Location

Snowmass Village, CO

Start Date

1-1-1995 12:00 AM

Description

Recently we have described an additive-subtractive phase modulated (ASPM) scheme which can be adapted to conventional subtractive speckle interferometry setups to reduce the noise susceptibility of these inspection tools [1–4]. In particular, these ASPM speckle interferometric techniques will freeze out unwanted environmental noise of frequencies much higher than video rates. In this study, we provide an experimental comparison of four speckle interferometric methods based on their performance under the influence of controlled noise. The performance was quantitatively determined using a parameter known as visibility which is a measure of the relative contrast between bright and dark fringes generated by each method. The four methods compared are conventional subtractive ESPI, conventional subtractive shearography, ASPM-ESPI and ASPM-shearography. All of these speckle techniques were configured for out-of-plane displacement or displacement gradient sensitivities.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

14A

Chapter

Chapter 1: Standard Techniques

Section

Radiographic and Optical Techniques

Pages

393-400

DOI

10.1007/978-1-4615-1987-4_46

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

A Comparative Study of Speckle Interferometric Techniques

Snowmass Village, CO

Recently we have described an additive-subtractive phase modulated (ASPM) scheme which can be adapted to conventional subtractive speckle interferometry setups to reduce the noise susceptibility of these inspection tools [1–4]. In particular, these ASPM speckle interferometric techniques will freeze out unwanted environmental noise of frequencies much higher than video rates. In this study, we provide an experimental comparison of four speckle interferometric methods based on their performance under the influence of controlled noise. The performance was quantitatively determined using a parameter known as visibility which is a measure of the relative contrast between bright and dark fringes generated by each method. The four methods compared are conventional subtractive ESPI, conventional subtractive shearography, ASPM-ESPI and ASPM-shearography. All of these speckle techniques were configured for out-of-plane displacement or displacement gradient sensitivities.