远视、散光)的光学区模型,也适用于波前像差引导的激光眼屈光手术.利用过渡区模型可提高手术后患眼的视觉质量.     

准分子屈光手术中非球面系数对球差以及切削深度的影响

角膜前表面是人眼屈光系统的主要组成部分,屈光手术通过角膜模型定量计算角膜的修正值,因此角膜模型的精确与否直接决定了手术的效果。一般认为角膜前表面是旋转对称的二次曲面,该曲面的一个重要参数是非球面系数Q。目前大部分的角膜切削模型都没有考虑Q对切削深度和像差的影响,本文基于Littman-Gullstrand模型眼建立模型,分析Q值对屈光手术中透射率、球差以及切削深度的影响。模拟结果显示,Q值对球差和切削深度有显著影响,Q绝对值逐渐增大时,球差S₁从正变为负,在Q＝－0.528处,可以认为角膜前表面产生的S₁为零。Q绝对值增大时,相对切削深度增大,即角膜边缘与角膜中央切削深度差异减小。     

产品质量的社会责任

产品的设计制造及其生产和经销企业在向社会提供产品的同时就伴随着产品的质量责任。这种责任大致分为两类,一是法律责任,二是社会责任。政府为了加强对产品质量的监督管理,提高产品质量水平,明确产品质量责任,保护消费者的合法权益,维护社会经济秩序,从而制定了有关产品质量的法律、法规。我国的产品质量法就生产者、销售者的产品质量责任和义务作出了明确的规定,这是以国家法律形式确定的,是产品质量责任和义务主体行为的范围限度。对生产者保证产品质量规定了三项要求,对产品或在其包装上的标识也有五项要求,同时规定生产者有…     

Implementation of an intuitive writing interface and a laparoscopic robot for gynaecological laser assisted surgery

The research reported in this paper aims at applying the human handwriting skill to improve and facilitate the control of laser-assisted laparoscopic surgery operations performed by gynaecological surgeons. For the purpose, a laparoscopic robot was interfaced with a digitizing tablet. This interface, further called the intuitive writing interface (IWI), directly converts the hand trajectory, handwritten on the tablet, into an input signal to the robot. It replaces the traditional complex manipulations performed by the surgeon during manual laparoscopic surgery by natural handwriting. It provides the surgeon with an intuitive 'what-you-draw-is-what-you-cut' control facility by employing his/her familiar handwriting skills to control the laser ablation process accurately. The system was successfully built and tested in vitro. Performance tests on the robot resulted in tracking errors in the order of 1 mm in the target plane at an ablation speed of 20 mm/s. The high accuracy of the system was successfully demonstrated by cutting characters 4 mm high on an apple. These results indicate that laser ablation performance is upgraded by the IWI to the accuracy levels of human handwriting, which is much higher than can be obtained with manual laser laparoscopy. Safety features include the use of pen contact with the tablet as a safety switch, and back drivability in the robot joints for easy manual positioning and evacuation in case of emergency.     

On-line computer system to minimize laser injuries during surgery: preliminary system layout and proposal of the key features

The aim of this paper is to investigate some new user interface ideas and related application packages which aim to improve the degree of safety in an operating room during surgical operations in which an invasive laser beam is deployed. The overall value of the proposition is that a means is provided which ensures the successful completion of the surgical case while minimizing the risk of thermal and mechanical injuries to healthy tissues adjacent to the surgical field. According to surgeons operating with a variety of CO2 lasers available at both the National Cancer Institute in Milan, Italy, and the Sackler School of Medicine, Tel Aviv University, Israel, each laser device presents different cutting and coagulation properties. In order to identify which 'ideal' procedure might corroborate the subjective impression of each surgeon and also to provide one common tool to ensure procedures with a high level of safety, the author has worked for several months with surgeons and technicians of both Institutions to define the general design of a new on-line surgical operation planning and design system to be used during the pre-operative briefing activities and also as a consultation tool during operation. This software package will be developed and tested on both 'C' and FORTRAN compilers running on a commercially available PC which is driving a continuous wave (CW) CO2 laser device via its Instrument Bus interface. The present proposal describes the details of a software package called LCA (Laser-beam Controller and Adviser) which performs several controls in parallel on the key output parameters of a laser beam device during its utilization in delicate surgical operations. The required performances of this device needed during a given surgical operation are pre-simulated and compared against the well-known safety limits, which are stored in the computer's mass storage. If the surgeon's decision about the laser device set-up are considered to be too close to the required physiological safety limits, then the SW alerts the surgeon and proposes alternatives based on other combinations of both HW and SW configurations. An additional application of LCA uses this SW as a warning tool during the operation itself. If a wrong set-up of the laser device is accidentally used, an alarm will be generated and the laser beam automatically switched-off prior to an 'incident report' printout. The operation will continue only when the surgeon validates the choices that the SW suggests for implementation. If necessary, the surgeon can switch off the device and continue to operate it manually. In this case, the surveillance mode will be totally excluded.     

