Optical recording system for wide angle objective for endoscope, has lens with surfaces, whose curve radii and focal lengths of system and another lens satisfy equations, where refractive index of former lens has preset value

摘要

The system has a lens (L1) e.g. concave meniscus converging lens and another lens (L2) e.g. convex converging lens arranged at an object side. A curve radius (r1) of an object-sided surface of the former lens, a curve radius (r2) of an image-sided surface of the former lens, a focal length of the system and a focal length of the latter lens satisfy a set of preset equations. A refractive index of the former lens is greater than 1.65, where the system is arranged at an end that is vertical to a guiding direction of an endoscope.