Abstract – The important function of headlights is correctly illuminate theroad by avoiding excessive glare. This task is controlled by type approvalrequirements and in-use exploitation requirements. Because of historical reasons present UN ECE type approvalrequirements for headlamps are relatively simple and require only minimumvalues. The other international requirements such as USA do not differ significantly. Contemporarytechnology and manufacturing possibilities allow for much better illuminatingperformance than this minimum requirements giving excess of luminous flux andoptical systems effectiveness. As a result many headlamps, especially OEM,exceed significantly minimum values allowing for good road illumination withsignificantly restricted glare. There are also differences between OEMheadlamps dedicated to different vehicles models, because different factorsinfluence final headlamps performance like outside look, geometrical size,manufacturing costs, technology used (as halogen, HID, LED, light source,reflection or projection system choice geometrical size etc.). The other reasonfor presence on market of different photometrical performance are replacementsmade by other than OEM headlamp manufacturers. Even such headlamps are usuallytype approved their performance usually differs from original parts.Manufacturers of replacement most often compete by price rather than quality. Aftercollision or crash headlamps are usually destroyed and during repair processfirst choice is price and good external look. In addition car owner or garageengineer have no possibility to compare and assess photometrical quality ofspare part. In such situation the most important factor is price.

To obtain basic impression regarding featuresand differences between OEM headlamps offered for different cars and theirreplacements the tests are carried out. Photometric characteristics aremeasured by “Headlight’s analyzer” – diagnostic tool with photometric cameraand appropriate software. Presently to compare headlamps can be used typeapproval requirements with measuring points and zones or e.g. CIE TC4-45method. For this tests for selected examples of headlamps was used general“expert” method comparing isolux lines at vertical screen and at the roadsurface.

Keywords:Headlamps, photometry, qualitycomparisons