In this post, Fang Huang, the Reilly Associate Professor of Biomedical Engineering in the Weldon School of Biomedical Engineering at Purdue University and a member of the Purdue Institute for Cancer Research, discusses his recently published research “A statistical resolution measure of fluorescence microscopy with finite photon,” which appears in Nature Communications, with the support of the National Institutes of Health, National Institute of General Medical Sciences.
What did you want to know?
Resolution, a microscope’s ability to distinguish closely spaced points, is the most essential feature of a microscopy system. Ernest Abbe first concluded that a microscope’s resolution is governed solely by light diffraction. This standard definition has remained unchanged since 1873. However, Abbe’s resolution is sufficient only when noise is neglectable: often in reflection microscopes and transmission microscopes. In contrast, modern fluorescence microscopy and nanoscopy methods operate almost exclusively under photon-starved conditions, where photon noise heavily affects the resolvability of an underlying structure. To date, photon noise remains one essential factor yet to be incorporated in the resolution limit theoretically.
What did you achieve?
Although researchers have long recognized that noise, inherent from photon counting process, can negatively impact resolution in microscopes, there have been no theoretical resolution measures quantifying the effect of noise on resolution. Our work is the first to provide a theoretical approach that quantitatively accounts for the impact of noise on a microscope’s resolution.
We developed a theoretical noise-considered resolution limit that enables the quantification of microscopes’ resolving power towards objects of different complexities using Fisher information theory. This information-based resolution (IbR) predicts noise-considered resolution limit for different imaging systems at finite photon levels where Abbe’s resolution is often unreachable due to noise. In the new theory, IbR, photons are now the information currency for the resolving power. With it, we can now quantify and distinguish the significant differences in the noise-considered resolution among various conventional and super-resolution imaging systems including wide-field, confocal, structure illuminated, and image scanning microscopy systems. In addition, IbR establishes a theoretical framework to design and optimize new and existing microscopy systems in achieving a targeted resolution.
What is the impact of this research?
IbR provides a new measure of quantifying the practical resolving power of microscopy imaging modalities considering finite photons. The noise-considered resolution measure offers a theoretical and statistical reference for fluorescence microscope imaging modalities in photon-limited conditions.