A Radial-shear Interferometer for Use with a Laser Source

An interferometer is described that combines the design simplicity of a laser interferometer and the insensitivity to vibration of a common-path instrument. It is used to test wave aberration in ‘single passage’.     

溶胶-凝胶法制备全反射型CO2激光空芯波导的可行性分析

通过对CO2激光空芯导研究现状的分析,指出了全拓射型空芯导目前所面临的问题,在此基础上结合溶胶－凝胶法的特点,提出了用溶胶－凝胶法制备全反射型CO2激光空芯波导反常色散膜的新思想,并分析了其在原理、工艺及光学上的可行性。     

Microlenses and Microlens Arrays Formed on a Glass Plate by Use of a CO(2) Laser

Microlenses and microlens arrays were formed directly on a surface of a glass plate by use of a CO(2) laser. When the surface of a glass plate is heated locally to a working point of the glass material by use of a focused CO(2) laser beam, it tends to become a hyperboloid owing to surface tension, which results in a microlens. A profile of the microlens was measured with an ultrahigh accurate three-dimensional profilometer (Model UA3P, Matsusita Electric Industrial Company Ltd.) that utilizes a specially designed atomic force microscope. An intensity profile and a spot diameter at the focus of the microlens were measured with a microscope and a CCD system utilizing a He-Ne laser as a light source. The focused spot FWHM diameter of 1.35 mum was obtained, and the modulation transfer function was derived from the spot profile. Microlens arrays were also fabricated and characterized.     

A Comparison of Laser Cladding Ni-based Coating on an Aluminium Alloy with CO_2 Laser and Nd: YAG Laser

ＡＣｏｍｐａｒｉｓｏｎｏｆＬａｓｅｒＣｌａｄｄｉｎｇＮｉ－ｂａｓｅｄＣｏａｔｉｎｇｏｎａｎＡｌｕｍｉｎｉｕｍＡｌｏｙｗｉｔｈＣＯ２ＬａｓｅｒａｎｄＮｄ：ＹＡＧＬａｓｅｒＬｉａｎｇＧｏｎｇｙｉｎｇＥｒｉｃ．Ｔ．Ｔ．ＷｏｎｇＨ．Ｃ．ＭａｎＸｉ’ａｎＪｉａ...     

Instability and Chaos in a CO 2 -like Laser with Intracavity Parametric Amplification

The modifications introduced in the operation of a Q-modulated CO₂-like laser system due to the presence of a parametric amplifier in the laser cavity are investigated. The equations of motion for the electric field and the population inversion are studied and integrated numerically. It is shown that the presence of the parametric amplifier leads to the birth of additional attractors. In general, the system follows a period doubling route to chaos and one out of the two pairs of attractors is stable. A similar behaviour is observed in the Lorenz model with a parametric amplifier or with a phase conjugate mirror.     

卤化银光纤CO2激光手术刀头

用卤化银多晶光纤制成了一种在关节式导光臂上使用的卤化银光纤手术刀头。手术刀头由耦合器、光纤连接器、柔性金属管、聚焦透镜座组成。其中柔性金属管依据用途能在0－90℃适当弯曲,弯曲半径＞15mm,长度＜250mm,输出连续激光功率大于12W,工作焦距5mm。光纤手术刀头端面带有气体保护装置,防止端面污染。具有防污结构的手术刀头整体直径小于5．6mm,因此适合在人体天然开口部位如口腔、喉、妇科、肛门及直肠等处进行使用。     

卤化银光纤式CO2激光手术刀

卤化银多晶光纤「ＡｇＣｌｘＢｒ（１－ｘ）,０≤ｘ≤１」是一种性能优良的中红外传能光纤。光纤原料采用高真空熔炼、氯气气氛下区域融熔和高真厂长发瓿内单昌生长等特殊工艺方法提纯,光纤用热挤压法成型。已制成的直径Φ１．０（ｍｍ）光纤Ｌ＝１．６４（ｍ）输出ＣＯ２激光功率〉２０（Ｗ）,损耗０．３￣０．５ｄＢ／ｍ,Ｆｏｒｕｒｉｅｒ红外光谱（ＦＴＩＲ）测量结果显示,光纤在４￣１６μｍ波段内有良好的透过率,用光纤制     

Measurement of the Absolute Frequencies of CO2 Laser Transitions by Multiplication of CO2 Laser Difference Frequencies

It is verified experimentally that frequency differences between CO2 laser lines and the harmonics of these differences can be used as intermediate frequencies to bridge the gap between microwave frequency standards and infrared frequencies. Criteria for the design of a microwave to 30-THz frequency chain are discussed, and experimental details of the measurement of five CO2 isotope laser frequencies to an accuracy of ±2 parts in 109 are presented. The values obtained for the CO2 isotope transitions are 26334.776614 GHz for P(40) of 13C16O2, 27979.469512 GHz for R(6) of 13C18O2, 28665.704581 GHz for P(6) of 12C16O2, 29442.483293 GHz for R(30) of 12C16O2 and 33328.991337 GHz for R(8) of 12C18O2.     

