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.
An optical communication transmitter (13), receiver (15), and transceiver (17) having distinctive retro-reflective elements (30) and/or reflectivity that can be modulated. In one embodiment, the retro-reflective elements (30) can have different shapes or patterns (32), irrespective of rotation or size. In another embodiment, the retro-reflective elements can have their reflectivity modulated (42) to have a distinctive pattern in time. The solution also provides the capability to direct a remote optical receiver (15) to an available port (17) with an appropriate FOV. In the case where retro-reflective elements are only shape distinctive, a method may be used to direct the remote OWLink (15) to an appropriate port (17) of the hub (54). In addition to the hub ports (17) used for data links, additional hub ports called command ports (60) are added that are only used during the initial link setup of remote units. The hub (54) contains enough command ports (60) such that one command port covers each possible FOV. All command ports contain the same retro-reflective element shape that is very distinct from other hub shapes, e.g. the largest.
A multi-channel optical communication system includes an optical transmitting apparatus and an optical receiving apparatus. The optical transmitting apparatus has a retroreflector and a modulator for modulating light reflected by the retroreflector according to a transmission signal. The light receiving apparatus has a light source and a demodulating circuit for demodulating the transmission signal modulated by the modulator from the light emitted from the light source and reflected from the retroreflector. The modulator includes a plurality of optical reflection devices arranged on a reflection plane of the retroreflector and capable of controlling optical reflection independently of each other and a circuit for separately controlling each of the optical reflection devices. The demodulating circuit includes a CCD having a plurality of photoreceptors arranged correspondingly to the arrangement of the optical reflection devices.
A method, a device and a system for communications to and from a retro-reflector device (302) is provided. The retro-reflector device (302) receives a first frame (400) encoded in an input beam (106). The retro-reflector device (302) creates and sends a second frame (420) in a first reflected beam (108) formed by the retro-reflector device (302) reflecting the input beam (106) along a path closely aligned with a path of the input beam. At least one of the first frame (400) and the second frame (420) includes medium access control information. In some implementations, the first frame (400) may include a data throughput rate (404, 406), a preamble (402) and an error correction code (412).
Free-space optical communication uses multibeam communications, for example between a base station and multiple remote stations. To improve efficiency and reduce complexity, the base station transmitter utilizes a single wide-angle objective lens for all of the optical beams' radiation sources. The optical radiation sources are provided with fiberoptic transmitting pigtails with output ends installed on a curved surface in relation to the single wide-angle objective lens at locations in the areas optically conjugated with the remote subscriber receivers. In a system for two-way communication, optical receivers are provided with fiberoptic receiving pigtails with input ends positioned on the curved surface at locations relative to the wide-angle objective lens, which are optically conjugated with the remote subscriber radiation sources. In the preferred embodiments, the mountings of the output and input ends of the transmitting and the receiving pigtails enable their movement along the curved surface as well as along an optical beam axis. Also, a preferred embodiment of the optical system enables movement of the wide angle objective lens together with the output and input ends of the transmitting and the receiving pigtails about horizontal and vertical axes.
An electronic receiver array for decoding data encoded into electromagnetic radiation (e.g., light) is described. The light is received at an ultra-small resonant structure. The resonant structure generates an electric field in response to the incident light and light received from a local oscillator. An electron beam passing near the resonant structure is altered on at least one characteristic as a result of the electric field. Data is encoded into the light by a characteristic that is seen in the electric field during resonance and therefore in the electron beam as it passes the electric field. Alterations in the electron beam are thus correlated to data values encoded into the light.
