Abstract

Talbot array illuminators (TAI’s) were first proposed by Lohmann as a means of creating optical interconnections.¹ TAI’s are phase gratings that, under coherent, plane wave illumination, give rise to 100% modulated, square wave field and irradiance patterns. These patterns bear a strong resemblance to the spatial structure of the phase grating itself (Figure 1). Such patterns are referred to as Lohmann images² to distinguish them from Talbot images. Talbot images are replicas of the complex field distribution immediately behind a periodic structure. Talbot images occur at integer multiples of the Talbot distance Z_T = 2d²/λ, where d is the grating period and λ is the wavelength of the illuminating radiation. By comparison, only a limited number of combinations of grating duty cycle w/d, phase depth ϕ, and propagation distance z will generate Lohmann images.

© 1998 Optical Society of America