APPARATUS FOR THE PRACTICE OF DOUBLE EXPOSURE INTERFEROMETRIC NON-DESTRUCTIVE TESTING

摘要

A machine for performing double exposure, interferometric analysis of the changes in an object surface that result from changes in the ambient pressure on the object, as by holography, includes a pressure chamber partially formed by a horizontal base plate (40) operative to support the test object and interferometric camera (26) on its upper surface. A semispherical pressure dome (44) is placed on the base over the test object (24) and camera. A manifold volume bounded by a thin resilient steel disc (54) has its pressure equalized with the area beneath the dome by passage (56) formed beneath the base plate. When the pressure is changed beneath the dome a similar pressure change occurs in the manifold volume beneath the base so that no net pressure forces are exerted on the base plate and no deformation of the camera or test object occurs.