US Patent 7187823 Contact-free slip ring for survey instrumentation

A contact free rotary transformer assembly can be used to transfer power and information between a stationary portion and a rotatable portion of a laser scanning device. The rotary transformer can consist of a pair of substantially parallel ferrite rings, each having disposed therein a coil for passing AC current. The assembly can use an optical fiber positioned near a rotational axis of the transformer to transfer optical information between the stationary and rotary portions. The optical fiber can include two portions connected by a rotational connection in order to allow the portions to rotate with respect to one another while maintaining the light path.