Virtual wave propagation using a digital micro-mirror device with diamond pixel configuration

Abstract

Virtual wave propagation is a promising technique for fast acquisition of intensity patterns at different propagation planes. This can be done by using a digital micro-mirror device (DMD) in a 4f optical system. Placing the DMD at the focal plane and uploading a binary hologram with the transfer function of a desired propagation distance generates a propagated intensity pattern at the image plane. However, DMDs with a diamond pixel configuration introduces a stretch distortion to the uploaded holograms. In this study, we propose a method for virtual wave propagation using DMDs with diamond pixel configuration taking into account the induced stretch distortion. Based on the scaling property of the Fourier transform, we introduce a stretch along the horizontal spatial domain, and a corresponding contraction along the vertical Fourier domain, to correct for the stretch distortion of the DMD. We also demonstrate that best results can be obtained when the encoded wavelength in the transfer function matches the wavelength of the light source. We envision this method to be helpful to multiple-plane phase retrieval techniques for potential dynamic imaging because of the option of adjustable and fast acquisition rate of intensity patterns.