title: Two-wavelength interferometer based on sinusoidal phase modulation with an acetylene stabilized laser and a second harmonic generation.
abstract: A two-wavelength interferometer (TWI) based on a sinusoidal-phase-modulation method with an acetylene stabilized laser and a second harmonic generation (SHG) was developed. The periodic non-linearity error for the TWI was estimated to be ± 0.1 µm at a dead path of 0.32 m. A long-term measurement showed that the TWI stability was ± 3 × 10(-7) at a dead path of 1.00 m for 12 hours with an ambient pressure variation of 3 hPa under controlled conditions of ambient temperature and humidity. Finally, we confirmed that the TWI has substantially better stability than a single-wavelength interferometer by comparing both interferometers with large temporal and spatial temperature variations.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Kawata
authors.forename: Kyohei
authors.initials: K
authors.lastname: Hyashi
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Aoto