At the invitation of Prof. Gao Liang, Prof. David W. Rosen from Georgia Institute of Technology visited MSE on June 21, 2017. He delivered a lecture entitled “Process Measurement and Control of Mask Projection Stereolithography Processes”. Teachers and students from other schools of HUST and other universities who carried out relative research also attended this report.

Exposure Controlled Projection Lithography (ECPL) is a variation in the manufacturing process of masked stereolithography lithography. Unlike other types of stereolithography processes, the ECPL system cures a 3D part by projecting from beneath a stationary and transparent substrate ultraviolet radiation, which is modulated by a sequence of bitmaps varying the exposure intensities, patterns and durations.

In the report, Professor David firstly introduced Georgia Institute of Technology and Singapore University of Technology and Design where he is currently taking a temporary post. Subsequently, he explained an in-situ interferometric curing measurement (ICM) system which has been developed to measure the ECPL process output of cured height profile. The exposure cured height is controlled by a closed-loop feedback on-off controller. The experimental results directly validate the ICM system’s real-time capability in capturing the process dynamics and in sensing the process output. A comprehensive error analysis was made for the uncertainties in the process of ECPL, external noise of ICM system noise and computational interruptions. The result showed that the system can be controlled by hardware to achieve submicron level control. In the end, he introduced the future research plan of his research team.

The report concluded successully with a lively discussion on ECPL and ICM issues among Prof. David and the teachers and students presented afterwards.

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Visiting campus

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