Abstract: A spatial atomic layer deposition apparatus that includes a depositor head having an active surface configured to discharge a flow of a first precursor gas, a flow of a second precursor gas, and a flow of an inert gas that separates the flow of the first precursor gas and the flow of the second precursor gas, a substrate plate that opposes the depositor head and has a support surface for retaining a build substrate, a plurality of gap detection sensors producing an output signal indicative of a distance between the active surface of the depositor head and the support surface of the substrate plate, and a controller that communicates with the plurality of gap detection sensors. The gap detection sensors permit a spatial orientation of the active surface of the depositor head and the support surface of the substrate plate to be determined in real-time and monitored.