High-Throughput and High-Sensitivity Terahertz Scanners for Non-Destructive Evaluation of Non-Conductive Coatings and Thermal Protection Systems in Space Applications

To address NASArsquo;s need for advanced non-destructive evaluation (NDE) sensors, Lookin, Inc. proposes to develop a transformative diagnostic tool to identify and localize visually inaccessible defects and damages in non-conductive coatings and thermal protection systems with significantly higher throughputs and over significantly larger volumes compared to what can be offered by existing NDE tools. More specifically, we propose to develop a contactless multi-pixel terahertz imaging system capable of capturing three-dimensional terahertz images of samples with a 5times;5times;20 cm3 volume and a scan rate of 100 Hz, while providing a signal-to-noise ratio of 65 dB and lateral/depth resolution of 100/10 micro;m. This terahertz imaging system is controlled by a data analysis algorithm that is capable of creating B- and C-scan images of the sample and automatically determining the position of the structural defects, such as cracks, voids, and delamination, within the samples.During the Phase I project, a laboratory prototype of the NDE scanner based of the multi-pixel terahertz imaging system will be developed by using a high-power terahertz source and a high-sensitivity terahertz focal-plane array. The prototype will be used to take terahertz images of non-conductive ceramic structures in laboratory environment to characterize tradeoffs between different system parameters such as scan rate, image depth, spatial/depth resolution etc. The data acquisition and analysis algorithms will be experimentally evaluated.During the Phase II project, a remote-controllable field prototype of the NDE scanner will be developed and the optimized system components will be packaged in a robust, portable platform suitable for in-situ NDE applications in field settings. The field prototype will be used to evaluate CMCs and other non-conductive composites used in aerospace systems and an advanced application software will be developed for the scanner with an easy-to-use guided interface.