Lighting and Illumination Fundamentals

Vocabulary and core concepts regarding the principles, units, and physical properties of lighting and illumination as discussed in the lecture.

Photometry

The science that deals with the measurement of light.

Incandescent

A type of artificial light with a stimulating effect that is conducive to drinking and induces sleep; considered best for bars and nightclubs.

Fluorescent

A type of artificial light that emits a light similar to daylight and is conducive to eating, reading, and studying.

Candle power

The unit of intensity of light of one standard candle whose light is concentrated at a point, with the source assumed to be at the center of a hollow sphere of one foot radius.

Standard candle

The brightness of a black body at the temperature of freezing platinum.

Lumen (L)

The unit of luminous flux, representing the amount of light falling on a surface from a source.

Foot candle (ft-c)

The unit for the power or intensity of light; the illumination at any point on a sphere's area when 1 lumen of flux is uniformly distributed over 1 square foot of area.

Formula for Illumination

$E = \frac{I}{D^2}$ where $I$ is the candle power of the source and $D$ is the distance from the source in feet.

Diffusion

A physical principle where light rays strike a rough, opaque surface which spreads and breaks up the light in various directions.

Polarization

A process where light rays strike a polarized glass, eliminating horizontal light rays and allowing vertical rays to penetrate, resulting in soft lighting.

Transmission

A physical principle where light rays strike a plain transparent glass surface which allows the rays to proceed farther.

Reflection

A process where light strikes a silvered surface and is reflected back with no diffusion; the angle of incidence is equal to the angle of deflection.

Refraction

A process where light rays strike clear glass at an angle and are reflected within the glass, continuing at another angle on the far side.

Candle Power Distribution Curve

A graphic representation of the distribution of light intensity of a luminaire.

Luminaries

A container of a source light.