Depth profiling of weakly absorbing samples by the crossed-beam photothermal deflection technique

Abstract

Abstract The depth profiling of a weakly absorbing sample using the crossed-beam photothermal deflection technique is theoretically described in terms of imaging resolution and contrast. The results show that, for the transverse deflection amplitude image of an optical or thermal defect in weakly absorbing material, the image contrast and depth-profiling ability increase markedly with increasing intersection angle of the two beams. Therefore an effective way to improve the resolution and contrast of the image is to increase the intersection angle, and the best image quality is obtained at normally crossed-beam case. The crossed-beam photothermal depth-profiling technique provides a quantitative microanalysis tool for the detection of optical or thermal defects located at any depth of weakly absorbing materials.