The extraction of information from laser anemometry data

• Published in: Physica scripta Vol. 19; pp. 412 - 425
• Main Authors: McWhirter, J G, Pike, E R
• Format: Journal Article
• Language: English
• Published: 01.04.1979
• ISSN: 0031-8949

A method for extracting the maximum amount of information about the velocity distribution from photon-correlation anemometry data is described. The method involves the use of the eigenfunctions and eigenvalues of the continuous 'impulse' (single velocity) response function for the apparatus and explicit formulae for these are given. The effects of discrete data points and truncation are considered. In this situation the problem is not properly defined without an a priori 'model' for the solution. Given such a model, the maximum information should be extracted by mapping it onto the space of eigenfunctions and optimising the parameters in this basis. However, numerical complexity has prevented this from being carried out yet. In certain situations, the difficulties caused by discrete data may be overcome to a good approximation by the use of B-spline functions. This technique is described here. The need to measure instrumental parameters such as beam radius, visibility and background is discussed.