Pulsed infrared laser irradiation of biological tissue: effect of pulse duration and repetition rate

E. Duco Jansen; Ravi K. Chundru; Salim A. Samanani; Todd A. Tibbetts; Ashley J. Welch

doi:10.1117/12.147672

7 July 1993 Pulsed infrared laser irradiation of biological tissue: effect of pulse duration and repetition rate

E. Duco Jansen, Ravi K. Chundru, Salim A. Samanani, Todd A. Tibbetts, Ashley J. Welch

Proceedings Volume 1882, Laser-Tissue Interaction IV; (1993) https://doi.org/10.1117/12.147672
Event: OE/LASE'93: Optics, Electro-Optics, and Laser Applications in Scienceand Engineering, 1993, Los Angeles, CA, United States

Abstract

Pulsed laser ablation is a trade off between minimizing thermal damage (for relatively long pulses) and mechanical damage (for relatively short pulses) to tissue adjacent to the ablation crater. Often it is not known what the optimal laser parameters are for a specific application, since clinically used parameters have at least partially been dictated by physical limitations of the laser devices. We recently obtained a novel type of cryogenic continuous wave holmium:YAG laser ((lambda) equals 2.09 micrometers ) with a galvanometric drive outcouple mirror that acts as a Q-switch. This unique device provides pulse repetition rates from a few Hz up to kHz and the pulse length is variable from microsecond(s) to ms. The effect of pulse duration and repetition rate on the thermal response of chicken breast is documented using temperature measurements with a thermal camera. We varied the pulse width from 10 microsecond(s) to 5 ms and fond that these pulse durations can be considered impulses of thermalized optical energy. In this paper some theoretical considerations of the pulse length will be described that support the experimental data. It was also found that even at 1 pulse per second thermal superposition occurs, indicating a much longer thermal relaxation time than predicted by a simple time constant model.

Citation Download Citation

E. Duco Jansen, Ravi K. Chundru, Salim A. Samanani, Todd A. Tibbetts, and Ashley J. Welch "Pulsed infrared laser irradiation of biological tissue: effect of pulse duration and repetition rate", Proc. SPIE 1882, Laser-Tissue Interaction IV, (7 July 1993); https://doi.org/10.1117/12.147672

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