Patent ID: 7701580

Claim:
A method of using a filter arrangement, the method comprising: while an object travels along a path past the filter arrangement and emanates light within an application's range of photon energies, transmitting/reflecting at least some of the emanating light through the filter arrangement; the act of transmitting/reflecting at least some of the emanating light through the filter arrangement including at least one of: while the object is in each of a substantially continuous series of two or more segments of the path, transmitting/reflecting respective portions of the emanating light through respective positions of a filter assembly within the filter arrangement; each of the respective positions having a respective transmission function within the range; two of the positions that are adjacent having respective transmission functions sufficiently different from each other that the difference causes time variation in the emanating light between the respective segments; and while the object is in each of a series of segments of the path, transmitting/reflecting a respective portion of the emanating light through a filter component within the filter arrangement; within the range, the filter component having a combined transmission function in which a set of two or more simpler transmission functions is superimposed; the set including first and second simpler non-uniform transmission functions, the set being superimposed such that time variation occurs in the emanating light in accordance with superposition of the first and second simpler non-uniform transmission functions.