Photonics Dictionary: L

A collector for photovoltaic power generation that consists of a thin plate that strongly absorbs sunlight striking its faces and luminesces efficiently. A large fraction of the luminescence is...

Luminosity refers to the total amount of energy emitted by an astronomical object, typically measured per unit time. It quantifies the intrinsic brightness of the object and is often expressed in...

Pertaining to electromagnetic radiation as perceived by the eye; that is, with the contributions as wavelengths in the visible region weighted according to V(λ), which symbolizes the spectral...

Ratio of radiant flux weighted according to V(l), the spectral luminous efficiency, to the corresponding radiant flux.

The total luminous flux given out per unit area; i.e., the sum of the luminous emittance and any radiation that is reflected from and/or transmitted through the surface: expressed as lumens per area.

Descriptive of the radiant power of visible light modified by the eye response. It is the measure of the flow of visible light energy past any given point in space in a given time period, and is...

Luminous flux emitted by a source in a given range of directions; the unit of measure is the lumen/steradian, now known as the candela.

A mixture of phosphor with a trace of a radioactive element that emits faint light continually. It is used on watch dials and as a marker inside dark rooms to show the location of switches.

A high-resolution spectroscopic device commonly used in the early 20th century as a component of double-beam interferometers. Light introduced at one end of the plane-parallel glass plate will be...

A dielectric sphere with an index of refraction that varies with distance from the sphere center. A parallel beam of rays is focused on the lens surface at a point diametrically opposite the...

An illuminometer designed to measure illumination in terms of luxes.

A spectrum that is continuous in the UV region with borders ranging from the visible to 300 A and lower.

The hydrogen-derived, ultraviolet radiation running from 1216 to 512 A, discovered by Theodore Lyman in 1914.

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