Application of single-element-detection spatial frequency modulation imaging to monitor process signatures within laser powder bed fusion melt pools, The

Laser Powder Bed Fusion (LPBF) is a form of metal additive manufacturing which uses a laser to melt metal powder together to produce fine-structure parts in geometries unattainable through traditional subtractive manufacturing methods. The time and length scales of LPBF make it challenging for traditional sensors to monitor defects, certify parts as they print, or provide control during the printing process. Commonly implemented detectors are photodiodes and cameras. Spatial Frequency Modulation Imaging (SPIFI) is a novel imaging technique which returns enhanced-resolution, enhanced-contrast images with single-element detectors and structured light, combining the benefits of cameras and single-element detectors with a further resolution enhancement. In this work, SPIFI was applied to monitor LPBF melt tracks with active illumination and by passively imaging the laser-metal interaction. First, SPIFI monitoring was benchmarked against the performance of a camera and was shown to be able to detect melt track geometry. Second, SPIFI monitored spatial information at length scales smaller than a LPBF melt pool. Third, a SPIFI system was developed to monitor the fusing beam in LPBF. Finally, a SPIFI system which could monitor temperature was created and demonstrated observation of thermal gradients within the melt pool. The spatial resolution of all systems was robustly characterized.

Name thesis:degree_name

Doctor of Philosophy (Ph.D.)

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Physics

Grantor dc:publisher

Colorado School of Mines. Arthur Lakes Library

Year dc:date.issued

2025

Author dc:creator

• Hunter, Scott A.

Advisor dc:contributor.advisor

• Squier, Jeff A.

Committee members dc:contributor.committeemember

• Adams, Daniel E.
• Durfee, Charles G.
• Higgins, Callie
• Brice, Craig Alan, 1975-

• beam shaping
• Fourier single pixel imaging
• laser powder bed fusion
• melt pool monitoring
• pyrometry
• thermal imaging

Statement dc:rights

• Copyright of the original work is retained by the author.

Language dc:language.iso

eng, English

Identifier

T 10036

OAI record oai:identifier

https://repository.mines.edu/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Anull%3A11124%2F182076