Accession Number : ADA138412

Title :   Techniques of Flash Radiometry.

Descriptive Note : Technical rept.,


Personal Author(s) : Leung,W P ; Tam,A C

PDF Url : ADA138412

Report Date : 20 Jan 1984

Pagination or Media Count : 33

Abstract : This document analyzes in detail flash radiometry techniques for determining the thermal diffusivity of thin condensed samples. Such techniques rely on the transient infrared radiation from the sample heated by a short-duration pulsed radiation. Exact analytical solution for the conventional transmission measurement (in which the excitation source and the infrared detector are on opposite sides of the sample) as well as the backscattering measurement (in which the excitation source and detector are on the same side of the sample) are presented with the effect of heat loss neglected. The analysis allows the determination of the thermal diffusivity and the absorption coefficients at the excitation wavelength and at the detecting wavelength of the sample from the experimental data. The effects of excitation pulse duration and finite rise time of the detection system are discussed. Experiments on pulsed radiometry measurements on thin film samples are performed to verify some of these theoretical predictions. Radiation loss and two-dimensional head diffusion loss are shown to be negligible for thin film samples. (Author)

Descriptors :   *Mathematical models, *Radiometry, *Thermal diffusion, *Thin films, *Methodology, Heat transmission, Sampling, Infrared radiation, Infrared detectors, Backscattering, Pulses, Absorption coefficients, Excitation, Heat loss, One dimensional

Subject Categories : Numerical Mathematics
      Test Facilities, Equipment and Methods
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE