Filter layers are essential in many applications in optics. Interference layer systems are used to effect virtually every conceivable optical property for filters. Thin layers achieve defined transmission properties and reflectivity for surfaces. The corresponding optical functions can be divided up into different groups.
Beam splitters are very frequently used. They are the easiest to produce and split the light of a specific wavelength or a spectral range into defined reflected and transmitted fractions.
Short-pass and long-pass filters transmit certain spectral ranges and block defined wavelengths. Often referred to as dichroitic beam splitters, these filters require a high degree of precision during manufacture. They can be produced with the aid of PVD processes.
Optical filters which transmit just one or several limited spectral ranges and which may block to a significant degree in the remaining spectral range.
Narrow-band or broad-band optical filters which split the incident light into two part-beams in a defined ratio.
Narrow-band or broad-band mirrors for reflecting UV radiation with simultaneous transmission or absorption of visible and infrared light.