IMAGING OPTICAL SYSTEM, STEREO CAMERA DEVICE, ON-VEHICLE CAMERA DEVICE, AND VARIOUS DEVICES

摘要

PROBLEM TO BE SOLVED: To provide an imaging optical system in which image height variation during a temperature load is suppressed, while it has low distortion, is compact, and has high performance and a large angular field, and it has a small F number and a large diameter.SOLUTION: In a retrofocus type lens constituted of a negative first lens group 1G located on an object side and a positive second lens group 2G located on an image side, while an aperture stop S is located therebetween, the first lens group 1G consists of, in order from the object side, a positive first lens L1, a negative second lens L2 and a positive third lens L3 which are in the meniscus shape convex to the object side. A biconvex air lens is formed of an end surface of the first lens group 1G and a top surface of the second lens group 2G. When a focal distance of the second lens group 2G is defined as f2, a focal distance of each positive lens in the second lens group is defined as frn, and a temperature coefficient of refraction factor of each positive lens is defined as dtn, 0.50<|f2/frn|<7.00 ...(1) and 0