| CPC G01B 9/02003 (2013.01) [G01B 9/02007 (2013.01); G01B 2290/70 (2013.01)] | 19 Claims |
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1. A metrology system, comprising:
a heterodyne light source, comprising:
a multiwavelength laser light source for providing at least a first wavelength laser beam at a first frequency, a second wavelength laser beam at a second frequency and a third wavelength laser beam at a third frequency, wherein the second frequency is different than the first frequency and the third frequency is different than the first and second frequencies;
an acousto-optic modulator which is configured to:
receive the first wavelength laser beam and generate a corresponding first frequency shifted laser beam with a polarization that is rotated relative to a polarization of the first wavelength laser beam;
receive the second wavelength laser beam and generate a corresponding second frequency shifted laser beam with a polarization that is rotated relative to a polarization of the second wavelength laser beam; and
receive the third wavelength laser beam and generate a corresponding third frequency shifted laser beam with a polarization that is rotated relative to a polarization of the third wavelength laser beam; and
a source optical arrangement which is configured to:
receive and combine the first wavelength laser beam and the first frequency shifted laser beam from the acousto-optic modulator and output a corresponding first combined beam, the source optical arrangement comprising a receiving optical element portion and a birefringent optical element portion, wherein the receiving optical element portion comprises a receiving optical element which the first wavelength laser beam and the first frequency shifted laser beam travel through and for which the receiving optical element portion is configured to receive the first wavelength laser beam and the first frequency shifted laser beam and to direct the beams along an optical path toward the birefringent optical element portion, and the birefringent optical element portion comprises a birefringent optical element which the first wavelength laser beam and the first frequency shifted laser beam travel through and for which the birefringent optical element portion is configured to receive the first wavelength laser beam and the first frequency shifted laser beam and combine the beams to output the corresponding first combined beam;
receive and combine the second wavelength laser beam and the second frequency shifted laser beam from the acousto-optic modulator and output a corresponding second combined beam, wherein the receiving optical element portion is configured to receive the second wavelength laser beam and the second frequency shifted laser beam and to direct the beams along the optical path toward the birefringent optical element portion, for which the birefringent optical element portion is configured to receive the second wavelength laser beam and the second frequency shifted laser beam and combine the beams to output the corresponding second combined beam with the first combined beam; and
receive and combine the third wavelength laser beam and the third frequency shifted laser beam from the acousto-optic modulator and output a corresponding third combined beam, wherein the receiving optical element portion is configured to receive the third wavelength laser beam and the third frequency shifted laser beam and to direct the beams along the optical path toward the birefringent optical element portion, for which the birefringent optical element portion is configured to receive the third wavelength laser beam and the third frequency shifted laser beam and combine the beams to output the corresponding third combined beam with the first and second combined beams; and
a processing portion that is configured to determine a measurement distance to a surface point on a workpiece, wherein the determination of the measurement distance to the surface point on the workpiece is based on a measurement process which utilizes the first combined beam, the second combined beam and the third combined beam.
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