METALIZED BEAMSPLITTERS e simplest type of beamsplitter is a piece of optically at glass coated on one side with a thin lm of reective material. You can obtain beamsplitters with xed ratios between 1:1 and 9:1, the most useful being 1:1. Cheaper beamsplitters are coated on thin material, and the second-surface reection can be a nuisance when it overlaps the rst-surface reection and causes interference patterns. A beamsplitter of thicker glass makes it easier to blank o the second-surface reection.