Abstract: There is provided an integrity monitor for a display system, the display system comprising an image source and a display. The integrity monitor comprises a controller configured to analyse sensed characteristics at one or more predetermined positions in an image area of the display system and to relate the sensed characteristics to predetermined characteristics of a stimulus, when injected into the system, thereby to determine the presence of a fault in the system. The sensed characteristics may be sensed optically or non-optically. The stimulus may be optical or non-optical.

Abstract: There is provided an integrity monitor for a display system, the display system comprising an image source and a display. The integrity monitor comprises a controller configured to analyse sensed characteristics at one or more predetermined positions in an image area of the display system and to relate the sensed characteristics to predetermined characteristics of a stimulus, when injected into the system, thereby to determine the presence of a fault in the system. The sensed characteristics may be sensed optically or non-optically. The stimulus may be optical or non-optical.

Abstract: A glare visor (13) for reducing ambient light intensity perceived by a wearer viewing a head-up display (3) employing display light (7) including a given wavelength(s) of light. The visor includes a visor body comprising optically transparent material which is partially absorbing of light of visible optical wavelengths thereby to reduce the intensity of ambient light transmitted therethrough to the wearer. A transparent optical coating (12) is formed upon a surface of the visor body which is partially transmissive of light of visible optical wavelengths amongst which it is preferentially transmissive of light of a sub-range of wavelengths for including therein the wavelength(s) of display light. This permits a perceived enhancement of contrast between display light (7) relative to ambient light (8).

Abstract: An image combiner for a viewing device, such as a night vision device, is disclosed for combining a first image, such as generated symbology, with a second image, such as a view of an outside scene in reduced lighting conditions. A waveguide is provided for capturing the first image from a first viewing direction, and for directing the first image in a second viewing direction, the second viewing direction being substantially coincident with a viewing direction of the second image, such that the first image can combine with the second image. At least a portion of the waveguide is arranged to substantially transmit the second image, such that the second image can pass substantially through the waveguide.

Abstract: A glare visor (13) for reducing ambient light intensity perceived by a wearer viewing a head-up display (3) employing display light (7) including a given wavelength(s) of light. The visor includes a visor body comprising optically transparent material which is partially absorbing of light of visible optical wavelengths thereby to reduce the intensity of ambient light transmitted therethrough to the wearer. A transparent optical coating (12) is formed upon a surface of the visor body which is partially transmissive of light of visible optical wavelengths amongst which it is preferentially transmissive of light of a sub-range of wavelengths for including therein the wavelength(s) of display light. This permits a perceived enhancement of contrast between display light (7) relative to ambient light (8).

Abstract: An image combiner for a viewing device, such as a night vision device, is disclosed for combining a first image, such as generated symbology, with a second image, such as a view of an outside scene in reduced lighting conditions. A waveguide is provided for capturing the first image from a first viewing direction, and for directing the first image in a second viewing direction, the second viewing direction being substantially coincident with a viewing direction of the second image, such that the first image can combine with the second image. At least a portion of the waveguide is arranged to substantially transmit the second image, such that the second image can pass substantially through the waveguide.