Photonics Dictionary: V

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...

Visual detection and ranging (ViDAR) is a technology that utilizes optical sensors, such as cameras or other imaging devices, to detect and track objects in the surrounding environment. Unlike...

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...