When compared to traditional lighting, LED (Light-Emitting Diode) offers advantages such as luminosity, reliability, and durability. It's been used in a variety of applications, including life, healthcare, smart farming, industry, and lighting, ranging from indoor to vehicle headlamps. The LED, on the other hand, is susceptible to thermal damage caused by the high junction temperature, which is especially true in high-power applications. As a result, to ensure reliability, exact certification of the optical power and junction temperature from the pilot line is required. The photo-thermal sensor is proposed in this study, which uses a sheet-type thermocouple made up of a photo-absorbent metal film and a thermocouple. This sensor is designed to provide low-cost certification in a pilot line for high-power luminous devices and optical monitoring of expensive luminaires such vehicle LED headlamps. From the transferred thermal power and absorbed optical power, the sensor is designed to detect the increasing temperature response of LED hot spots. Based on the introduced sensor equation, the temperature response of each sheet-type thermocouple is used as a signal output of the absorbed optical power and hot spot temperature. The sensor equation is modelled using the lumped capacitance model of each sheet-type thermocouple, with the view factor and additional optical power absorption component taken into account. The experiment is compared to the measured reference value from the integrating sphere and the associated thermocouple at a junction to evaluate the proposed thermal sensor. For an optical power of 645 mW, the experiment result reveals a maximum inaccuracy of 3%.
Author(S) Details
Youyoung Kim
School of Mechanical Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea.
Jae-Young Joo
Korea Photonics Technology Institute, Gwangju 61007, Korea.
Jong-Min Kim
School of Mechanical Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea.
Sun-Kyu Lee
School of Mechanical Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea.
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