Biomedical Imaging Organization for South East Europe or BIO-SEE was formed in the Spring of 2022 with the help of a grant from the Chan Zuckerberg Initiative (CZI) to address the need for a regional network of biomedical researchers interested in advanced imaging techniques. We were delighted when we were asked to share our knowledge of super-resolution microscopy and how we are able to get past the diffraction limit of light.
Conical diffraction is a well-known optical phenomenon that has only recently drawn the attention of the microscopy community for its beam-shaping potential. It occurs when polarized light aligned into a biaxial crystal spreads to form a hollow cone within the crystal and emerges with cylindrical light patterns that can be shaped and scanned with features sharper than the diffraction limit. Here, we present the conical diffraction phenomenon and some of its most useful properties for microscopy. We then show how it can be deployed and integrated into super-resolution fluorescence microscopy and its applications.