Q uantitative measurements of shapes, displacements and deformations of opaque objects, as well as of refractive properties of transparent media, through spatial and temporal fringe patterns analysis is done by applying two basic techniques. The first one is the phase modification technique (shifting or modulating). The second one is the Fast Fourier Transform technique (FFT) , assisted by some sort of heterodyning. FFT is also the choice for a single frame, not-modified (not-heterodyned) , interferogram analysis. In this case however, because the lack of a spatial carrier, the sign of the phase cannot be determined. A solution to this problem is a technique that requires only two (but nevertheless two) phase-shifted interferograms. In this paper we propose a holographic interferometry method based on wavelength multiplexing in which no spatial carrier neither second, phase shifted interferogram is required. Using the Lippmann-Denisyuk single beam holographic setup, an interferogram from a deformable object is recorded with multiple laser wavelengths in a panchromatic emulsion. A reconstruction of the 3D object in (natural if RGB laser lines are used) colors is observed, superimposed with a multicolor fringe pattern. The object phase is then computed from the multiple single-wavelength fringe patterns, allowing the measurement of the object deformation. This work is aiming at quantitative analysis of highly dynamic objects.
We present the investigation which was conducted to improve the spatial and temporal performances of a deflecting system for display addressing. In a first part we describe the operation principle used to increase the optical deflection angle of an acousto-optic deflector. We show that it is possible to obtain an angular amplification simply by using a grating at grazing incidence angle ; the diffraction is then close to 90°. Experimental tests made with a 1200gr/mm grating have shown that an amplification of the deflection angle as high as 10 can be obtained. In a second part we introduce a complete set-up composed by the association of MEMS, Acousto-optic and grating. All those components are used to achieve a compact addressing system.
Photopolymers are widely used to elaborate diffractive components by light wavefront engineering. Photopolymer material is light structured through wavefront engineering causing interferences that will be printed in photopolymer layer to constitute the diffractive structure. We show that good diffractive components results can be obtained with photoprotein produced by metal doping of selected proteins coming form biology or biotechnology. We validate this for one application concerning the diffractive storage.
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