X-ray shearing interferometer for non-destructive testing

This paper presents an X-ray shearing interferometer in which two X-ray beams to be interfered travel through an object. The interferometer is constructed by cutting monolithically a single silicon crystal. It has four parallel blades. After transmitted through the four blades, two of the beams are superposed on each other to interfere. An object is inserted between the second and third plate and both of the beams to be interfered are arranged to travel through the object. The phase difference between the two beams can be measured with the interference fringes. A phase shift method is adopted to measure the phase difference smaller than one fringe. Defects of the object in the order of mu m may be detected with this method. Experimental results using objects made of acrylic resin and thin film is presented to prove the validity. The possibility of the method as a nondestructive testing is discussed.