Generation of a phase contrast Talbot array illuminator with electric controlling

Abstract

A hexagonal phase contrast Talbot array illuminator based on an electro-optically tunable phase grating made from periodically poled Mg-doped LiNbO3 crystal is presented theoretically and experimentally. Both the effects from external electric field and diffraction distance on the intensity distribution of diffraction field are demonstrated by numerical simulation. The simulated results show that higher light compression ratio (LCR) in a hexagonal sample area can be achieved at a suitable diffraction distance under lower electric field. The experimental Talbot diffraction imaging was successfully obtained by modulating phase difference and fractional Talbot distance, and the intensity distribution agrees with the simulated results well. For the hexagonal phase contrast array illuminator with duty cycle of 63%, the highest LCR of 4.2 units can be obtained under phase difference of 0.80 π and diffraction position of 0.38 times Talbot distance.