The ratio of the diameter of the entrance pupil in an optical system to the equivalent focal length of that system. The relative aperture is denoted as a fraction in which f, the equivalent focal length, is the numerator, and it is symbolized by f/...

Method for reducing laser speckle in which the object field comes from a real diffuse object or the reconstructed object...

An electro-optical infrared tracker consisting of a beamsplitter, an illuminating source, an image dissector tube and an...

iris or adjustable radially symmetric opening used for allowing the passage of useful light

Also referred to as the axial ray (or a-ray), a marginal ray originates from the axial point of the object and passes...

A ray of an image-forming bundle that passes through the edge of the entrance pupil or aperture stop. Usually used in...

The ray of an oblique pencil beam that passes through the center of the pupils. It is the effective axis of the oblique...

The solid angle of a detector or system pupil as seen by the source.

In optics, the term image jump refers to a displacement or shift in the apparent position of an image when a change occurs...

The separation between the exit pupils of a binocular instrument. This usually is adjustable so that it can be set equal to...

The expression denoting the ratio of the equivalent focal length of a lens to the diameter of its entrance pupil.

Opsins are a group of light-sensitive proteins found primarily in the retinas of vertebrate and invertebrate eyes, as well...

That level of retinal illuminance resulting when a surface with a luminance of 1 candela/m2 is viewed through a pupil with...

In a visual optical system, the axial distance from the last mechanical surface of the eyepiece to the exit pupil.

A physical stop that is conjugate to the entrance pupil and is used primarily to reduce diffraction effects at longer...

A special-purpose camera used by ophthalmologists to photograph the retina of the eye. The optical system operates through...

A term pertaining to devices (generally optical) designed for use with both eyes viewing through a single exit pupil. The...

In a lens or other optical system, the image of the aperture stop as seen from object space.

A figure of merit corresponding to the amount of light seen by a viewer through binoculars. A higher number indicates a...

A type of stereoscopic photography in which the distance between the two view points is greater than the average...

1. In the eye, the opening in the iris that permits light to pass and be focused on the retina. 2. In a lens, the image of...

There are three types of telecentric lenses: -Image-space telecentric lenses are those in which the aperture stop is...

Also termed eye distance. The distance between the vertex of the last optical surface of a visual optical system and the...

The image of the aperture stop, usually the objective lens, that is produced by the eye lens. When the exit pupil of the...

In a lens or other optical system, the image of the aperture stop as seen from image space.

A small low-power microscope or magnifier with a scale that is used to measure the exit pupil diameter and eye relief on...

An imaging system designed to highlight small deviations in a planar reflective object such as a mirror. The system can be...

The distance between the two eye pupils when the observer is viewing distant objects (normal = 62 mm).

Essentially, a hologram of a hologram, in which the first-generation hologram is masked with a narrow slit. During image...

The equivalent f number of a fictitious lens that has a circular opening and 100 percent transmittance, which would give the...

An instrument for measuring the diameter of the human eye pupil.

A reflecting prism that is rhomboidal in shape. It has two parallel transmitting faces, and two parallel reflecting faces;...

The distance between pupil centers in a two-pupil system, measured perpendicularly to the optic axis.

The Foucault test is performed by moving a knife edge laterally into the image of a small point source. The eye, or a...

A graph of the intersections of a fan of rays with the final image plane, plotted as a function of the positions of the rays...

In an optical system, the space between the object being viewed and the system entrance pupil.

A dark region created by spherical aberration of an eyepiece's exit pupil. Because of the aberration, an observer's eye must...