Precision laser adjustment using CW diode laser

Precision adjustment has many applications in various fields, particularly in laser generation systems and precision engineering. In this paper, a laser forming method for the precise adjustment of a rod with a diameter of several millimeters is investigated. Experiments on precision laser adjustment are carried out using a fiber-coupled passively cooled CW diode laser. The effect of important parameters is investigated in detail. Parametric studies are carried out to determine suitable processing windows at which a small and stable laser-adjusting angle is obtained. A coupled thermomechanical model established using the finite element method is validated and applied to predict the deformation of the rod and better understand the mechanism of precision laser adjustment. A simple closed-form expression for the precision laser-adjusting angle is proposed. An application on precision laser adjustment is presented.     

快速调整激光干涉仪光线准直系统的设计

使用激光干涉仪能够很好地解决数控机床定位精度差的问题,然而调整激光器的方向,使激光束与所测机床轴的移动方向平行是一项很重要而且麻烦的工作。为快速准确调整激光器方向,在对激光干涉仪工作原理深入研究的基础上,分析了激光束偏心的原因,构建了以PLC为控制核心,驱动两台电机控制干涉仪平移与旋转运动,实现快速调整激光干涉仪激光束准直。实验结果表明,此设计节省了大量人力、时间的开支,能够控制干涉仪快速对准,具有工业应用推广价值。     

Advances in hybrid laser joining

This paper presents vibration reduction control of a voice coil motor (VCM)-driven actuator for SPM applications. We had developed a VCM nanoscanner. The scanner has flexure hinges structure. However, the VCM nanoscanner has some problems of thermal drift and small damping compared to the PZT driven nanoscanner. Especially, the small damping coefficient of the VCM nanoscanner causes mechanical vibration when the control input signal is near to the resonance frequencies of the scanner. Additionally, disturbance to the VCM scanner and electronic noise in the sensor also causes the mechanical vibration when they are near to the resonant frequencies. The mechanical vibration reduces the servo bandwidth as well as the accuracy, which deteriorates the AFM image of the samples. We design input shaping prefilter to reduce the signal applied to the VCM nanoscanner and electronic noise in the sensor whose frequency is close to the resonant frequency of the VCM nanoscanner. We measure the time and frequency response of the VCM scanner without using the prefilter and with using the prefilter. Finally, the topology images of a bare wafer are measured and compared using the AFM.     

激光切割机中激光喷嘴设计研究

激光切割技术因其独特的优势,在现代制造领域占有越来越重要的地位。本文主要采用空气动力学原理对喷嘴内部进行了气流特性分析,提出了拉法尔喷嘴的设计方法,对于今后激光切割机中激光喷嘴设计具有一定指导作用。     

基于五束光的三维多普勒测振仪设计

为了实现物体的三维振动分析测量,设计了一种基于五束激光的多普勒振动测量系统.该系统将五束激光汇聚到一个焦点,并照射到被反射膜覆盖的被测物体表面,经过反射后,散射光被光电二极管接收,并进入高精度信号处理系统,分别得到五路振动信息,通过计算机处理后,可以分别解析得到包括频率和振幅的三维振动信息.实验结果表明,该系统有望被应用于高精度的无接触振动测量.     

Effect of laser beam incidence angle on cladding morphology in laser cladding process

The change of angle θ between laser cladding powder plane and substrate plane will lead to changes in cladding layer's geometric morphology. Therefore, we established a quantitative numerical prediction model for cladding layer geometry. In this model, we consider the variation of θ, the laser energy attenuation rate and the temperature rise of the powder particles. At the same time, the simulation results were verified by experiments. The results show that when θ is in the range of 50°~90°, the initial temperature is 298 K, the scanning speed is 3.75 mm/s, and the laser spot diameter is 4.5 mm, the Fe#1 powder cladding can achieve better forming effect on Q235. In general, with the decrease of θ, the height of the cladding layer decreases and the width of the layer increases. However, when θ is less than 50°, the quality of the formed morphology significantly deteriorated. The experimental results are in good agreement with the simulation results, which verifies the validity and reliability of the model. This work provides a theoretical reference for further understanding the relationship between the laser cladding morphology and the incident angle.     

