Thermal inspection of low emissivity surfaces using a pulsed light emitting diodes (PLED) heat source

Joseph N. Zalameda; Peter W. Spaeth; Samuel J. A. Hocker

doi:10.1117/12.3016162

7 June 2024 Thermal inspection of low emissivity surfaces using a pulsed light emitting diodes (PLED) heat source

Joseph N. Zalameda, Peter W. Spaeth, Samuel J. A. Hocker

Proceedings Volume 13047, Thermosense: Thermal Infrared Applications XLVI; 1304716 (2024) https://doi.org/10.1117/12.3016162
Event: SPIE Defense + Commercial Sensing, 2024, National Harbor, Maryland, United States

Abstract

Thermal inspections of a structure typically utilize a flash or quartz lamp heat source located on the same side of an infrared camera. The heat source provides light energy for heating while the infrared camera measures the surface transient temperature response. The inspection can be difficult for low emissivity surfaces for several reasons. First, the high intensity light can reflect off the surface and cause “burn-in” to the camera’s detector. The “burn-in” can take time for the sensors to recover and potentially damage the detector. Secondly, the heat source after pulsing has a transient cool down component. The cool down component can be reflected and therefore superimposed over the structure’s thermal response, which can cause an error (false defect indications) in the inspection. Lastly, the heat source is spectrally broad and therefore while heating, infrared components of the heat source can produce non-uniformity in the measured temperature field. Typically for the inspection of low emissivity surfaces, paint or other emissivity enhancing coatings are applied before inspection. In this paper, a pulsed light emitting diodes (PLED) heat source is used. The PLED heat source is spectrally narrow, contained within the visible band, and therefore not detectable by the infrared camera. The PLED heat source is configured to reduce any transient cool down components that could produce false defect indications. The PLED thermal inspections are compared to flash thermography inspections on unpainted aluminum samples with simulated corrosion and an additively manufactured Ti-6AL-4V metal specimens.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Joseph N. Zalameda, Peter W. Spaeth, and Samuel J. A. Hocker "Thermal inspection of low emissivity surfaces using a pulsed light emitting diodes (PLED) heat source", Proc. SPIE 13047, Thermosense: Thermal Infrared Applications XLVI, 1304716 (7 June 2024); https://doi.org/10.1117/12.3016162

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