Nail clipper allows for removal of any excess nail that is jagged or has been missed. Nail clippers occasionally come with a pocket knife or a nail catcher; the multi-purpose nail clipper was invented by Hungarian inventor David Gestetner. The nail clipper consists of a head which may be concave or convex. Specialized nail clippers which have convex clipping ends are intended for trimming toenails, while concave clipping ends are for fingernails. The cutting head may be manufactured to be parallel or perpendicular to the principal axis of the cutter. Cutting heads which are parallel to the principal axis are made to
Telecentric lens Telecentric lens A telecentric lens is a compound lens that has its entrance or exit pupil at infinity; in the prior case, this produces an orthographic view of the subject. This means that the chief rays (oblique rays that pass through the center of the aperture stop) are parallel to the optical axis in front of or behind the system, respectively. The simplest way to make a lens telecentric is to put the aperture stop at one of the lens's focal points. An entrance pupil at infinity makes the lens object-space telecentric. Such lenses are used in machine vision systems