PURPOSE: To improve the stability in initialization and to speed up the initialization, by deforming laser lights from a laser light source into an oval sheet beam by means of a beam converter and stopping lens and irradiating the sheet beam upon a rotationally moving reversible optical disk.
CONSTITUTION: When focal lengths of cylindrical lenses 2 and 3 are represented by f1 and f2, respectively, and the interval between the lenses 2 and 3 is selected as f1+f2, lights coming out from a high-output laser 1 become flat parallel lights after passing through the lenses 2 and 3 and then magnification (m) is expressed by m=f2/f1. When the effective aperture of a stopping lens 4 is represented by D, it is desirable to expand to luminous flux from the high-output laser 1 to m=D/. When the focal length of the stopping lens 4 is represented by f0 and, for example λ=0.5145μn, D=m, =5mm, and f=50mm, the light spot formed on the surface of a disk 5 becomes an oval spot of about 50μm×10μm. When the major axis direction of the spot is oriented in the radial direction of track, about thirty tracks can be irradiated at once, if the track pitch is, for example, 1.6μm.
OONISHI KUNIKAZU
OSHIMA MASAHIRO
TSUNODA YOSHITO
TERAO MOTOYASU
| JPS5195807A | 1976-08-23 | |||
| JPS60106031A | 1985-06-11 |
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