Common path interferometric techniques for removing the undiffracted beam in phase-only holographic generation of multifoci patterns

Abstract

We present two interferometric techniques for the efficient removal of the undiffracted beam in multifoci patterns generated by holographic method. This optimizes the performance of holograms encoded on a phase-only spatial light modulator that produces the undiffracted beam due to its limited fill factor. In both techniques, we modify the same phase hologram to generate a beam that destructively interferes with the undiffracted beam. The first technique involves the design of a hologram using the Gerchberg-Saxton algorithm to include a corrective interfering beam. The second technique generates a zero-order beam by encoding a phase-scaled version of an existing hologram. Destructive interference is attained by incorporating an appropriate phase shift on the scaled hologram. We analyze the viability of both techniques by evaluating the efficiency when applied on a spatial light modulator with a limited fill factor.