However, annealing, regarded as two-step ion exchange, can not only improve the distribution of refractive index but also eliminate inner stress of a len and enhance its mechanical performance.

• 研究发现在制作梯度折射率透镜过程中，一次离子交换后的折射率分布并不理想。而退火作为二次无源离子交换既可改善折射率的分布，可消除透镜的内应力，增强机械性能。