LED近场测试.doc

kengLEDs’ near-field distribution testing Abstract: With the development and application of LEDs,it is becoming increasingly important to be able to measure the performance of LEDs and LED-based systems in accurate and meaningful ways.The intended purpose of the measurement to inform development, to characterize or evaluate finished products, for production quality control, or for in-use performance assessment determines by the photometric and colorimetric quantities which are important to measurement.Considering the evolution of LED from point light source to surface light source,far-field distribution measurement can’t satisfy the measurement requirement.So that the selection of the new measurement about near-field testing method and system is necessary.Near-field testing contains more spatial photometric and colorimetric information than far-field testing,also the far-field characteristic distribution can be extrapolated from the near-field one.In addition,the precise measurement will support LED luminaire design. Near-field testing has many advantages,such as measuring LED dies and package,supporting optical engineering package design,optical engineering package design,producing headlamps, and so on. Near-field testing measures luminance (spatial distribution) of the LED at many view angles, which includes luminous intensity data. with an imaging detector (CCD camera) rotated about the LED, this test will provides luminance matching view angle data. A testing system named goniophotometers are designed to very accurately measure the near-field luminance distribution of a light source. It can capture the output light distribution at the source from multiple viewing angles ,gain the corresponding data,then make a near-field model to analyze by a software. Off course this system has a number of physical configurations . With two independent axes of rotation, this system maintains precise positioning between the DUT (device under test) and the imaging colorimet