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 ability to modulate only either phase or amplitude of light. These limitations result in 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 and to develop a new algorithm for simultaneously generating a batch of phase-only holograms using 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.