Optical-fiber electronic speckle pattern interferometry (ESPI) is a non-contact, non-destructive examination technique with the advantages of rapid measurement, high accuracy, and full-field measurement. The optical-fiber ESPI system used in this study was compact and portable with the advantages of easy set-up and signal acquisition. By suitably configuring the optical-fiber ESPI system, producing an image signal in a charge-coupled device camera, and periodically modulating beam phases, we obtained phase information from the speckle pattern using a four-step phase shifting algorithm. Moreover, we compared the actual defect size with that of interference fringes which appeared on a screen after calculating the pixel value according to the distance between the object and the CCD camera. Conventional methods of measuring defects are time-consuming and resource-intensive because the estimated values are relative. However, our simple method could quantitatively estimate the defect length by carrying out numerical analysis for obtaining values on the X-axis in a line profile. The results showed reliable values for average error rates and a decrease in the error rate with increasing defect length or pressure.
© 2013 Optical Society of Korea
(060.0060) Fiber optics and optical communications : Fiber optics and optical communications
(060.2340) Fiber optics and optical communications : Fiber optics components
(120.0120) Instrumentation, measurement, and metrology : Instrumentation, measurement, and metrology
(120.2650) Instrumentation, measurement, and metrology : Fringe analysis
Original Manuscript: October 19, 2012
Revised Manuscript: December 27, 2012
Manuscript Accepted: December 28, 2012
Published: February 25, 2013
Seong Jong Kim, Young June Kang, and Nak-Jung Choi, "Optical-fiber Electronic Speckle Pattern Interferometry for Quantitative Measurement of Defects on Aluminum Liners in Composite Pressure Vessels," J. Opt. Soc. Korea 17, 50-56 (2013)
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