Photopolymer diffractive optical elements in electronic speckle pattern shearing interferometry

Abstract

In this paper we present an electronic speckle pattern shearing interferometer using a photopolymer diffractive optical element in the form of a holographic grating, in combination with a ground glass to shear the images. The sheared images on the ground glass are further imaged onto a CCD camera. The distance between the grating and the ground glass can be used to control the shear and to vary the sensitivity of the system. The direction of sensitivity is easily controlled by rotation of the diffraction grating around its normal.Introducing photopolymer holographic gratings in ESPSI gives the advantage of using high aperture optical elements at relatively low cost. The fact that the diffractive optical element is a photopolymer layer on glass substrate with thickness of 2mm makes for a compact optical system. The system was successfully used for detection of the resonant frequencies of a vibrating object.Most of the published work on vibration analysis is analytical. Very few experimental results are available in the literature. The well known laser Doppler vibrometers (LDV) and accelerometers used for modal analysis are pointwise measurement techniques, although multipoint LDV is available at significant cost. advantage of shearography over electronic speckle pattern interferometry is that ESPSI is relatively insensitive to external disturbances. Another advantage of the proposed system is that it could be easily converted to a phase-shifting electronic speckle shearing interferometer.

An Experimental Study of the Vibrational Characteristics of a Diamond Circular Blade Using Electronic Speckle-Pattern Interferometry and FEM

“…The beam reflected from the beamsplitting wedge is expanded by the micro-lens 11, collimated by the lens 12 and scattered by the transmitting diffuser 13, forming a diffuse reference wave. On the beam splitter 9, it is combined with the subject and, after refraction in the camera lens, forms a speckle reference field on the matrix surface (Mihaylova et al 2004), (Mihaylova et al 2006). The contrast of the resulting speckle pattern will be maximum at the same average intensities and consistent polarizations of the interfering beams.…”

Properties of methylene blue in the presence of zeolite nanoparticles

“…In addition to development of novel photopolymer compositions, the dye-zeolite interactions are also important for other applications in the field of photoelectronics and water purification. [7][8][9][10][11] Three main methods are applied for dye incorporation in zeolites including (1) ion exchange where the extra framework cations compensating the negative charge of zeolite framework are replaced by cationic dye (for example methylene blue), (2) in situ encapsulation, where the dyes are added to the starting reacting mixture, and (3) vapor phase deposition of dyes on zeolite samples after dehydration. 12,13 The dyes incorporated in the zeolites show interesting optical effects such as anisotropic light absorption, luminescence, and fluorescence phenomena caused by the preferred orientation of the transition-dipole moment of the confined dye molecules.…”