LIGHTING TERMS

argand lamp

lamp invented by a swiss named Argand in 1783. had a round wick with providison for the introduction of air inside the wick as well as around the outside

astral lamp

oil lamp with swinging tubular arms, generally furnished an Argand burner; used in early 19th C

adaptation

process by which the eye adjusts to change in light level

ambient light

general light, often indirect, or entering a room from an adjacent space.

baffle

an opaque or translucent element used to shield a lamp from view or to absorb unwanted light

ballast

a device used with HID and fluorescent lamps to establish the circuit conditions necessary to start and operate lamp

bare lamp

an unshielded light source

blinding glare

intense glare that you cannot see for a short period of time

concealed light

any artificial light source concealed behind a decorative facing

contrast

the difference in luminance between an object and its background

dichroic mirror

an optical filter that selectively reflects some wavelengths while transmitting others

diffuse reflection

one that appears scattered, either in reflection or transmission

dimmer

a device used to regulate the intensity of light from a lamp

directional light

light that is focused and forced to travel in a particular direction either by reflector or baffle. this may be a spotlight of any sort or a lamp with an opaque shade so that the light goes in a particular direction

disabling glare

glare that reduces visibility and visual performance

discomfort glare

annoying glare but often does not reduce visibility and visual performance

eyeball

recessed or semi-recessed lighting unit with a rotating spherical element that may be turned to project light in any direction below the ceiling line

fiber optics

a way of transmitting light through long flexible glass or plastic fibers, using the principle of total intern refraction

filter

a device to change the quality of light affecting the magnitude and/ or spectral make-up [in transmission]

fluorescence

the emission of light, only during the absorption of radiation of a different wavelength

illuminance

the density of a light on a surface

louvers

a series of baffles, usually geometric, used to shield a lamp from view at certain viewing angles

projector

a lighting unit which concentrates light in a limited angle and intensifies it

shielding

a general term used to describe devices that block, diffuse, or redirect light such as a louver or lampshade

spill light

a term applied to any stray light outside the main concentration of the beam usually controlled by louvers, baffles, etc

veiling reflection

glare where reflection reduces contrast and so prevents detail being discerned

work plane

usually the horizontal surface at which a task is performed and at which light levels are specified and measured