Patent ID: 6317265
Filing Date: 2001-11-13
Classification: G02B

Abstract:
A multi-path interference filter comprising:input and output optical pathways that transmit a propagating beam of light;an optical path length difference generator having a stack of planar partially reflective surfaces that are spaced apart in a direction of beam propagation by at least one wavelength of the propagating beam;each of said partially reflective surfaces reflecting a separate portion of the propagating beam through a different physical path length also equal to at least one wavelength in the direction of beam propagation;the stack of planar partially reflective surfaces including at least three planar partially reflective surfaces oriented normal to a common optical axis;the stack of partially reflective surfaces being formed by a contiguous stack of parallel plates having the at least three partially reflective surfaces located at interfaces between the parallel plates;the input and output pathways including an input and an output located adjacent to each other, each straddling an opposite side of and spaced apart from the common optical axis; anda focusing optic that recombines the separate beam portions producing a pattern of interference that modifies a spectral power distribution of the propagating beam.