Inline Spectroscopy as Process Analytical Technology for Photoresins: Identity, Concentration, Conversion and Drift

Inline spectroscopy becomes process analytical technology only when the optical interface, sampling volume, preprocessing and calibration model are controlled well enough to relate a spectrum to a declared material state. Window fouling, path length, bubbles, pigment scattering and local flow can dominate apparent spectral change. Chemometric models should declare calibration domain, reference method, preprocessing and prediction uncertainty. Real-time Raman can track depletion of reactive bands and reveal initiation, rate changes and endpoint behaviour. A spectrum can confirm that a material belongs to the expected class while still missing a concentration shift within that class. Qualification therefore depends on preserving the measured state, configuration and exception history needed to distinguish these mechanisms in production rather than relying on nominal recipe identity alone.

ER-342 · Version 0.5.