Patent ID: 7920269

Claim:
A system for measuring interferences, comprising: a first source, said first source being a first single-frequency light source; an optical delay line device, delaying beams by an optical phase modulation; a first detect device, said first detect device being a first interferometer; a second detect device, said second detect device being a second interferometer; and an optical path module, comprising a plurality of paths for beams to pass through, wherein said plurality of paths comprise: a first path, leading from said first source to a sample; a second path, leading from said sample to said first detect device; a third path, leading from said first source to said optical delay line device; a fourth path, leading from said optical delay line device to said first detect device; a fifth path, leading from said optical delay line device to said second detect device; and a sixth path, leading from said first source to said second detect device; wherein the length of said fourth path is changed by said optical phase modulation so as to shift the phase of a first interference signal between the beam passing through said second path and the beam passing through said fourth path, and said first detect device receives and detects the phase shift of said first interference signal; wherein the length of said fifth path is changed by said optical phase modulation so as to shift the phase of a second interference signal between the beam passing through said fifth path and the beam passing through said sixth path, and said second detect device receives and detects the phase shift of said second interference signal.