| 摘要 |
PURPOSE:To miniaturize a reproducing optical system by scanning and detecting the center frequency in the frequency band which is restricted in a scanning type filter, corresponding to a driving current which modulates a semiconductor laser of the light source side. CONSTITUTION:The modulator 20 is connected to the DC power supply 19 with the optical detector 39, and scans with time the center frequency of the frequency band which is restricted in the scanning type filter 44, corresponding to the driving current from the power supply 19 which modulates a light beam from the semiconductor laser 35. By this scanning, refractive index discontinuity part 34 are expressed such that '1' is recorded when they are arranged at regular intervals and '0' is recorded when they are not. When discontinuity part 34 are recorded at any positions and modulated light beams of each frequency from the laser 35 are guided, the reflected guided light is detected, and electrical output of the time series signal waveform is obtained corresponding to each position of the discontinuity part 34. |
