Photonics Dictionary

A device that calibrates the size, position or distance of objects imaged on a video screen.

Videography refers to the process of capturing moving images and recording them in a digital format. It involves the use of video cameras, lighting equipment, and audio recording devices to create...

A small television tube originally developed for closed-circuit television. It is about 1 inch in diameter and 5 inches long. Its controls are relatively simple and can be operated by unskilled...

A camera that permits adjustments in the perspective of an image; this is accomplished by the camera design, which permits tilt, swing, rise or fall of the image transmitted. Also known as a...

In an optical system, the gradual reduction of image illuminance as the off-axis angle increases, resulting from limitations of the clear apertures of elements within the system.

The product of the actual base or baseline of a rangefinder or heightfinder, and the power or magnification of the instrument.

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...

Virtual reality (VR) is a computer-generated simulation of a three-dimensional environment or experience that can be interacted with and explored by an individual using electronic devices, such as a...

The use of miniature scanners to project raster-scanned video images directly onto the surface of the human retina, eliminating the need for a projection surface.

The maximum distance at which the eye can perceive and evaluate objects.

1. An instrument used to determine the visual range in an environment. 2. A type of photometer that artificially reduces an object's visibility to threshold limits and records the quantity of...

That term pertaining to the spectral region that can be perceived by the eye.

An instrument that uses an erbium:glass laser to determine cloud height from the ground.

The numerical definition of the ability of an observer to perceive fine detail. The average value may be taken as one minute, or 6.7 cycles/mm, at 250 mm (normal viewing distance).

An imaginary line between the object, through the nodal point of the eye, and the fovea, or point of finest retinal acuity.

A pair of stars (double star) that can be seen separately with a telescope, generally by setting a filar micrometer for the separation and position angle. Observation of visual binaries improves with...

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.

Having the characteristics of glass.

The transparent fluid that fills the portion of the eye between the eye lens and the retina (the posterior chamber).

A blank area (caused by insufficient inking of the paper) that falls within the range of an intended character stroke in an optical character-recognition system.

The induced birefringence in isotropic gases that results when the gases are placed in strong fields.

Volume Bragg gratings (VBGs) are specialized optical elements that consist of periodic variations in refractive index throughout the volume of a transparent material, typically a photosensitive glass...

Volumetric imaging refers to the capture, visualization, and analysis of three-dimensional (3D) information from a volume of space. Unlike traditional two-dimensional (2D) imaging, which provides...

A vortex phase plate is an optical device designed to impart a phase singularity, commonly referred to as a vortex or phase vortex, onto a light beam. This singularity results in a phase profile...

A system used for gratings that consists of a concave mirror, a grating and a plate holder mounted normal to the grating to reduce astigmatism and spherical aberration. The mounting yields a...

In the context of electronics and semiconductor manufacturing, a wafer refers to a thin, flat disk or substrate made of a semiconducting material, usually crystalline silicon. Wafers serve as the...

The power that gives rise to the production of energy at the rate of 1 joule per second.

1. An undulation or vibration; a form of movement by which all radiant energy of the electromagnetic spectrum is estimated to travel. 2. A type of surface defect, usually due to improper polishing.

Also referred to as physical optics - the area of optics in which the wave nature of light is essential when defining its propagation. To exploit the wave phenomena of light, one must interact light...

An optical element having two principal axes, slow and fast, that resolve an incident polarized beam into two mutually perpendicular polarized beams. The emerging beam recombines to form a particular...

The continuous group of waves that persists for a short time only.

In considering a field of electromagnetic energy emanating from a source, the wavefront is a surface connecting all field points that are equidistant from the source.

For each mode in an optical waveguide, the term used to describe the process by which an electromagnetic signal is distorted by virtue of the dependence of the phase and group velocities on...

A device that consists of two types of mode converters, one of which must be magnetic. It is nonreciprocal because the coupling constants of the two mode converters have a different phase relation...

A waveguide is a physical structure or device that is designed to confine and guide electromagnetic waves, such as radio waves, microwaves, or light waves. It is commonly used in communication...

A system that allows the transmission of more than one signal over a common path, by assigning each signal a different frequency band. Also known as frequency division multiplexing.

A photofluorescent compound that, when used with a scintillating substance, absorbs photons and emits related photons having a greater wavelength. In this way a phototube or photocell may employ the...

Electromagnetic energy is transmitted in the form of a sinusoidal wave. The wavelength is the physical distance covered by one cycle of this wave; it is inversely proportional to frequency.

The law stating that the just-perceptible increment of stimulus is a constant fraction of the stimulus.

An optical filter so constructed that the density increases progressively from one end to the other, or angularly around a circular disc.

A diffraction pattern sampling unit composed of a 32-element monolithic silicon photodiode array and a readout unit. The intensity on each detector element can be separately read out by means of a...

An optical element having plane-inclined surfaces. Usually the faces are inclined toward one another at very small angles. Wedges divert light toward their thicker portions, and may be circular,...

The Weissenberg method, named after the German physicist Karl Weissenberg, is a technique used in x-ray crystallography for obtaining high-quality diffraction patterns from single crystals. This...

A well plate, also known as a microplate or microtiter plate, is a flat plate with multiple small wells or depressions arranged in a grid pattern. Each well serves as a separate container for holding...

Whispering gallery mode (WGM) refers to a phenomenon in wave physics, particularly in optics, where waves, such as light or sound waves, are trapped and circulate along the periphery of a curved...