Annealing of Compression Molded Aspherical Glass Lenses

Abstract

Residual stresses and refractive index of molded glass lenses are important quality indicators of their optical performance. In this research, the control of residual stresses and refractive index variation of molded glass lenses were experimentally investigated by postmolding annealing. Residual stresses were quantitatively measured using a circular polariscope. Refractive index was reconstructed and calculated by an optical setup based on Mach–Zehnder interferometer. In addition, geometry of the aspherical surface of lens was also evaluated before and after annealing. The comparison between the measured results before and after annealing showed that residual stresses and refractive index variation were well controlled and the shape of the aspherical surface was largely retained. This comprehensive experimental study demonstrated a suggestion to improve quality of the compression molded glass lens by postmolding annealing for high-precision optical applications.