Patent ID: 8670122

Claim:
A SPR measuring device comprising: a circularly polarized heterodyne light source that produces a circularly polarized heterodyne light beam; a beam splitting element that splits the circularly polarized heterodyne light beam into a reference beam and a signal beam; a first light sensing unit that receives a reference light intensity of the reference beam; a SPR sensor that receives the signal beam and reflects a reflected signal beam; a second light sensing unit that receives a reflected light intensity of the reflected signal beam; and a processing circuit that calculates a phase difference between the reference light intensity and the reflected light intensity; wherein the circularly polarized heterodyne light source includes: a heterodyne light source produces a heterodyne light beam, the heterodyne light source includes: a wavelength-modulated light source that produces an incident beam; a beam splitter that splits the incident beam into a first transmitted beam and a first reflected beam; a light shielding element that receives the first reflected beam; a polarization beam splitter that splits the first transmitted beam into a second transmitted beam and a second reflected beam; a first reflector that reflects the second transmitted beam back to the polarization beam splitter; and a second reflector that reflects the second reflected beam back to the polarization beam splitter; the reflected second transmitted beam and the reflected second reflected beam are recombined to form the heterodyne light beam that is output through the beam splitter; and a phase retardation component that retards the heterodyne light beam to produce the circularly polarized heterodyne light beam.