Patent ID: 6163401
Filing Date: 2000-12-19
Classification: G02B

Abstract:
An observation optical system for non-flexible endoscopes which is to be disposed in an elongated insert section of a non-flexible endoscope having said insert section comprising:an objective lens system; anda relay lens system,wherein said relay lens system comprises a plurality of relay lens modules each of which relays a real image on an objective lens side to the opposite side, and each of which comprises plural lens elements, at least one relay lens module of said plurality of relay lens modules produces undercorrected longitudinal chromatic aberration and at least another relay lens module of said plurality of relay lens modules produces overcorrected longitudinal chromatic aberration, andwherein longitudinal chromatic aberration is corrected in said observation optical system as a whole by canceling said undercorrected longitudinal chromatic aberration with said overcorrected longitudinal chromatic aberration.