Inspection of birefringent media by photoelasticity: from diffuse light polariscope to laser conoscopic technique

Luigi Montalto; Nicola Paone; Daniele Rinaldi; Lorenzo Scalise

doi:10.1117/1.OE.54.8.081210

26 June 2015 Inspection of birefringent media by photoelasticity: from diffuse light polariscope to laser conoscopic technique

Luigi Montalto, Nicola Paone, Daniele Rinaldi, Lorenzo Scalise

Author Affiliations +

Optical Engineering, Vol. 54, Issue 8, 081210 (June 2015). https://doi.org/10.1117/1.OE.54.8.081210

Abstract

A reliable and noninvasive measurement method for the inspection of naturally birefringent transparent media is presented in this paper. It allows us to achieve a spatially resolved analysis of the stress state of birefringent materials. The developed system is based on photoelasticity and exploits a controlled laser conoscopy technique and a scanning system to perform local measurements in the volume dimensions of the media, which can be displaced over a grid of points. The configuration of the proposed laser conoscopic system is presented, and a dedicated algorithm, designed to perform digital analysis of the fringe patterns, is also described. The design and the realization of the system are discussed, as well as the advantages of the proposed system over the classic diffuse light polariscope technique. The method has been experimentally validated through laboratory tests on birefringent samples with known induced stress. The system has demonstrated its sensitivity to stress and its capability to achieve a spatial resolution on the order of 0.1 mm to resolve stress gradients (uncertainty on the stress amplitude of ±0.1 MPa).

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Luigi Montalto, Nicola Paone, Daniele Rinaldi, and Lorenzo Scalise "Inspection of birefringent media by photoelasticity: from diffuse light polariscope to laser conoscopic technique," Optical Engineering 54(8), 081210 (26 June 2015). https://doi.org/10.1117/1.OE.54.8.081210

Published: 26 June 2015

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