In this presentation, we will describe the design, fabrication and characterization of flat lenses that operate in any desired spectral regime. Specifically, we will describe flat lenses in the visible band, in the visible and near-IR band, and also in the LWIR band. We have shown that multi-level diffractive optics, when designed properly can enable high efficiency broadband imaging . Here, we will extend the performance to the IR and show experimental results. We further compare our optics with metalenses, and emphasize that metalenses offer no additional advantage . In fact, metalenses are far more challenging to fabricate. Please refer to papers below for details.
 M. Meem, A. Majumder and R. Menon, “Full-color video and still imaging using two flat lenses,” Opt. Exp. 26(21) 26866-26871 (2018).
 S. Banerji, M. Meem, B. Sensale-Rodriguez and R. Menon, “Imaging with flat optics: metalenses or diffractive lenses?,” arXiv:1901.05042 [physics.optics]
Micropatterning on oblique and multiplane surfaces remains a challenge in microelectronics, microelectromechanics, and photonics industries. We describe the use of numerically optimized diffractive phase masks to project microscale patterns onto photoresist-coated oblique and multiplane surfaces. Intriguingly, we were able to pattern a surface at 90 deg to the phase mask, which suggests the potential of our technique to pattern onto surfaces of extreme curvature. Further studies show that mask fabrication error of below 40-nm suffices to conserve pattern fidelity. A resolution of 3 μm and a depth-of-focus of 55 μm are essentially dictated by the design parameters, the mask generation tool, and the exposure system. The presented method can be readily extended for simple and inexpensive three-dimensional micropatterning.