多波长光纤激光器的研究

以一种环形腔结构的 MW- EDFL为例 ,详细说明了多波长光纤激光器的结构特点、工作原理和研究现状 ,同时介绍了几种多波长光纤激光器的最新报道 ,并预言了多波长光纤激光器的广泛应用     

A universal pyrometer for molecular-beam epitaxy setups

A universal fiber-optic pyrometer for the molecular-beam-epitaxy growth module developed in collaboration with JSC Semiconductor Technologies and Equipment is described. This instrument is designed for controlling the technological process of growing semiconductor heterostructures on substrates of various types (GaAs, InP, Si, and sapphire). The pyrometer allows measurements of the temperature of semiconductor substrates to be performed in the range 450–1200°C with an accuracy no worse than ±0.5% under the conditions when such characteristics as the emissivity of the material, the transparency of the optical medium, and the dimensions of the studied surface are unknown. These feasibilities can be realized owing to the use of a procedure of periodic calibration of the pyrometer against an actual object directly during the technological cycle with the use of additional information on the object temperature.     

Multiwavelength optical pyrometer for shock compression experiments

A system for measurement of the spectral radiance of materials shocked to high pressures ( approximately 100 GPa) by impact using a light gas gun is described. Thermal radiation from the sample is sampled at six wavelength bands in the visible spectrum, and each signal is separately detected by solid-state photodiodes, and recorded with a time resolution of approximately 10 ns. Interpretation of the records in terms of temperature of transparent sample materials is discussed. Results of a series of exploratory experiments with metals are also given. Shock temperatures in the range 4000-8000 K have been reliably measured. Spectral radiance and temperatures have been determined with uncertainties of 2%.     

Two-color optical charge-coupled-device-based pyrometer using a two-peak filter

A two-color optical charge-coupled-device (CCD)-based pyrometer was developed using a multipeak interference filter with a color CCD sensor to measure multicolor signals with specified wavelengths. The effective and simple method adjusts the fixed spectrum response characteristics of a color CCD to allow improved temperature measurements. This pyrometer system not only has the advantage of traditional two-color (two-wavelength) pyrometry, but also overcomes the restrictions of color CCDs that can only be applied in waveband measurements. The measurement performance of the system using a two-peak filter (λ(1)=643?nm,?λ(2)=564?nm) was evaluated by blackbody experiments. The results show that the low temperature detection limit is increased about 200 K with an increase in the sensitivity of the measured signals compared with the original system without two-peak filter [Fu, et al., Opt. Laser Technol. 42, 586 (2010)]. And the effective temperature range is also increased when T > 1233 K. The measured ratio C(R)/C(G) is monotonically relative to the temperature, which simplifies the measurements. The temperature sensitivity of 2.49 is larger and more uniform than the temperature sensitivity of 1.36 in the previous original system. Thus, the measurement performance of the new system is greatly improved. Finally, as an application, the surface temperature distribution of stainless steel sample in hot environments was determined by this new CCD-based pyrometer. The results agree well with the spectrometer-based results and further verify the applicability of the new system.     

标准具型光纤氢气传感器

为了测量某部件贮存环境中氢气浓度 ,特提出了这种新型氢定量分析工具。通过对国内外各种氢气传感器的研究和探索 ,将光纤传输、标准具透射、钯膜的氢吸附、吸收光谱定量分析各种技术运用为一体 ,开发出了这种传感器     

An immersible fiber-optic fluorometer

An immersible fiber-optic fluorometer is used to investigate the sea water composition and the phytoplankton content at various depths. Owing to the design features of its immersed part, the fluorometer is capable of making continuous measurements at a widely varying water illuminance. A procedure for calculating the basic structural components of the immersed module is described. Results of laboratory testing of the fluorometer are presented.     

多波长激光扩束器的光学设计

在激光雷达以及光谱仪定标时常常需要较宽以及高准直性的激光光束。设计了一出射光束为16mm,扩束比为20倍的激光扩束器光学系统。通过移动激光扩束器的物镜与目镜间隔,可以实现光谱范围在543.5~850nm的激光扩束;比较了使用该激光扩束器发射的准直激光束与理想的单色平行光充满成像光谱仪的入瞳孔径后成像光谱仪传递函数的变化,说明该光学系统可行。     

Scanning optical pyrometer for measuring temperatures in hollow cathodes

Life-limiting processes in hollow cathodes are determined largely by the temperature of the electron emitter. To support cathode life assessment, a noncontact temperature measurement technique which employs a stepper motor-driven fiber optic probe was developed. The probe is driven inside the hollow cathode and collects light radiated by the hot interior surface of the emitter. Ratio pyrometry is used to determine the axial temperature profile. Thermocouples on the orifice plate provide measurements of the external temperature during cathode operation and are used to calibrate the pyrometer system in situ with a small oven enclosing the externally heated cathode. The diagnostic method and initial measurements of the temperature distribution in a hollow cathode are discussed.     

Testing a fiber-optic ionizing-radiation detector

A fiber-optic ionizing-radiation detector is composed of a scintillation sensor, an optical fiber, and a photodetector. Due to the miniature size and the high radiation resistance, the detector is capable of measuring the characteristics of powerful neutron and γ-ray fields with a high spatial resolution. A prototype of the detector has been tested using a ⁶⁰Co γ-ray source with a dose rate as great as 200 R/S. The dynamic range of dose measurements is no less than 10⁵. The detector signal is linearly dependent on the radiation dose rate. The ratio of the useful signal to the background due to radioluminescence of the optical fiber is presented for different types of scintillators.     

