#LED LIGHT TABLE MEASURING CAPABILITY PLUS#

Measured color temperature uniformity of LED manufacturer sorted single white LEDs within a LED arrayĬurrent state of the art LED intensity and color measurement devices employ spectral measurement technology.

#LED LIGHT TABLE MEASURING CAPABILITY PLUS#

Plus their large linear dynamic range and fast response time makes them irreplaceable for several applications. Note that filter photometers are still widely used and do an excellent job when properly specified and applied. Quasi-monochromatic LEDs and blue LED stimulated white LED emission spectra are totally different than that of the calibration source and may create further unknown increases in measurement uncertainty.

This is due to the filter photometer spectral mismatch error. However, measurement uncertainties increase significantly for light sources with a different spectral distribution than the calibration source like fluorescence tube lamps (FTL) and compact fluorescence lamps (CFL) which have higher blue spectral content. Test light sources with a similar broadband, continuous with low blue spectral content emission spectra can be measured using the filter photometer with acceptable measurement uncertainties. Filter photometers and luminous color meters are typically calibrated with CIE Standard Illuminant A calibration lamps which are tungsten halogen lamps operated at 2856°K. For decades the filter photometer has been the basic tool for all kinds of light measurement applications in research and industry. The spectral response of these detectors are made to match the CIE and DIN standardized V(λ), Y(λ) and Z(λ) spectral functions as close as possible. Traditional light and luminous color meters are built with photometric V(λ) and colorimetric RGB filtered detectors. Since high volume LED sorting by the manufacturer cannot be done under real operation conditions the LED processing industry requires measurement technology that supports sorting and qualification at the implementation stage.ĬIE and typical filtered detector V(λ)response with tungsten lamp and white LED emission spectrum This difference between sorting test and operation temperature seems to be the reason that upon visual inspection unacceptable variations in the finished assembled LED matrix are noticed. In the LED sorting measurement process which lasts only a few milliseconds per LED the junction and phosphor temperature of blue LED stimulated white LEDs will be much cooler as compared to the operation temperature in the actual application. That's why for best accuracy the light source under test is burned-in to a stable operating temperature before measurement. As with any light source the LED light and color specifications are effected by operating temperature. Due to the high volume production demands the measurement process had to be fast with the LED under test under operation for only a few milliseconds. The low tolerance variations required LED manufacturers to respond by improved processing technologies and compensation for any remaining differences caused by the sorting and binning of the LEDs. This article describes measurement technologies and quantities useful for LED qualification as well as the description of a LED lightmeter for industrial use. Since the human eye is extremely sensitive to differences in color and intensity of lighting devices when placed side by side, tolerances in intensity and color temperature become critical.

An LED luminaire or fixture is constructed by combining many single LEDs in a matrix configuration. Tremendous progress in the development of functional high efficiency high power white LEDs has made it possible to employ them in general lighting fixtures replacing traditional bulb and other type lamps. Solid state lighting employing Light-Emitting Diodes (LEDs) is evolving and transforming the entire world of lighting.

Led light table measuring capability