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Accession Number:
ADA151333
Title:
Optical Monitoring of Photo-Acoustic Pulse Propagation in Silicon Wafers.
Descriptive Note:
Technical rept.,
Corporate Author:
IBM RESEARCH LAB SAN JOSE CA
Report Date:
1985-02-15
Pagination or Media Count:
18.0
Abstract:
The technique of photo acoustic PA pulse generation and dection has been used by many workers for measuring the elastic and electrical properties of solids. Such work generally involves the use of short laser pulses to produce transient surface or bulk heating and consequent PA pulses. The advantages of PA measurements compared to conventional acoustic measurements using transducers for generation are that a single narrow acoustic pulse can be produced, large-amplitude waves can be generated, acoustic waves can be produced in difficult samples like powders or flames and mechanisms of laser-matter interactions can be investigated. Most previous studies for PA monitoring in solids have used transducers for detection. Optical detections have been used for measuring the small buckling due to photo-thermal heating at the incidence position and for measuring the thermal refractive index variations close to the illuminated region these measurements are really optical monitoring of photo-thermal PT heating. An interferometric detection scheme has been employed to measure PA waveforms in metals. In this letter, we report the use of optical monitoring for totally noncontact and nondestructive detection of a PA pulse produced by a weak laser pulse aprox. or energy in opaque solids and show that the PA pulse can be detected up to a propagation distance of several cm.
Distribution Statement:
APPROVED FOR PUBLIC RELEASE
