Definitions

1. With respect to angular subtense, a source of light, such as a star, that is very small. In a lab, a point source may be simulated by imaging a large source onto and through a pinhole, or by...

Fiber optic cable in which the arrangement of fibers within the bundle has been made random so that output light will be uniformly distributed and not relay the image of the light source at the input...

A ray of an image-forming bundle that passes through the edge of the entrance pupil or aperture stop. Usually used in connection with meridian rays, an upper rim ray is one that passes through the...

A circular lamp or bundles of optical fibers placed around the perimeter of an objective lens to illuminate the object field below it.

A line formed by the principal (center) ray of an oblique bundle of rays.

An arrangement of optical fibers in a bundle whereby the geometric configuration of the input end differs from that of the output end without changing the total area; for example, a circular bundle...

In fiber optics, the condition in which each fiber of a bundle carries a separate channel.

Image displacement by a decentered lens, rotated on a chuck whose axis of rotation passes through the geometrical center of the rim of the lens, when the light source is at an infinite distance. It...

An Abbe condenser in which the upper lens element is fixed. The lower lens may focus the illumination between the elements so that it emerges from the fixed lens as a large-diameter parallel bundle....

An image that is formed when rays emerging from an optical system are diverging from the optical axis. The virtual image is formed where the bundle of diverging rays appear to intersect each other...

A Cassegrain telescope having a parabolic primary mirror, a spherical secondary mirror and a zero-power doublet in the converging bundle for aberration correction.