Precision glass molding technology for XY polynomial freeform optical elements with simulations and experiments

Area of Science:

• Optical engineering
• Materials science
• Manufacturing technology

Background:

• Precision glass molding (PGM) is mature for aspheric lenses but nascent for freeform optics.
• Conventional ultra-precision methods for freeform elements are costly and multi-step.
• PGM offers an efficient and economical alternative for freeform lens production.

Purpose of the Study:

• To investigate and optimize PGM technology for freeform optical elements.
• To establish a pre-compensation model for freeform mold cores.
• To predict and minimize residual stresses in molded freeform lenses.

Main Methods:

• Finite element method (FEM) simulations to predict residual stresses.
• Experimental verification of molding temperature, rate, and force effects.
• Development and application of a pre-compensated mold core model.

Main Results:

• FEM simulations accurately predicted residual stress trends with varying process parameters.
• Optimal process parameters yielded a PV value of approximately 1.5µm.
• The pre-compensated mold core reduced the molded lens PV value to below 1µm.

Conclusions:

• The established pre-compensation model is valid and effective for improving freeform lens molding accuracy.
• PGM technology, enhanced by mold core pre-compensation, is a viable method for mass-producing high-precision freeform optical elements.
• Optimized process parameters and mold design are crucial for achieving low residual stress and high surface quality.