Deep in vivo two-photon microscopy with a low cost custom built mode-locked 1060 nm fiber laser

Here we demonstrate that a mode-locked ytterbium fiber laser for two-photon fluorescence microscopy can be built for $13,000. The laser emits at a wavelength of 1060 nm with a usable average power of 1 W at a repetition rate of 40 MHz and a compressed pulse width of 81 fs at the sample. The laser is used to obtain deep in vivo two-color images of layer-V pyramidal neurons expressing YFP and vasculature labelled with Texas Red at depths up to 900 mu m. The sub-1 mu m features of dendritic spines can be resolved at a 200 mu m depth. (C) 2016 Optical Society of America