Laser excited super resolution thermal imaging for nondestructive inspection of internal defects

TL;DR

This paper introduces a laser-excited super resolution thermal imaging method that enhances nondestructive internal defect detection in materials by combining advanced thermography, multiple measurement configurations, and compressed sensing-based image processing.

Contribution

It presents a novel photothermal super resolution technique that improves internal defect detection in additively manufactured metals using laser excitation and compressed sensing.

Findings

Outperforms conventional thermography in defect resolution

Effective in detecting closely spaced internal cavities

Versatile across multiple measurement configurations

Abstract

A photothermal super resolution technique is proposed for an improved inspection of internal defects. To evaluate the potential of the laser-based thermographic technique, an additively manufactured stainless steel specimen with closely spaced internal cavities is used. Four different experimental configurations in transmission, reflection, stepwise and continuous scanning are investigated. The applied image post-processing method is based on compressed sensing and makes use of the block sparsity from multiple measurement events. This concerted approach of experimental measurement strategy and numerical optimization enables the resolution of internal defects and outperforms conventional thermographic inspection techniques.