A high speed wavefront determination method based on spatial frequency modulations for focusing light through random scattering media

Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, USA.
Optics Express (Impact Factor: 3.49). 02/2011; 19(4):2989-95. DOI: 10.1364/OE.19.002989
Source: PubMed


A large number of degrees of freedom are required to produce a high quality focus through random scattering media. Previous demonstrations based on spatial phase modulations suffer from either a slow speed or a small number of degrees of freedom. In this work, a high speed wavefront determination technique based on spatial frequency domain wavefront modulations is proposed and experimentally demonstrated, which is capable of providing both a high operation speed and a large number of degrees of freedom. The technique was employed to focus light through a strongly scattering medium and the entire wavefront was determined in 400 milliseconds, ~three orders of magnitude faster than the previous report.

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    • "By adjusting the phase of each channel to obtain constructive interference at the bead, the light can be brought to an interferometric focus at its position, thus increasing the bead's fluorescence. To increase the speed of the phase estimation, different methods have been applied, such as a genetic algorithm (GA), spatial frequency modulation and parallel wavefront optimization method [7] [8] [9]. Fast light modulators, such as the Digital Mircomirror Device (DMD) from Texas Instruments and segmented deformable mirrors from Boston Micromachines, have also been used to further speed up the optimization process [10] [11]. "
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