Investigation of third harmonic generation confocal microscopy with aberrations

Abstract

A confocal configuration is added to the detection path in third harmonic generation (THG) microscopes for resolution improvement. The three-dimensional (3D) point-spread function (PSF) is a key indicator for the practical imaging ability of THG confocal microscopy. However, due to the coherent emission feature of THG, the 3D PSF for THG confocal microscopy is still pending and has not been investigated. In this paper, we have presented, for the first time to our knowledge, the 3D PSF model of THG confocal microscopy under circularly or radially polarized excitations. To make our study more realistic, based on the proposed model, the 3D PSF distributions of THG confocal microscopy with aberrations are analyzed further. The effects of the size of the confocal pinhole are also discussed. This work is important for the interpretation of THG confocal microscope images and for the adaptive aberration correction in THG confocal microscopy.