Abstract:According to the development requirements of lightweight, miniaturization, and low cost of infrared imaging guidance system, the lightweight design of the optical lens in the guidance system is carried out. By analyzing the principle and processing technology of the metalens lens wavefront control, a mid-infrared wavelength metalens based on silicon and barium fluoride materials is designed by using the transmission phase control principle. The working wavelength is 3 μm, the lens thickness is less than 1 mm, the weight is less than 50 mm, the weight is less than 10 g, the thermal expansion coefficient is low, and the environmental adaptability is good. The finite difference time-domain (FDTD) method is used to simulate the metalens, and the simulation time is shortened by setting symmetric boundary conditions. The simulation results show that when the numerical aperture of the metalens is 0.45, the focusing efficiency is 85% and the focal spot size is 3.4 μm.