In-Situ Raman Spectroscopy for Process Optimization in Volumetric 3D Printing

Volumetric 3D printing via Xolography enables the fabrication of complex objects with micrometer resolution in a matter of minutes. Dual-color photoinitiators (DCPIs) and twowavelength irradiation are crucial for the spatial control of photopolymerization. To date, process optimization has largely relied on post-print evaluation, lacking real-time insights into the polymerization kinetics. We present a novel methodology using in-situ Raman spectroscopy to characterize the dual-color curing response of spiropyran-based DCPIs. By implementing a dual-wavelength irradiation setup, we monitor the degree of curing (DoC) as a function of applied light doses and compare different resin formulations. Our results provide quantitative data on bond conversion and polymerization rates, allowing for the precise derivation of contrast parameters, efficiency as well as the process window for Xolography. This approach offers a robust framework for the rational design of resin compositions and the optimization of illumination protocols, ultimately enhancing the efficiency and reliability of volumetric additive manufacturing. 48 ive Fertigung und Materialbearbeitung Tobias Biermann D O N N E R S T A G