Abstract: A fast response thermometer is designed by using a pt100 surface mounted resistor.The effect of temperature on the photoelectric parameter of a high power LED supplied by a constant current source or a constant voltage source respectively is investigated real-timely by using the thermometer,which has less measurement error and higher measurement efficiency.The experimental results show that when the LED＇s temperature rises,the luminous intensity of the LED increases under the constant voltage source and decreases under the constant current source,and the luminous efficiencies of the LED all decrease under the both sources.

Key words: white LED, luminous intensity, temperature characteristics