in the form of localized electrical charge that varies with incident light intensity. As shown in the schematic the photons are transform to electrons by the detectors and the electrons are converted to readable electrical signal in the circuit board. The electrical signal is then convoluted with a point spread function (PSF) to sample the original signal. As such, image resolution is highly dependent on the number of detectors and the point spread function will determine the image resolution. Image artifact and noise Most fluorescence imaging techniques exhibit background noise due to illuminating and reconstructing large slices (in the z-direction) of the samples. Since TIRFM uses an evanescent wave to fluoresce a thin slice of the sample, there is inherently less background noise and artifacts. However, there are still other noises and artifacts such as poisson noise, optical aberrations, photobleaching, and other fluorescence molecules. Poissonian noise are fundamental uncertainties with the measurement of light. This will cause uncertainties during the detection of fluorescence photons. If N photons are measured in a particular measurement, there is a 63% probability that the true average value is in the range between N +√N and N −√N. This noise may cause misrepresentation of the object at incorrect pixel locations. Optical aberrations can arise from diffraction of fluorescence light or microscope and objective misalignment. Diffraction of light on the sample slide can spread the fluorescence signal and result in blurring in the convoluted images. Similarly, if there is a misalignment between the objective lens, filter, and detector, the excitation or emission beam may not be in focus and can cause blurring in the images. Photobleaching can occur when the covalent or noncovalent bonds in the fluorophores are destructed by the excitation light and can no longer fluoresce. The fluorescing substances will always degrade to some extent by the energy of the exciting radiation and will cause the fluorescence to fade and result in a dark blurry image. Photobleaching is inevitable but can be minimized by avoiding unwanted light exposure and using immersion oils to minimize light scattering. Autofluorescence can occur in certain cell structures where the natural compound in the structure would fluoresce after being excited at relatively shorter wavelengths (similar to that of the excitation wavelength). Induced fluorescence can also occur when certain non-autofluorescent compounds become fluorescent after binding to certain chemicals (such as formaldehyde). These fluorescence can result in artifacts or background noise