Patent ID: 7515335

Claim:
A relay set ( 4 ′) for the optical system of a rigid endoscope, said optical system comprising an objective ( 1 ) at the distal end, an ocular ( 5 ) at the proximal end and between them a relay lens system including several relay sets ( 2 , 3 , 4 ′), said relay set ( 4 ′) consisting of: two half sets ( 4 . 1 , 4 . 2 ) having the same lens units ( 11 . 1 , 12 . 1 , 13 . 1 ; 11 . 2 , 12 . 2 , 13 . 2 ) arranged symmetrically with respect to the center ( 10 ) of the relay set ( 4 ′), wherein each half set ( 4 . 1 , 4 . 2 ) is of a triplet design, including first and second positive power lens units ( 11 . 1 , 13 . 1 ; 11 . 2 , 13 . 2 ) at the ends and one negative power lens unit ( 12 . 1 ; 12 . 2 ) in the middle, wherein the first positive power lens unit is an inner end lens unit and adjacent the inner end lens unit of the neighboring half set and the second positive power lens unit is an outer end lens unit, and wherein in each half set the outer end lens unit is of plane-convex form and the middle lens unit is of plane-concave form, said outer and middle lens units ( 11 . 1 , 12 . 1 ; 11 . 2 , 12 . 2 ) being cemented together at the plane faces.