DIFFUSED LIGHT INTERFEROMETRY FOR MEASUREMENT OF ISOPHACHICS
NATIONAL TECHNICAL UNIV ATHENS (GREECE) LAB FOR TESTING MATERIALS
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A simplified optical method, based on interference phenomena of diffused light, is described for the determination of isopachic patterns. Procedure consists in using a monochromatic diffused light beam to illuminate the model surface. If an optically flat glass plate, used as datum plane, is brought in contact with the model front surface an interference pattern is produced related to the thickness of the airfilm between the datum plane and the surface of the model. Interference patterns before and after loading of the specimen allow the determination of isopachics. Curves of variation of interference fringes throughout the surface of the specimen, before their use for the determination of thickness variation, must be readjusted in convenient scale as well as for the elimination of superimposed simple interference patterns due to arbitrary inclination of the datum optical plane before and after loading. The method does not necessitate a complicated equipment. It is straightforward and very sensitive, and can be applied to transparent as well as to opaque models made of metal sheets.
- Test Facilities, Equipment and Methods