Patent ID: 6781757
Filing Date: 2004-08-24
Classification: G02B,Y10S

Abstract:
A polarization independent tunable optical filter system comprising:a filter of the type which reflects a pass signal and transmits a drop signal according to frequency, mounted for rotation with respect to the input beam such that the angle of incidence of the input beam varies as the filter is rotated through a variety of tuning orientations; and a retro reflector assembly situated and aligned to intercept light reflected from the filter, the retro reflector assembly including: a quarter wave plate, and a retro reflector element, wherein the pass signal reflected off the filter a first time passes through the quarter wave plate a first time, reflects off of the retro reflector, and retraces its path to pass through the quarter wave plate a second time, and reflect off of the filter a second time regardless of the filter tuning orientation.