Enhanced image upsampling with time-multiplexed phase holography using batch gradient descent

Generation of light patterns through computer-generated holography is limited by spatial light modulators with finite resolution and pixel pitch, and their capability to modulate only either phase or amplitude. These limitations lead to finite far-field sampling and speckle-like noise. In this study, we consider the signal bandwidth of the propagating wavefront to understand the cause of the noise. We use it to develop a new algorithm to simultaneously generate a batch of phase-only holograms using a gradient descent. When displayed in sequence, the holograms improve the time-averaged quality and increase the resolution of the projected reconstructed image compared to alternative approaches. We verify the results both numerically and experimentally. This method will benefit precision-critical fields such as holographic photolithography.