Method for designing metalens used for image sensor

A method for designing a metalens used for an image sensor, and the metalens comprising a substrate and a plurality of unit cells, wherein the method comprises:

• S1:
• determining a target waveband;
• S2:
• according to the target waveband, determining an initial structure parameter of the unit cells and an initial material parameter of the unit cells;
• S3:
• optimizing the initial structure parameters of the unit cells and the initial material parameters of the unit cells, so as to obtain a plurality of target parameters of unit cells;
• the target parameters of unit cells comprise:
• a phase of the unit cells and transmittance of the unit cells for an oblique incident light;
• S4:
• determining whether the transmittance of the metalens with the target structure parameter of unit cells meets the target transmittance;
• if so, outputting the target parameter of unit cells;
• if not, updating the initial structure parameter of the unit cells and the initial material parameter of the unit cells, and repeating the steps from S2 to S4 until the optimized transmittance of the metalens with the target parameter of unit cells meets the target transmittance.