Patent ID: 7463668

Claim:
A cavity, continuously tunable over a wavelength range, comprising: a first reflecting unit configured to at least partially reflect an incident beam of electromagnetic radiation towards a second reflecting unit, said second reflecting unit configured to at least partially reflect an incident beam of electromagnetic radiation back towards said first reflecting unit, both reflecting units providing the formation of resonance modes of said electromagnetic radiation within said cavity, wherein an optical path of said beam within said cavity is defined in length by said first and second reflecting units, a grating, which is arranged within said optical path of said beam being reflected by said first reflecting unit, said grating configured for tuning the wavelength of said beam, wherein said second reflecting unit is configured to rotate about an axis by at least 360 degrees and provides a continuous movement of said second reflecting unit along a circle path with respect to said grating to continuously vary the optical path length of the cavity, said circle path of said second reflecting unit comprising at least a portion being arranged to intersect with said beam, which is redirected by said grating.