Opt Express. 2023 May 8;31(10):15384-15391. doi: 10.1364/OE.486756.
Optics in the mid-wave-infra-red (MWIR) band are generally heavy, thick and expensive. Here, we demonstrate multi-level diffractive lenses; one designed using inverse design and another using the conventional propagation phase (the Fresnel zone plate or FZP) with diameter = 25 mm and focal length = 25 mm operating at =4m. We fabricated the lenses by optical lithography and compared their performance. We show that the inverse-designed MDL achieves larger depth-of-focus and better off-axis performance when compared to the FZP at the expense of larger spot size and reduced focusing efficiency. Both lenses are flat with thickness ≤0.5 mm and weigh ≤3.63 g, which are far smaller than their conventional refractive counterparts.
中波红外（MWIR）波段的光学元件通常较重、较厚且昂贵。在这里，我们展示了多层衍射透镜；一个是使用逆设计，另一个是使用传统的传播相位（菲涅耳波带片或 FZP），直径为 = 25 毫米，焦距 = 25 毫米，工作波长为 =4m。我们通过光学光刻法制造了这些透镜，并比较了它们的性能。我们表明，与 FZP 相比，逆设计的 MDL 在牺牲更大的光斑尺寸和降低聚焦效率的情况下，实现了更大的景深和更好的离轴性能。这两个透镜的厚度均 ≤0.5 毫米，重量均 ≤3.63 克，远小于其传统折射对应物。
