Variable beam splitters have an inhomogeneous layer distribution on a square substrate. These components are used to produce two beams in an assembly with a single laser source. Variable beam splitters have an advantage when the laser power of both the partial beams needs to be identical following the last optic in the system, this is impossible with conventional beam splitters because the different components transmit light unevenly.
The beam splitter designs depend on the wavelength: if a variable beam splitter is developed for a wavelength of 532nm, it does not function at another wavelength. For example, for 1064nm designs, transmissions from 45% to 55% and 10% to 70% are available, or for the wavelength 753nm transmissions from 4% to 20% are available.