Integrated simulation of an aspheric lens combining injection moulding analysis with ray tracing

The present study covers an integrated simulation method for injection-moulded plastic lenses by combining a ray tracing simulation with a finite element (FE) analysis of injection moulding. Traditional ray tracing methods have based on the assumption that the optical properties of a lens are homogeneous throughout the entire volume. This assumption is to a certain extent unrealistic for injection-moulded plastic lenses because material properties vary at every point due to the injection moulding effects. To take into account the effects of the inhomogeneous optical properties of the moulded lens, a new ray tracing scheme is proposed in conjunction with an FE analysis of the injection moulding. A numerical scheme is developed to estimate the distribution of refractive indices from injection moulding analysis, and to calculate ray paths on every element layer with more realistic information of the refractive indices. A fully three-dimensional FE analysis is then performed for the aspheric lens moulding process. Through the FE analysis, the distribution of the refractive indices of the lens can be obtained on every mesh point. This information is then used to calculate the ray paths based on the FE mesh of which nodal points have unique index values. The proposed tracing scheme is implemented on the tracing of an aspheric lens, and its validity is ascertained through experimental verification.