Optical Filters By Lasertec Inc.

Optical filters, generally, belong to one of two categories. The simplest, physically, is the absorptive filter, while the latter category, that of interference or dichroic filters, can be quite complex. Optical filters selectively transmits light having certain properties (often, a particular range of wavelengths, that is, range of colours of light), while blocking the remainder. They are commonly used in photography, in many optical instruments, and to colour stage lighting. In astronomy, optical filters can be used to eliminate light from the Sun or from a star much brighter than the target object[1]. Even seeing Mercury can necessitate using optical filters from extreme northern latitudes like Scandinavia or Alaska where the sky is invariably bright whenever the planet is above the horizon due to the low angle at far elongations