Modified pulse-phase thermography algorithms for improved contrast-to-noise ratio from pulse-excited thermographic sequences. (December 2020)

• Record Type: Journal Article
• Authors: Netzelmann, Udo; Müller, David
• Is Part Of: NDT & E international. Volume 116(2020)
• Publication Date: 2020-12
• Subjects: Pulsed thermography -- Pulse phase thermography -- Noise reduction -- Contrast-to-noise ratio; Nondestructive testing -- Periodicals; Contrôle non destructif -- Périodiques; Electronic journals; 620.1127
• DOI: 10.1016/j.ndteint.2020.102325
• Languages: English
• ISSNs: 0963-8695

Abstract

Abstract: Two modified algorithms for pulsed phase thermography were defined. The principle is to mask out parts of the thermal signal that only add noise but contain no significant information. A first algorithm uses a frequency dependent Gaussian window function. A second algorithm leads to a rectangular window function. The algorithms were tested on synthetic signals modeling a circular hidden defect in a plate and experimentally by flash excited thermography on a steel and a polymer sample. For both materials, a significant improvement of the contrast-to-noise ratio from the defects was obtained for higher analysis frequencies. Highlights: Improvement of defect contrast-to-noise ratio in pulse-phase thermography (for higher analysis frequencies) . Demonstration using an analytical defect model and corresponding experiments . Sensitive screening technique for pulsed excitation with unknown defect depth .