| With the development of society,imaging optical systems can be seen everywhere in daily life,and people’s requirements for the imaging performance of the optical system are gradually improving.According to the aberration theory,correcting aberrations in an optical system,usually increases the complexity of the system,including increasing the number of lenses and surface curvature.Although binary optical elements have been shown to reduce the complexity of optical systems,they are still limited by the refractive index of the material and the thickness of the device.Metalenses,a new type of optical element composed of metasurfaces,have attracted extensive attention because they can freely control electromagnetic waves in a planar shape,and are in line with the development trend of miniaturization,thinness,and easy integration of optical systems today.However,metalenses suffer from aberrations(spherical aberration,off-axis aberration,chromatic aberration,etc.),which limit their development.Although there have been studies on these issues,there are still some problems: The hyperbolic phase metalens can correct spherical aberration only for incident plane waves,the function is relatively simple;moreover,wide field of view(FOV)achromatic metalenses designed by traditional methods are difficult to manufacture.However,the FOV and spectral bandwidth are two important indicators of optical systems,which have great value in practical applications.Based on the above problems,this paper studies the aberration theory and correction technology of metalenses.The main research contents include:1.For the problems that traditional hyperbolic metalenses can correct spherical aberration only for incident plane waves,the function is relatively simple,a design method of the polarization multiplexing metalens for simultaneously correcting the spherical aberration of infinity and finite objects is proposed,which can achieve diffraction-limited focusing of the x-polarization plane wave and the y-polarization spherical wave.The metalens designed based on this method can image targets with different object distances without zooming,which is expected to simplify the design complexity of traditional zoom optical systems.2.For the problem that wide FOV achromatic metalenses designed by traditional methods are difficult to manufacture,a wide FOV achromatic metalens based on a single-layer metalens is proposed to correct the aberration by using an aperture and metasurface.Two devices,a three-wavelength(473 nm,532 nm,and 632.8 nm)achromatic wide FOV metalens and a continuous bandwidth(492 nm-592 nm)achromatic wide FOV metalens,are designed to prove the method.The metalenses show good aberration correction performance and are expected to be applied in imaging,holography,machine vision,and other fields. |
