18 June 1999 Noncontact photoacoustic spectroscopy (NCPAS) for photoablation control: data acquisition and analysis using cluster analysis
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Proceedings Volume 3591, Ophthalmic Technologies IX; (1999) https://doi.org/10.1117/12.350581
Event: BiOS '99 International Biomedical Optics Symposium, 1999, San Jose, CA, United States
Abstract
Laser photoablation using UV or IR lasers is known to trigger a photo acoustic event. Different target materials can be discriminated by analyzing the photoacoustic signal. In vitro measurements of NCPAS have revealed the necessity to integrate a number of variable elements (tissue hydration, fluence, laser beam diameter, distance to microphone, etc.). This study defines the parameters needed for the initiation of a self learning system for target material recognition. A UV excimer laser (λ=193 nm; Summit Technology, UV 200L) was used to ablate organic polymers (PMMA, PA, PVC), normal and porcine corneal scar tissue, and human cornea in vivo. NCPAS was performed using a microphone (up to 200 kHz) as a detector. During photoablation, the acoustic signal was analyzed by a multiport A/D IBM PC based digital oscilloscope. The data obtained were imported into a Matlab language program and analyzed. NCPAS allows the discrimination of different materials by a characteristically frequency shift of the photoacoustic signal. Detection and online material recognition using NCPAS is a step on the way to a `smart' laser control, based on an artificial neuronal network.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Holger Specht, Holger Specht, Thomas Bende, Thomas Bende, Benedikt J. Jean, Benedikt J. Jean, Wolfgang Fruehauf, Wolfgang Fruehauf, } "Noncontact photoacoustic spectroscopy (NCPAS) for photoablation control: data acquisition and analysis using cluster analysis", Proc. SPIE 3591, Ophthalmic Technologies IX, (18 June 1999); doi: 10.1117/12.350581; https://doi.org/10.1117/12.350581
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