Systems and methods for providing and enhancing electromagnetic radiation beam radial energy homogeneity and intensity vs. wavelength content, for reliably directing electromagnetic radiation emitted by a source thereof in a common direction, for achromatically reducing spot size on a sample (eg. liquid cavity containing lenses and low aberration 1:1 imaging systems modified to perform as spatial filters), and for directing different wavelengths into different detectors, in ellipsometer, polarizer or the like systems.