| 摘要 |
PURPOSE:To perform recording and erasing of information through reversible changing by beforehand changing vapor-deposited thin film to a blakened saturated state of high optical density, and applying light irradiation of the selective microparts of the film in this state to change the same to a whitened state of low optical density thereby recording information. CONSTITUTION:A black disc 1 consists basically of a base material 2 and a recording film 3. In whitened signal recording, for example, a semiconductor laser light source 4 is subjected to intensity modulation by current waveforms 6 so as to generate the modulated light having power levels, and the beam thereof is reduced to a microspot diameter of about 1mu by combinations 7, 9 of lenses and irradiates the black disc film. When the pulse width is <=1musec in correspondence to the rotating direction 5 of the disc 1, whitened bits 10 are formed, by which signal recording is accomplished. Reproducing of the recorded signal is accomplished by detecting the change in the transmittance or reflectance of the recorded bit parts by the use of the same optical system. |
