Optical glass has been widely used in optical device manufacturing due to its high degree of physical and chemical homogeneity, which is considered as one of most important indicators of optical performance. Thermal stress during production has a significant impact on the optical homogeneity of the glass and it is primarily generated from temperature difference at different parts of the glass during annealing process which includes coarse and fine phases. Accumulation of thermal residual stress at early cooling stage will not only cause the cracking of the glass during process, but also affect the following fine annealing, especially, for the symmetric pattern of stress distribution. This paper focuses on mitigating of radiation influence and controlling cooling rate during coarse annealing in order to reduce thermal residual stress in the process. Numerical models are established to simulate the coarse process and investigate the homogeneity of temperature distribution at different conditions. Simulation results show that the coarse annealing process can be optimized through changing glass configuration and cooling rate.

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