| 摘要 |
PROBLEM TO BE SOLVED: To provide a bi-telecentric optical system with improved telecentric performance.SOLUTION: A bi-telecentric optical system 1 comprises a front group 10 and a rear group 20 in order from the object side, where the front group 10 comprises a negative first lens 11, a positive second lens 12, a third lens 13 having a convex surface on the object side, and a fourth lens 14 having a concave surface on the image side in order from the object side, and where the rear group 20 comprises fifth through eighth lenses 21-24 located symmetrically to the front group 10 with respect to a point of symmetry predefined as a point FP on an optical axis AX. The front group 10 and the rear group 20 are arranged such that a rear focal point of the front group 10 and a front focal point of the rear group 20 roughly coincide. |
