HOLO/OR suggests you read the application notes and standard product page on Beam Splitter for full description of the product. In order to calculate your smallest spot size, please refer to the Diffraction. – Separation distance is 3mm, effective focal length (EFL) is 100mm, wavelength is 1064nm, and difference in point spacing is about 0. A beamsplitter is an optic that splits light into 2 directions. a laser beam) into two (or sometimes more) beams, which may or may not have the same optical power (radiant flux).