Abstract: A data display method and apparatus for use in a vehicle, e.g. for use by the pilot of an aircraft, wherein each eye (EL, ER) of the user (23) is presented with a virtual image at infinity of a respective one of two largely identical displays (31L, 31R). By arranging for corresponding elements (33) of the two displays representative of a controller in the vehicle at a position accessible to the user to have a transverse positional disparity the virtual images of the corresponding elements appear to the user to fuse together to form a single image (I2) in a plane of the controller at a finite distance from the user within the vehicle thereby to facilitate operation of the controller by the user. Other corresponding elements (41, 43, 45, 47, 49) of the two displays (31L, 31R) will normally have no such positional disparity so that their virtual images fuse to present an image (I1) at infinity as in known binocular head-up display (HUD) systems.

Abstract: An apparatus for indicating the position of an object in a three dimensional space is described. The apparatus includes a video arrangement for producing a stereoscopic image of a scene including the object. Overlay generators superimpose on this image a stereoscopic image of a cursor. Cursor control means are provided for varying the apparent position of the cursor in the scene and for providing an output representing the apparent position of the cursor.

Abstract: A magnetic field sensor in the form of an arcuate element comprising two superimposed strips of material is described. The magnetostrictive constant along the longitudinal axis of one of the strips is greater than that of the other strip, the latter strip carrying at each end a post. In use of the sensor a single mode optical fibre is attached to the element via the posts such that the part of the fibre between the posts extends along a chord of the arc defined by the element. A variation in applied magnetic field in the plane containing the arc gives rise to a variation in the part of the fibre between the posts. Light passing through the fibre is thus phase shifted by an amount dependent on the value of the applied magnetic field.

Abstract: A method and apparatus for determining the relative positions of a first object (1) and a second object (3). The method comprises illuminating the first object (1) so as to produce a shadow (17) of the first object on a surface (15) lying at a known position with respect to the second object (3) and forming a two dimensional image of a scene including the surface (15). The distance between the position of the shadow (17) and a reference position (19) in the two dimensional image is monitored, and this distance is used to derive information relating to the relative positions of the first object (1) and the second object (3).