Numerical simulation of residual stress and birefringence in the precision injection molding of plastic microlens arrays

Microlens arrays are critical components in the assembly of display devices used in various telecommunication products. The optical quality of these plastic lenses is very sensitive to the presence of residual stress. In this paper the distribution of residual stress and birefringence of these microlens arrays has been investigated. It is found that maximum residual stress always occurs in the regions near the gate. The predicted trends and patterns of the residual stress and birefringence distribution agree well with the experimental results. The effects of six main processing parameters on maximum value of residual stress are studied. The noticeable discrepancy between the simulation and the experimental results are discussed.