Tunable filter using a wave plate
AssigneeOptoplex Corporation
InventorsDaryuan Song, YUNG-CHIEH HSIEH
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Abstract
Tunable filters are provided that have transmittances that are independent of the polarization state of an incident beam. The tunable filters include an interference bandpass filter positioned to transmit an input beam of light to produce transmitted light. A wave plate is positioned to rotate the polarization of the transmitted light and a reflector is positioned to reflect the rotated light so that it propagates through the wave plate a second time and then passes through the interference filter a second time to produce second transmitted light.
Claims34
An apparatus, comprising:
- an interference bandpass filter positioned to transmit an input beam of light to produce transmitted light;
- a first wave plate positioned to rotate the polarization of said transmitted light to produce first rotated light;
- and
- a reflector positioned to reflect said first rotated light so that it propagates through said wave plate a second time to produce second rotated light, wherein and second rotated light passes through said interference filter a second time to produce second transmitted light.
A method, comprising:
- transmitting an input beam of light through an interference bandpass filter to produce transmitted light;
- rotating with a first wave plate, the polarization of said transmitted light to produce first rotated light;
- and
- reflecting, with a reflector, said first rotated light so that it propagates through said wave plate a second time to produce second rotated light, wherein and second rotated light passes through said interference filter a second time to produce second transmitted light.
An apparatus, comprising:
- an interference bandpass filter;
- a reflector;
- and
- means for polarization rotation, wherein said means for polarization rotation is positioned between said interference bandpass filter and said reflector, wherein the polarization orientation of a beam that propagates through said interference filter will be rotated 90 degrees by said means for polarization rotation to produce a polarization rotated beam and wherein said reflector will cause said polarization rotated beam to propagate through said interference bandpass filter a second time.
Dependencies are inferred from the claim text.