GB2369736A

GB2369736A - Using cylindrical lenses to facilitate optical communications with moving devices

Info

Publication number: GB2369736A
Application number: GB0029345A
Authority: GB
Inventors: Martin Lawrence
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-12-01
Filing date: 2000-12-01
Publication date: 2002-06-05
Also published as: GB0029345D0

Abstract

An invention is described that allows optical communication to be made with moving vehicles. The invention depends on the properties of lensing systems to transform lines into point sources and vice - versa. Lines of information are projected by beams of light transmitted normally as vehicles move (alternatively the line is transmitted and the vehicle moves through it). By transforming the projected line into a point source information can be transmitted at high data rate allowing, for example, the reception or transmission of e - mails from such a moving vehicle. The system as described could also operate with stationary sources.

Description

Optical Communication Links for Dense Hubs and Moving Vehicles Introduction This invention relates to a method of optically relaying information through free space, either from or to moving vehicles, but not limited to such.

The use of mobile phones, laptops etc. is very widespread. In ordinary circumstances communication to or from such is straightforward, i. e. ; turning on a mobile phone connects it to the network, a laptop need only be plugged into a telephone socket to facilitate the sending or receiving of e-mails. In some circumstances however, these procedures cannot be implemented, for example in a moving body (such as a car) there is no phone socket, whilst connecting to a mobile network from within a car or a train can be difficult because of poor reception. The invention described below allows the sending or receiving of certain messages in circumstances where network connection in any other form might be limited. The specific situations identified are messaging to and from moving bodies such as cars or trains but also at densely used connection points (eg; airports) where the heavy use of mobile phones sometimes makes connecting to the network difficult. However, the invention is not necessarily limited to these specific situations.

Description In its physical embodiment the first part of the invention consists of an optical transmit/receive head, which transmits or receives the information via optical beams.

This is connected to the laptop (or mobile phone) either directly (i. e. can be considered part of the laptop etc. ) or via a suitable connecting cable (which might be an electrical cable or a fibre optic cable) with a port at one end (which might also be electrical or optical), to connect to the laptop or mobile phone (or the like), and a port at the other to connect to the optical head, and possibly a further box containing electronics. (These latter may alternatively be sited in the transmit/receive head, or in the laptop/mobile etc, this being the assumed case in the description following.) This part of the equipment can be considered to look like a medical stethoscope.

The second part of the invention consists of the collector or transmitter of the information-carrying beam. This part of the apparatus is critical and is the principal substance of this invention. It is a known property of cylindrical lenses (or sets of lenses combined to give the overall effect of a cylindrical lens) that the lens transforms a circular point source of light into a straight line after transmission through the lens. Due to the reversibility of light rays a straight line of light impinging on such a lens would be focussed to a circular spot. Thus the information-carrying light from the moving vehicle can be seen to illuminate a'line'as the vehicle moves along the road (or track) alongside which the lens is placed. This'line'is focussed to a spot by the cylindrical lens thereby eliminating the effect of the motion of the vehicle on the collection of the information. In reverse, the availability of information across a'line'allows collection by the moving vehicle. All of this also works in a situation where both bodies are stationary, as long as both sets of apparatus are within the beam collection areas. This part of the invention could look like an'optical wall'.

In more detail, at the optical transmit/receive head-end is a suction-type or adhesive connector (or similar) to allow fixing of the assembly to, eg; a car window.

Information is passed in to or out from this assembly as a collimated beam. Within this head is a lensing arrangement that takes (or passes) the information either to (or from) a fibre cable (which might be the connecting cable) or directly onto a suitable photodiode or from a laser or light-emitting diode. (These latter may be in the optical head or in the laptop or phone). Also within this part of the apparatus is an electrical circuit that takes the data from the original source (computer or mobile telephone) and re-constitutes it so that it can be transmitted at a much higher data rate. This piece of the apparatus allows 2-way messaging so that within it incoming messages are received and re-timed so that they can be sent on to the computer (telephone etc) at an acceptable bit-rate.

