Comparison of 3D structured patterns with tunable frequency for use in Structured Illumination Microscopy

Structured illumination microscopy (SIM) doubles the lateral resolution and produces optically-sectioned images. In SIM, the illumination system is modified in order to illuminate the sample by a structured pattern. Previously, axially-localized high-contrast sinusoidal patterns generated using a slit-prism illumination system based on a Fresnel biprism were investigated. In this contribution, we propose a Wollaston prism to replace the Fresnel biprism and produce the corresponding 3D structured illumination pattern. In this study, both optical elements are illuminated by the light emerging from an axial point source. Our results show that the benefits of using a Wollaston prism instead of a Fresnel biprism are twofold: (1) there is no envelope modulation perturbing the sinusoidal patterns and thereby reducing their visibility, and (2) the region of interference fringes is significantly larger than the one created by the Fresnel biprism.