Optical rotary joints, methods of mounting same in a properly-aligned manner, and optical reflector assemblies for use therein

An optical rotary joint for enabling optical communication between a rotor and a stator, said rotor having a longitudinal axis, comprising:

• at least one optical source mounted on one of said rotor and stator for transmitting an optical signal in a radial direction with respect to said longitudinal axis;
• at least one first reflector mounted on the other of said rotor and stator for reflecting the optical signal transmitted from said optical source, said first reflector comprising a concave first reflective surface, a line in a plane taken through said first reflective surface being configured as a portion of an ellipse having first and second focal points, to provide a constant optical path length that is independent of the angular position between said rotor and stator, said first focal point being positioned substantially coincident with said rotor axis;
• a second reflector having a second reflective surface for receiving the optical signal reflected at said first reflective surface and for reflecting such received optical signal, and a receiver arranged to receive the optical signal reflected at said second reflective surface;
• said first reflective surface being configured as a portion of an ellipsoid and said second reflective surface being configured as a portion of a cone positioned at the second focal point of said first reflective surface, whereby an optical signal reflected by said first reflective surface toward said second focal point converges to a spot on said second reflective surface and is reflected in a different direction as a function of the apex angle of said cone, the area of said spot on said second reflective surface being smaller than the area on said first reflective surface where said optical signal is incident for reflection toward the second focal point;
• an optical fiber having an entrance end and an exit end, a lens assembly arranged adjacent to said fiber entrance end for directing an optical signal reflected by the spot on said second reflective surface into said optical fiber;
• and
• said receiver being arranged proximate said fiber exit end to receive the optical signal reflected by said second reflective surface and exiting said optical fiber.