Time lapse imaging using two-photon systems has traditionally relied on the same serial scanning as confocal imaging has and therefore suffers from the same time limitations on signal acquisition. While faster scanning regimes (as discussed below) represent a simple and common approach to this problem, such approaches reduce dwell time per pixel and can compromise signal-to-noise ratio. Furthermore, simply increasing excitation power is frequently not an option because above a certain intensity chromophore saturation and biological tissue photodamage occur. Consequently many experimenters use a laser power just below the photodamage and/or chromophore saturation threshold to maximize signal without inducing damage. In some cases this means much of the available laser power is not used, though in deep tissue imaging this is often not the case since more power must be used to overcome scattering.