Comparison of BaTiO3 Optical Novelty Configuration and Photothermal Lensing Configuration inPhotothermal Experiments
Photorefractlve BaTiO3 Is used as an optlcal novelty fllter to highlight the hlgh spatlal frequency components of the photothermal signal. A real-time phase gratlng recorded In BaTiO3 acts as a matched rejectlon spatlal filter for the probe laser. This reduces the statlonary background from the optical signals thereby Increasing slgnal contrast ratlos. Rejectlon of the monotonous statlonary slgnal provides a powerful means of Improving the photothermal signal. This paper describes the constructlon of this novel apparatus and the experlments performed In order to compare lts performance wlth photo- thermal lensing results. A theory that explains photothermal signal fllterlng wlth BaTiO3, as an adaptive spatlal frequency fllter is presented. Results comparlng the optical signals obtalned In a photothermal lensing experiments and those obtalned In the BaTiO3 optlcal novelty fllter experlments are presented. The optical novelty fllter signals demonstrate a remarkable Improvement In the signal contrasts for moderate photothermal-lnduced phase shifts.
Comparison of BaTiO3 Optical Novelty Configuration and Photothermal Lensing Configuration in Photothermal Experiments Shashi D. Kalaskar and Stephen E. Bialkowski Analytical Chemistry 64 1824 1992