Detour phase Talbot array illuminator

In this Letter, we propose a simple and effective approach for transforming a conventional Talbot array illuminator ( TAI) with multilevel phase steps into a binary-phase TAI ( BP-TAI) through detour phase encoding. The BP-TAI is a binary ( 0 pi) phase-only diffractive optical element, which can be utilized to generate a large-scale focal spots array with a high compression ratio. As an example, we design a square BP-TAI with the fraction parameter beta = 15 for achieving a square multifocal lattice with a high compression ratio beta(2). Theoretical analysis and experimental results demonstrate that the detour phase encoding is efficient for designing the BP-TAI, especially with the high compression ratio. Such results may be exploited in practical large-scale optical trapping and X-ray imaging.