Phase Control Spatial phase control or modulation is accomplished without altering the intensity profile of an incident beam. Light linearly polarized parallel to the extraordinary axis of the material is phase modulated by the voltage applied across individual pixels. An optical path difference between adjacent pixels, tunable to one full-wave, is easily accomplished. Amplitude Control Spatial light modulators are also used for amplitude control or modulation. The spatial light modulator modifies the beam intensity, but also spatially alters the phase profile, which may be undesirable.
Correction is accomplished by using two spatial light modulators in series.
The first performs the necessary amplitude modulation, also introducing a phase change. The second spatial light modulator restores the original, or desired phase relationship between pixels. Polarizers are optional with an amplitude spatial light modulator. These polarizers are both rotatable and removable from the spatial light modulator housing. Electrical connections exit one side of the optical head for convenience in handling and mounting.