Two-Wavelength Displacement-Measuring Interferometer Using Second-Harmonic Light to Eliminate Air-Turbulence-Induced Errors

Abstract

In order to eliminate air-turbulence-induced errors in the measurement of linear displacement, an interferometer with two different laser beams using second harmonic generation (SHG) has been developed. These beams have wavelengths of 488 nm, emitted from an Ar + laser, and 244 nm, which is the second harmonic generated by a nonlinear crystal β-BaB 2 O 4 inserted in the Ar + laser cavity. Demonstration experiments have proven the system's efficacy in eliminating air-turbulence-induced errors.