Enhancement of second harmonic microscopy images in collagen-based thick samples using radially polarized laser beams

Abstract

[EN][The visualization of collagen-based tissues imaged with second harmonic generation (SHG) microscopy strongly depends on the polarization state of the scanning laser beam. This has been often explored using spatially homogeneous states (mainly linear or circular). However, vector beams (i.e. laser beams with spatially non-uniform polarization states) have become a powerful tool in different research field and technological applications. In particular, radially polarized vector beams are known to provide a tight focal spot and lateral resolution enhancement. Here we propose the use of radially polarized beams to improve the quality of SHG microscopy images. The performance of this particular type of vector beam is compared to that obtained with a circularly polarized light beam for different non-stained specimens and depth locations. Results show that independently of the sample’s thickness, the efficiency of SHG processes is increased when using the radially polarized beam, also leading to a higher image quality. Our results open the route for using vector beams to get a better visualization of biological details within the imaged areas, especially at deeper locations.