A stochastic model for electron multiplication charge-coupled devices--from theory to practice.

Electron multiplication charge-coupled devices (EMCCD) are widely used for photon counting experiments and measurements of low intensity light sources, and are extensively employed in biological fluorescence imaging applications. These devices have a complex statistical behaviour that is often not fully considered in the analysis of EMCCD data. Robust and optimal analysis of EMCCD images requires an understanding of their noise properties, in particular to exploit fully the advantages of Bayesian and maximum-likelihood analysis techniques, whose value is increasingly recognised in biological imaging for obtaining robust quantitative measurements from challenging data. To improve our own EMCCD analysis and as an effort to aid that of the wider bioimaging community, we present, explain and discuss a detailed physical model for EMCCD noise properties, giving a likelihood function for image counts in each pixel for a given incident intensity, and we explain how to measure the parameters for this model from various calibration images.

Multicolour single molecule imaging on cells using a supercontinuum source.

Multicolour single molecule fluorescence imaging enables the study of multiple proteins in the membranes of living cells. We describe the use of a supercontinuum laser as the excitation source, show its comparability with multiplexed single-wavelength lasers and demonstrate that it can be used to study membrane proteins such as the ErbB receptor family. We discuss the benefits of white-light sources for single molecule fluorescence, in particular their ease of use and the freedom to use the most appropriate dye without being constrained by available laser wavelengths.