Patent ID: 7218650

Claim:
For use with a laser source providing light along a reference axis, an optical filter comprising: a first filter element having a first angular sensitivity to the reference axis and for tuning a wavelength of the light in response to changes in an angle of incidence of the light upon the first filter element; a second filter element having a second angular sensitivity to the reference axis for tuning the wavelength in response to changes in an angle of incidence of the light upon the second filter element, wherein the second angular sensitivity substantially cancels the first angular sensitivity, wherein the wavelength of the light is not tuned by simultaneous rotation of the first and second filter elements relative to the reference axis; and a support having a first side wall with a first tapering angle and a second side wall opposite the first side wall and with a second tapering angle, the first filter element being mounted to the first side wall, the angle of incidence of the light upon the first filter element being defined by the first tapering angle, the second filter element being mounted to the second side wall, the angle of incidence of the light upon the second filter element being defined by the second tapering angle.