The CRONUS-3P from Light Conversion is an Optical Parametric Oscillator based Laser Source that operates from 1250 to 1800 nm. It provides an output power of over 1500 mW with a pulse duration of less than 85 fs and has a single-shot repetition rate of 2 MHz. This femtosecond pulsed laser has a beam diameter of 1.5-2.5 mm and a beam divergence of less than 1 mrad. It is tunable from 1250 to 1800 nm which covers the biological transparency windows at 1.3 μm and 1.7 μm for three-photon microscopy (3PEF). This laser has an integrated group delay dispersion (GDD) compensation technique which ensures optimal pulse duration at the sample and optional automated beam steering to guarantee laser pointing stability. It also has automated dispersion compensation and automated beam resizing & collimation features. The laser source is available in a module and is ideal for advanced nonlinear microscopy.