Label-free high-resolution white light quantitative phase nanoscopy (WLQPN) system.

We present a high-resolution WLQPN system that can be utilized to visualize nanoparticles and sub-cellular features of the biological specimens. The 5-phase shifting technique, along with deconvolution, is adopted to obtain super- resolution in phase imaging. The phase shifting technique can provide full detector resolution, making it beneficial as compared to the well-known Fourier analysis method. The Fourier transform method requires minimum angle of sin - 1 3 f x λ , where f x is maximum achievable spatial frequency. It limits the highest achievable resolution to much below the actual diffraction limit of the system. Thus, to obtain a high-resolution phase map of the biological specimen, a two-step process is adopted. Firstly, the phase map is recovered using the 5-phase shifting algorithm, with full detector spatial resolution. Secondly, the complex field is obtained from the recovered phase map and further processed using the Richardson Lucy total variation deconvolution algorithm to obtain super-resolution phase images. The present technique was tested on 1951 USAF resolution chart, 200nm polystyrene beads and E-coli bacteria using a 50X, 0.55NA objective lens. The 200nm polystyrene beads are visually resolvable and sub-cellular features of the E-coli bacteria are also observed, suggesting a significant improvement in the resolution This article is protected by copyright. All rights reserved.