Design of He-Ne laser beam focusing lens based on Zemax

In order to obtain a reasonable He-Ne laser beam focusing lens, the high refractive index double pieces with front convex is used and Zemax is adopted for optimization and design. A He-Ne laser beam focusing lens with dispersion speckle diameter of 0.002mm was obtained. Spherical aberration of the axial point was modified. The diameter of the dispersion speckle of the lens is smaller than that of single piece, which is 0.0019mm. The spherical aberration is modified to -0.05mm～+0.05mm. The area compassed by MTF curves increases. So the brightness of the center is increased, which meets practical needs.