被动毫米波辐射成像系统中的通道误差研究

在被动毫米波成像系统中,仪器的误差对系统性能有很大的影响,主要有天线误差和通道接收机误差。本文研究被动毫米波辐射成像系统中的通道误差对系统温度灵敏度的影响。通过对系统的通道滤波器的频率响应建模,对造成系统通道误差的各个误差源进行了理论的分析,并通过计算机仿真得到各个误差源对温度灵敏度影响。可知通道的带宽不一致对温度灵敏度影响很小,而中心频率、群延迟和初始相位的不一致却对温度灵敏度有很大的影响,这对通道误差的分配有很大的理论指导意义。     

PTR技术中空间分辨率的频率特性

给出了光热辐射测量（ＰＴＲ）技术中空间分辨率的定义。理论分析和实测结果表明，空间分辨率随调制频率的升高而提高。     

紫外辐射和红外辐射的应用与探测器件

本文简略介绍了紫外辐射和红外辐射的特性和应用。近来随着紫外辐射和红外辐射的应用，辐射测量技术和测量仪表也得到了发展。     

Reference Blackbody Sources in the 100–3500 K Range for Precision Measurements in Radiometry,Photometry, and Optical Thermometry

A wide range of precise blackbody radiation sources that cover the entire optical wavelength range from IR to near-UV at working temperatures from 80 to 3500 K and provide highly stable and uniform radiation has been developed at VNIIOFI. The unique characteristics of blackbody sources have made them the basis of national primary measurement standards and precision calibration facilities in Russia as well as other in world-leading metrology centers in USA, Germany, UK, France, China, and other countries. __________ Translated from Izmeritel'naya Tekhnika, No. 11, pp. 29–34, November, 2005.     

Pitfalls in the in vitro determination of sunscreen protection factors using broad band ultraviolet radiation detectors and solar simulating radiation

Reliable in vitro techniques for assessing sunscreen protection factors have relied upon obtaining the forward scattering transmission spectrum of the test compound applied to a suitable substrate such as mouse or human epidermis. A theoretical analysis of alternative techniques using broad-band ultraviolet radiation detectors in conjunction with a source of simulated sunlight shows that the method is likely to yield unreliable values of sun protection factors and the reasons for this are discussed.     

X射线辐射测量

在过去的几年里,人们使用同步辐射技术在X射线波段实现了基于辐射源和基于探测器的辐射测量,电子储存环被用作主辐射源标准,而低温辐射计(ESR)被用作主探测器标准。因为低温辐射计需要强的单色辐射,所以,这种方式也必须使用同步辐射。文中对能量色散探测器和硅光电二极管的探测效率和响应度做了校准,其相对不确定度约1%,所得结果与模型计算值做了比较。     

Measurement of the Thermal Diffusivity of Solids with an Improved Accuracy

A photothermal radiometry technique is being developed at the NPL with the goal of improving the accuracy of thermal diffusivity measurements. The principle is to perform a laser-induced thermal experiment while simultaneously making accurate measurements of the experimental boundary conditions. A numerical three-dimensional heat diffusion model based on thermal transfer functions has been developed to account for the measured boundary conditions. The thermal diffusivity is determined from the experimental data by a nonlinear, least-squares fit to the model. Experiments carried out on pure metals at 900 K demonstrate good agreement between the theoretical predictions and experimental data, and uncertainties of about 1.5% for the thermal diffusivities of platinum, titanium, and germanium were obtained.     

Algorithms for Fresnel Diffraction at Rectangular and Circular Apertures

This paper summarizes the theory of Fresnel diffraction by plane rectangular and circular apertures with a view toward numerical computations. Approximations found in the earlier literature, and now obsolete, have been eliminated and replaced by algorithms suitable for use on a personal computer.     

Application of the laser flash diffusivity method to thin high thermal conductivity materials

The evolution of semiconductor devices and the dramatic increases in the power dissipation per unit volume of ever smaller microelectronic devices means electronic packaging technologies must evolve to manage the dissipation of heat. One of the major issues is the development of new packaging materials optimised for heat management. Future packaging will incorporate layers with thermal diffusivities exceeding that of copper in thin, sub-millimetre foils. Metrology techniques are needed to measure the thermal diffusivity of these thin, thermally fast materials. As some new materials are developed only in the form of thin substrates the laser flash technique is limited in its application to these materials. This paper addresses the application of a nanosecond pulsed laser flash instrument to the measurement of thermal diffusivity of thin high thermal conductivity materials and the errors associated with the measurement. An experimental comparison is made with a laser flash instrument where the laser pulse is of higher energy but millisecond pulse duration. Received: 25 October 1997/Accepted: 2 January 1998