Single‐Layer Aberration‐Compensated Flat Lens for Robust Wide‐Angle Imaging

Abstract

Metasurfaces are planarized and miniaturized versions of conventional optical elements. Subwavelength‐thick single‐layer metalenses have diffraction limited resolution for on‐axis imaging but relatively low resolution for off‐axis imaging due to off‐axial aberrations. The aberrations of planar single‐layer metalenses have been corrected by patterning two metasurfaces on both sides of a substrate to form metalens doublets with a thickness of hundreds of micrometers to millimeters. The multilevel diffractive lenses are demonstrated to achieve wide angle imaging with a thickness of several micrometers, however, the off‐axial aberrations are not compensated. Here, an epsilon‐greedy algorithm‐based scheme for achieving a planar wavelength‐thick single‐layer aberration‐compensated (SLAC) flat lens consisting of dielectric nanoring structures fabricated by 3D printing are proposed. The scheme is experimentally validated via a SLAC flat lens. This SLAC flat lens has a thickness of 1 µm, a numerical aperture of 0.45, a focal length of 1 mm, a full field of view (FOV) of 32° that enables aberration‐compensated imaging along the focal plane and monochromatic microscopic imaging with resolution better than 2.2 µm at a wavelength of 633 nm. This scheme can lead to ultrathin wide‐FOV flat lens designs as well as low‐cost mass production, which has various applications in miniscopes, mobile camera modules, and machine vision.

Broad‐Bandwidth Micro‐Diffractive Optical Elements

“…[ 6 ] Micro‐diffractive optical elements (M‐DOEs), widely used in integrated optics, are a type of ultrathin phase elements operating via interfering and diffracting for generating the desired light field. [ 7,8 ] In particular, the diffractive element changes the propagation path of incident light utilizing the geometry of flat grating patterns, [ 9,10 ] in contrast to the refractive element [ 11–13 ] that uses the 3D curved surface to deflect light paths. Because a diffractive element does not have a substantial thickness, an optical system including such elements can be designed to have the following characteristics: small size, light weight, and compact configuration.…”

Multifunctional Beam Manipulation at Telecommunication Wavelengths Enabled by an All‐Dielectric Metasurface Doublet

“…Recently, a comatic aberration‐compensated metalens, which consists of dielectric nanoring structures of different heights fabricated by 3D printing, has been demonstrated for wide‐angle imaging. [ 19 ] An ultrathin metalens based on the scheme of hybridizing nanoring structures into a single layer could lead to a wide field of view as well as low‐cost mass production. Besides, cascaded metasurfaces are known to be useful for mitigating chromatic aberration.…”

Low-Loss Coupling from Coated Plano Convex Lens to Single Mode Solid Core Fibers Laser by Lensing Scheme

“…A lensed equation (f = R/n-1, where n is the index of refraction and R is the radius of curvature of the lens surface) can be used to compute the focal length of each CPCL. [17][18][19] When the light source's area is smaller than the core's, a lensed system is utilized to connect the source and the optical cable. The lensing strategy enhances the FCE in SMFs based on the given properties.…”