Midrange transilluminator
Transilluminator, with wratten filters, photographed through interference filters
Note that transilluminator passes both blue and far red light
Upper bulb is presumably older and gives off less blue (UV)
The eye easily sees fluorescence of the orange filter
Yellow filter (below) protects the orange filter from excitation
Keep in mind what happens when you reverse the order of filters
Blocking both stray blue and far red light, makes the transilluminator filter indistinguishable from the border (black) Midrange transilluminator