Methodology for spectral emissivity measurement by means of single color pyrometer

The application of non-intrusive optical devices, such as infrared pyrometers able to measure the temperature of surfaces, makes possible the evaluation of emissivity curve of the tested materials at different temperature values. In this paper the authors propose a methodology for the spectral emissivity measurement by means of a single color pyrometer providing a semi-empirical formula, obtained experimentally at CIRA’s laboratory. The semi-empirical formula allows to know the actual emissivity value of the sample’s surface for whatever emissivity value set up on the pyrometer. The agreement between the experimental emissivity and the emissivity predicted by semi-empirical formula was verified.     

Dispersion, aberration and deconvolution in multi-wavelength fluorescence images

The wavelength dependence of the incoherent point spread function in a wide-field microscope was investigated experimentally. Dispersion in the sample and optics can lead to significant changes in the point spread function as wavelength is varied over the range commonly used in fluorescence microscopy. For a given sample, optical conditions can generally be optimized to produce a point spread function largely free of spherical aberration at a given wavelength. Unfortunately, deviations in wavelength from this value will result in spherically aberrated point spread functions. Therefore, when multiple fluorophores are used to localize different components in the same sample, the image of the distribution of at least one of the fluorophores will be spherically aberrated. This aberration causes a loss of intensity and resolution, thereby complicating the localization and analysis of multiple components in a multi-wavelength image. We show that optimal resolution can be restored to a spherically aberrated image by constrained, iterative deconvolution, as long as the spherical aberration in the point spread function used for deconvolution matches the aberration in the image reasonably well. The success of this method is essentially independent of the initial degree of spherical aberration in the image. Deconvolution of many biological images can be achieved by collecting a small library of spherically aberrated and unaberrated point spread functions, and then choosing a point spread function appropriate for deconvolving each image. The co-localization and relative intensities of multiple components can then be accurately studied in a multi-wavelength image.     

辐射光纤高温计及其系统的研究

为解决特殊情况下的高温在线测量，研制了一种辐射光纤高温计。介绍了仪表的工作原理、光滤波及测试结果的处理。     

3D printed fiber-optic nanomechanical bioprobe

Ultrasensitive nanomechanical instruments,e.g.atomic force microscopy(AFM),can be used to perform delicate biomechanical measurements and reveal the complex mechanical environment of biological processes.However,these instruments are limited because of their size and complex feedback system.In this study,we demonstrate a miniature fiber optical nanomechanical probe(FONP) that can be used to detect the mechanical properties of single cells and in vivo tissue measurements.A FONP that can operate i...     

微小型光纤陀螺组合分时复用技术

为了有效减小多轴光纤陀螺组合的功耗、体积和重量,实现光纤陀螺组合的微小型化,应用分时复用技术,提出了一种基于3×3耦合器,工作在850 nm短波长的光纤陀螺分时复用组合结构。分析了陀螺输出数据处理方法,得到了分时复用光纤陀螺组合的相对极限零偏稳定性。建立了分时复用光纤陀螺切换模型,揭示了分时复用导致光纤陀螺轴向切换必然存在一个过渡过程,分析了过渡过程对陀螺组合静态、动态特性的影响。结果显示,光纤陀螺组合的相对零偏稳定性是传感方法的2.1倍,最大输入信号检测带宽为1.1 kHz,标度因数的不对称性和非线性度均小于50×10-6。最后,通过仿真进行了实验验证,结果表明,该技术可以用于中低精度微小型多轴光纤陀螺组合中。     

基于CCD的双光束多波长紫外可见吸收检测器

由于传统的多波长紫外可见吸收检测器无法克服光源波动造成的噪声和漂移,故设计开发了一种基于CCD的双光束多波长紫外可见吸收检测器.光源发出的光聚焦后被分束镜分成信号光和参考光,信号光射入到样品检测池中.从样品检测池中出射的信号光经过斩光器聚焦在狭缝上,被凹面光栅分光成像于CCD的一部分光敏面上.参考光在CCD的另一部分光敏面上分光成像.在光路系统和外围电路的辅助配合下,可以用一片CCD实现信号光谱,参考光谱和暗电流的精确测量.由于采用参考光光谱和CCD暗电流对信号光谱进行实时补偿,可以使基线短期噪声降低为1×10-5 AU,漂移降低为1×10-4 AU/h.     

Integration of fiber-optic sensors in measuring machines

In last years, optical metrology due to its capability in miniaturization and sensitivity became the primary solution in measurement of complex geometries and fragile pieces. Here, we propose a promising approach to perform highly accurate distance measurements using low-coherence fiber-optic sensors for quality inspection of nozzle orifices in fuel injection systems. In this effort, we develop an adaptive image processing algorithm in MATLAB and install the necessary hardware on a form tester to accelerate and simplify the aligning process. As a result, the repeatability of measurements is one order of magnitude improved while the standard deviation is almost 60% reduced.     

基于DSP和FPGA的多路型光纤光谱仪系统

描述了一种能同时快速地测量多达八组的光谱信号并具有实时光谱处理能力的新型多路型光纤光谱仪系统。该多路型光纤光谱仪以多个CCD作为光电探测器,以FPGA作为控制核心产生各种控制时序,利用DSP进行光谱数据处理并实现与PC机的USB通信。概述了整个系统的构成,给出了光谱采集的光学平台设计,研究了在DSP和FPGA控制下光谱数据的采集和处理过程。为了避免测量时各个通道光谱数据的相互串扰并控制光谱峰值的随机漂移,除采用传统的滤波电路和电源稳压技术之外,提出了利用FPGA内部编程的方法来解决IC芯片内部电容效应的新技术。光谱测试结果表明,该系统具有良好的长期稳定性、较大的信号动态范围和较高的信噪比,适合于各种场合的光谱及相关参数测量。