title: Real-time compensation of the refractive index of air in distance measurement.
abstract: A two-color scheme of heterodyne laser interferometer is devised for distance measurements with the capability of real-time compensation of the refractive index of the ambient air. A fundamental wavelength of 1555 nm and its second harmonic wavelength of 777.5 nm are generated, with stabilization to the frequency comb of a femtosecond laser, to provide fractional stability of the order of 3.0 × 10(-12) at 1 s averaging. Achieved uncertainty is of the order of 10(-8) in measuring distances of 2.5 m without sensing the refractive index of air in adverse environmental conditions.
authors.forename: Hyun Jay
authors.initials: HJ
authors.lastname: Kang
authors.forename: Byung Jae
authors.initials: BJ
authors.lastname: Chun
authors.forename: Yoon-Soo
authors.initials: YS
authors.lastname: Jang
authors.forename: Young-Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Seung-Woo
authors.initials: SW
authors.lastname: Kim