Abstract: In a radiographic apparatus a source of radiation is arranged to scan a planar spread of radiation in a plane about the body of a patient being examined. A plurality of detector devices is arranged to provide data representing the absorption of the radiation along a plurality of paths within the spread, for different orientations in the plane, for processing to determine a distribution of absorption coefficients for a planar slice of the body. The arrangement is such that a predetermined number of the detector devices are irradiated by the spread of radiation at any time and the actual devices irradiated change progressively as the scan progresses.

Abstract: In a radiological apparatus wherein radiation is passed through a body along a plurality of co-planar paths, attenuator means is utilized to tend to compensate for differences in the lengths of said paths within a body being examined. The attenuator means, however, introduces a variation into the radiation spectrum and the invention provides means for compensating for such variation. Such compensating involves processing output signals derived from detector means disposed to receive the radiation after it has traversed the body and the attenuator means.

Abstract: Magnetic record media including permanent structures of aligned acicular particles have been proposed as a means of identifying and authenticating a medium. A method of recording and reading out information on such media without interference from the permanent structure remanence variation is described. Suitable forms of magnetic record media and their manufacture are described. The use of the media and method for security documents such as credit cards is also described.

Abstract: Radiographic apparatus is described for evaluating the absorption coefficient of a body at each of a plurality of locations distributed over a planar slice disposed cross-sectionally of the body. A source is arranged to produce a fan-shaped, planar beam of radiation which is directed through the body, in the plane of said slice, and the source is orbited around the body about an axis perpendicular to the plane of said slice. Detectors are provided, and orbited in synchronism with the orbital motion of the source, each to detect the radiation emergent from the body along a plurality of paths. In order to render the paths substantially linear despite the orbital motion, a lateral scan is imposed upon the source which is sufficient, over a predetermined time period, to substantially cancel the orbital motion and replace it by a lateral motion.

Abstract: In an X-ray apparatus for examining a body a source of a fan of radiation and detectors of the radiation along beams in the fan are traversed in a plane to provide data for a plurality of sets of parallel beams in the plane. An orbital motion is provided to give data for further sets at different inclinations in the plane. The data can be processed by arrangements using such "parallel" sets. The orbital motion is continuous during the traverse but the extent of angular change in one lateral scan is kept small so that lack of parallelism in the "parallel" sets does not give excessive errors.

Abstract: In a frequency selective steering system for automatic vehicle guidance, a phase locked loop is used to derive from a sum signal containing wanted and unwanted signal frequencies a reference signal equal in phase and frequency to the wanted signal. The reference signal is used to derive from a difference signal also containing wanted and unwanted signal frequencies an error signal dependent on the phase of the wanted signal only. The error signal is used to control the steering of the vehicle.

Abstract: Scanning imaging systems are described in which an image of a viewed area is scanned across a detector by a line and frame scanning arrangement including a rotatable faceted mirror drum which is of smaller size than hitherto as radiation going to and from the drum passes through an optical system of two elements separated by their focal length. For radiation passing to the drum the optical system can be an objective lens and a collimating lens to produce a small exit pupil within the circumcircle of the drum facets. The drum and a plane oscillatable mirror may both scan the viewed area image of collimated radiation across the detector to permit the generation of a sequential radiation intensity signal and recreate an image, which may be viewable by eye through the optical system, by scanning a beam of parallel light of intensity corresponding to the radiation signal.

Abstract: Apparatus is so constructed as to employ a sampling beam of radiation of a form which at least approximates to a sinusoidal distribution of intensity between the extremities of its skirts, and is such that the range of sinusoidal variation has an extent of approximately four sampling intervals, whereby the sampling beams have themselves the effect of band limiting the required data to a spatial frequency of approximately half the sampling frequency.

Abstract: Radiological apparatus is described which is capable of performing analogue superposition of respective signals indicative of the absorption suffered by penetrating radiation on traversing each of a plurality of co-planar, linear paths through a body, some of which paths intersect. The signals are altered by processing to render them suitable for additive superposition, and the superposition is achieved by means of at least one charge storage tube. The altered signals, or signals related thereto, are applied to the target (or targets) of the tube (or tubes) and are deposited on respective linear regions thereof, the orientation of a linear region relative to the target (or targets) corresponding to the orientation relative to the body of the path giving rise to the relevant signal.

Abstract: Radiological apparatus is described for producing a representation of the variation of absorption coefficient with position over at least one planar slice taken cross-sectionally through a body under examination. The source of radiation comprises an X-ray tube having a target with an extended dimension in a direction substantially perpendicular to the plane of the aforementioned planar slice, and means is provided for scanning the electron beam of the tube along the extended dimension of the target so as to scan the X-radiation relative to the body in said direction.

