Fiber optic rotary joint
View Patent ↗This invention eliminates the lens/prism assemblies and the multiple pick-up fibers that must be multiply lensed to a detector to get sufficient signal strength for the system to work. This invention also compensates for some of the rapid rise and fall time of the present system. A single pick-up, either a fiber or a photodiode, is placed at the end of a waveguide. A lens or lens system is used to focus a single optical signal on to the fiber face or the photodiode active area. Various light injection techniques, such as fibers, fiber/lens assemblies, lensed VCEL, lasers, or LEDs can be utilized because of the location in the system.
1. A fiber optic rotary joint, comprising:
a stator and a concentric rotor relatively rotatable with respect to one other through a full 360° revolution;
an arcuate waveguide disposed on one of said rotor or stator, said waveguide having an arcuate length of less than 360° and having a flat reflecting surface disposed along an arcuate wall inside said waveguide;
a single light receiver operatively associated with said waveguide;
wherein said reflecting surface is so configured and arranged that light entering said waveguide will be directly reflected off said reflecting surface on to said light receiver;
a plurality of light transmitters positioned on the other of said stator or rotor, each of said light transmitters being adapted to emit an optical signal and being of such a number and of such circumferential spacing that at least one transmitter will always be operatively arranged to transmit said optical signal into said waveguide;
means for substantially simultaneously emitting an optical signal from each of said plurality of light transmitters; and
means to focus said reflected optical signal on said light receiver.
2. The fiber optic rotary joint of claim 1 wherein said reflective surface is at least partially raised with respect to the arcuate surface of said waveguide.
3. The fiber optic rotary joint of claim 1 wherein said light transmitter include a lens.
4. The fiber optic rotary joint of claim 1 wherein said plurality of said light transmitters are substantially equally circumferentially spaced.
5. The fiber optic rotary joint of claim 1 wherein said light receivers include a lens and a photodiode.
6. The fiber optic rotary joint of claim 1 and further comprising a plurality of optical fibers each coupled at one end thereof to a corresponding one of said light signal transmitters and at an opposite end thereof to a light source.
7. The fiber optic rotary joint of claim 6 wherein each of said plurality of optical fibers has approximately the same length.
8. The fiber optic rotary joint of claim 7 wherein said light source is laser.
9. The fiber optic rotary joint of claim 7 wherein said reflective surface occupies a chordal distance of about 60° to 70°.
10. The fiber optic rotary joint of claim 1 wherein said receiver includes a lens, a fiber, and a photodiode.
11. The fiber optic rotary joint of claim 1 and further comprising a plurality of said reflective surfaces.
12. The fiber optic rotary joint of claim 1 wherein there are twenty light transmitters.
13. The fiber optic rotary joint of claim 1 wherein said joint is an off-axis joint.
14. The fiber optic rotary joint of claim 1 wherein said reflective surface occupies a chordal distance of about 1°.
15. The fiber optic rotary joint of claim 1 wherein said light transmitters are located on one vertical plane, and said waveguide is located on a second vertical plane spaced from said first plane.
16. The fiber optic rotary joint of claim 1 wherein air separates said plurality of light transmitters from said waveguide.
17. The fiber optic rotary joint of claim 1 wherein said light transmitter is one of a fiber, fiber/lens assembly, a lensed VCEL, a laser, or an LED.
18. The fiber optic rotary joint of claim 1 wherein said light receiver is a fiber.
19. The fiber optic rotary joint of claim 1 wherein said waveguide occupies a chordal distance of about 27°.
20. The fiber optic rotary joint of claim 1 wherein light transmitters are spaced approximately 20° apart.
21. The fiber optic rotary joint of claim 1 wherein said waveguide has a U-shaped cross-section.
22. The fiber optic rotary joint of claim 1 wherein signal received by each light receiver is received at approximately the same amplitude.