Dichroic beamsplitters have use in astronomical research
Dichroic beamsplitters are manufactured to a surface accuracy of λ/20 p-v at 633 nm, surface quality of 10/5, microroughness of less than 1 nm rms, and up to 500-mm diameter. An extensive range of coatings can be supplied, designed to operate at the required angle of incidence. They are used in terrestrial and spaceborne telescope spectrographs.
Optical Surfaces
Kenley, U.K.