Efficient Measurement of Large Light Source Near-field Color and Luminance Distributions for Optical

Hubert Kostal*, DouglasKreysar, RonaldRykowski

KXOptoelectronics,Shanghai

ABSTRACT

Thecolorandluminancedistributionsoflargelightsourcesaredifficulttomeasurebecauseofthesizeofthesourceandthephysicalspacerequiredforthemeasurement.Wedescribeamethodforthemeasurementoflargelightsourcesinalimited space that efficiently overcomes the physical limitations oftraditional far-field measurement techniques.Thismethod uses a calibrated, high dynamicrange imaging colorimeter and a goniometric system to move the lightsourcethroughanautomatedmeasurementsequenceintheimagingcolorimeter’sfield-of-view.Themeasurementisperformedfromwithinthenear-fieldofthelightsource,enablingacompactmeasurementset-up.Thismethodgeneratesadetailednear-field color and luminance distribution modelthat can be directly converted to ray sets for optical design andthatcan be extrapolated to far-field distributions forillumination design. The measurements obtained showexcellentcorrelationto traditional imaging colorimeter and photogoniometer measurement methods. Thenear-fieldgoniometerapproach that we describe is broadly applicable to general lighting systems,can be deployed in a compactlaboratoryspace,andprovidesfullnear-fielddataforopticaldesignandsimulation.

Keywords:imagingcolorimetry,opticaldesign,illuminancedistribution,near-fieldmodels,imaginggoniometer