StellarNet spectrometers for LED testing

June 6, 2008
Date Announced: 06 Jun 2008 LEDs are ubiquitous in the world today, from automobile lights to billboard displays to entertainment lighting. Solid-state technology is transforming the lighting industry and LEDs will eventually replace incandescent and 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. These spectrometers do not use 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 instrument. 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 detector array resulting in uniform resolution and minimized stray light. 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 measure in tenths of a second, allowing the LED sorting machine to run at maximum speed. The advantages of using miniature ruggedized spectrometers are the low maintenance and portable measurements. 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. StellarNet is an industry-leader in low cost spectrometers for process control applications.

Ryan Flaherty, StellarNet Inc. 14390 Carlson Circle Tampa, FL 33626 USA

E-mail:[email protected]