Photonics Dictionary

Designating any instrument in which both eyes can be used to view the image to achieve a stereoscopic effect, or merely to facilitate observation. See also prism binoculars.

The adjustment of a binocular instrument so that the lines of sight of both telescopes are parallel.

The glossy appearance of an object viewed, because of the binocular combination of two very unlike colors.

A device having a pair of decentered lenses, one for each eye, that focuses on a single object as a magnifier. It is often supplied with a forehead fixture or an elastic headband to leave the hands...

A microscope designed with two eyepieces (oculars), permitting the use of both eyes when viewing through the instrument.

The difference in angular bearing of an object as seen by the two eyes, due to the separation of the visual optical axes.

The absolute luminance threshold for detection by the two eyes.

The ability of the two eyes to see an object from two slightly different points of view. This difference allows an individual to perceive the depth and dimension of the object in view.

An instrument, similar in design to regular binoculars, that can transmit and enlarge infrared images.

A pair of telescopes with prismatically erected images, mounted side by side with the eyepieces at the interocular distance of the observer. This separation is adjustable with a convenient millimeter...

A term pertaining to devices (generally optical) designed for use with both eyes viewing through a single exit pupil. The term may be distinguished from binocular in that biocular instruments contain...

The vertical angular disparity between the lines of sight of the left and right systems in a binocular instrument. Dipvergence is plus when the right image is below the left image.

1. In optics, the bending of rays away from each other. 2. In lasers, the spreading of a laser beam with increased distance from the exit aperture. Also called beam spread. 3. In a binocular...

A defect of a binocular instrument causing two images to be seen separately instead of being fused. It is caused when the optical axes of the two telescopes are not parallel. In minor cases, the eyes...

Also known as ocular. The lens system used between the final real image in a visual optical system and eye. It acts as an image magnifier. Many types of eyepieces are known; e.g., the Huygens used in...

A handheld binocular telescope that is commonly of the Galilean type.

The field of view (FOV) refers to the extent of the observable world or the visible area that can be seen at any given moment through a device, such as an optical instrument, camera, or sensor. It is...

The locus of the points in the field of binocular vision that are observed singly. The images of these points correspond to the respective retinal points.

The separation between the exit pupils of a binocular instrument. This usually is adjustable so that it can be set equal to the observer's interocular distance, a normal range being from 55 to 75 mm.

A binocular microscope designed for the viewing of stereo pairs. As these stereoscopic image pairs are seen through a microstereoscope, they are merged into a single image allowing the brain to...

A 45-90-45° reflecting prism whose surfaces form the 90° angle reflecting the light beam through a total angle of 180°. The corners of the prism are rounded to minimize breakage and simplify...

The arrangement of two Porro prisms so that the inverted image formed by certain types of optical instruments is the same as the object. The first prism, which is set at 90° to the second, inverts...

A prism is a geometric optical element with flat, polished surfaces that refract light. It is typically a solid, transparent object with at least two flat surfaces that are inclined relative to each...

A figure of merit corresponding to the amount of light seen by a viewer through binoculars. A higher number indicates a brighter image in low-light situations. The relative brightness value is...

A reflecting prism that is rhomboidal in shape. It has two parallel transmitting faces, and two parallel reflecting faces; the latter are oblique to the former (usually but not necessarily at...

The ability to perceive binocularly the apparent depth and relative distance of objects.

The perception of depth due to binocular vision.

A rangefinder similar to a pair of binoculars with a long base, a dot or other wander mark provided in each eyepiece field, together forming an apparent point in space. When one dot is moved...

The angular field of view that is seen by the eyes when fixed on a point straight ahead. The normal binocular visual field is approximately 130° in diameter.