| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a radar device for measuring the distance and speed of an object with high accuracy at low cost.SOLUTION: A laser beam outputted from a laser 10 is intensity-modulated with a periodic signal from an oscillator 11 by a modulator 12 before being outputted. The periodic signal is a cosine wave, the frequency of which is a minimum value f0 at which a Doppler frequency fd can be measured. The laser beam reflected by an object is subjected to optical heterodyne detection by a multiplexer 16 and a photodetector 17 before being inputted to a BPF 18 and 19, respectively. The electric signal inputted to the BPF 18 is passed for only a band near the frequency f0 and the passed signal is inputted to phase difference detection means 20. A distance is calculated by comparing a difference in phase between the periodic signal from the oscillator 11 and the periodic signal. On the other hand, the electric signal inputted to the BPF 19 is passed for only a band near the fd, and the passed signal is inputted to frequency analysis means 21. Then, a frequency spectrum is calculated, and a speed is calculated from the Doppler frequency fd.</p> |
