Characterizing light engine uniformity and its influence on liquid crystal display based vat photopolymerization...

Area of Science:

• Additive Manufacturing
• Photopolymerization Science
• Optical Engineering

Background:

• Vat photopolymerization (VP) is a rapidly advancing additive manufacturing technology.
• High reproducibility of printed parts is expected as VP methods mature.
• Current liquid crystal display (LCD)-based VP light engines lack detailed characterization, raising concerns about their suitability for demanding applications.

Purpose of the Study:

• To comprehensively map the optical properties of a 405 nm LCD-based VP light engine.
• To assess if current light engine manufacturing tolerances meet additive manufacturing needs.
• To investigate the impact of light engine spatial variations on polymerization and part fidelity.

Main Methods:

• Characterization of irradiance, spectral properties, and optical divergence across the LCD-based VP light engine.
• Derivation of a photon absorption figure of merit.
• Fabrication and analysis of printed test parts to evaluate spatial heterogeneity effects.

Main Results:

• Significant spatial variations were observed in irradiance, spectral characteristics, and optical divergence.
• These optical heterogeneities directly influence the extent of photopolymerization and surface texture of printed parts.
• A derived photon absorption figure of merit and printed parts confirmed that spatial variations impact part fidelity.

Conclusions:

• Spatial heterogeneity in LCD-based VP light engines is a significant factor affecting printed part quality and reproducibility.
• The findings explain potential causes of variable part quality in additive manufacturing.
• There is a clear need for enhanced optical performance and tighter manufacturing tolerances in LCD-based VP printers.