Probing Temperature and Degree-of-conversion States via Tomographic Fluorescence Imaging

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Lak, Sui Man
Li, Chi Chung
Toombs, Joseph
de Beer, Martin
Taylor, Hayden

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University of Texas at Austin


Tomographic volumetric additive manufacturing rapidly solidifies freeform objects via photopolymerization, which raises both local temperature and degree-of-conversion (DOC). Insitu monitoring of temperature and DOC during the printing process is crucial for metrology and process control. In this study, we propose a tomographic fluorescence imaging technique to detect the spatiotemporal evolution of temperature and DOC during volumetric printing. Our solution employs a fluorescent dye that is sensitive to both variations in temperature and DOC. DOC is considered as a function of, and is expressed in, the absorbed optical dose of the resin. By tomographically measuring changes in the dye’s fluorescence intensity and feeding such changes to a temperature–dose–intensity calibration, the local dose and temperature during the print can be confined to a set of possible states. At exemplar locations where a priori information is known for one quantity, the other quantity can be resolved. This work illustrates the potential of and lays foundations for the development of two-wavelength spatiotemporal measurement systems that uniquely resolve both temperature and DOC.


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