ACCURATE MEASUREMENT OF HIGH-SPEED, UNSTEADY TEMPERATURE-FIELDS BY HOLOGRAPHIC-INTERFEROMETRY IN THE PRESENCE OF PERIODIC PRESSURE VARIATIONS

This paper expands the applicability of holographic interferometry to measurements of unsteady temperature distributions for physical situat ions characterized by periodic pressure variations. For this purpose a new analytical model that accounts for pressure variations in the int erpretation of the interferometric fringe pattern was elaborated. This model was then implemented into the newly developed evaluation proced ure that is based on the measurement of the interference order as a co ntinuous function of two spatial coordinates and time, by employing di gital image processing algorithms. To validate the evaluation procedur e, the oscillating temperature fields in a model of a thermoacoustic r efrigerator were measured. These measurements proved the validity of t he approach by indicating very good agreement with existing theory.