Patent ID: 6611342
Filing Date: 2003-08-26
Classification: G01D,G02F

Abstract:
An apparatus comprising:an optical interferometer having at least first and second reflectors along a path of an input light beam, the first and second reflectors being spaced along the input beam by a distance equal to an integer number of half wavelengths of a resonant wavelength of the input beam, wherein the second reflector has a reflectivity that is substantially greater than a reflectivity of the first reflector, the first and second reflectors defining a resonant cavity for the resonant wavelength between the reflectors, components of the input beam other then the resonant wavelength being reflected back along the beam path substantially at the first reflector, and components of the input beam at the resonant wavelength resonating in the cavity and being reflected back along the beam path substantially at the second reflector; wherein at least one birefringent material occupies at least part of the resonant chamber, the birefringent material altering a polarization attribute of the resonant wavelength; wherein the optical interferometer reflects both the resonant wavelength and the components other than the resonant wavelength backwards along the path of the input beam but the polarization attribute of the resonant wavelength is altered in a manner distinct from the components other than the resonant wavelength.