The performance of an adaptive optics system using a Liquid Crystal on Silicon (LCoS) spatial light modulator under white-light illumination was investigated. A novel LCoS device (Holoeye Photonics AG, Germany) capable for 6-Pi phase modulation before phase wrapping was confronted to a previous 2-Pi LCoS system. A dedicated experimental setup was built incorporating the two modulators, so that simultaneous operation and comparison of both could be performed. The apparatus included a Hartmann-Shack wavefront sensor. Programmed Zernike polynomials were produced at different wavelengths. Chromatic degradation was systematically below the chromatic aberration of the eye. Differences across wavelengths at the tails of the spectrum were inferior to 10%. The 6-Pi phase modulator exhibited a slightly slower temporal response than the standard 2-Pi device, still in the useful range for visual applications. The employment of the 6-Pi device has the potential of reducing the diffraction ghost produced by phase wrapping, presenting in addition lower chromatic dispersion than in 2-Pi devices. The 6-Pi LCoS device presents advantages for being incorporated in adaptive optics systems for visual applications.
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