讨论了多层衍射光学元件的光学成像性质.给出了优化设计多层衍射光学元件最大光栅厚度的方法,分析了构成多层结构的每块单层衍射元件的衍射效率对整体衍射效率的贡献作用.在0.436～0.656 μm的可见光波段,多层衍射光学元件最低衍射效率可达到98%以上,克服了单层衍射元件偏离设计波长后衍射效率显著下降的缺点,改善了宽波段衍射效率.将多层衍射光学元件应用在折、衍射混合光学系统中能够明显提高系统的成像质量,同时使得光学系统体积减小,重量减轻,并且在某些系统中可以避免使用昂贵的特殊材料,从而可以降低光学系统的成本价格.

Optical imaging characteristics of multi-layer diffractive optical elements (DOEs) were discussed.Optimization design of the maximum grating depth of multi-layer DOEs was presented and diffractive efficiency contribution of the two single-layer DOEs which composed multi-layer DOEs to the efficiency of the whole element was analyzed principally.The minimum diffractive efficiency of multi-layer DOEs could be greater than 98% in 0.436~0.656 μm visible waveband.So multi-layer DOEs could improve broadband efficiency while for single-layer DOEs,the broadband efficiency falls down obviously when the wavelength is off the design wavelength.Multi-layer DOEs used in hybrid diffractive-refractive optical systems have benefits to imaging quality to reducing weight and complexity of optical systems.Instead of employing special expensive material in some systems,cost of optical systems was reduced.