An on-line microcomputing system for the acquisition and processing of data from a fourier spectrometer

A microcomputing system has been developed to provide on-line data acquisition and analysis for a Fourier transform spectrometer, and the interface between the spectrometer and the microcomputer is described in detail. The system has been equipped with software which includes a fast Fourier transform programme for use in either conventional or dispersive Fourier transform spectroscopy, and programmes for calculating the optical constants and dielectric functions of solids from complex spectra obtained by dispersive Fourier transform spectroscopy.     

The far infrared complex reflectivity of GaTe

The room temperature polarized complex (amplitude and phase) infra-red reflection spectra of single crystal monoclinic GaTe have been measured between 20 and 400 cm^?1 using a dispersive Fourier transform spectrometer. The measurements allow the experimental zone centre transverse and longitudinal phonon modes and optical constants to be determined without recourse to oscillator fit models or Kramers-Kronig analysis. Infrared power transmission measurements have allowed all fifteen predicted modes to be identified and the results are compared to recent Raman work.     

Measurement of the optical constants of crystal quartz at 10 K and 300 K in the far infrared spectral range: 10–600 cm−1

The optical constants of crystal quartz in the far infrared (10 – 600 cm^?1) are reported at room temperature and at 10 K, for both polarizations parallel and perpendicular to the c-axis, respectively extraordinary and ordinary ray. These constants are obtained from the analysis of the transmissivity channeled spectra below 300 cm^?1, and from the analysis of the reflectivity spectra between 300 – 600 cm^?1, measured by using a grating infrared spectrometer. The extrapolated zero frequency refractive indices of quartz obtained in the present work are: n_o(0) = 2.106 and n_e(0) = 2.153 at 300 K; n_o(0) = 2.072 and n_e(0) = 2.130 at 10 K.     

Spectroscopic studies of optical materials in the far infrared: The case of crystal quartz

Spectroscopic studies using far infrared reflectivity and transmissivity measurements between 10 and 600 cm^?1, were performed on plane parallel quartz crystal plates, in the temperature range 10–300 K. The temperature dependence of the optical mode parameters is reporeted for both polarizations parallel and perpendicular to the c-axis. The extraordinary optical constants of quartz are determined at 10 and 300 K, from the A₂ transmissivity channeled spectrum, between 10 and 300 cm^?1.     

Optical remote sensing of aircraft emissions with the K300

The K300 double pendulum interferometer, a compact high-resolution Fourier transform spectrometer designed for outdoor optical remote sensing in the infrared spectral region, is described. The remote diagnostic of hot aircraft engine emissions is a very interesting application of the infrared spectroscopy. First results of such measurements performed with the Kayser-Threde double pendulum interferometer K300 at the DLR airport, Oberpfaffenhofen, on 15 January 1992, are discussed     

Temperature-dependent emissivity of silicon-related materials andstructures

The results of an ongoing collaborative project between the New Jersey Institute of Technology (NJIT) and SEMATECH on the temperature-dependent emissivity of silicon-related materials and structures are presented in this study. These results have been acquired using a spectral emissometer. This emissometer consists of a Fourier Transform Infra-Red (FTIR) spectrometer designed specifically to facilitate simultaneous measurements of surface spectral emittance and temperature by using optical techniques over the near- and mid-IR spectral range and temperatures ranging from 300 K to 2000 K. This noncontact, real-time technique has been used to measure radiative properties as a function of temperature and wavelength for a wide range of silicon-related materials and structures. The first results of the temperature and wavelength dependent emissivity and hence refractive index of silicon nitride, in the literature, is presented in this study     

Oxidation of glow discharge a-Si:H

The optical constants of glow discharge hydrogenated amorphous silicon have been determined by ellipsometry measurements. From their evolution during exposure to air the growth of the oxide layer on amorphous silicon at room temperature has been evaluated.     

