We present a novel structured illumination optical metrology system for in-situ, real-time monitoring of advanced manufacturing processes. Key aspects of this technology include 1) surpassing classical resolution limits independent of the contrast mechanism, 2) high-speed imaging (can be performed with a single ultrafast laser pulse), 3) is compatible with long working distance optics, and 4) can be deployed in an environment where the specimen scatters the signal light. This combination of characteristics helps address challenges in the advanced manufacturing industry and can ultimately be used to validate statistically significant process parameter-signature-quality relationships with quantified uncertainty. For example, we demonstrate, for the first time to our knowledge, the coaxial monitoring of melt track formation in steel powder in a laser powder bed fusion environment with a structured illumination system.

Quantitative comparisons are given that validate the resolution enhancements that follow from this optical metrology method. To date we have used excitation wavelengths that span from 523 nm to 7 micrometers, and have shown resolution gains in linear, linear fluorescence, nonlinear fluorescence, second and third harmonic generation imaging modalities. Exposure times can range from the excitation pulse itself, and 100 Hz frame rates can be achieved. The overall architecture of the optical system is simple to deploy, and robust in operation. Real-time signals will be presented.