Super-resolution

Super-resolution

The ordinary imaging system is under the diffraction limit, the smallest beam diameter of a point source in the system. Super-resolution is the approach for beyond the diffraction limit with various methods. This laboratory focuses on expanding the spatial frequency information beyond cut-off frequency, the diffraction limit in the Fourier domain. As a Fourier series, the higher spatial frequency information makes the higher resolution in the space domain.

SI-FINCH

FINCH, Fresnel incoherent correlation holography, is a self-interference system for obtaining hologram from incoherent holography. Because the self-interference system has a unique PSF, it has a double cut-off frequency than the ordinary coherent system.

Structured illumination (SI) uses the designed pattern as the incident angle that duplicates and superposes the spatial frequency information. The phase-shifting method extracts the high spatial frequency information from the superposed one.

SI-FINCH is the combination of both method to surpass the resolution limit of incoherent holography

Sub-pixel shifting

The sub-pixel shifting method uses the quantization problem as a breakthrough. For the same wavefront, the sub-pixel shifted detector has a different quantized result from the original detector position. By numerical analysis with several sub-pixel shifted images, the spatial frequency information expands on the shifted axis.