In one example in accordance with the present disclosure, an emitter system is described. The emitter system includes an array of emitters. Each emitter emits waves towards a target surface. The emitter system also includes a control system. The control system includes a sensing system to determine whether emitters in the array are properly positioned relative to the target surface. A controller of the control system adjusts emitter sets of the array of emitters based on an output of the sensing system.