Just to clarify this, a fax modem connection to a laptop might operate at 28.8 or possibly 56 kilobits per second. The optical head system contains electronic circuitry that re-times such data so that it can be transmitted (or received) at (say) 155 megabits per second, therefore very substantially shortening the actual time needed to transmit the quantity of information that constitutes the message. This piece of the apparatus attaches to a train or car window and points at the'transmit/receive'apparatus to secure the connection or can be hand-held (e. g. , at an airport).

The cylindrical-lens based apparatus also contains items such as laser or lightemitting diodes (for transmitting) as well as photodiodes (for receiving) and suitable electronics that allow the re-timing of messages so that a very fast data transfer link can be made to (or from) the optical head as it passes, while transferring standard speed messages into (or from) the main network. The principal item is the cylindrical lens which will need to be of a suitable size and shape and tolerance to suit variations in height or pointing. Activation signal beacons could be placed immediately before reaching the cylindrical lens apparatus to pre-activate the link.

An amount of additional technical detail attaches to the operation of the optical transmit/receive head and the cylindrical lens receiver (referred to below as the 'optical wall'). For example, there will need to be an additional protocol to'enable'the optical link, then standard modem protocols within the optically-transmitted message. There also needs to be methods of converting data transmission speeds within the'optical head'although most of this is prior art. Some further information on how this can be expected to operate can be given by an example of anticipated usage.

A person is travelling in a train, and discovers poor and intermittent mobile telephone reception. Instead of trying to send (receive) an e-mail via a mobile telephone connection the laptop is connected to the optical head. This is stuck to the train window via its suction or adhesive pad. As the train approaches the'optical wall'the link is activated, then as the optical path connects, a rapid exchange of protocols registers the user to the network, then downloads/uploads e-mail in a very short space of time (by using very rapid transmission). Although the train is moving, the time taken to exchange messages is very short, and therefore the train has only moved a very short distance in this period of time. For typical vehicle speeds, e-mail message lengths and projected optical link bandwidth the sending of a typical e-mail would be accomplished in the time taken for the vehicle to have moved tens of centimetres.

This invention can be seen as an addition to present-day systems.

Two diagrams, showing the operation of cylindrical lenses and the operation of this invention as a specific method of optically transmitting and/or receiving data from moving bodies are appended.

Diagrams Figure I shows the operation of a cylindrical lens, specifically light emanating from a point source being transformed into a line.

Figure 2 (a) shows the capture of information and its transfer from a line to a point Figure 2 (b) shows how data, emitted at a normal to the direction of travel illuminates a'line' onto the landscape.

Claims

Claims 1. An apparatus that can carry out the functions described, consisting of an optical head that transmits (or receives) information through free space to allow connection from or to a laptop computer, or other computer, mobile phone or the like, and a receive/transmit station that uses the property of a line-to-spot transformation lens or lenses, (or spot-to-line transformation), to effectively nullify (over a short distance) the traversal of the lens by a moving body that is transmitting or receiving information, thus allowing the information to be given to or collected from any moving body whilst it is within the lens collection area.
2. An apparatus as in claim 1 above where the lensing arrangements that effect the nullifying of relative movement are of any compound or multiple type or are of single construction but which regardless of such details allow the spot-to-line or line-to-spot transformation function to occur.
3. An apparatus as in claim I above where the arrangements to collect (distribute) information via the lensing system described may use additional unspecified optical elements to achieve the purpose.
4. An apparatus substantially as that described above which can also be used to collect/distribute information from a stationary source.
5. Any apparatus similar to that described here that might alternatively use an optical head as described, embedded within a computer or mobile phone, as well as an optical head that can be remotely attached by cable (either optical or electrical) to the computer or mobile phone at one end and affixed to (for example) a car window at the other.
6. An apparatus similar to that described in claims 1 and 4 where the optical head could be hand-held as well as fixed, for example at an airport where pointing the optical head at the optical wall may be the simplest way of achieving a connection.