SOPRA SE300: a new tool for high accuracy characterization of multilayer structures

In order to characterize 300-mm wafers at different stages of the IC manufacturing, a new tool based on spectroscopic ellipsometry has been recently developed at SOPRA. This new instrument called SE-300 has some important new features compared to the other ellipsometers of SOPRA or of the competition. First the optical setup allows to obtained very small measurement spots down to 35×45 μm in polychromatic light to be able to work from deep UV 190 nm to near infrared; second the combined monochromator/spectrometer is directly setup on the analyser arm and allows both multichannel and scanning measurements on the same spot. Scanning measurement made with a real double monochromator including prism and grating allows very accurate measurement that can be used to extract optical indices and solve complex multilayer structures. Multichannel measurements are made through a prism/grating spectrometer with quasi-linear dispersion in wavelength. All the elements (robotics, prealigner, XYZ mapping, pattern recognition) are fully compatible with the new generation of 300-mm wafers. Practical results obtained in a realistic environment (I300I acceptance tests and MEDEA project) are presented.     

分光谱型天空背景辐射计的研制

为满足对天空背景辐射进行实时光谱测量和特征提取的需求,基于光纤光谱仪研制了一台一体化天 空背景辐射计,可测量340$\sim$1030 nm波长范围内的天空背景辐射光谱,波长分辨率优于0.5 nm, 具有定点测量、全天空扫描测量两种工作模式。在介绍系统总体结构的基础上,描述了光学组件、 转台系统、跟踪模块、嵌入式控制系统及恒温控制模块等硬件部件的结构,以及上位机软件的 设计思路、设备工作流程和定标方式。最后分析经光谱辐射定标后的测量数据,初步验证设备 工作的可靠性,为天空背景辐射的实时测量及光谱特性研究提供了有效手段。     

YbF3和YF3薄膜在0.4~14 μm超宽光谱内光学常数反演

为了获得红外低折射率材料的光学常数,采用电子束热蒸发技术在多光谱硫化锌基底上以不同的基底温度分别制备了单层氟化钇(YF₃)和氟化镱(YbF₃)薄膜。通过分光光度计和傅里叶变换红外光谱仪分别测试其在可见至远红外波段的透射率光谱曲线,使用包络法和色散模型拟合相结合的方法对其在可见至红外波段的光学常数进行了反演,得到了其在0.4~14 μm波段内的折射率与消光系数。采用椭偏测试结果验证了YF₃和YbF₃薄膜在0.4~1.6 μm波段内的光学常数正确性;将拟合得到的光学常数代入TFCalc 膜系设计软件,计算得到的单层薄膜的透射率光谱曲线与实测的光谱曲线吻合较好。实验结果表明,该方法获得的在超宽光谱0.4~14 μm范围内的光学常数准确、可靠。     

紫外─远红外宽波段NiMn2O4及Mn1.56Co0.96Ni0.48O4光学性质的研究

Mn-Co-Ni-O作为一种重要的热探测材料被广泛应用于各类领域。作者使用研磨和烧结的方法制备了NiMn2O4和Mn1.56Co0.96Ni0.48O4块体材料。通过X射线衍射实验研究了两种块体的结晶情况,发现半径较大的Co阳离子的加入会导致块体结晶性变差。通过椭圆偏振光谱测试分别获得了NiMn2O4和Mn1.56Co0.96Ni0.48O4在紫外-远红外宽波段的光学常数和介电常数,发现添加离子后二者光学性质(光学常数的强度和峰位)具有一定区别。利用傅里叶光谱仪得到了两种材料的反射光谱,并与用光学常数计算出的数值进行了比较,最后评估了表面粗糙度对反射谱的影响。     

Superfluorescent fiber source at 3.9 μm in the attenuation minimum of the atmospheric window 3–5 μm

Superfluorescence has been demonstrated for the first time at 3.9μm in holmium-doped fluoride glass optical fiber. Fluorescence measurements were possible at room temperature while pumping around 650 nm. Cooled to 173 K superfluorescence was obtained.     

C-T型平板波导红外光谱仪系统自身背景辐射的分析与抑制

红外光谱仪内部背景辐射在长波红外波段（8~12 m）影响比较显著,会严重降低光学系统的分辨率和信噪比。利用TracePro光学分析软件,对基于交叉非对称Czerny-Turner （C-T）型平板波导红外光谱仪进行了背景辐射分析,包括机械构件表面发射率以及光学元件表面温度对背景辐射的影响。引入了杂光系数作为评价指标,根据仿真分析结果,在高低温箱中,对该红外光谱仪的背景辐射影响采取抑制措施并进行了实验测量,实验结果证明:采取背景辐射抑制措施后,C-T型平板波导光谱仪系统的杂光系数在常温下（298 K）能达到5%以下。     

The far infrared optical properties of InP at 6 and 300 K

The amplitude and phase reflection spectra of InP have been determined in the far infrared at 6 and 300 K by dispersive Fourier transform spectroscopy and used to calculate values of the optical constants and dielectric functions in the region of the fundamental lattice resonance.     

