PRODUCING DISTINGUISHABLE LIGHT IN THE PRESENCE OF AMBIENT LIGHT

摘要

A process and apparatus for producing distinguishable light, in the presence of ambient light is disclosed. The process involves admitting light in a first wavelength band through a first light admission port into a first optical cavity at least partially defined by a first reflector operable configured to reflect light out of the first optical cavity. The process also involves filtering ambient light reflected into the first optical cavity and entering and exiting a first space defined about the first light admission port such that ambient light outside the first wavelength band is attenuated on entry and exit from the first space.