My Hologram is Turquoise and getting bluer.
I installed a HALOGEN lamp kit a long time ago.
I think it's necessary to have this much brighter light source with my simple system.
I have just knocked up a translucent green filter (self adhesive green acetate on a clear acrylic plate) about 200mm square. Screwed this to the cabinet base about 150mm from the lamp to avoid heat probs.
Works very well - the hologram is now mostly GREEN!
I guess another layer of green acetate could be applied if more "greening" is desired.
