| 摘要 |
PURPOSE:To reduce the cost and to obtain practical performance by composing a scanning optical system lens of one element which meets specific requirements. CONSTITUTION:The scanning optical system lens consists of one element which has a concave troidal surface 2 and a convex troidal surface 3 from the side of a deflector; and -0.5f<r1x<-2f, -0.1f<r1z<-0.5f, 1.5<n<1.8, d1<0.3f, and 0.3f<t hold, where (n) is the lens refractive index, d1 is the distance between a deflection position and a 1st surface, and (t) the center thickness of the lens. Here, (f) is the (f) value of an ftheta characteristic, r1x is the radius of curvature of an (i)th surface in a scanning direction, and r1z is the radius of curvature of the (i)th surface in the subscanning direction. Further, the compact scanning optical system lens 11 which has a tilt angle correcting function and the ftheta characteristic and is widened in the maximum visual angle is obtained. |
