Endoscope optical system

Abstract

The endoscope optical system has an objective with an object-side negative lens cluster, the constructional design of which should minimise or exclude image scale defects, such as distortion and field curvature. The object-side negative lens cluster comprises two menisci each having negative refractive power. The individual defects of distortion occurring at the surfaces are reduced as a result of the meniscus-like design, and a flattened image field, that is prevention of field curvature, is achieved as a result of splitting the lens cluster into two menisci. The object-side meniscus may be designed as a single lens or as a cemented component comprising an outer lens and an inner lens. Since the distortion defect at the cement surface has a negative sign, the defects are thus partially compensated at the outer surfaces of the meniscus.

Dependencies are inferred from the claim text.