1985 Sylvania FNE Green (12 V 50 W)

Sylvania’s early colored dichroic MR16 lamps are interesting for the fact that it is their primary multilayer mirror which is tuned to reflect a desired light color while transmitting the complementary color. The company made four different lamps of such kinds and this FNE is designed to project a green light beam forward while the complementary magenta light is transmitted towards the back side of the lamp. This particular model was the most difficult one to manufacture because the two edges of the dichroic mirror’s reflected wavelength band lie around the middle of the visible spectrum while the production method resulted in a ±25 nm variation in the position of the optical cutoffs. Such variation resulted in a greater color variation, and in lot more scrap, than with any other colors. In the case of blue, yellow, and red dichroic lamps, only one optical cutoff lies in the visible domain while the other one is either in the UV or in the IR end of the spectrum, which greatly reduces the impact of coating tolerances on the resulting light color variation.