Optical Review

, Volume 6, Issue 4, pp 273–283

Wavelength-Tunable Laser-Diode Interferometer


DOI: 10.1007/s10043-999-0273-3

Cite this article as:
Ishii, Y. OPT REV (1999) 6: 273. doi:10.1007/s10043-999-0273-3


Laser diodes (LDs) have been applied to a phase-measuring interferometer through the wavelength tunability of LDs by controlling their currents. Laser-diode interferometers based on a heterodyne technique are reviewed. A two-wavelength laser-diode interferometer is demonstrated with current control of dual LDs in opposite directions. A synthetic wavelength makes it possible to extend the range of interferometric measurements. The wavelength is controlled by the laser injection current and is stepwise or rampwise changed to introduce a time-varying phase difference between the two beams of an interferometer with unbalanced optical path lengths. The optical output is demodulated with a phase-extraction algorithm. Systematic phase errors caused by the LD-power variation and by the difference between the beat frequency and ramp frequency are analyzed. A feedback interferometer with electronics is used to eliminate the phase error by locking the interferometer on a preset phase. Typical experimental results are shown.

Key words

laser diodewavelength tunabilityphase measurementphase-shifting methodheterodyne interferometerfeedback controltwo-wavelength interferometersystematic phase errors

Copyright information

© The Optical Society of Japan 1999

Authors and Affiliations

  1. 1.University of Industrial TechnologyDepartment of ElectronicsHashimotodai, SagamiharaJapan