Light+Vocabulary

**LIGHT VOCABULARY**
 * Alabaster **: genuine alabaster is a very fine variety of crystalline gypsum (hydrous calcium sulfate) found in nature. It is translucent and its color is often white, pearly, or silky colorless but it, more often than not, has subtle reddish-brown bands of iron oxide running through it. It is often used for decorative objects such as light fixtures or figurines.

**Baffle**: in lighting this is usually a grooved surface that deflects and controls the “flow” of light to soften it and minimize reflected glare. Baffle trims (sometimes called step baffle trims or stepped baffle trims), made of plastic or metal, are often integral parts of recessed downlights. They are often colored a flat black to absorb some of the light but can have other finishes such as flat white, brushed copper, or brushed nickel.

**Ballast**: an electrical device used with fluorescent and HD (high intensity discharge) lamps (light bulbs) to supply sufficient voltage to start and operate the lamp but then to limit the current during operation.

**Barn Doors**: 2 or 4 adjustable opaque plates attached to the front of a luminaire, such as a track fixture or a theatrical spotlight, which are used to shape and focus the light on a designated area, such as a framed work of art or a stage scene.

**Beam Spread**: a measure of the spread of light from a reflectorized light source, a special-shaped lamp with a reflective coating inside the bulb to direct the light forward. The beam spread may be very narrow (narrow spot), very wide (wide flood), or something in-between (narrow flood, for example). Examples of "reflectorized light sources" are MR11, MR16, PAR20, PAR30, PAR38, R40, ER30, and BR30 lamps.

**Bollard**: an outdoor luminaire that is a short (usually about 2-4 feet in height) but very sturdy vertical post with the light source located at or near the top. Bollards are typically used to light walkways in commercial settings.

**Brick Light**: a light fixture (usually the size of a brick) that can be recessed in a brick wall with its face parallel to the surface of the brick surface in order to light a walkway, a step, a landing, or a path

**Bulb**: a colloquial term for a lamp. In the lighting industry, the term, bulb, refers only to the glass envelope of the lamp. Some lighting professionals contemptuously refer to "bulbs" as those things that are planted in the ground.

**Cave Effect**: an unwanted consequence often associated with parabolic troffers, the cave effect is created when the light fixtures in a room apply no direct light to the upper part of walls due to an extreme cut-off angle.

**Circline**: a type of fluorescent lamp that is made up of a circular tube of glass; when placed in a light fixture the ballast that powers this type of lamp is usually located in the center of the circline lamp

**Downlight**: a small light fixture recessed into the ceiling that usually concentrates the light in a downward direction. Synonyms: recessed downlight, “can”, recessed can.

**ER Lamp**: a type of incandescent reflector lamp with the reflector shaped like an ellipsoid (a 3-dimensional ellipse) with the lamp's filament located at one of the two foci of the ellipsoid so that the light is focused directly in front of the lamp at the second foci

**Faceplate**: the metal or plastic plate installed over an on/off switch, dimmer, or receptacle, which covers the wall opening and protects the wiring inside the junction box

**Light Trespass**: also known as "spill light". Light that is emitted into an unintended area.

<span style="font-family: Georgia,serif;">**Louver**: a type of “screen” made of translucent or opaque material and geometrically designed to prevent lamps from being viewed directly within a given angle. Louvers are intended to minimize direct or indirect glare.

<span style="font-family: Georgia,serif;">**Opaque**: a term that describes a material that does //**not**// transmit //**any**// visible light. A wooden door, aluminum foil, and bricks are all examples of opaque materials.

<span style="font-family: Georgia,serif;">**Pendant**: pendant lights can provide both task and general lighting. Equipped with shades or globes to avoid glare, they are suspended from the ceiling over dinette tables, game tables, kitchen counters, or other work areas. When used over end tables or night tables, they free up the space occupied by table lamps. In general, pendants should be hung about 30 inches above the tabletop and be about 12 inches narrower than the table on all sides. Not to be confused with a jewelry pendant, which is usually a small to medium-sized ornamental piece of jewelry attached to a necklace or bracelet.

<span style="font-family: Georgia,serif;">**Sconce**: an ornamental light fixture attached to a wall.

<span style="font-family: Georgia,serif;">**Wall Sconce**: a luminaire (light fixture) affixed to the wall and usually decorative in nature.

<span style="font-family: Georgia,serif;">**Wall Washing**: a lighting technique that produces a relatively smooth, even level of illumination on a wall that minimizes the apparent texture of the surface.