Simultaneous Imaging Achiral and Chiral Domains beyond Diffraction Limit by Structured-illumination Microscopy

Abstract

Modern optical microscopy methods have been advanced to provide super resolution at high imaging speed, but not chirality discriminative. We recently proposed chiral structured-illumination microscopy (SIM) method to image chiral fluorescent domains at sub-wavelength resolution. Chiral SIM is suitable for imaging chiral domains at sub-wavelength resolution but loses the high spatial frequency of the achiral ones. In order to obtain the full picture of all fluorescent domains at sub-wavelength resolution, we propose an advanced version of chiral SIM, termed double SIM, which enables simultaneous imaging of achiral and chiral domains at sub-wavelength resolution. In double SIM, the illumination field must be spatially structured both in the intensity and optical chirality so that moiré effects can be concurrently generated on the achiral and chiral fluorescent domains of a sample. This allows down-modulating the high spatial frequency of both domains at the same time and thus provides sub-wavelength details after image reconstruction. To generate the illumination field with concurrently structured intensity and optical chirality, we propose interfering two coherent circularly polarized light with the same handedness at the sample plane. We introduce the working principle of double SIM and theoretically demonstrate the feasibility of this method using different kinds of synthetic samples.