The Cambridge CO2 Laser Saturation Spectrometer

Abstract

This paper presents advances in development and application of the Cambridge saturation spectrometer since the Eighth National Quantum Electronics Conference in 1987. Sample cell evaluation is discussed and a molecular beam sample-cell device is presented. An application to the spectroscopy of CF₃Br is described along with preliminary experiments to establish a frequency standard at 10 μm using OsO₄.     

CO2 Laser Cutting of Calcareous Stones

Portugal is one of the major European producers of natural stones. In the last decade, transformation of stones has been privileged in most of the companies and the quantity of finished product for exportation increased with a major added value. New technologies and processes have been investigated. For example, CO₂ laser has been used for cutting, marking, and drilling. The major advantage of this tool is its flexibility, and thus, it improved the working environment significantly. This article presents a report on the use of CO₂ lasers in the cutting process of marbles and limestones. The cut quality was evaluated by adjusting the laser output power and assist gas type and pressure. The CO₂ laser can be used as a feasible tool for cutting ornamental stones. Due to the economic reasons, it is specially adequate for cutting nonlinear shapes where conventional cutting tools, such as the diamond wires and saws, have limitations on both the shape and the dimensions to be cut.     

A Large-Area PVDF Pyroelectric Sensor for CO 2 Laser Beam Alignment

We present the design of a large-area (50 mm times 50 mm) polyvynilidene fluoride (PVDF) pyroelectric sensor array for industrial CO₂ (lambda = 10.6 mum) laser beam positioning. The array dimensions were chosen to match the area typically monitored in the alignment procedure of external optics (beam steering moving arm system, for example) used to redirect the laser beam from the laser output window to a remote working station. The instrument is provided with a tilted, high reflection, ZnSe plate which partially transmits the laser beam onto the sensor array. From positioning simulations with a Gaussian laser intensity profile with a sigma = 3.2 mm standard deviation (equivalent spot size 3sigma cong 20 mm), the positional accuracy along the two orthogonal array dimensions was found to be better than 0.02 mm for an 8 times 8 array and one order of magnitude higher for a 16 times 16 array. The centroid position of a CO₂ industrial laser beam was evaluated by integrating the pyroelectric current for a time comparable to the time duration (100-200 ms) of the laser pulses used in the alignment procedure.     

Frequency Modulation Spectroscopy with a Tunable CO(2) Sideband Laser: Ozone Detection

The unblended ozone line at 1044.533 cm(-1) was acquired by using the frequency modulation technique. A tunable CO(2) sideband laser with a GaAs waveguide modulator with a tuning bandwidth of 20 GHz in the mid-infrared region was used for this sideband at 1-MHz frequency with a peak-to-peak amplitude of 1 V was imposed on the first tunable sideband. The signal was passed through a 1-m cell and collected with an EG&G detector. The signal-to-noise ratio obtained wasapproximately 100:1.     

A Numerical Investigation on a c.w. High-power,Electron-beam,Pre-ionized He : N 2 : CO 2 : CO Laser

We studied some kinetic, fluid-dynamic and electrical problems arising in the numerical modelling of a c.w. TE high power CO₂ laser operating with N₂, He and CO additives. We adapted a five-temperature pulsed laser model to the c.w. case by coupling a set of fluid-dynamic equations to the kinetic set. We added the rate equation for the secondary electron density. We calculated in some detail the ionization term and fitted experimental results to determine attachment and recombination coefficients in the discharge chamber. In order to solve our equations a numerical code has been developed. By this means we investigated the effects of temperature, density and velocity variations in the flowing mixture on the small signal gain of the device. We obtained profiles in the laser chamber of the sustainer current, small signal gain and fluid-dynamic parameters. A simple (Fabry-Perot) optical cavity model has been used to calculate output power and electrical efficiency of the device. A comparison of numerical code predictions and experimental results is presented.     

Laser remote sensing of atmospheric ammonia using a CO2 lidar system

A CO2 differential-absorption lidar system has been used for the remote sensing of ammonia in the atmosphere. For CO2 lidar returns backscattered from topographic targets at ranges up to 2.7 km, the path-averaged sensitivity of the DIAL system was 5 ppb of NH3 . Concentrations of atmospheric ammonia were found to vary during the day from undetectable levels (<5 ppb) to as high as 20 ppb, depending on temperature and humidity conditions.     

2kWCO2激光器孔栏限模腔的研究

本文实验研究了几种不同菲涅耳数的孔栏限模平凹腔的输出特性,讨论了光栏孔径、腔结构参数、输出镜透过率和光轴失调等对激光功率和光束模式的影响。     

多孔介质对CO2露点影响的激光测试

本文建立了一套用激光测试多孔介质中露点的系统,用玻璃珠作多孔介质,研究了CO2在多孔介质中的露点压力,表明多孔介质对CO2露点压力存在影响,越靠近CO2临界点,影响越小。