Broadband Achromatic Polarization Imaging Based On Metasurface

Polarization images can reflect the polarization of the light and broaden the dimension of imaging,which are widely used in remote sensing,display,medical imaging and other fields.Efficient acquisition of the polarization has become the key to polarization imaging technology.The polarization imaging system based on polarization optical components such as detector is complex and not easy to integrate.The miniaturized and low-loss Metasurface can flexibly regulate the phase,amplitude and polarization of light,which is a hot research topic to explore the integrated polarization imaging system.In this thesis,two integrated full Stokes polarization imaging models are designed by introducing the metasurface structure into the polarization imaging system,and the finite-difference time-domain algorithm(FDTD)is used for numerical calculation and verification.First,multiple polarization-dependent metalens are designed based on the principle of modulation of the phase and polarization of the metasurface.The metalens can realize the functions of single-polarization state focusing and orthogonal dual-polarization state independent focusing,which provides a theoretical basis for the construction of the full Stokes polarization imaging model.Then,a six-pixel "super-imaging element" model is proposed to realize full Stokes polarization imaging with simultaneous detection of linearly and circularly polarized light.The structure focuses three sets of orthogonal polarized light in the same focal plane,and achieves full Stokes parameter detection by calculating the focused light intensity.The numerical calculation results show that the reconstructed Stokes parameters are consistent with the incident light Stokes parameters,which verifies the accuracy of the full Stokes polarization imaging model.Finally,for the dispersion problem of polarization imaging,a four-pixel "super image element" model is proposed to realize the wide band polarization imaging function.To facilitate the achromatic design,the structure is simplified to four pixels according to the Stokes theory,and the broadband Stokes polarization imaging function is realized by focusing the linear and circular polarization broadband on the same focal plane.The numerical calculation results show that the Stokes parameters of the broadband reconstruction are basically consistent with the incident light Stokes parameters,which verifies the feasibility of the model.