Numerical Alignment of Spatial Light Modulators for Complex Modulation in Holographic Displays

Spatial light modulators (SLMs), used for wavefront modulation in holography, present considerable limitations. Undesired contributions, e.g., zeroth diffraction order and twin images, degrade image quality, whereas higher diffraction orders limit the imaging window. We present an innovative approach for displaying complex information with two SLMs by numerically compensating for the physical misalignment of devices. This complex display enables the reduction of noise that originates from twin images, and extends the imaging window. Our alignment method is demonstrated in the case of complex modulation, though its application can be extended to other cases where precise alignment of multiple SLMs is needed.