Abstract: An optical switching system particularly useful in optical networks where waveguides are required from one node to several others, to provide multiple paths in the event of an outage on a particular waveguide is provided. The switching system is a one sided switch having p ports and allows any of the p ports to be connected with any other of the p-1 ports.

Abstract: A sleeve for retaining a plurality of optical fibers in a close or contacting relationship is provided. The sleeve has a bore receiving a number of optical fibers. The internal surface of the bore is such that when that number of optical fibers are contained therein the bore surface defines a perimeter substantially equally spaced about the external surfaces of the optical fibers. Advantageously the sleeve of the present invention may be sealed about the plurality of fibers by vitrification or adhesive to support the fibers or fiber ends without causing unequally distributed stress in the fibers. Signal quality is thus better assured.

Abstract: A method and circuit is disclosed wherein two beams exiting opposite ends of a resonant optical cavity, such as a Fabry-Perot (FP) etalon for example, are provided via waveguides or via free space directed by mirrors to a combining region where the beams can interfere with one another to provide a desired output response. In one embodiment, multiplexed channels of light can be demultiplexed by the device described heretofore, or alternatively, the phase relationship between these two beams can be altered prior to their being combined to provide, for example, a linearized output response useful in applications such as wavelength locking. By varying the reflectivity of the optical cavity reflectors and/or by varying the phase relationship between the two beams exiting the optical cavity, a variety of desired output responses can be realized.

Abstract: A reference system for an optical wavelength scanner, used for measuring wavelengths of radiation from an optical device. The system utilizes a wavelength reference comprising a fixed fiber Fabry-Perot (FFP) filter in combination with a reference fiber Bragg grating (FBG) having an accurately known reflection wavelength to minimize the effects of drift and non-linearities in the scanner and to allow a simple flexure element to be used to position a dispersive grating. The wavelengths of the reference comb of the fixed FFP are determined by reference to that of the reference FBG. Then, the peaks or notches in the light intensity from the device under test are located with respect to the comb of peaks produced by the reference. In a most simple embodiment two ports are coupled so as to provide their output light to the dispersive element simultaneously and only a single collimating lens is required for collimating light from the output ports.

Abstract: A multi-stage optical isolating device having at least three stages includes birefringent crystals for separating shifting and combining an incoming beam of light into orthogonal polarized beams. The multi-stage device also includes at least three Faraday rotators that rotate incoming light propagating through the device in a same direction. The inclusion of a reciprocal rotator in the form of a half-wave plate advantageously obviates orienting the Faraday rotators differently.

Abstract: A record-playback attack on a security system involves recording authorisation information such as passwords and playing them back to the server at a later time to unlawfully access a system. A method is disclosed for detecting record-playback of biometric information. When biometric information is provided to a server, it is always slightly different due to the nature of human input, health, etc. When two biometric input samples are substantially identical, a record-playback attack on system security is suspected and access is denied.

Abstract: A secure card such as a credit card having a magnetic strip thereon is disclosed. The magnetic strip is coated with a thin amorphous layer having electrical characteristics and a processor. In a first state, the amorphous layer acts to interfere with reading of information from the magnetic strip. Identification of a user of the card as an authorized user thereof results in a second state in which the information stored in the magnetic strip is accessible. For example, biometric identification or the use of a PIN entered either directly into the card or through an input terminal cause the processor to switch power from the amorphous strip thereby removing the interference and unmasking the information on the magnetic strip.

Abstract: A method of enhancing network security is provided for a communication session initiated between a first computer and a second other computer. From the first computer to the second computer in communications therewith a process for securing communications therebetween is transmitted. One such process is a biometric characterisation process for characterising fingerprints. The process is for execution on the second computer and is selected to be compatible therewith. Communications from the second computer to the first computer are secured using the transmitted process on the second computer and using, on the first computer, a compatible process to the transmitted process. The host computer can modify or replace the process or data particular to the process before each session, during a session, or at intervals.

Abstract: In the past, user authorization based on biometric information was conducted by correlating a single instance of biometric information against a template. By using this method, a percentage of the population is difficult to authenticate. Further, due to skin damage and injuries, sometimes biometric information is not suited to identification. A sore throat affecting voice information and scraped finger tips affecting fingerprint information are two examples of common problems with authorization in dependence upon biometric information. A method of authenticating a user in dependence upon biometric input information is disclosed. The method allows a user to select biometric information sources and a number of repetitions for each source in order to customize the process of biometric user authentication.

Abstract: Due to the frequency dependence of phasing mechanisms applied in planar printed reflectors, when using planar printed reflector antennas beam squint occurs as the frequency is scanned within the operating band. In order to reduce or eliminate beam squint, an incident signal incident upon a reflector is altered in such a way that the outgoing signal retains a same direction. In an embodiment, this is achieved by providing feed elements in different locations, each feed element for feeding a signal of a different frequency. In another embodiment, two reflector arrays are used wherein beam squint caused by the first reflector array is compensated for by the second reflector array.

