Photothermal excitation represents a significant instrumentation advance for imaging with dynamic modes of the atomic force microscope (AFM). Using a power-modulated laser to directly drive the cantilever oscillation provides substantial benefits over conventional piezoelectric excitation. Here we discuss photothermal excitation and its implementation as blueDrive by Oxford Instruments Asylum Research. We explain its operating principles and discuss its use for a range of practical applications. The results show that blueDrive sets new standards for imaging in liquid, visualizing dynamic events, and mapping nanomechanical properties.