Highly Sensitive Pulsed Digital Holography for Built-in-defect analysis with a laser excitation.

Schedin, Staffan and Pedrini, Giancarlo and Tiziani, H.J and Aggarwal, A.K. and Gusev , M.E. (2001) Highly Sensitive Pulsed Digital Holography for Built-in-defect analysis with a laser excitation. Applied Optics, 40 (1). pp. 100-103. ISSN 0003-6935

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Abstract

A highly sensitive method is presented for noninvasive defect analysis on thin structures with a Q-switched double-pulsed ruby laser with frequency doubling (347 nm). In our research we feature an all-optical arrangement, where a focused laser pulse derived from the same ruby laser (694 nm) acts as a built-in synchronous excitation source for digital holographic interferometry. The recordings are made with a CCD camera for capturing two holograms (two states of the specimen) corresponding to the two UV laser pulses with a short time separation (10–50 μs). Subtraction of the phase distribution in two digital holograms gives a fringe phase map that shows the change in deformation of the specimen between the recordings. The advantage of the proposed method is two fold. First, the use of a shorter wavelength results in a higher sensitivity. Second, owing to the induced synchronous built-in optical excitation, the specimen is not subjected to any external physical excitation devices. Experimental results are presented on identification and evaluation of defects in thin metal sheets.

Item Type: Article
Subjects: CSIO > Optics
Depositing User: Ms. J Shrivastav
Date Deposited: 29 Mar 2012 15:10
Last Modified: 23 Apr 2012 14:40
URI: http://csioir.csio.res.in/id/eprint/146

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