Development of laser interferometer with picometer resolution using frequency tunable laser

The 5th report: Compensation of the displacement measurement due to the fluctuation of the air refractive index

Abstract

The fluctuation of refractive index of air in the applications of laser interferometer is a dominate uncertainty source of the measurement. In this report, we have been developing a displacement measuring system by using phase modulation homodyne interferometer (PMHI) and an external cavity laser diode (ECLD) in which the air refractive index fluctuation is measured and the measurement uncertainty generated by this refractive index fluctuation is compensated.