1990 GE-Thorn M249Y Yellow Dichroic MR16 halogen lamp

MR16 Halogen lamps become particularly common in display and accent lighting in the late 1980´s and 1990´s due to their small size and reflector allowing good beam control and small fittings.
In order to create collored light that still had the same crisp look it was not possible to use organic lockers as they would break down due to the lamps heat. Colored glass is also difficult as it Amy have other physical properties the the standard glass sued on these lamps as well as being more expensive to manufacture and Amy contain toxic heavy metal ions. In order to get around that corner special dichroic filters wer developed which were applied either on the lamps lens or the lamps reflectors. These filter only let past a certain wavelength of light while reflecting the rest back. When the coating is applied on the reflector itself, only the desired wavelength are reflected while the other are let pass, an example of that being classic Coll beam MR16 lamps. If the coating is on the lamp lens only the desired light colour is left thru and the other colours are left are reflected back.