Patent ID: 7288755
Filing Date: 2007-10-30
Classification: G01J

Abstract:
1. A light detector comprising: a photodetector operative to convert received light into an electrical signal; an amplifier coupled to said photodetector, said amplifier operative to amplify an output signal of said photodetector; a first filter coupled to receive an output signal of said amplifier, the first filter operative to output an AC signal indicative of only one type of artificial light; a first indicator directly coupled to an output of said first filter, the first indicator having a first indication device; a second filter coupled to receive an output signal of said amplifier, the second filter operative to output an AC signal indicative of a type of artificial light different than that of the first filter; and a second indicator directly coupled to an output of said second filter, the second indicator having a second indication device; wherein: a first filter AC output signal of sufficient strength causes the first indicator to activate the first activation device unless a stronger second filter AC output signal is received simultaneously by the second indicator; and a second filter AC output signal of sufficient strength causes the second indicator to activate the second activation device unless a stronger first filter AC output signal is received simultaneously by the first indicator.