Interior Lighting for Designers

tor, MR lamps are produced with beam-
spreads from 7° (very narrow spot) to 60°
(wide flood).
MR lamps are available in both 1^38 in
(MR11) and 2 in (MR16) diameters with
either a miniature two-pin or turn-and-lock
(50 W only) base. MR11 lamps are offered
in 12 W, 20 W, and 35 W versions. MR16
lamps are offered in 20 W, 35 W, 42 W, 50
W, 65 W, 71 W, and 75 W versions. MR16
IR (infrared-reflecting) lamps are available in
20 W, 35 W, 37 W, 45 W, and 50 W ver-
sions.

Originally all MR11 and MR16 lamps

had glass bulbs, two-pin bases, open fronts,

and dichroic reflector coatings. These coat-

ings remove two-thirds of the infrared heat

from the projected beam and pass it through

the back of the lamp, with the advantages

described earlier for dichroic PAR38 cool-

beam lamps.

The compact size of these lamps encour-

aged the design of compact luminaires. This

often caused severe problems of heat build-

up, however, because heat that is usually

radiated from the front of a directional lamp

now passes through the back and into the

luminaire. To correct this problem, lamp

manufacturers developed some MR11 and

MR16 lamps with an aluminum-reflector

coating that substitutes for the dichroic

coating. This aluminum reflector coating

also prevents “spill” light from the back of

the lamp.

MR lamps are also available with a glass

cover on the front of the lamp to protect

against shattering of the halogen tube and,

in some cases, to spread and smooth the

beam. Other variations include reflectors

made of aluminum instead of glass and turn-

and-lock bases instead of the two-pin bases.

Lamps with improved dichroic coatings pro-

vide constant color over lamp life, longer

lamp life, and improved lumen mainte-

nance.

Colored Light

Colored light is commonly described in terms

of hue, saturation, and brightness. Hue is

the quality that is called red or green. Satu-

ration is the strength or depth of the color—

the amount by which the light appears to

differ from white. A deep red light, for exam-

ple, is said to be of high saturation; pink is a

red of low saturation. Brightness is the per-

ceived quantity of light, without regard to

hue or saturation.

INCANDESCENT LAMPS

Figure 6.12AR70 and AR111 lamps at one-half actual
size.

Figure 6.13MR11 and MR16 lamps at one-half actual
size.