where expertise comes together - since 1996

Web's Largest Portal of Nondestructive Testing (NDT)
Open Access Database (Conference Proceedings, Articles, News), Exhibition, Forum, Network

All Forum Boards
Technical Discussions >
Optical Beam Deflection method
Career Discussions
Job Offers
Job Seeks
Classified Ads
About NDT.net
Articles & News

879 views
03:31 Mar-14-1999
Frederic Brossard
Optical Beam Deflection method

I'm involved in developing for my thesis a simple and cheap
technology(a dream)to detect small defects in aluminium and
glass samples using laser ultrasound.
The optical beam deflection technique using a laser diode and a
photodiode to monitore the generated lamb waves seems to be the
best adapted but i'm still worried about the advantages of such
technique compared with EMAT.(spatial time domain...)
I'm looking for information/references/advices about OBD and its
performance compared with electromagnetic transducers.
Any assistance to achieve my objective would be greatly appreciated!


 
03:02 Mar-15-1999

Robert (Rocky) A. Day

Engineering
Milky Way Jewels,
USA,
Joined Nov 1998
40
Re: Optical Beam Deflection method

The optical beam deflection method is fairly cheap to instrument and reasonably versatile. It usually features a differential technique using two photodiode which are nulled against each other in the quiescent state. When the beam is deflected the diodes are no longer nulled and each reads in opposite sense which increases the signal. I have used the method on surface waves and seen it used in water for bulk waves. Bandwidth is excellent but it is not a high sensitivity method and signal averaging is used in most NDT cases to get a good signal-to-noise ratio. I have put a diagram of a typical beam deflection system on my web site at http://www.xdcr.com/beam.gif

: I'm involved in developing for my thesis a simple and cheap
: technology(a dream)to detect small defects in aluminium and
: glass samples using laser ultrasound.
: The optical beam deflection technique using a laser diode and a
: photodiode to monitore the generated lamb waves seems to be the
: best adapted but i'm still worried about the advantages of such
: technique compared with EMAT.(spatial time domain...)
: I'm looking for information/references/advices about OBD and its
: performance compared with electromagnetic transducers.
: Any assistance to achieve my objective would be greatly appreciated!




 
04:46 Mar-25-1999

Liviu Singher

R & D,
Technion,
Israel,
Joined Nov 1998
11
Re: Optical Beam Deflection method The optical beam deflection method or otherwise
known also as "optical triangulation" is one of
the less sensitive optical methods to detect
minute displacements. To compare with EMAT, it
is advisable to use an optical interferometric
technique.

: I'm involved in developing for my thesis a simple and cheap
: technology(a dream)to detect small defects in aluminium and
: glass samples using laser ultrasound.
: The optical beam deflection technique using a laser diode and a
: photodiode to monitore the generated lamb waves seems to be the
: best adapted but i'm still worried about the advantages of such
: technique compared with EMAT.(spatial time domain...)
: I'm looking for information/references/advices about OBD and its
: performance compared with electromagnetic transducers.
: Any assistance to achieve my objective would be greatly appreciated!




 
00:41 Jun-11-1999
Michael Fisch
Re: Optical Beam Deflection method Hello, i have designed several beam-deflection systems for looking at disk surfaces. My first design was with Robert Bruce back in 1986




 


© NDT.net - The Web's Largest Portal of Nondestructive Testing (NDT) ISSN 1435-4934

Open Access Database, |Conference Proceedings| |Articles| |News| |Exhibition| |Forum| |Professional Network|