We put forward a non-contact method for determining the transient two-dimensional (2D) temperature distribution of light emitting diodes (LEDs). A high-speed camera is employed to acquire the 2D reflective light of blue LED under test (468 nm) illuminated by a red LED (690 nm) as the incident light source to avoid the band-gap modulation effect. The 2D transient temperature distribution is derived in terms of temperature-dependent reflective light intensity relationship. Two cases are studied to test the system in this work under (1) 1980 fps frame rate with time resolution of 505 µs at 300 mA, and (2) 5600 fps with time resolution of 179 µs at 500 mA. Compared with the conventional infrared thermal imaging (TI) method, the spatial resolution and the time resolution of this proposed method increase up to one and two orders of magnitude, respectively.

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