| 摘要 |
PURPOSE:To easily perform focus control, by arranging a light beam form arranging means to illuminate a lengthy area in a direction of an information track by changing the shape of an illuminating light beam, in an illuminating optical system. CONSTITUTION:In an optical ROM card 2, a prescribed length of information track if formed by arranging the appropriate number of recording bits that are information units in a direction of B, and a band is formed by arranging the appropriate number of tracks in a direction of A, and the whole of information areas is formed by arranging the appropriate number of bands in the direction B. The card 2 is arranged within a plane including directions of A and B, and is carried in the direction of A or B by a carrying mechanism. Divergent light from a light source 22 is changed to a parallel beam of light at a collimator lens 24, and furthermore, it is focused only in a direction of the inside of a paper plane in figure by a cylindrical lens 26, and is reflected on the plane 28 of a half mirror, and furthermore, it is focused on a condenser lens 30, and photoirradiating area can be reduced by form-shaping the light beam, thereby, it is possible to heighten illuminating intensity per unit area on an information track 42, to deepen focusing depth in an image-forming system, and to easily perform the focus control. |
