| 摘要 |
PURPOSE:To constitute a small-sized, wide-angle telecentric variable magnification system, by providing at least one group of lenses, which move on an optical axis according to magnification, behind a diaphragm. CONSTITUTION:In a thin telecentric system, an object side is a rear one. When there is only one group of thin lenses behicnd a diaphragm, d=f as a telecentric condition, where (d) is a distance to the rear-side lens group and (f) is the focal length of the rear-side lens. During magnification variation, the condition should be satisfied all the time, and the diaphragm and lens group behind it move in one body on the optical axis while holding a constant interval (d). Even when there are two or three groups behind the diaphragm, the telecentric condition is found similary, and the equation in the figure holds, where d1 is a distance between the diaphragm and the 1st lens groups, d2 and d3 are intervals between the lenses, and f1, f2 and f3 are focal lengths. |
