Abstract: A position detector is provided for detecting the relative movement of first and second members which are mounted for relative movement along a measuring path. One of the members comprises a magnetic field generator for generating a magnetic field and the other member comprises first and second conductors which are inductively coupled to said magnetic field generator. The arrangement of the first and second conductors and the magnetic field generator is such that output signals are generated in a first and second receive circuits whose position varies with the relative movement between the two members. In addition to carrying information relating to the relative position between the two members, the signals induced in the receive circuits also comprise information defining the relative orientation of the two movable members, and by suitable processing of the received signals the relative orientation of the two members can also be determined.

Abstract: A position detector is provided for detecting the relative movement of first and second members which are mounted for relative movement along a measuring path. One of the members comprises a magnetic field generator for generating a magnetic field and the other member comprises first and second conductors which are inductively coupled to said magnetic field generator. The arrangement of the first and second conductors and the magnetic field generator is such that output signals are generated in a first and second receive circuits whose position varies with the relative movement between the two members. In addition to carrying information relating to the relative position between the two members, the signals induced in the receive circuits also comprise information defining the relative orientation of the two movable members, and by suitable processing of the received signals the relative orientation of the two members can also be determined.

Abstract: 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.

Abstract: A position detector is provided for detecting the relative movement of first and second members which are mounted for relative movement along a measuring path. One of the members comprises a magnetic field generator for generating a magnetic field and the other member comprises first and second conductors which are inductively coupled to said magnetic field generator. The arrangement of the first and second conductors and the magnetic field generator is such that output signals are generated in a first and second receive circuits whose position varies with the relative movement between the two members. In addition to carrying information relating to the relative position between the two members, the signals induced in the receive circuits also comprise information defining the relative orientation of the two movable members, and by suitable processing of the received signals the relative orientation of the two members can also be determined.

Abstract: A position detector is provided for detecting the relative movement of first and second members which are mounted for relative movement along a measuring path. One of the members comprises a magnetic field generator for generating a magnetic field and the other member comprises first and second conductors which are inductively coupled to said magnetic field generator. The arrangement of the first and second conductors and the magnetic field generator is such that output signals are generated in a first and second receive circuits whose position varies with the relative movement between the two members. In addition to carrying information relating to the relative position between the two members, the signals induced in the receive circuits also comprise information defining the relative orientation of the two movable members, and by suitable processing of the received signals the relative orientation of the two members can also be determined.

Abstract: There is described a computer network in which a free space light beam is modulated to convey data to and from a network device. The light beam is generated by a signalling device which includes an optical system which collects the light beam and directs the light beam in an exit direction, and also includes a detector which detects the presence of a network device and a beam alignment system which varies the exit direction to align the light beam with the network device. The computer network has particular application in business premises such as an office. The computer network also has applications in public transport stations, for example an airport, and a public transport vehicle, for example an aeroplane.

Abstract: A position detector is provided for detecting the relative movement of first and second members which are mounted for relative movement along a measuring path. One of the members comprises a magnetic field generator for generating a magnetic field and the other member comprises first and second conductors which are inductively coupled to said magnetic field generator. The arrangement of the first and second conductors and the magnetic field generator is such that output signals are generated in a first and second receive circuits whose position varies with the relative movement between the two members. In addition to carrying information relating to the relative position between the two members, the signals induced in the receive circuits also comprise information defining the relative orientation of the two movable members, and by suitable processing of the received signals the relative orientation of the two members can also be determined.

Abstract: The invention provides a number of improvements useful in printers which may be of the fixed, portable or hand-held types. In one aspect, the printer, which comprises a housing, a printing unit, means for feeding to said printing unit a substrate onto which indicia are to be printed, means for feeding a thermal transfer ribbon to said printing unit, and means for providing electrical power to operate the printer, is characterized by means permitting independent movement of said substrate and said thermal transfer ribbon within said printing unit. In another aspect, the printer includes means for supplying power to operate the printer, for example dynamo driven by a manual trigger. In a further aspect, the means for supplying power comprises a piezoelectric motor.

Abstract: Improved printers are disclosed which are characterized by means for inputting data which is arranged to function without the use of an alpha-numeric keyboard. The data inputting means may be a cursor moving device operating in conjunction with a graphics display system; a graphics display system having a touch-sensitive screen; a speech recognition unit; a memory or "smart card"; or an integral bar code reader. The cursor moving devices may be, for example, a tracker ball or a mouse.

Abstract: An assay technique for qualitative and quantitative detection of a chemical, biochemical or biological detection of a chemical, biochemical or biological species in sample. The technique comprises: (a) coating at least a predetermined part of a pre-formed surface on a substrate with a thin film of a material capable of binding the species to be assayed, the pre-formed surface being optically active with respect to radiation at least over a predetermined band of wavelengths; (b) contacting the coated surface with sample; and (c) observing the optical properties of said pre-formed surface in order to determine a qualitative and quantitative change in optical properties as a result of the binding of the species onto said thin film of material. The optical properties as a result of the pre-formed surface may be observed before and after step (b) in order to determine any change in optical properties, or they may be monitored during step (b). The pre-formed surface is preferably a grating.

Abstract: Magnetic devices are disclosed which include an article comprising a substrate and a thin coating of a magnetic material, in which:(a) said substrate is a flexible, laminar material; (b) said magnetic material is an amorphous metal glass of high intrinsic magnetic permeability, with low or substantially zero magnetostriction, and with low coercivity; and (c) said thin coating of a magnetic material is not greater than 6 microns in thickness. This article can be used as, or to make, an antipilferage tag or marker. Deactivation materials and configurations are also disclosed, as well as techniques, in particular sputtering or PVD, for producing such a tag.

