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Optical Engineering

Beam shaping using liquid crystal-on-silicon spatial light modulators for laser ultrasound generation
Author(s): Michael K. Kalms; Sandra Hellmers; Philipp Huke; Ralf B. Bergmann
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Paper Abstract

The application of laser ultrasound for nondestructive testing of carbon fiber–reinforced plastics (CFRP) and carbon fiber–reinforced thermoplastics (CFRTP) is shown. Laser-generated excitation creates a three-dimensional, thermoelastic zone which emits ultrasound waves during expansion and contraction. In order not to exceed the damage threshold of the material to be tested usually only a low-energy density and therefore a weak excitation of ultrasound waves can be achieved. For instance, the use of a YAG laser type with a wavelength around 1 <italic<μ</italic<m leads to a very low absorption in the matrix of CFRP while the absorption in the fibers is very high. As a consequence the excitation is often destructive. To solve this problem, we describe the successful introduction of a spatial light modulator to laser ultrasound allowing for tailored spatial energy distributions for efficient nondestructive excitation of ultrasound waves within CFRP or CFRTP.

Paper Details

Date Published: 25 April 2014
PDF: 7 pages
Opt. Eng. 53(4) 044110 doi: 10.1117/1.OE.53.4.044110
Published in: Optical Engineering Volume 53, Issue 4
Show Author Affiliations
Michael K. Kalms, Bremer Institut für angewandte Strahltechnik GmbH (Germany)
Sandra Hellmers, Bremer Institut für angewandte Strahltechnik GmbH (Germany)
Philipp Huke, Bremer Institut für angewandte Strahltechnik GmbH, Klagenfurter Straße 2, Bremen 28359, Germany (Germany)
Ralf B. Bergmann, Bremer Institut für angewandte Strahltechnik GmbH (Germany)

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