Super-resolution Microscopy Based On Vector Super-resolution Lens

In recent years,breaking the diffraction limit and realizing super-resolution microscopic imaging has become a hot spot in optical research.The proposal of optical super-oscillation breaks the diffraction limit at the device level and provides a new idea for realizing label-free far-field super-resolution imaging.At present,most illumination beams of the label-free far-field super-resolution imaging system are scalar light fields,which leads to conflicts between focal spot compression and sidelobe suppression.Vector light fields such as radially polarized light can focus on a focal spot with a smaller size than the scalar light field,which is of great significance for improving the microscopic resolution.However,the vector light field measurement method lacks theoretical proof,and the three polarization components of the focused light field cannot be measured independently and quickly.Thus,in this thesis we propose a focused light field polarization measurement theory,design a focused light field polarization measurement experimental system,develop vector super-resolution focusing lens,and realize super-resolution microscopy based on the longitudinally polarized light field illumination of the vector super-resolution lens.Now list the main work of this thesis as following:(1)We proposed the polarization measurement theory of focused light field based on polarization conversion microscopy,and theoretically studied the measurement methods of the transversely polarized light field and the longitudinally polarized light field of the focused focal spot.We designed and built an experimental test system that can quickly and independently measure the three polarization components of the focused light field,Then we write the computer software and measure super-resolution focused light field of linearly polarized light,circularly polarized light and radially polarized light.(2)For the wavelength λ=632.8 nm,the vector super-resolution focusing lens was designed,simulated by COMSOL,fabricated and tested.The lens has a radius of300λ(189.84μm),a focal length of 100λ(63.28 μm),a numerical aperture of 0.95,and a diffraction limit of 0.527 λ.The experimental results show that the FWHM of the inner diameter of the transversely polarized light field is 0.32λ,the sidelobe ratio of the transversely polarized light field is 35%,the FWHM of the longitudinally polarized light field is 0.42λ,the sidelobe ratio of the longitudinally polarized light field is 18%,and the FWHM of the total field is 0.44λ,the sidelobe ratio of the total field is 18%,and a super-resolution optical needle with a length of about 7λ is formed near the focal length.(3)We designed a super-resolution microscopy system based on longitudinally polarized light field illumination of vector super-resolution lens,prepared sub-wavelength grating samples with different periods,control a two-dimensional nano-stage to scan the samples and finally achieved an imaging resolution of 0.41λ.