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Compact Measurement of the Optical Power in High-Power LED Using a Light-Absorbent Thermal Sensor.
You-Young Kim1, Jae-Young Joo2, Jong-Min Kim1
1School of Mechanical Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea.
Sensors (Basel, Switzerland)
|July 24, 2021
Summary
A novel photo-thermal sensor offers low-cost qualification for high-power Light-Emitting Diodes (LEDs). This sensor accurately monitors optical power and junction temperature, ensuring LED reliability in various applications.
Area of Science:
- Materials Science
- Optoelectronics
- Thermal Engineering
Background:
- Light-Emitting Diodes (LEDs) offer superior luminescence, reliability, and durability over conventional lighting, finding applications in diverse fields from healthcare to automotive lighting.
- High-power LEDs are susceptible to thermal damage due to high junction temperatures, necessitating precise optical power and junction temperature qualification for reliability.
- Current qualification methods can be costly, especially for pilot lines and expensive luminaires like automotive LED headlamps.
Purpose of the Study:
- To propose a low-cost photo-thermal sensor for precise optical power and junction temperature qualification of high-power LEDs.
- To enable reliable monitoring of LED hot spots and optical power in pilot lines and automotive headlamps.
- To develop a sensor that utilizes temperature response for accurate measurement based on a derived sensor equation.
Main Methods:
- Development of a sheet-type thermocouple sensor incorporating a photo-absorbent metal film and a thermocouple.
- Design of the sensor to detect temperature increases in LED hot spots caused by transferred thermal and absorbed optical power.
- Experimental evaluation by comparing sensor output with reference measurements from an integrating sphere and attached thermocouple.
Main Results:
- The proposed photo-thermal sensor effectively detects temperature responses related to absorbed optical power and hot spot temperature.
- Experimental validation demonstrated the sensor's capability to provide optical power and junction temperature signals.
- The sensor achieved a maximum error of 3% for optical power measurements up to 645 mW.
Conclusions:
- The developed photo-thermal sensor provides a viable low-cost solution for qualifying high-power LEDs.
- The sensor enables accurate optical power and hot spot temperature monitoring, crucial for ensuring LED reliability.
- This technology is particularly beneficial for pilot line qualification and monitoring of high-value luminaires like automotive LED headlamps.
