Photobleaching and phototoxicity are unavoidable in fluorescence microscopy. The phenomenon of photobleaching occurs when, as a result of photo-induced modifications to the molecular structure, a fluorophore permanently loses the ability to fluoresce. Phototoxicity arises from photoinduced generation of singlet oxygen and/or other toxic by-products. Both phenomena are detrimental to fluorescence microscopy applications, especially in the case of live-cell imaging, where real-time effects can impair the cell under study. Therefore it is critical to reduce these consequences to a negligible level. One means of achieving this reduction without sacrificing image fidelity is to employ a new technique called active illumination microscopy (AIM). AIM works by maintaining a fixed detection signal via fast feedback control of the microscope illumination power. Ultimately, this approach permits fluorescence microscopy with an improved signal-to-noise ratio (SNR) and little to no image saturation, resulting in clear, crisp high-fidelity images.