Vibration measurements by pulsed digital holographic endoscopy
2005 (English)In: Eighth international symposium on laser metrology: macro-, micro-, and nano-technologies applied in science, engineering, and industry, Bellingham: SPIE - International Society for Optical Engineering, 2005, 729-734 p.Conference paper (Refereed)Text
Digital holographic interferometry in combination with a flexible fiber endoscope allows high precision measurements of deformations on hidden objects surfaces, inside cavities and objects with small access apertures. A digital holographic endoscopy system is described with a frequency-doubled, twin oscillator Q-switched pulsed Nd:YAG laser as light source. A sequence of digital hologram pairs are recorded with a maximum repetition rate of 260 ms. Each digital hologram is captured at separate video frames of a CCD-camera. The time separation between the laser pulses from each cavity can be set in the range from 50 to 500 mu s. The digital holograms are transferred to a PC via a frame grabber and evaluated quantitatively by the Fourier transform method. The resulting phase fringe pattern has the information needed to evaluate quantitatively the amount of the deformation. Experimental results of vibration measurements of hidden mechanical and biological object surfaces are presented. The quality of the results obtained by mechanical object surfaces is usually higher than for biological surfaces. This can be explained easily by the fact that a biological surface is much more complex than a mechanical surface in the sense that some parts of the surface may reflect the light well whereas other parts may absorb the light. Also, biological surfaces are translucent, which means that part of the light may enter inside the sample where it may be absorbed or reflected.
Place, publisher, year, edition, pages
Bellingham: SPIE - International Society for Optical Engineering, 2005. 729-734 p.
, Proceedings of the society of photo-optical instrumentation engineers (SPIE), ISSN 0277-786X ; 5776
pulsed digital holography, fibre optic endoscope, dynamic measurements, vibrations analysis, non-destructive testing
Atom and Molecular Physics and Optics
IdentifiersURN: urn:nbn:se:umu:diva-120447DOI: 10.1117/12.611745ISI: 000228899900090ISBN: 0-8194-5757-4OAI: oai:DiVA.org:umu-120447DiVA: diva2:929651
8th International Symposium on Laser Metrology, FEB 14-18, 2005, Merida, MEXICO