Dynamic manipulation of a laser beam using a liquid crystal spatial light modulator
Holograms with (a) sinusoidally varying and (b) binary transmittances described in the plane. The resulting diffraction orders described in the Fourier plane with and as the spatial frequency coordinates are seen in (c) and (d), respectively. The Fourier planes of the two holograms are obtained numerically by performing Fourier transforms of the respective transmittance functions.
(Color online) (a) Structure of a liquid crystal cell. Arrangement of molecules in the twisted nematic cell (b) in the absence of any electric field and (c) in the presence of an electric field .
(Color online) Arrangement to generate an arbitrary reconfigurable wavefront: twisted nematic modulator TNLCSLM, polarizer Pol, lenses and ; is the backfocal plane of .
(Color online) Plots of (a) , (b) , (c) corresponding to , and (d) corresponding to .
(Color online) (a) The aberration function defined as the deviation from a plane reference wavefront at the entrance pupil of a lens. Also shown is the Airy disc pattern, the focal plane intensity of an unaberrated beam. (b) Simulation results showing gray scale image representations (top) of the Zernike modes and the resulting focal plane intensities (bottom), for and 11 (from left to right).
The experimental setup. The laser is a He–Ne laser source , BX represents the beam expander, wave plate, FP is the Fourier plane.
Images (captured by a CCD camera) of the diffraction orders corresponding to the (a) normal and (b) helical beams, after initial aberration correction, the (c) normal and (d) helical beams, after incorporation of tilt in BX, and the (e) normal and (f) helical beams, after correction of aberrations due to the tilt in BX.
Zernike mode polynomials representing a few common classical aberrations.
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