激光拉曼分光计中杂散光的检测

本文介绍了一种激光拉曼分光计中杂散光的检测方法,可将测量限扩展到10~(-12)量级以下。对杂散光的检测方法和数据处理作了叙述和评价,给出了典型的杂散光分布曲线。研究了双单色仪各狭缝对杂散光的影响,对合理选择缝宽作了讨论。最后,根据实测数据对Spex 1403型双单色仪的杂散光水平作了评估。     

一种利用干涉滤光片测量分光光度计杂散光的新方法

本文介绍了一种利用干涉滤光片测量分光光度计杂散光的新方法。实验证明：该方法更能全面地测量分光光度计的杂散光值，解决了传统方法只测单边或在几个特定点处测量的缺点，可实现在任意波长点处进行杂散光测量。     

绝对辐射温度计杂散光抑制的仿真分析

绝对辐射温度计可用于高温段热力学温度测量,其滤光片辐射计所接收的信号十分微弱,杂散光将会对实验结果产生一定影响.使用基于蒙特卡罗法的光线追迹模拟软件Trace Pro建立模型进行仿真测试,可以得到因内壁多次反射而产生的杂散光情况.通过安装挡光板和使用高吸收率涂层等方式,可对杂散光进行抑制.本文为减小绝对辐射温度计多次反射杂散光提供了解决思路,并给出了相应的模拟结果.     

激光Raman分光计中杂散光的测试方法、技术及其最新进展（Ⅱ）──测试技术研究进展及其检测标准的几点考虑

重点就激光Ｒａｍａｎ分光计中杂散光测试的若干方案与主要技术进行了全面综述与评价,简单介绍了近十年来国内有关激光Ｒａｍａｎ分光计中杂散光测试与研究工作的发展概况、实验结果及其最新进展,并就建立有关“激光Ｒａｍａｎ分光计中杂散光检测标准”提出了几点考虑或建议。     

激光Raman分光计中杂散光的测试方法、技术及其最新进展（Ⅰ）──测试原理、困难与方法特点及其应用场合

简单介绍了激光Ｒａｍａｎ分光计中杂散光测试的基本原理及其主要困难与问题，重点就杂散光测试中的五种方法进行了综述与评价，并根据诸方法的特点，就其应用场合问题提出了几点看法或建议。     

多参数食品现场快速检测仪光度线性校准装置——标准滤光片的研制

为了满足多参数食品现场快速检测仪光学性能的校准需求,本文研制了其光度线性校准装置——标准滤光片.针对多参数食品现场快速检测仪的圆形比色池,设计了专用滤光片支架,通过减少杂散光,以保证透射比的准确测量.标准滤光片的标称值约为5％～90％,其均匀性、正反面差别、稳定性均满足JJG1034-2008《光谱光度计标准滤光器检定...     

利用光纤和调制半导体激光的准直方法

本提出了一种新的激光光纤准直方法。利用光传播的平行性和直线性，光学准直技术被用于精密地建立几何参数的测量基准，在这些应用中，光束、处理电路的漂移、杂散光是影响测量精度的主要因素。为了消除这些影响，本利用调制半导体激光技术和光纤技术形成准直光束，四象限探测器进行探测，相敏检波技术对光电调制信号进行解调，所有的信号共享同一信号处理信道，且光束的调制频率远离杂散光的频率范围，激光光束漂移杂散光、电路漂移被抑制，在１ｍ范围获得了０．３μｍ的准直精度。     

单色仪的杂散光及其测量

本文探讨了可定量描述光谱仪器杂散光特性的谱杂散光系数和总杂散光系数的概念和数学表达式,提出一种测量单色仪标称波长上的光谱透射率(相对值)的方法,并以此对近红外单色仪的杂散光特性进行了测量,给出测量结果。作者认为,用这种方法测量和描述杂散光较为符合实际情况,能够比较准确地表示光谱仪器的杂散光特性。     

杂散光对分光光度计测量结果的影响探讨

杂散光是分光光度计检定中一个必检的重要指标,其大小决定仪器的合格与否,而且,杂散光的偏差对于分光光度计测量结果有很大的影响。本人结合实际工作对杂散光的来源、杂散光对分光光度计测量结果的影响、杂散光的检测、如何减小杂散光对分光光度计测量结果的影响等方面进行了分析。     

对紫外可见分光光度计杂散光检定用标准物质的探讨

本文介绍了用国家标准中心推出的ＢＷ２０１９截止滤光片标准物质检定紫外、可见分光光度杂散光是一种较好的方法，并评价ＢＷ２０１９截止滤光片与滤光液的优缺点。     

Deep-ultraviolet Raman microspectroscopy: characterization of wide-gap semiconductors

We have developed a high-throughput deep-ultraviolet (DUV) Raman microspectrometer with excitation from a continuous wave (cw) laser operated at 244 nm that enables us to characterize thin surface layers of wide-gap semiconductors. This spectrometer system consists of a filter spectrometer for the rejection of stray light and a high-dispersion spectrograph combined with a liquid nitrogen cooled charge-coupled device (CCD) detector and extends the low-frequency limit of the observable spectral range down to 170 cm(-1). In the microscope we use a Cassegrain reflective objective for the collection of the scattered light and an off-axis mirror for introduction of the excitation laser light. DUV Raman spectroscopy has been applied for studying wide-gap semiconductors including SiC and AlGaN epitaxial films and shallow implanted layers of these materials. Raman spectra of various crystals have also been measured for examining the performance of this system. Resonance enhancement of Raman bands has been observed for several semiconductors, and the results are discussed.     

