Abstract: A telecentric zoom lens having telecentric forming aperture optically and preferably mechanically intermediate an objective lens and a zoom group. The aperture is fixed along an optical axis and selected to provide a constant speed on an image side of the lens system. The location of the aperture relative to the zoom group maintains telecentricity of the lens in object space.

Abstract: An oblique viewing system is attachable to a microscope to selectively obtain a perpendicular view (along the optical axis of the microscope) and oblique views of surfaces of objects under inspection. The attachment is connected to the microscope's objective end by a coupling on a housing containing the viewing system. The system includes a folding mirror and an oblique viewing mirror, spaced from the folding mirror and having its reflecting surface facing the object under inspection. A latching or a toggle mechanism, connected to a rotatable support for the folding mirror, enables that mirror to be set in either of two positions, one out of the way of the perpendicular path to provide a perpendicular view and the other to orient the reflecting surface thereof to face the reflecting surface of the oblique viewing mirror along an optical axis there between.

Abstract: A binocular opthalmometer has rotatable imaging optics which provide an image of a referencing element (mire) to a binocular viewing assembly. The viewing assembly is held stable (horizontal) by referencing it to a fixed support or stand in which the rotatable optics are journaled. The referencing mechanism is provided by a shaft mounted for rotation about an axis radially spaced from the axis of rotation of the imaging optics and which is rotatably coupled at one end to the stationary support and at the other end to the viewing assembly.