Complete thermal, optical & electrical characterisation of LEDs

Content Dam Leds En Ugc 2011 01 Complete Thermal Optical Electrical Characterisation Of Leds Leftcolumn Article Thumbnailimage File
29613 0 thumb Date Announced: 06 Jan 2011

Pro-Lite has released the Labsphere TOCS series of integrating sphere spectroradiometers which provide complete thermal, optical and electrical characterisation of LEDs and LED modules in strict accordance with the IESNA standard methods LM-79 & LM-80. A TOCS system is based upon a 20, 40, 65 or 76-inch interior access sphere with provision for both 2pi forward & 4pi total flux measurements.

The amount and colour of light from LEDs varies greatly with both operating current and temperature. A TOCS integrating sphere system is a fully integrated, out-of-the-box spectroradiometer that can characterise the variation of luminous flux (in lumens) and colour (correlated colour temperature in Kelvin) from LED products as a function of temperature and electrical drive level. A TOCS spectroradiometer system saves time and money compared with performing thermal, electrical & optical characterisation tests manually, while the fact that the TOCS is a turn-key test station means no time is wasted integrating a system from disparate components.

A TOCS system comprises an interior access integrating sphere coupled to a fast CCD spectrometer. The device under test is held on a temperature controlled electrical socket which is placed at the external source port on the sphere for 2pi flux measurements. The system includes a choice of calibration source (external 2pi, internal 2pi or 4pi), auxiliary lamp for correction of sample absorption and power supplies for the calibration and auxiliary lamps.

A TOCS spectroradiometer system is controlled from a Windows® PC using Labsphere's menu driven TOCS application software. The optical parameters reported include the spectral radiant flux, luminous flux, CIE chromaticity (xy, u'v'), correlated colour temperature (CCT), dominant wavelength, spectral purity and the colour rendering index (Ra, R1-14). The electrical parameters reported are the drive current and voltage, the power consumed, and the luminous efficacy (electrical to optical efficiency), reported in lumens per Watt. The case temperature of the LED or LED module is also recorded.

TOCS software allows users to control the LED temperature and operating current at specified ranges. This control enables the software to measure and characterise the device under test over a wide range of temperatures. System software can automate procedures for measuring the spectral characteristics and controlling current and temperature. Software simultaneously collects electrical, optical and thermal data which is graphed and viewed on screen, or can be exported to a spreadsheet for further analysis.

Pro-Lite Technology Ltd Innovation Centre University Way Cranfield, MK43 0BT, UK Tel: +44 (0) 1234 436110


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