| 摘要 |
A light beam scanning system having an automatic focus correction, comprises a flat carrier having first and second oppositely facing reflective surfaces at least one of which has variations defining a recorded signal, first and second lens assemblies positioned against the first and second reflective surfaces, respectively, an optical assembly providing a light beam path between the first and second lens assemblies and a light source. A light beam emitted from the light source is guided to the first reflective surface of the carrier through the first lens assembly and reflected from such first surface and passed through the first lens assembly, along the optical path between the first and second lens assemblies and through the second lens assembly. The first and second lens assemblies are arranged so that their respective image magnifications or magnification factors satisfy a specific interrelation, thereby to establish the autofocusing of the light beam at the second reflective surface. The light beam directed toward the first reflective surface is focused by said first lens assembly at a point which is spaced along said path from said first surface in the direction toward said first lens assembly. |
