Location

Seattle, WA

Start Date

1-1-1996 12:00 AM

Description

The acousto-optic interaction affords a convenient way of optically probing ultrasonic waves in medical diagnosis and nondestructive evaluation. The effects of ultrasonic waves on the light transmitting through transparent media arise from the refractive index variations produced by ultrasonic waves. The index variations may be detected by optical deflection, diffraction or interference methods [1–4]. In Raman-Nath regime, the acoustic waves act as a moving phase grating and diffract the light into different orders. Schlieren visualisation derived from this mechanism has been extensively used to ultrasonic measurements in liquids. In solid media, the acousto-optic effects become more complicated because of the induced optical birefringence. The usual photoelastic method consists in detecting the change in the polarization state of the light caused by ultrasonic waves [5]. Both of the methods are only amplitude-sensitive to ultrasonic waves.

Volume

15A

Chapter

Chapter 2: Emerging Inspection Technologies

Section

Laser Ultrasonics

Pages

623-630

DOI

10.1007/978-1-4613-0383-1_80

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

A Laser Interferometric Method for Small- and Finite-Amplitude Ultrasonic Waves’ Detection in Transparent Media

Seattle, WA

The acousto-optic interaction affords a convenient way of optically probing ultrasonic waves in medical diagnosis and nondestructive evaluation. The effects of ultrasonic waves on the light transmitting through transparent media arise from the refractive index variations produced by ultrasonic waves. The index variations may be detected by optical deflection, diffraction or interference methods [1–4]. In Raman-Nath regime, the acoustic waves act as a moving phase grating and diffract the light into different orders. Schlieren visualisation derived from this mechanism has been extensively used to ultrasonic measurements in liquids. In solid media, the acousto-optic effects become more complicated because of the induced optical birefringence. The usual photoelastic method consists in detecting the change in the polarization state of the light caused by ultrasonic waves [5]. Both of the methods are only amplitude-sensitive to ultrasonic waves.