Noncontact detection of ultrasonic waves using fiber optic Sagnac interferometer

被引：44

作者：

Jang, Tae Seong ^{[1
]}

Lee, Seung Seok ^{[1
]}

Kwon, Il Bum ^{[1
]}

Lee, Wang Joo ^{[1
]}

Lee, Jung Ju ^{[1
]}

机构：

[1] Department of Mechanical Engineering, Korea Adv. Inst. of Science/Technol., Taejon 305-701, Korea, Republic of

来源：

| 2002年 / Institute of Electrical and Electronics Engineers Inc.卷 / 49期

关键词：

Birefringence - Frequencies - Interferometers - Laser beams - Light polarization - Nondestructive examination - Oscillations - Piezoelectric transducers - Surface waves - Ultrasonic waves;

D O I：

10.1109/TUFFC.2002.1009334

中图分类号：

学科分类号：

摘要：

This paper describes a fiber optic sensor suitable for noncontact detection of ultrasonic waves. This sensor is based on the fiber optic Sagnac interferometer, which has a path-matched configuration and does not require active stabilization. Quadrature phase bias between two interfering lasor beams in the Sagnac loop is applied by controlling the birefringence using a fiber polarization controller. A stable quadrature phase bias can be confirmed by observing the interferometer output according to the change of phase bias. Additional signal processing is not needed for the detection of ultrasonic waves using the Sagnac interferometer. Ultrasonic oscillations produced by conventional ultrasonic piezoelectric transducers were successfully detected, and the performance of this interferometer was investigated by a power spectrum analysis of the output signal. Based on the validation of the fiber optic Sagnac interferometer, noncontact detection of laser-generated surface waves was performed. The configured Sagnac interferometer is very effective for the detection of small displacement with high frequency, such as ultrasonic waves used in conventional nondestructive testing (NDT).

引用