Imaging of custom-made single scatterers with the confocal laser scanning microscope

Abstract

In this work, we investigate image formation in the confocal laser scanning microscope for different single scatterers, both theoretically and experimentally. For spherical scatterers, an effective and fast algorithm was implemented to calculate the confocal image for different diameters and wavelengths. Measurements on a polystyrene sphere (PS) with a diameter of 20 µm confirmed the expected effects, for example, the appearance of a central signal similar to the point spread function of the optical system. Custom single scatterers were produced using 3D-direct laser writing (DLW), including a sphere with dimensions comparable to the aforementioned PS sphere. Despite an inevitably lower surface quality and symmetry, only minor differences were observed in the confocal image of the 3D-DLW sphere compared to a near-perfect PS sphere. Having verified the experimental images of spheres with the computed theoretical data, confocal measurements of four platonic bodies produced by 3D-DLW were measured with the goal to contribute to the understanding of image formation involving more complex scattering geometries.