Abstract: A probe provides electrical communication between a coating and a processing system. One optional feature includes an outwardly projecting, electrically conductive engaging member that is held in a captivation structure releasably retained in a housing and engages a contact that is inside the probe and connected with the processing system. Another optional feature of the probe provides the electrically conductive engaging member in the form of a pin or pins captivated in a light-transmissive structure adjacent a light-emitting source. Another optional feature of the probe includes a restraining structure that defines a frustoconical seat for engaging a conical distal end of an electrically conductive pin that is adapted to contact the coating.