Influence of Spectral Bandwidth on the Working Curve in Vat Photopolymerization

Area of Science:

• Additive Manufacturing
• Polymer Science
• Optical Engineering

Background:

• Vat photopolymerization fabricates 3D parts by curing liquid resin with patterned light.
• The working curve measurement (cured depth vs. radiant exposure) is foundational.
• The current Jacobs model assumes monochromatic light, often showing data deviations.

Purpose of the Study:

• To extend the Jacobs model for vat photopolymerization to polychromatic (broadband) light sources.
• To explain deviations in the Jacobs model using an optical 'inner filter' effect.
• To provide an empirical model for better experimental data fitting and parameter estimation.

Main Methods:

• Derivation of a polychromatic mathematical model for the working curve.
• Experimental validation using broadband light sources (e.g., LEDs).
• Theoretical analysis of the 'inner filter' effect and absorption spectra.

Main Results:

• The polychromatic model accurately describes working curves with broadband light sources.
• Deviations from the Jacobs model are explained by the 'inner filter' effect.
• Model performance depends on light source bandwidth and resin absorption spectrum gradient.

Conclusions:

• The extended Jacobs model improves predictions for vat photopolymerization with LEDs.
• Understanding the 'inner filter' effect is crucial for accurate working curve analysis.
• This work enhances the link between working curve measurements and photophysical properties.