Title: Compact measurement of the optical power in high-power LED using a light-absorbent thermal sensor

Abstract

LED (Light-Emitting Diode) presents advantages such as luminescence, reliability, durability compared with conventional lighting. It has been widely applied for life, healthcare, smart farm, industry, and lighting from indoor to the automotive headlamp. However, the LED is vulnerable to thermal damage originated from the high junction temperature, especially in high power applications. Hence, it requires precise qualification on the optical power and the junction temperature from the pilot line to secure reliability. In this study, the photo-thermal sensor is pro-posed by employing a sheet-type thermocouple composed of photo-absorbent metal film and thermocouple. This sensor aims low-cost qualification in pilot line for high-power luminous devices and optical monitoring of costly luminaire such as automobile LED headlamp. The sensor is designed to detect the increased temperature response of LED hot spots from the transferred thermal power and absorbed optical power. The temperature response of each sheet-type thermocouple is utilized as a signal output of the absorbed optical power and hot spot temperature based on the introduced sensor equation. The proposed thermal sensor is evaluated by comparing the experiment with the measured reference value from the integrating sphere and the attached thermocouple at a junction. The experiment result reveals 3% of the maximum error for the optical power of 645 mW.

Biography

Jaeyoung Joo received B.S degree mechanical engineering from the Yeungnam University, Daegu, South Korea, the M.S. and Ph.D. degree in Mechanical Engineering from the Gwangju Institute of Science and Technology, Gwangju, South Korea. He is a senior research engineering with the Korea Photonics Technology Institute in Gwangju, South Korea, where he is engaged in advanced LED lighting technology and integrated optical system for monitoring and sensing applications in industrial fields. His research interests include the micro LED light source and display technology, developing integrated system for lighting control with optical sensor linked to automatic shade, curing technology for silicone encapsulant for LED.