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Signalling system
| Details |
Inventors: Green, Alan E.; Morrison, Euan; Pettigrew, Robert M.;
Assignee: Quantumbeam Limited (Ickleton, GB)
Primary Examiner: Mullen; Thomas
Assistant Examiner:
Attorney, Agent or Firm: Nixon & Vanderhye PC
A signalling system includes first and second signalling devices. The first signalling device including a retro-reflector modulator, having a lens, a modulator and a reflector, and being operable to receive, modulate and reflect the modulated signal back to the second signalling device. The second signalling device including a signal generator, a receiver for receiving the modulated signal from the first signalling device and a processor for retrieving modulation data from the received modulated signal. The lens of the first signalling device includes a telecentric lens. |
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DETAILED DESCRIPTION According to one aspect, the present invention provides an alternative point to multipoint signalling system.
According to this aspect, the present invention provides a point to multipoint signalling system, comprising a first signalling device and a plurality of second signalling devices, wherein the first signalling device comprises: means for receiving signals transmitted from the plurality of second signalling devices, means for modulating the received signals with respective modulation data for the second signalling devices and means for reflecting the modulated signals back to the respective second signalling devices, and wherein each second signalling device comprises: means for generating a signal, means for transmitting the generated signal to said first signalling device, means for receiving the modulated signal which is reflected back from said first signalling device, and means for retrieving the modulation data from the reflected signal.
The present invention also relates to a retro-reflector for use in a signalling system.
Optical retro-ref lectors are commonly used in a wide variety of applications from precision metrology to "cats-eye" road markers.
The main function of the retro-reflector is to reflect incident light back towards the source.
There are currently three different types of optical retro-reflectors commonly in use, namely the spherical reflector, the corner cube reflector and the plane mirror.
Plane mirrors are only effective as optical retro-reflecting elements when they are carefully aligned with the source, so that the reflective surface is orthogonal to the direction of travel of the light emitted from the source.
Corner cube reflectors typically comprise an arrangement of three mutually perpendicular mirrors.
Alternatively, they can be constructed from a glass prism with three mutually perpendicular reflecting surfaces formed by the faces of the prism.
Light incident on such a corner cube reflector is reflected from all three surfaces and travels back towards the source parallel to its original path
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Optical Systems 
