MWIR_MDL_Optics_Express.pdf (8.2 MB)
Multilevel diffractive lens in the MWIR with extended depth-of-focus and wide field-of-view
preprintposted on 2023-02-01, 14:17 authored by Rajesh Menon, Tina Hayward, Syed Qadri, Nicole Brimhall, Freddie Santiago, Marc Christophersen, Christopher Dunay, Richard Espinola, Teddy Cheung
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 approaches and another using the conventional propagation phase (the Fresnel zone plate or FZP) with diameter = 25um and focal length = 25um operating at $\lambda=4\thinspace\mu$m. We fabricated the lenses by optical lithography and characterized their performance. We show that the inverse-designed MDL achieves larger depth-of-focus and better off-axis performance when compared to the the FZP at the expense of larger spot size and reduced focusing efficiencies. Both lenses are flat with thickness <=0.5mm and weigh <= 3.63g, which are far smaller than their conventional refractive counterparts.