DOING IT WITH MIRRORS
CD 1966022 E&MP27.108
July 26, 1948
This instrument in the General Electric Illuminating Laboratory, Schenectady, N.Y., measures the light output of streetlights from all angles.
The mirror, reflecting the image of the engineer making a test, may be moved through a full circle around the light.
At any point in the circle, light beams striking the mirror are reflected to an electric eye 25 feet away, which measures the light coming from the luminaire at that particular angle.
The object of the test is efficiency -- to make sure that the light goes where it is needed most
Original Caption by Science Service