Endoscope objective lens and endoscope

Abstract

The invention provides an object lens for endoscope, which not only ensures the long rear cut-off distance, but also excellently corrects the lateral chromatic aberration, wherein a negative first lens (L1) having concave surface toward image side, a first joint lens (L23) formed by jointing a second lens and a third lens, one positive and one negative, a positive fourth lens (L4) having the side with large absolute value of plane or curvature radius toward object side, and a second joint lens (L56) with integral positive refractive force formed by sequentially jointing a positive fifth lens and a negative sixth lens from the object side are arranged in sequence from the object side, which fulfill the conditions (1), (2): (formula), wherein, f is focus; Bf is the rear cut-off distance; v5 is the abbe number of the fifth lens; the v6 is the abbe number of the sixth lens; RA is the curvature radius of the joint surface of the second joint lens; d6 is the central thickness of the sixth lens; n6 is the refractive rate of the sixth lens.

Description

Objective lenses and endoscopes for endoscopes technical field The present invention relates to an objective lens for an endoscope and an endoscope, in particular to an objective lens for an endoscope suitable for use by arranging a prism for bending an optical path or the like between the objective lens for an endoscope and its imaging surface, and a This endoscope is an endoscope with an objective lens. Background technique Conventionally, endoscopes have been used at medical sites and the like to observe and treat the inside of patients. As an endoscope, a direct-view endoscope in which an observation objective lens is disposed at the distal end of the insertion portion of the endoscope inserted into the body and a solid-state imaging device is disposed on the imaging surface of the objective lens to observe the long-axis direction of the insertion portion is often used. Most endoscopes of this type are arranged so that the light-receiving surface of the solid-state im...

AI Technical Summary

Problems solved by technology

However, as the back focus increases, the light height of this optical component decreases and the correction effect of chromatic aberration of magnification becomes weaker, and its correction becomes difficult

Especially in an optical system with a back focus longer than 2.5 times the focal length, correction of chromatic aberration of magnification is not easy because there is no lens at a position close to the imaging plane

Images