| 摘要 |
PROBLEM TO BE SOLVED: To provide the scanning optical device in which a proper focal position is easily and surely obtained even in the case that dispersion is in existence in the characteristic of a condenser lens. SOLUTION: A chart 3 where a white part and a black part appear alternately at a prescribed interval is coated to an original placing face on a glass plate 58 being a component of an original platen and the white part and the black part are recognized from an opposite side of the original placing face. A laser beam is emitted to the chart 3, and based on the amplitude of a light receiving signal, the focal position of the laser beam is adjusted. |