Abstract: The present invention relates to a coupling element for coupling between optical elements, for instance a ferrule encased fiber end and a lens, two lenses, or filter and lens assemblies, which provides a reliable joint with a determined spacing and angular orientation between them if needed. Advantageously, the coupling in accordance with the present invention does not obscure optical transmission through the coupling with an epoxy layer. A stand off element is provided which has opposite reference surfaces for joining the end faces of the optical elements and a central aperture, slot or equivalent open area for light transmission. In use the open area is aligned, for example with the fiber end and the desired port in the lens. Adhesive connection can be provided between the opposite surfaces of the stand off element and the coupling end faces of the optical elements. No epoxy is applied over the open area. Other securing methods such as external securing elements can be used.

Abstract: In the design of transcutaneous energy transfer devices, variation in spacing between coils results in energy transfer efficiency changes. These changes may have significant effect on a system. It is proposed to provide a plurality of implanted coils for receiving energy simultaneously. Preferably, a plurality of coil pairs is used for transferring energy simultaneously. Also, a feedback system for use in a multiple coil system is disclosed.

Abstract: This invention relates to a seamless system for controlling the flow of fluids, such as liquids or compressed air, through a non-fragmented length of flexible tubing. It incorporates into a single system a number of functions currently performed with separate valves within conventional dental handpiece fluid flow control units. The invention can be fitted to an existing flexible fluid supply line, within a dental delivery system without destructive insertion or removal of any intermediary parts and without contact with the fluid medium itself. The invention is conceived to accommodate from the outside, three contiguous portions (a first, an intermediate and a second portion) of a non-fragmented length of flexible tubing.

Abstract: A polarization beam splitter combiner uses a birefringent crystal that is a fraction of the size of conventional crystals used in similar devices. Since the crystal is considerably shorter in length, the beam passing through the crystal can be uncollimated, spreading very little from one end to the other. Launching uncollimated beams through a short small crystal obviates the requirement for lenses at the end face of the crystal having two waveguides coupled thereto. Since lenses are not required the waveguides at the input/output end face can be very closely spaced apart. Conventional lensed devices utilizing a pair of lenses at an input/output end face must be considerably larger in order to accommodate the lenses and resulting collimated beams.

Abstract: A multi-pass optical filter using two identical filters provides narrower band filtering by double filtering an optical signal passing therethrough. Although passing a beam of light at an optical filter having a substantially thick optical thickness is known to have significant coupling losses due to angular misalignment of the output beam and the receiving optical fibre, it has been found that twice filtering in the conventional manner by serially coupling two same filters increases coupling losses. However, this invention provides a coupling arrangement wherein losses are significantly lessened by offsetting the axes of the lensed filters such that the beam exiting the first filter couples into the second filter as it would be reflected backward into the first filter.

Abstract: An optical filter is provided having first and second graded index (GRIN) lenses preferably disposed in a coaxial relationship so that they have a common optical axis. Each of the GRIN lenses has an end face providing a port at predetermined location. The ports are disposed on opposite sides of the optical axis and each of the ports is substantially equidistant from the optical axis, so as to be oppositely offset from the optical axis by a same amount. The filter also includes an optical interference filter disposed between other end faces of the first and second graded index lenses. By providing at least four spaced ports, equidistant from the optical axis, such that two ports form a first couplet on opposite sides of the axis from each other and such that two other ports form a second couplet on opposite sides of the axis from each other, wherein one of the ports of one couplet is optically coupled with one of the ports from the other couplet, an add and drop circuit may be realized.

Abstract: A method is disclosed for improving portability of secure encryption key data files. The method provides for re-securing key data files according to different security processes for mobility. For porting an encryption key secured using a fingerprint authentication process to a system having only a password authentication process, a user selects password authentication process, provides a fingerprint and is authorised, provides a new password and then the encryption key is accessed according to the fingerprint authentication process and secured according to the password authentication process. This allows the use of specialised security hardware at one location while retaining an ability to transport encryption keys in a secure fashion to other locations, which do not have similar security hardware.

Abstract: A system and method for constructing documents has files containing data and instructions. The data forms logical streams for provision to output means. According to the method, a plurality of referents referring to logical streams of data are provided. A plurality of different referent scopes with which referents are associated and used and outside of which referents within a scope are inaccessible are also provided. Referents are then inserted into the logical stream of data and within a referent scope from the plurality of referent scopes. The logical streams of data referred to by referents within a referent scope are then resolved but resolving of a referent scope does not necessarily result in a resolved logical stream of data absent referents. Once the referent scopes are resolved, the resulting logical data stream is provided to the output device as a constructed document. A system having parts for performing the steps of the method is also disclosed.