DEVELOPMENT AND APPLICATION OF METHODS OF EXPERIMENTAL MECHANICS. INTERPRETATION OF FRINGES IN STRESS-HOLO-INTERFEROMETRY.
Rept. no. 24, Jan-Jul 70,
CATHOLIC UNIV OF AMERICA WASHINGTON D C STRESS ANALYSIS LABS
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Previous studies had concluded that stress-holo-interferometry patterns consist of the independent superposition of the isopachic family with half order fringe shifts and the isochromatic family. It is shown here that this interpretation is not always valid and can result in serious errors in some cases. In particular, it is demonstrated that the position and even the existence of the fringes are affected by the interaction of the isopachics and isochromatics. This effect is most pronounced when the two families of fringes are nearly parallel and of approximately the same spatial frequency. The independent superposition interpretation is most accurate when the two families of fringes are orthogonal, whatever the ratio of spatial frequencies might be. These properties are illustrated using computer generated holographic interference patterns. In an appendix the general theory of stress-holo-interferometry is presented using matrix vector methods. The result of this analysis is a general expression for the observed light intensity of a stress-holographic-interference patterns for any arrangement of the polarization optical elements. The analysis also explains the origin of each of the terms in the light intensity expression. Author
- Lasers and Masers