Optical time-of-flight measurement based on data transmission in a ring oscillator.
We introduce a novel optical propagation delay measurement scheme for distance estimation. It is based on a ring oscillator in which the oscillation signal is replaced by the clock information contained in optical data. A clock-and-data recovery can recover the oscillation signal at the receive end. Correlation of the received pattern with the transmitted pattern and a measurement of the bit duration by a frequency counter allow to determine the distance. The scheme has been realized at 1550 nm wavelength, using an externally modulated laser, a commercial 155.52 Mb/s clock-and-data recovery and a field-programmable gate array. Short-term repeatability is <10 microm at an equivalent free-space distance of 72 m. Measurement interval is 0.1 s. At 3 km distance the relative repeatability is 8.10(-8). The readout can be corrected with measured temperature data.
Noé
Reinhold
R
University of Paderborn, EIM-E, Warburger Str. 100, 33098 Paderborn, Germany. noe@upb.de
Koch
Benjamin
B
Sandel
David
D
D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000295:instrumentation* / Q000379:methods; D055096:Optical Devices; D009991:Oscillometry / Q000295:instrumentation*; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*