Abstract: This application discloses a method of recognizing and/or locating preselected categories of articles, which comprises applying to the articles a plurality of magnetic elements in predetermined associations (e.g. with predetermined numbers of magnetic elements and with predetermined spacings between said elements), whereby when the articles are caused to move relative to a predetermined interrogating magnetic field, each particular association of magnetic elements gives rise to a magnetic signature whereby the article or category of article carrying each of the predetermined associations can be recognized and/or located. A series of tags or markers for use in such a method, as well as a system for determining the location and/or identity of an article within an article conveying network, are also disclosed.

Abstract: An assay technique for qualitative and quantitative detection of a chemcial, biochemical or biological detection of a chemical, biochemical or biological species in sample. The technique comprises (a) coating at least a predetermined part of a pre-formed surface on a substrate with a thin film of a material capable of binding the species to be assayed, the pre-formed surface being optically active with respect to radiation at least over a predetermined band of wavelengths; (b) contacting the coated surface with sample; and (c) observing the optical properties of said pre-formed surface in order to determine a qualitative and quantitative change in optical properties as a result of the binding of the species onto said thin film of material. The optical properties of the pre-formed surface may be observed before and after step (b) in order to determine any change in optical properties, or they may be monitored during step (b). The pre-formed surface is preferably a grating.

Abstract: A data storage medium is provided which is suitable for production or replication by moulding, casting, embossing or a similar process against a tool. The data storage medium comprises an optically sensitive layer at or adjacent to one surface of the medium, said one surface of the medium comprising a plurality of topographical features or structures disposed in a regularly repeating pattern, said pattern being free from undercutting so that the medium can be produced and/or replicated by molding, casting, embossing or similar process against a tool. The optically sensitive layer is preferably overcoated with a thin film of a metallic material which conforms to the topography of said surface.

Abstract: An optical data storage medium is disclosed for use in an optical read/write system using an optical read wavelength of W, the medium including a textured region having raised areas and depressed areas disposed in a regular array with a period (pitch) not greater than W and a depth (peak-to-trough) in the range 10 to 1,000 nanometers. The medium comprises a substrate and a regular array of zones of magneto-optic material disposed at least over the peaks and troughs of the surface texture and conforming to the surface texture. In many embodiments, there is also a layer or a regular array of zones of an optically reflective material. In one embodiment, the texture is shallow, being generally in the range 10 to 120 nanometers. In a second embodiment, the depth of the texture is at least one tenth of the value of W. In any of the embodiments, there may be a dielectric layer over the top of the structure.

Abstract: An interferometer which comprises: (1) a single, coherent light source; (2) a first converging lens positioned on the optical axis of said coherent light source; (3) a beam-splitting arrangement positioned on said optical axis and spaced from said first converging lens by a distance greater than the focal length of said lens; (4) a second converging lens positioned on said lens; (4) a second converging lens positioned on said optical axis to receive and to focus the two beams emanating in use from the beam-splitting arrangement; and (5) a mirror arrangement positioned so that the beams focussed by said second converging lens impinge on the mirror system and so that the reflected beams are brought to intersect at a focal point and with a large angle between the principal rays of the two beams.

Abstract: A method of forming an image and a radiation-sensitive medium suitable for carrying an image is disclosed. The medium comprises a substrate having a surface structure comprising grooves with a depth of 20 to 100 nanometers. At or close to the surface structure there is a layer of radiation-responsive material which is such that irradiation of selected parts of the structure with radiation of a predetermined polarization causes radiation to be absorbed at the irradiated parts of the surface so that corresponding areas of the radiation-responsive layer are affected in a way which makes such areas distinguishable from the remaining, non-irradiated areas of the radiation-responsive layer. An image and/or data may be stored in such a medium in analogue, digital or pictorial form, or in a combination of any two or all three of these forms. The invention also provides primary and secondary pre-formed data carrying media, the secondary media being replicated from the primary media.

Abstract: Displacement measuring apparatus comprises a light source (10), a lens (12), and index grating (14), a reflective scale grating (16), and three photodetectors (18) at positions corresponding to the zero order and positive and negative first order images of the source (10). The index grating (14) has a castellated surface profile with a mark/space ratio (a/b, FIG. 3) and a castellation height (h, FIG. 3) chosen so that the three photodetectors (18) see wavefronts having a phase separation of 120. The electrical signals from the photodetectors (18) are used to sense the magnitude and direction of movement of a reading head carrying the components (10, 12, 14 and 18) with respect to the scale grating (16).

Abstract: A data storage medium is provided which is suitable for production or replication by moulding, casting, embossing or a similar process against a tool. The method for manufacturing a data storage medium has a surface or a surface region which is strongly absorbent of at least a predetermined band of wavelengths of electromagnetic radiation. The surface or surface region includes a layer of a heat sensitive material which has a textured surface pattern the pitch of which is smaller than the shortest wavelength of the predetermined band of wavelengths, and the depth (peak-to-trough) of which is at least 100 nm. The surface pattern is free from undercutting, and can comprise an array of protuberances or one or more sets of grooves (which may be intersecting). The textured surface pattern is further coated with a thin film of a high-opacity material, e.g. gold, the thickness of the overcoating preferably being such as to give no more than 10% transmission of incident radiation.

Abstract: Apparatus for detecting a datum position in a range of movement of a movable member, comprises a composite grating comprising first and second gratings. The first grating has first and second grating halves and the second grating has third and fourth grating halves which are respectively identical to the first and second grating halves except that the third and fourth grating halves are separated by a spacing. The image of the third grating half is reflected upon the image of the first grating half, the image of the second grating half upon the fourth grating half, the first grating half upon the third grating half and the fourth grating half upon the second grating half. A quadrant detector detects the intensity of the interference images and provides a difference signal which passes through zero at the datum position of the member.