点激光测头激光束方向标定

为了使点激光测头能在任意方向上实现测量功能,提出一种逆向工程中标定激光束方向的方法,设计了一种标定面方向可调的标定块配合标定。标定过程中,让激光测头在标定面上分别沿X、Y、Z3个轴方向做等间距运动,根据进给步长与激光束长度变化量之间的关系确定激光束的方向。以三坐标测量机为平台,给出了以任意方向安置点激光测头时,测量值从传感器坐标系到基准坐标系的转换过程,并对标定算法及整个标定过程进行了详细描述。最后,通过与接触式测量进行对比实验,验证标定后点激光测头的测量效果。实验结果表明,用该方法标定的点激光测头在3σ范围内沿任意方向的测量误差为(0.0452±0.0168)mm,满足逆向工程的测量要求。     

Calibration of laser Doppler vibrometer and laser interferometers in high-frequency regions using electro-optical modulator

We proposed a new primary calibration method of a laser Doppler vibrometer (LDV) using the optical modulated excitation of an electro-optical modulator and validated this approach by comparing mechanical modulated excitation with homodyne laser interferometer at the National Metrology Institute of Japan (NMIJ). The velocity sensitivity of the LDV was evaluated with the uncertainty budget at a high-frequency range up to 1 MHz, which is indicated as the upper limit of 50 kHz in ISO (International Organization for Standardization) 16063–41. As the results, we confirmed that velocity sensitivities between optical and mechanical modulated excitations are flat within their uncertainty from 100 Hz up to 1 MHz. Moreover, in order to evaluate the accurate phase shift of the accelerometer up to 20 kHz using optical modulated excitation, we also revealed the reliability of two time shifts between homodyne and heterodyne laser interferometers.     

Short pulse laser train for laser plasma interaction experiments

A multiframe, high-time resolution pump-probe diagnostic consisting of a consecutive train of ultrashort laser pulses (approximately ps) has been developed for use with a chirped pulse amplification (CPA) system. A system of high quality windows is used to create a series of 1054 nm picosecond-laser pulses which are injected into the CPA system before the pulse stretcher and amplifiers. By adding or removing windows in the pulse train forming optics, the number of pulses can be varied. By varying the distance and thickness of the respective optical elements, the time in between the pulses, i.e., the time in between frames, can be set. In our example application, the CPA pulse train is converted to 527 nm using a KDP crystal and focused into a preformed plasma and the reflected laser light due to stimulated Raman scattering is measured. Each pulse samples different plasma conditions as the plasma evolves in time, producing more data on each laser shot than with a single short pulse probe. This novel technique could potentially be implemented to obtain multiple high-time resolution measurements of the dynamics of physical processes over hundreds of picoseconds or even nanoseconds with picosecond resolution on a single shot.     

Online measurement and correction of post-weld shift in laser welding packaging for laser diodes

In order to measure and correct post-weld shift (PWS) which is inherent in the laser welding packaging process for laser diodes, a novel method based on strain gauges was proposed to perform online measurement of the welding shift in real time. This method can measure micro-displacement caused by laser welding in two directions with submicrometer accuracy. The direction and magnitude of PWS can be determined from measurement results, and then correction welding is applied to compensate the PWS in prescribed direction. The measurement system was established and experiments of laser welding, PWS measurement, and correction for specially designed laser diode packaging assembly are conducted. Experimental results show that the proposed method is able to measure the PWS accurately in real time, and the coupling light power can be regained to over 90% of the power before welding with laser hammering technique according to measurement results. With advantages of low cost, comparable accuracy, and real-time measurement, the proposed method will be very useful for improving the packaging productivity and performance for widely used transistor outline (TO)-Can style laser diodes.     

激光显示中散斑的减弱

为减弱激光显示中散斑的影响,在对散斑对比度进行理论分析的基础上,提出了一种利用位相光学元件减弱散斑的方法。实验以绿光为光源,让激光束通过位相光学元件,再经过CCD相机和图像处理系统处理,得到屏幕上散斑对比度和光强的变化。实验结果表明:散斑的对比度降低到3.7%,可满足激光显示中对散斑减弱的要求。该方法具有简单易行、成本低、适合批量化生产等优点。     

基于光纤激光器的相干多普勒激光雷达

介绍了一种基于掺铒光纤激光器的相干测速激光雷达,该雷达具有成本低、可靠性高和结构新颖的特点。雷达系统的光路完全采用通信用光纤器件构成,单模光纤耦合器用作分光器和混频器,偏振无关的光纤环形器用作光学天线收发开关,所有光路器件采用单模光纤连接。雷达系统采用频谱分析法进行鉴频获取中频信号的中心频率。研制了原理样机并进行测速试验,系统可以探测的最小速度小于0.4 mm/s,测速精度优于0.1%,输出非线性度小于70×10~(-6)。