Super-resolved CARS by coherent image scanning

TL;DR

This paper introduces a super-resolution CARS microscopy technique using phase-resolved image scanning microscopy, achieving up to twice the resolution of standard CARS by incorporating inline interferometry and phase sensitivity.

Contribution

The authors develop a simple, low-intensity super-resolution method for CARS microscopy that enhances resolution and contrast through phase-resolved interferometry, compatible with existing setups.

Findings

Achieves up to two-fold resolution increase over conventional CARS.

Enables phase-sensitive imaging for additional contrast.

Compatible with standard forward-detected CARS systems.

Abstract

We present super-resolved coherent anti-Stokes Raman scattering (CARS) microscopy by implementing phase-resolved image scanning microscopy (ISM), achieving up to two-fold resolution increase as compared with a conventional CARS microscope. Phase-sensitivity is required for the standard pixel-reassignment procedure since the scattered field is coherent, thus the point-spread function (PSF) is well-defined only for the field amplitude. We resolve the complex field by a simple add-on to the CARS setup enabling inline interferometry. Phase-sensitivity offers additional contrast which informs the spatial distribution of both resonant and nonresonant scatterers. As compared with alternative super-resolution schemes in coherent nonlinear microscopy, the proposed method is simple, requires only low-intensity excitation, and is compatible with any conventional forward-detected CARS imaging setup.