Focusing coherent light through opaque strongly scattering media

Author(s): I. M. Vellekoop and A. P. Mosk

Abstract:

“We report focusing of coherent light through opaque scattering materials by control of the incident wavefront. The multiply scattered light forms a focus with a brightness that is up to a factor of 1000 higher than the brightness of the normal diffuse transmission.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 32, Issue 16, pp. 2309-2311
DOI: 10.1364/OL.32.002309

Multipoint phase calibration for improved compensation of inherent wavefront distortion in parallel aligned liquid crystal on silicon displays

Author(s): Joaquín Otón, Pierre Ambs, María S. Millán, and Elisabet Pérez-Cabré

Abstract:

“The inherent distortion of a reflective parallel aligned spatial light modulator (SLM) may need compensation not only for the backplane curvature but also for other possible nonuniformities caused by thickness variations of the liquid crystal layer across the aperture. First, we build a global look-up table (LUT) of phase modulation versus the addressed gray level for the whole device aperture. Second, when a lack of spatial uniformity is observed, we define a grid of cells onto the SLM aperture and develop a multipoint calibration. The relative phase variations between neighboring cells for a uniform gray level lead us to build a multi-LUT for improved compensation. Multipoint calibration can be done using either phase-shift interferometry or Fourier diffraction pattern analysis of binary phase gratings. Experimental results show the compensation progress in diffractive optical elements displayed on two SLMs.”

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Publication: Applied Optics
Issue/Year: Applied Optics, Vol. 46, Issue 23, pp. 5667-5679, 2007
DOI: 10.1364/AO.46.005667

Hybrid multinary modulation using a phase modulating spatial light modulator and a low-pass spatial filter

Author(s):

Abstract:Zoltán Göröcs, Gábor Erdei, Tamás Sarkadi, Ferenc Ujhelyi, Judit Reményi, Pál Koppa, and Emoke Lorincz

“We propose a method for performing binary intensity and continuous phase modulation of beams with a spatial light modulator (SLM) and a low-pass spatial filtering 4-f system. With our method it is possible to avoid the use of phase masks in holographic data storage systems or to enhance the phase encoding of the SLM by making it capable of binary amplitude modulation. The data storage capabilities and the limitations of the method are studied.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 32, Issue 16, pp. 2336-2338 (2007)
DOI: 10.1364/OL.32.002336