Interference illumination of three nonzero‐order beams for LCOS‐based structured illumination microscopy

Abstract

To avoid the need for a mask and polarisation-adjusting devices, and to solve the problem of low fringe contrast caused by the reflected light along with 0th-order diffraction beam, this paper presents an illumination method using three nonzeroorder diffraction beams in liquid crystal on silicon (LCOS)based structured illumination microscopy. Here, a LCOS-based spatial light modulator (SLM) is used to diffract the collimated light and a rotating frosted film is used to reduce the spatial coherence of the laser; then, the fringe is produced by adjusting the SLM angle to allow three nonzero-order diffraction beams to interfere on the sample surface. Interference fringes with high contrast in all directions can be obtained without considering polarisation control and the removal of the 0th-order diffraction beam, which demonstrates that the optical setup is simple and easy to control. We carried out experiments on a photolithographic pattern on a silicon chip, and the resolution after reconstruction is 210 nm, reaching the theoretical resolution at our experiment condition and nearly half of the Rayleigh resolution limit (100× objective, NA = 0.8), which is 406 nm.