Holographic detection of unbonded or delaminated surfaces of materials and structures is improved by using helium instead of air in vacuum test chamber. Helium has index of refraction closer to vacuum (unity) than air. Therefore changes in chamber pressure during test do not alter index of refraction as much as they do with air. With air, much of detail is lost, particularly in curved areas.
Improved flaw-detection method
NASA Tech Briefs ; 4 , 3
1980-04-01
Miscellaneous
No indication
English
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