Abstract: Apparatus is described for performing a computerized axial tomographic examination of a body. The apparatus contains a source of x-radiation and detector devices mounted to face one another across an opening for the body, the source being arranged to project said radiation in a plane towards the detector devices. The source and detector devices are rotated about an axis passing through said opening and means are disclosed for locating the body in said opening and for adapting the apparatus to accommodate a body which is not centrally located in said opening.

Abstract: A method of printing wherein magnetic particles dispersed in an ink are selectively orientated prior to printing onto a document where the particles are aligned on a carrier while the ink is in a low viscous state and the printing is effected when the ink is in a high viscous state. The method by which the viscosity is changed is the selective application of heat.

Abstract: In an apparatus for examining a body with penetrating radiation a source and detector arrangement scan about the body to irradiate the body along a plurality of beam paths lying in a plane. Output signals are provided from weighted components where each component relates to the absorption of the radiation along one of a set of adjacent and substantially parallel beam paths. The weighting is according to a function chosen so that the output signals are restricted to a chosen spatial frequency band to reduce errors in a representation, if the distribution of absorption of the radiation through the body, constructed from the output signals. The weighting may be provided by optical means between scintillator crystals and photomultipliers forming the detector arrangement.

Abstract: A tracking and/or guidance system is disclosed for defining a route to be followed by a vehicle or projectile to a target. The system includes a tracking device which is arranged firstly to operate in an acquisition mode, applicable when the vehicle or projectile is close to the device, and subsequently to be progressively converted into a tracking mode as the distance between the vehicle or projectile and the device increases. In the acquisition mode, the device has a wide field of view but is relatively insensitive to deviations of said vehicle or projectile from said route. As the aforesaid distance increases, however, the field of view is progressively reduced and the sensitivity to said deviations is progressively increased. The invention thus provides a system which is suitable for the both initial acquisition and long range guidance of a vehicle or projectile aimed towards a distant target whilst using a conveniently small detector arrangement.

Abstract: There is disclosed a synthetic aperture radar arranged to survey a region from a mobile location. The radar returns received from the region are first phase weighted by a series of predetermined factors. They are then stored and combined with later returns to give an output signal which has a maximum value when any target present in the region is in a predetermined direction from the location.

Abstract: A bagging machine is combined with a gramophone record moulding machine. In the bagging machine, pivotable suction means removes the front bag from a stack of bags having their open ends uppermost. The rear edge of the mouth of the bag is held by a stationary member so that the mouth is opened when the suction head grips the front surface of the first bag in the stack and pivots away from the stack. A record is delivered down a chute into the opened bag which is then released by the suction head to fall to collection means such as a box. The stack of bags are supported on a carrier, and in order to prevent the second bag (and possibly further bags) from lifting due to friction between bags as the first bag is removed, means are provided in proximity to the upper edges of at least the first few bags in the stack. In the specific embodiment described, these means comprise a pair of ears bent out of the plane of the member which holds the rear edge of the bag mouth.

Abstract: There is disclosed a synthetic aperture radar arranged to survey a region from a mobile location. Radar pulses are transmitted in sets, the pulses from each set being transmitted from congruent positions. The returned echoes of the pulses of each set are then compared to substantially remove signals relating to static targets. The signals relating to the doppler shifts of returns from moving targets are processed by a correlator covering a frequency band sufficient to include such signals or further signals indicative of them and produced as a result of the sampling nature of the pulsed radar.

Abstract: For examining a body by means of X-rays or other penetrating radiation, data is determined representing the absorption suffered by each of a plurality of beams which are passed through the body. The beams are effectively arranged in a plurality of sets of beams, in a single plane, at many different angles. The arrangement is such that the amount of information provided by the beams is a function, which is in part non-uniform, of the beam position in the set. A reconstruction of the distribution of absorption of the radiation within a part of the body is derived from the absorption data so determined.

Abstract: 1. Radar apparatus comprising means for generating a series of pulses of oscillation, scanning aerial means for transmitting said pulses as a beam narrow in azimuth in different directions sequentially, the repetition frequency of said pulses being sufficiently high in relation to the angular velocity of the aerial means and the angle of the beam that a plurality of successive transmitted pulses impinge on a point target, a coherent receiver for reflected energy, means for storing returns derived from said receiver in response to a plurality of successive pulses of oscillation from said transmitting means, means for selecting returns corresponding to a predetermined range stored in said storing means, and means for examining selected returns to detect a cyclic component of substantially constant periodicity indicating the presence of a target at said predetermined range having a radial velocity relative to the apparatus represented by said periodicity.

Abstract: In radiographic apparatus arranged to investigate a region of a body which can include a moving member, for example the heart of a human patient, means are provided for compensating (at least in part) for the blurring of the radiograph which might be caused by the motion of said member. The motion of the member is monitored and used either to periodically interrupt the irradiation of the body each time the motion becomes too great or enable information which might be confused, due to the motion, to be rejected before the radiograph is produced.