Study On Photothermal Interference Phenomena

Photothermal effects and interference techniques are united greatly in the photothermal interferometric detection technique. Various applications of the technique have been developed over a wide range of science and technology, including physics, chemistry, biology, material engineering and so on. As a developing technique, the detection technique needs not only to be developed to new fields, but also to be improved and consummated. This paper mainly focuses on the development of the photothermal interferometric detection technique and its applications. The main contents in this dissertation are the following:1) When the focused laser beam irradiates a single layer film-substrate, the interference effect of reflection beams is studied both experimentally and theoretically. The three-beams interference effect is presented. The related theoretical intensity profile of interference fringe is obtained. In terms of the theory, the characteristics of the interference fringe and the influence of some main factors on the fringe are analyzed. The experiments, which are carried out with a single layer film-substrate and the glass substrate, have shown that the theoretical analysis is correct.2) Based on the former interference effect, a novel photothermal interference technique is presented. The temperature profile of the sample and the photothermal signal are presented in terms of our theory model. We studied the photothermal interference phenomena in the theory. With a addition phase in the Fresnel diffraction integral, three beams are presented. Making use of the theoretical model, the influence of the film and the substrate on the photothermal signal is studied. Therefore we can measure the character of the film and the substrate using this photothermal interference phenomena.3) A model of a slot and a position detector to measure the shift of the interference fringe is presented. We optimize this way in the theory and gain the optimal position of the detector when measure the shift. Meanwhile the influence of some main factors on the fringe is analyzed.4) In terms of the photothermal technique, a measurement system is established and the photothemal signal is successfully measured. Meanwhile the photothermal interference phenomena is analyzed by the experiment. In addition, the novel method is applied to the...