| 摘要 |
PURPOSE: To increase a rate of change in a measured value of a reference position mark even in a range with smaller position deviation in the subscanning direction and to eliminate the effect of a difference Vdif between Vblack and Vc on focus adjustment. CONSTITUTION: The chart has a position adjustment mark 14 having a width changing linearly in the subscanning direction, at least two reference position marks 24, 25 having different width with respect to a light receiving range of an image pickup element 3, and a black mark 26 having a sufficient width to generate a black level reference signal. Furthermore, in the adjustment method of an image pickup element optical unit, the reflected light of the adjustment chart is received by the image pickup element to select an image signal of one mark where a position deviation in the subscanning direction of the image pickup element unit and a level of the image signal are proportional to each other among the image signal of the marks and the position deviation in the subscanning direction is adjusted based thereon and the image signal of a black mark 26 is used for a black level reference signal for the calculation of focus to adjust the focus. |
