Resolution enhancement of the microscopic imaging by unknown sinusoidal structured illumination with iterative algorithm.

Microscopy by sinusoidal structured illumination is a conventional method to improve resolution, which largely depends on accurate knowledge of the illumination pattern. Two steps are included in the reconstruction process of our proposed technique. The first step solves the parameters of the structured illumination in the spatial domain. Besides the phase-shifting amounts, the period, the modulation factor, and the background intensity of the pattern are extracted from three segmented raw images by the iterative algorithm. The second step is retrieval and synthesis of the low- and high-frequency information of the object in the Fourier space with obtained data. Since the unknown object information is not involved in the pattern parameters' solving process, it is possible to figure out the problem with higher precision and less requirements. We test the performance of this method in the experiments. The resolution is improved with the designed carrier frequency of the illumination pattern.