Based on that the laser rod is equivalent to gradientindex rod (GRIN), a new thermal lens focal length expression was achieved.
把激光棒等效为梯度折射率棒，得到了新的热透镜焦距公式。
2
The accurate expressions to calculate the aberration for two sorts of lens decrease on the increase of gradientindex.
严格的数值计算结果表明：两类透镜的纵、横向球差都随折射率梯度的增强而减小。
3
The spherical gradient refractive index micro-lens with small volume and short optical path can be easily shaped and conveniently adjusted, and has no spiral rays and low spherical aberration.