StellarNet offers eXtreme Spectrometers for LED Sorting

Date Announced: 02 Apr 2008

LEDs are ubiquitous in the world today; from automobile lights to billboard displays, LEDs are everywhere. Solid-state technology is transforming the lighting industry and LEDs will eventually replace fluorescent lamps altogether.

In order to have uniform lightning, it is important for LEDs to match exactly in color. LED sorting machines are using extremely fast fiber optic spectrometers with millisecond timeframes for color sorting of LEDs. The color parameters of LEDs can be determined by a radiometrically calibrated fiber coupled spectrometer, such as the StellarNet EPP2000C Concave Grating USB2 Spectrometer.

The LED’s emitted light is collected via fiber optic cable which is connected to the optical entrance of a spectrometer. Inside the spectrometer’s optical bench, the light is collimated onto a concave grating which projects a flatfield wavefront image onto a CCD2048 detector array. This image is read out by high speed electronics which transfers the data into colorimetric values (x and y) and LED specific quality parameters, such as dominant wavelength and CCT (see Figure 1).

An important aspect of this application is the speed and accuracy with which the LEDs can be classified. The EPP2000C spectrometers can run at a 1 ms integration time, allowing the LED sorting machine to run at maximum speed. The advantages of using miniature ruggedized spectrometers are the low maintenance and deadtime of the LED sorting machine. The PC connected to the spectrometer gets the LED data through high speed USB2 interface and can control the sorting valves of the LED sorting machine. These spectrometers use no mirrors or moving parts, which translates to very low stray light values and uniform resolution across the entire spectral range. With this design, the unit is very rugged and can be vibrated, dropped, etc. with no harm to the optical bench. StellarNet is an industry-leader in low cost spectrometers for process control applications.

For more information, please email us at

Michelle Ritchie StellarNet Inc. 14390 Carlson Circle Tampa, FL 33626 USA


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