Silver thiogallate (AgGaS2)--Part II: Linear optical properties

New measurements are presented on the absorption of silver thiogallate and related to fundamental mechanisms. All available data on the refractive indices of silver thiogallate, including new results for the visible, have been incorporated into sets of Sellmeier expressions. Different Sellmeier constants are given for visible and infrared wavelengths and also for crystals from different sources. Confirmation of some predictions from these Sellmeier expressions has been obtained by second-harmonic generation (SHG) experiments with a tunable optical parametric oscillator. Preliminary results on laser damage are summarized.     

Optical and ac conductivity investigations on Sn doped Ag2S thin films under the structural transition framework

This work deals with further optical and electrical investigations on Sn content in Ag₂S sprayed thin films and the beneficial effect of using this type of doping in addition to the results recently reported by R. Boughalmi, A. Boukhachem, I. Gaeid, K. Boubaker, M. Bouhafs, M. Amlouk, Mater. Sci. Semicond. Process. 16 (2013) 1584. The refractive index and extinction coefficient values in terms of Sn content were deduced from transmittance and reflectance data. Moreover, study of dielectric constants has been conducted; the dispersion parameters and high- frequency dielectric constant are determined. Finally, the electrical conductivity and conduction mechanism of these films are studied using an impedance spectroscopy technique in the frequency range 5 Hz–13 MHz at various temperatures (100–230 °C). Besides, the temperature dependence of ac conductivity measurements has been analyzed under the structural transition framework from β- to α-Ag₂S phases.     

Magnetic and photomagnetic properties of polycrystalline wide-gap semiconductor Cd1-xMnxTe thin films

The magnetic and photomagnetic properties of polycrystalline Cd_1-xMn_xTe thin films prepared by radio frequency (rf) sputtering have been investigated. Magnetization measurements were carried out using a rf superconducting quantum interference device magnetometer in the temperature range of 1.8∼300K at various magnetic fields up to 5.5 T. For temperatures above 40K, Curie-Weiss behavior was observed with a negative Weiss constant indicating predominantly antiferromagnetic interactions. Spin-glass transitions occurred at low temperatures. Photoinduced magnetization has been observed when the sample was illuminated by unpolarized light from an optical fiber.     

Free carrier optical absorption at 10.6 μm in GaAs

Optical absorption measurements at 10.6 μm have been perfor-med in chromium doped GaAs samples using a calorimetric tech-nique at 300 K, and an optical system to determine the varia-tion of the absorption versus temperature between 300 K and 650 K. Hall effect measurements have also been carried out in the same temperature range. The optical absorption cross sec-tion for both electrons and holes are discussed and experi-mentally determined. A semi-empirical formula is deduced which permit the calculation of the 10.6 μm free carrier absorption at any temperature and doping level provided the electron mobility is known. Besides free carrier and multi-phonon absorption another mechanism must be considered to explain the experimental data. Possible effect of small pre-cipitates is discussed.     

Study of the far infrared optical properties of KI by dispersive Fourier transform spectrometry

The optical constants of KI have been determined in the far infrared at 200 and 300K by dispersive Fourier transform spectrometry and used to calculate the imaginary part of the anharmonic self-energy of the q?o transverse optic mode. The overall agreement, both quãlitatively and quantitatively, with calculations by Berg and Bell and by E?dridge and Kembry which include contributions from cubic anharmonicity is good.     

Gaussian optical design of a submillimeter-wave and far-infrared laser sideband heterodyne spectrometer

A submillimeter-wave/far-infrared (SMM/FIR) laser sideband heterodyne spectrometer has been built for molecular rotational spectroscopy application in the frequency range of 600–3000 GHz. Based on Gaussian optics, optical system of the spectrometer is designed to be quasi-achromatic and low losses. In this article the optical design and the performance of the spectrometer are presented.