SENSITIVE PHOTOTHERMAL INTERFEROMETRIC DETECTION METHOD FOR CHARACTERIZATION OF TRANSPARENT PLATE SAMPLES

In this article, a recently developed, sensitive photothermal interfer ometric detection technique, in which an interference fringe pattern f ormed by overlapping two reflected probe beams from the front and rear surfaces of the sample was used to measure the photothermal signal, a nd its application for characterization of transparent (or partially t ransparent) plate samples were theoretically and experimentally invest igated in detail. The theoretical descriptions of the intensity distri bution of the interference fringe pattern and the photothermal signal with pulsed excitation were presented. Experiments were conducted with plate samples of optical glasses doped with heavy-metal ions and the results were compared with the theoretical ones. Good agreement betwee n theoretical and experimental results demonstrated the proposed photo thermal interferometric detection technique to be a sensitive photothe rmal method for the study of the thermophysical properties of transpar ent samples. Its applicability to weak absorption or spectroscopy meas urement and microvolume trace analysis was also discussed. (C) 1996 Am erican Institute of Physics.