Applications in holographic and electronic speckle pattern interferometry of a photopolymer holographic recording material

This paper presents the use of an acrylamide-based photopolymer as the recording medium in holographic Interferometry. The recorded hologram can also provide a speckle reference image for out-of-plane sensitive electronic speckle pattern interferometry. This dual use of the hologram is demonstrated in the testing of thick plastic PVC pipes, which were internally pressurized. The radial strain was measured using holographic interferometry by measuring the out-of-plane motion of the object due to a known change in pressure inside the cylinder. The radial strain for the same magnitude of internal pressure change was also investigated using electronic speckle pattern interferometry (ESPI) by using the hologram stored in the photopolymer acting as a holographic optical element. A hologram was also recorded at a wavelength of 532nm and the image was reconstructed at laser diode wavelength of 784nm. The hologram was used in an ESPI system as before. As the diode can be wavelength modulated, digital phase shifting can be implemented in both interferometric techniques for detailed fringe analysis.