Gec Avionics Limited

Bae Systems Electronics Limited

Richard K Howard

Colin K Marshall

A head up display system comprises an image generator supported and boresighted within a cockpit. The system includes a housing to support the generator and a holographic combiner which is upstandingly supported on top of the housing . In operation, the generator forms an image at object surface and a relay lens arrangement receives, collimates and conveys the image along an optical pathway and through an exit pupil . A prism and a mirror are arranged along the pathway to fold the pathway from a generally horizontal direction to a generally vertical direction towards the combiner . The image enters the prism and is totally internally reflected from a first portion of a first reflection surface towards a first portion of a second reflective surface where it is again totally internally reflected through a second portion of the first surface which allows the image to pas therethrough for reflection by the mirror back through the second portion and through a second portion of the second surface and on to the combiner

Head up displays

A method of producing a reflection hologram wherein light from a source (29) is directed onto the hologram recording medium (23) via a lens (21) which causes light reaching the medium (23) to pass through a construction point (33). The light beam is arranged where it is incident on the lens (21) to be of small cross-sectional area compared with the lens aperture and is arranged to scan over the lens aperture so that the beam scans the medium (23) in a regular pattern of overlapping narrow bands. In this way the hologram may be made to have uniform spectral properties despite a non-uniform energy distribution in the beam.

Reflection holograms formed by scanning

A method and apparatus for making reflection holograms wherein a film (27) of light sensitive material in which the hologram is to be formed is rotated about a first axis (Y--Y) which is itself rotated about a second axis (X--X) which intersects the first axis at a position (Z) spaced from the film so that a coherent light beam (29), which is directed onto the film and whose axis passes through the point of intersection of the axes, scans the film in a pattern of overlapping narrow bands. The bands may be rectilinear or circular.

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Chatham, United Kingdom

Richard K Howard