受激拉曼散射阈值光强的测定

本文提出一种测量受激拉曼散射阈值光强的方法,利用光学多道分析仪的递增延迟时间功能控制调Q开关,改变输出的激光光强以达到测量阈值光强的目的。这种方法适用于对激光光强表现出阈值特性的物理量的测量。     

Image processing method to improve AOTF spectral resolution and spatial resolution

Abstract

An acousto-optic tunable filter (AOTF) causes the diffracted angle and wavelength to spread, leading to loss of resolution. The light intensity detected by a CCD pixel equals the true intensity plus the stray light caused by the spread of the wavelength and diffraction angle. Here, the true intensity is obtained using neighbourhood estimate recursive correction iteration, improving the spectral and spatial resolution. The spread of acoustic wave angles caused by diffraction is analysed. The reason for the spreads is analysed and derived. A method is reported for measuring the correspondence between the wavelength and diffraction angle spread, using an AOTF, an angle measurement spectrometer and a fibre spectrometer. The iterations’ stop condition is analysed. The improved theory is verified by an AOTF spectral imaging experiment.     

Steady-state and transient ultraviolet resonance Raman spectrometer for the 193-270 nm spectral region

We describe a state-of-the-art tunable ultraviolet (UV) Raman spectrometer for the 193-270 nm spectral region. This instrument allows for steady-state and transient UV Raman measurements. We utilize a 5 kHz Ti-sapphire continuously tunable laser (approximately 20 ns pulse width) between 193 nm and 240 nm for steady-state measurements. For transient Raman measurements we utilize one Coherent Infinity YAG laser to generate nanosecond infrared (IR) pump laser pulses to generate a temperature jump (T-jump) and a second Coherent Infinity YAG laser that is frequency tripled and Raman shifted into the deep UV (204 nm) for transient UV Raman excitation. Numerous other UV excitation frequencies can be utilized for selective excitation of chromophoric groups for transient Raman measurements. We constructed a subtractive dispersion double monochromator to minimize stray light. We utilize a new charge-coupled device (CCD) camera that responds efficiently to UV light, as opposed to the previous CCD and photodiode detectors, which required intensifiers for detecting UV light. For the T-jump measurements we use a second camera to simultaneously acquire the Raman spectra of the water stretching bands (2500-4000 cm(-1)) whose band-shape and frequency report the sample temperature.     

Simple spectral stray light correction method for array spectroradiometers

A simple, practical method has been developed to correct a spectroradiometer's response for measurement errors arising from the instrument's spectral stray light. By characterizing the instrument's response to a set of monochromatic laser sources that cover the instrument's spectral range, one obtains a spectral stray light signal distribution matrix that quantifies the magnitude of the spectral stray light signal within the instrument. By use of these data, a spectral stray light correction matrix is derived and the instrument's response can be corrected with a simple matrix multiplication. The method has been implemented and validated with a commercial CCD-array spectrograph. Spectral stray light errors after the correction was applied were reduced by 1-2 orders of magnitude to a level of approximately 10(-5) for a broadband source measurement, equivalent to less than one count of the 15-bit-resolution instrument. This method is fast enough to be integrated into an instrument's software to perform real-time corrections with minimal effect on acquisition speed. Using instruments that have been corrected for spectral stray light, we expect significant reductions in overall measurement uncertainties in many applications in which spectrometers are commonly used, including radiometry, colorimetry, photometry, and biotechnology.     

拉曼光谱仪相对强度标准物质量值表达及不确定度评定

拉曼光谱仪常用于纯定性分析、高度定量分析和测定分子结构。然而,相对强度未经校准的拉曼谱图会出现变形和失真,造成不同仪器的测量结果缺乏可比性。选用中国计量科学研究院研制的标准物质候选物,使用激光共聚焦拉曼光谱校准装置对标准物质候选物进行定值、均匀性和稳定性检验,并评定了其不确定度。结果显示标准物质候选物具有良好的均匀性,且在1年的有效测量内具有良好的稳定性,与NIST的标准物质SRM2243相比,校准结果等效、一致。     

全息窄带带阻滤光片用于拉曼光谱测试仪

在测量物质的拉曼光谱时,存在着比拉曼散射光强103~06倍的瑞利散射光,会严重影响拉曼光谱信号的获取。为此,研制了半宽度分别为18nm(峰值波长532nm)和25nm(峰值波长633nm)、光学密度均大于4的重铬酸盐明胶全息窄带带阻滤光片,并将它们用于由平场光谱仪、CCD探测器和计算机控制系统等组成的小型拉曼光谱测试仪中,以滤除瑞利散射光,获得信噪比较高的拉曼光谱信号。对四氯化碳、乙醇以及丙酮等液体样品进行测量的结果表明,在拉曼光谱测试仪中采用该全息窄带带阻滤光片后,可快速测得待测样品的波数低至217cm-1的拉曼光谱。     

Quantitative Raman reaction monitoring using the solvent as internal standard

Despite its potential, the use of Raman spectroscopy for real-time quantitative reaction monitoring is still rather limited. The problems of fluorescence, laser instability, low intensities, and the inner filter effect often outscore the advantages as narrow bands, the use of glass fibers, and low scattering of water and glass. In this paper, we present real-time quantitative monitoring of the catalyzed Heck reaction by using the solvent as internal standard. In this way, all multiplicative distortions, e.g., laser intensity variations or absorbance of the laser light, can be corrected for. We also show that a limited amount of fluorescence does not hamper the analysis. Finally, we present a new method to correct for the inner filter effect, i.e., the absorbance of Raman scattered light by the reaction medium. Simultaneous absorption measurements of the reaction mixture enable accurate correction of Raman signals for the inner filter effect. Thus, for reaction monitoring applications, a Raman spectrometer should be equipped with an absorbance measurement device.