Seiichi KAKUMA^*, Kohhei OHMURA and Ryoji OHBA

Division of Applied Physics, Graduate School of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo 060-8628, Japan

(Received February 7, 2003; Accepted May 19, 2003)

Length resolution of optical-frequency-domain-reflectometry (OFDR) is improved by reducing the chirping fluctuation of a laser diode. The fluctuation is detected as the frequency deviation of a beat signal from a reference interferometer, which is used as the control signal for servo-control of the laser diode (LD) drive current. As a result of the effective chirping stabilization, chirping span limited-resolution is achieved. In addition, use of a block gauge as the path difference of the reference interferometer enables the OFDR system to improve accuracy of the length as well as the resolution.

Key words: optical frequency domain reflectometry, block gauge, laser diode, length measurement

^*E-mail address: kakuma@eng.hokudai.ac.jp