| 摘要 |
PURPOSE:To improve the precision of measurement and follow-up characteristics to a change at high speed, by fitting an optical fiber laser Doppler shift to a mobile body and thereby measuring directly the speed of the mobile body. CONSTITUTION:An optical fiber laser Doppler speedometer having a speed probe wherein a distributed refractive-index type lens 9 and an optical fiber 7b are incorporated is fitted to an electric railcar 5. Beams from a laser 6 are given to the lens 9 through a splitter 12 and emitted to a railroad 16, a body to be measured. Laser beams diffused by the railroad 16 are subjected to a Doppler effect, fall on the speed probe, and are transmitted to a beam receiver 13 via the splitter 12. At the receiver 13, reflected beams and diffused beams are subjected to heterodyne detection, beat frequency signals are given to an indicator 15 via an F-V transducer 14, and thus a value proportional to the speed of the electric railcar 5 is indicated. |
