Fiber optic coupling devices are used in a wide variety of applications to couple an optical signal from one optical fiber, or optical fiber bundle, to another optical fiber or optical fiber bundle. Fiber optic rotary joints allow optical signals to be transferred between fibers located on members that are rotating with respect to each other. Fiber optic rotary joints are generally categorized as either an on-axis rotary joint or an off-axis rotary joint. In an on-axis rotary joint, the optical fibers that will communicate lie along the axis of rotation or an off-axis rotary joint in which the optical fibers do not lie along the axis of rotation, typically because the axis of rotation is inaccessible. Off-axis rotary joints generally include channel waveguides to direct the optical signal. In this regard, off-axis rotary joints generally include multiple optical sources, driven by one or more lasers, and multiple receivers in communication with respective channel waveguides. The technology employed in these two types of rotary joins is quite different.
