| 摘要 |
PURPOSE:To easily and inexpensively attain high-density and high-speed optical recording by splitting a light beam and converging them on a recording medium with a first beam as the signal beam of a second higher harmonic, and a second beam as a bias beam. CONSTITUTION:Light containing information from a laser 1 is shaped into a parallel beam through a collimator lens system 2 and after that, splitted into a light beams LB1 and LB2 by a beam splitter 3-1. The beam LB1 is converted into the second higher harmonic through a non-linear optical element 6 and becomes a signal light beam LBS. The light beam LB2 is so deflected as to get mixed with the beam LBS through optical systems such as mirrors 7, a neutral density filter 8. The beams LBS and LB2 mixed by a semi- transmision beam splitter 3-2 are converged by a converging lens 4 and form a bit 9. The diameters of the converged beams on a recording medium 5 the beam LBS is about 1/2 as large as the case of a reference wave, the diameter of the LB2 is twice as large as that, therefore, the optical direct-current bias recording is attained so as to automatically cover the signal bit. |
