The SKED: Speckle knife edge detector

S. D. Sharpies, R. A. Light, S. O. Achamfuo-Yeboah, M. Clark, Michael Geoffrey Somekh

Research output: Journal article publicationConference articleAcademic researchpeer-review

13 Citations (Scopus)

Abstract

The knife edge detector - also known as optical beam deflection - is a simple and robust method of detecting ultrasonic waves using a laser. It is particularly suitable for detection of high frequency surface acoustic waves as the response is proportional to variation of the local tilt of the surface. In the case of a specular reflection of the incident laser beam from a smooth surface, any lateral movement of the reflected beam caused by the ultrasonic waves is easily detected by a pair of photodiodes. The major disadvantage of the knife edge detector is that it does not cope well with optically rough surfaces, those that give a speckled reflection. The optical speckles from a rough surface adversely affect the efficiency of the knife edge detector, because 'dark' speckles move synchronously with 'bright' speckles, and their contributions to the ultrasonic signal cancel each other out. We have developed a new self-adapting sensor which can cope with the optical speckles reflected from a rough surface. It is inelegantly called the SKED - speckle knife edge detector - and like its smooth surface namesake it is simple, cheap, compact, and robust. We describe the theory of its operation, and present preliminary experimental results validating the overall concept and the operation of the prototype device.
Original languageEnglish
Article number012004
JournalJournal of Physics: Conference Series
Volume520
Issue number1
DOIs
Publication statusPublished - 1 Jan 2014
Externally publishedYes
Event3rd International Symposium on Laser Ultrasonics and Advanced Sensing, LU 2013 - Yokohama, Japan
Duration: 25 Jun 201328 Jun 2013

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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