Lighting and Color Introduction Lighting Science - Illuminating ...

8/18/2011PhotometryPhotometry involves the physical measurement of visible lightenergy and attempts to compensate for the psychophysicalattributes of the human response and physical units of power.Photometry is just like radiometry except that everything isweighted by the spectral response ( luminosity) of the humaneye as defined by the CIE.PhotometryThe photometric quantity, Luminance, is derived from thecorresponding radiometric quantity, Radiance, and the CIEStandard Luminosity Function. We can think of the luminosityfunction as the transfer function of filters which approximatethe sensitivity of the human eye.Radiometric CIE Standard Luminosity PhotometricQuantityFunction (V )QuantityExample:Illuminance: 500lxLuminance: 15cd/m 2Relationship between radiometric units and photometric unitsComing soon to a theater near youMany systems and methods have been devised to quantify light sources so thatcommunication of color would become easier and more accurate. Thesemethods attempt to provide a way of expressing a light sources color and energyoutput and tolerances numerically, in the same way we express length andweight. In some of our follow up presentations we will discuss some of thesemetrics in more detail. Some of these topics will include:• Color Science•Lighting Measurements and Metrics• Colorimetry versus Spectroradiometry• Use of Instruments• Understanding Lighting Values Luminance / Illuminance• Spectral Power Distribution SPD• Comparing Light Sources• Color Rendering Index CRI and CQS•CIE Method for Assessment of Daylight• LM 79, LM80 and Energy Star RequirementsAnd much more!12