Determination of the relative positioning of a laser machining beam and a process gas jet on a laser machine tool are accomplished by motion of detections made while moving the machining beam and gas jet in relation to a detection element. In some cases actions of the beam and gas jet themselves are detected, such as by cutting light response and sensor deflection caused by the gas jet. Relative head positions at the time of the deflections are used to calculate misalignment between the laser beam and gas jet.