| 摘要 |
PURPOSE:To vary optical path length without varying a slit exposure part by providing the object side and image side of an imaging lens system each with one roof prism movably, and by displaying the roof prism linearly for a change in copying magnification. CONSTITUTION:For copying with contraction magnification (m) (m<1), a roof mirror 10 is displaced to a position 10', and a roof mirror 12 is also displaced to a position 12'. In this case, the extents (a) and (b) of displacement are f(1-m)/ 2m and f/2(1-m), respectively, where (f) is the focal length of an imaging lens system 11. For copying with enlargement magnification (m') (m'>1), the roof mirror 10 is displaced to a position 10'', and the roof mirror 12 is also displaced to a position 12''. Their extents of displacement are c=f(m'-1)/2m' and d=f/2 (m'-1), respectively. In the displacement, a slit exposure part P is not varied. |
