USING LASAR HOLOGRAPHY FOR NONDESTRUCTIVE TESTING

Experimental work has revealed the feasibility of employing holographic interferometry in the testing of as- machined, rough, black- matte carbon shapes. The analysis indicates that the fringe reduction methods can be applied to cylinders and cone frustums of small half- angles as long as the type of loading is controlled. A loading which causes uniform strain on circumferential belts of the cylinder is useful regardless of the general variation on different belts spaced along the axis of the cylinder. The same analysis procedure can be used on cones as long as theyapproximate cylinders in that the cone angle i%s small and they are loaded with a uniform internal pressure. Precise fixturing and load control are necessary to prevent tilting, translation, and variations in average strain of the test object when numerous views are taken around the circumference of the test object.