Application of Photopolymer Holographic Gratings

Two optical set-ups for electronic speckle pattern shearing interferometry (ESPSI) using photopolymer diffractive optical elements are presented. Holographic gratings are recorded using an acrylamide based photopolymer material. Since the polymerisation process occurs during recording, the holograms are produced without any development or processing. In both ESPSI systems the photopolymer gratings are used to shear the image. In the first ESPSI system only one grating is used in combination with a sheet of ground glass. The distance between the grating and the ground glass can be used to control the amount of the shear. The sheared images on the ground glass are further imaged onto a CCD camera. In the second ESPSI system two gratings are used to shear the image. The gratings are placed between the object and an imaging lens in front of the CCD camera. The distance between the two gratings controls the size of the shear. The ESPSI system with two photopolymer holographic gratings is compact and suitable for industrial applications. Introducing photopolymer holographic gratings in ESPSI gives the advantage of using high aperture optical elements at relatively low price. Both of these interferometric systems are simple and flexible.