An instrument includes: one or more scanning mirrors to receive an OCT sample beam and to scan the sample beam in two orthogonal directions； and an optical system to receive the sample beam and provide the sample beam to an eye. The optical system includes: a first lens having a first focal length, disposed along an optical path from the scanning mirror(s) to the eye at a distance from the cornea which is approximately equal to the first focal length, and a second lens disposed along the optical path between the first lens and the scanning mirror(s). The second lens receives the sample beam from the scanning mirror(s) and provides the sample beam to the first lens as a converging beam such that, as the sample beam is scanned, the sample beam passes through a pivot point located along an optical axis between the eye and the first lens.
