Comparative holographic interferometry: a nondestructive inspection system for detection of flaws

• Published in: Experimental mechanics Vol. 25; no. 4; pp. 325 - 337
• Main Author: RASTOGI, P. K
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01-12-1985
• Subjects: Applied sciences; Exact sciences and technology; Industrial metrology. Testing; Mechanical engineering. Machine design; Non-destructive testing: methods and equipments; Nondestructive test; Optical method; Fatigue; Holographic interferometry; Experimental study; Defect detection; Crack
• ISSN: 0014-4851; 1741-2765
• DOI: 10.1007/BF02321330

Recent development in comparative holographic interferometry, a direct nondestructive flaw detection method, are discussed. Attention is given to the ability of the systems to integrate the master displacement-field storage capacity in the interferometric system. The basic operating principles of three comparative holographic systems are described, including: holographic signature encoding; recording of an encoded interference mask; and multiple holographic signature encoding. Methods for generating auxiliary fringes are considered as well as techniques for fringe localization. The effect of misalignments in the optical setup on moire fringe patterns is examined. Experimental results are presented which demonstrate the efficiency of the technique in fatigue flaw detection applications. A schematic diagram of a typical comparative holographic interferometric system is provided. (I.H.)