Design of a Talbot array illuminator based on two-dimensional binary phase grating

Abstract

Talbot effect is one of the most basic optical phenomena that has received extensive investigations both because it is a fundamental Fresnel diffraction effect and also because of its wide applications. As one of the most important applications of fractional Talbot effect, Talbot array illuminators have been in-depth studied since Lohmann and Thomas put forward for the first time. Talbot array illuminator has become an important optical element that has wide applications in optical interconnection, optical communication and optical computing because of its high diffraction efficiency, simple optical structure, compactness and low-cost. Researches have proposed different one-dimensional and two-dimensional Talbot array illuminators and developed mathematical equations to calculate pure-phase distributions. In this paper, we presented a two-dimensional Talbot array illuminator based on a pure phase grating with phase modulation (0, π/2). Theoretical analysis proved that the Talbot array illuminator with a compression ratio of 2 can be realized by Fresnel diffraction theory of a grating. In experiment, the two-dimensional chessboard-like binary phase grating was fabricated through the photoresist onto an optical glass substrate with an index of refraction of 1.52 at a wavelength of 632.8nm by using of the traditional binary-optics fabrication methods. Experimental results are in good agreement with the theoretical analysis. We believed that the proposed Talbot array illuminator should be interesting for practical applications.