Helmet Mounted Sight (Green)

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The Company Research Laboratory (FARL) designed a monocular Helmet Mounted Sight for the RAF Mk4 Helmet. Five such HMS were built for the MoD(PE) and five for the Airborne Display Division.

The image source is a 32x32 LED matrix which is projected via a spherical visor with a dichroic patch to the pilot's right eye. This HMS worked in conjunction with the HOPS Helmet Tracker an optical system also designed by FARL. The LED display is driven by special hybrid electronic modules on the helmet which in turn receive the computed symbology from a Matrix Symbol Generator designed around the Texas 9900 Processor.

The HMS Visor is retained by a novel latching mechanism, of Company design, which enabled the system to survive windblast testing at 450 knots.

The Mk4 HMS was successfully evaluated during 1979/80 in the Cranfield Institute of Technology "Paris" four seat high speed jet liaison aircraft.