Endoscope objective

Abstract

Abstract PURPOSE:To obtain the objective which has its distortion removed sufficiently and is uniform in the brightness of an image from the center to the periphery by providing a 1st group which has negative refracting power and a 2nd group which has positive refracting power and making the 1st group satisfy specific conditions. CONSTITUTION:The objective consists of the 1st group with the negative refracting power and the 2nd group with the positive refracting power; and the 1st group has one concave surface which satisfies an expression I and faces the image side and one surface is an aspherical surface which satisfies an expression II as to >=50% of effective area determined by luminous flux of maximum image height. Here, R1 is the radius of curvature of the concave surface, (f) the focal length of the whole system, w1 and w0.5 visual field angles at image height I and image height a half as large as the maximum image height, and K1 and K0.5 values of K corresponding to the image height I and the image height a half as large as the maximum image height when K=sintheta2/tantheta (theta1: angle of light incident on the aspherical surface closest to the object side from the object side to the optical axis, theta2: angle of light right after the main light beam is refracted by the aspherical surface closest to the image side to the optical axis). Consequently, the distortion is corrected and the loss of the quantity of light is small at the periphery of the image plane.

Inventors

• 👤 Iwao Kanamori
• 👤 金森　巌
• 👤 Minoru Okabe
• 👤 岡部　稔

Bibliographic Details