3D Super-Resolution Reconstruction Using Microsphere-Assisted Structured Illumination Microscopy

In this letter, we present a wide-field three-dimensional (3D) profiling technique with enhanced lateral resolution by combining structured illumination microscopy (SIM) with super-resolution microsphere-assisted 2D imaging method. In the measurement, a silicon microsphere is placed on the nanoscale sample to improve the spatial resolution. After that, a sinusoidal pattern produced by digital micro-mirror devices (DMD) is projected through the microsphere onto the sample. The modulation evaluation of the reflected patterns is utilized to reshape the 3D profile precisely. The experiment is conducted on the grating sample with 220 nm line-width which beyond the diffraction limit of the ordinary SIM system. The results show that the 3D map of the sample with enhanced lateral resolution can be achieved using a silica microsphere with 20 μm diameter. The measurement system is relatively simple and can achieve a very high effective numerical aperture easily. The advantages are significant with the potential to be applied in many domains from nanotechnology to biology.