Event Title

Laser Ultrasound in Single Crystal Silicon

Location

Snowbird, UT, USA

Start Date

1-1-1999 12:00 AM

Description

Laser generated ultrasound has been quite extensively studied in single crystal silicon [1,3]. Off-epicentral waveforms have been measured in plate like samples, these are quite complex as silicon is quite strongly anisotropic with one of the shear waves exhibiting cusps. Cusps form due to severe beam steering in some anisotropic materials, Any ultrasonic experiment actually measures the wave surface (represents energy transport) and not the velocity surface [4]. The normal to the slowness surface represents the direction of energy transport, hence it is a useful representation when considering beam steering effects. Materials with incurved slowness surfaces exhibit cusps. Even in isotropic materials laser generated off-epicentral waveforms are complex, both longitudinal and shear waves have radial and tangential components of displacement. At angles greater than the critical angle the head wave appears and the shear wave drastically changes form.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

18A

Chapter

Chapter 1: Elastic Waves and Ultrasonic Techniques

Section

Laser Ultrasonics and Applications

Pages

341-348

DOI

10.1007/978-1-4615-4791-4_42

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Laser Ultrasound in Single Crystal Silicon

Snowbird, UT, USA

Laser generated ultrasound has been quite extensively studied in single crystal silicon [1,3]. Off-epicentral waveforms have been measured in plate like samples, these are quite complex as silicon is quite strongly anisotropic with one of the shear waves exhibiting cusps. Cusps form due to severe beam steering in some anisotropic materials, Any ultrasonic experiment actually measures the wave surface (represents energy transport) and not the velocity surface [4]. The normal to the slowness surface represents the direction of energy transport, hence it is a useful representation when considering beam steering effects. Materials with incurved slowness surfaces exhibit cusps. Even in isotropic materials laser generated off-epicentral waveforms are complex, both longitudinal and shear waves have radial and tangential components of displacement. At angles greater than the critical angle the head wave appears and the shear wave drastically changes form.