Investigation Of Far-field Broadband Super-resolution Imaging Method Based On Super-oscillatory Phenomenon

With the rapid development of the biomedicine,microelectronics and material,conventional optical imaging system could not satisfy the requirement of detecting and imaging with super-resolution.Thus,overcoming the obstacle of the diffraction limit and realizing the super-resolution imaging have been the crucial issues in the optical imaging field.In order to beat the diffraction limit,a series of super-resolving techniques were brought out,such as the STED and SIM based on the florescent microscope and the near-field SNOM.They all made significant contributions to the super-resolving imaging,but they still have some limitations,like complex near-field manipulation,pre-labeling of specific specimen or special structure illumination.Lately,Optical super-oscillation phenomenon seems to provide a novel method of far field super-resolution imaging.By employing the complex destructive interference of light with different spatial frequencies and variant phases,super-oscillation phenomenon can occur at the far-field localized region and lead to super-resolution imaging.The advantage of this technique is that it can achieve focused super-resolution imaging without the limitations on the target objects and the illumination method.So far,this method has been proved experimentally by many previous researches.However,the presented super-oscillation devices are suffered from narrow bandwidth that cannot realize the goal of broadband far-field super-resolution imaging.To solve these problems,we carried out the researches on broadband far-field super-resolution imaging in this thesis.This thesis mainly includes the following works.(1)We designed a device that can achieve broadband far-field super-oscillation imaging.Such super-oscillation device is a metasurface that composed of a series of nano-gratings with different orientations.Instead of using phase retardation in tradition binary phase pupil filter or spatial light modulator,this metasurface could achieve dispersionless phase manipulation for the transmitted light with cross-polarization based on the V shape antenna and Pancharatnam-Berry phase.By combining with an achromatic lens,the metasurface thus could theoretically obtain the broadband super-oscillation focusing and imaging.Using this super-oscillation device,we successfully obtained a minimal resolvable ability to 0.64 of Rayleigh criterion in experiment.(2)In order to solve the problem that the imaging region is limited by the high-intensity side lobe,we put forward two solutions.1)For the targets that could be controlled,far-field broadband super-oscillation imaging is finally achieved by scanning with a hole.2)For telescope system that the target is located at infinite.A super-critical device is proposed and designed with the minimal resolvable ability of 0.7 of diffraction limit.The super-resolution imaging of large targets is successfully realized by this device in theory and in experiment simultaneously.Compared with super-oscillation device,although the super-critical device slightly reduces the resolution,the intensity of side lobe can be suppressed greatly and thus can meet the requirement of imaging with large field of view.(3)The fault tolerance performances of super-oscillation device and super-critical device are analyzed in this part.Firstly,we retrieved the Zernike polynomial expressions for various aberrations based on the presented analytical models.Secondly,with these expressions,a fault tolerance analysis model is proposed.According to the criterion indexes in this model,the dependences of these two devices with different aberrations are illustrated.It can be inferred from our results that super-oscillation device is more sensitive to spherical aberration and distortion,while super-critical device is more sensitive to astigmatism and distortion.Generally speaking,super-oscillation device needs more careful control of aberrations.