Structured Illumination (SIM) imaging is extremely sensitive to spherical aberration. To get the highest quality images (or even to get proper reconstruction), you need to minimize spherical aberration. This means:
You should use high precision 0.17 mm coverslips
You should mount in an appropriate mounting medium. Nikon recommends mounting either in 2,2-thiodiethanol or in Prolong Gold (for a hard-set mounting medium). If using Prolong Gold, be aware of potential shrinkage when it cures.
