Asymmetric Dual-Axis Goniometer for Positioning on a Sphere

The ability to position an object at various locations corresponding to a portion of a spherical surface has long been accomplished using nested goniometers, in which, as observed from above, the apparent motion is readily described in a Cartesian ("XY") frame. In certain applications, however, a more suitable basis of motion would be described in a polar coordinate ("R-Theta") frame. The implementation and advantages of such a device is described here.