title: Two-wavelength laser diode interferometer with time-sharing sinusoidal phase modulation.
abstract: We describe an interferometer system that uses two separate wavelengths to measure step height. The overlapping interference images detected by a CCD camera are easily separated by an ordinary integrating-bucket method and time-sharing sinusoidal phase modulation, in which two laser diodes are alternately modulated with a sinusoidal signal. A phase map is obtained only for the laser diode into which the modulation signal is injected. In this instance, a 1-microm step height was accurately detected.
authors.affiliation: Faculty of Engineering, Niigata University, Japan. takamasa@eng.niigata-u.ac.jp
authors.forename: Takamasa
authors.initials: T
authors.lastname: Suzuki
authors.forename: Takayuki
authors.initials: T
authors.lastname: Yazawa
authors.forename: Osami
authors.initials: O
authors.lastname: Sasaki