Real-time monitoring of exposure controlled projection lithography (ECPL) process
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Exposure Controlled Projection Lithography (ECPL) is a stereolithographic based additive manufacturing process in which photopolymer resin is used to fabricate lens shaped features. During this process, a dynamic mask projects radiation patterns through a transparent substrate onto the photopolymer resin to grow features from the substrate surface. The Interferometric Cure Monitoring (ICM) system utilizes the principle of Mach-Zehnder interferometer to measure the change in refractive index of the photopolymer resin. The goal of this thesis is to conduct real-time metrology for both the height and the lateral dimensions of the cured part fabricated by the ECPL process. The developed method involves using an electronic iris system to build up a multiple-point interferometry based monitoring system. The developed method could be used to establish real-time feedback control for the additive manufacturing process.