HELMET SUPPORTED OPTICAL SYSTEMS WITH FOUR REFLECTIONS

A helmet supported optical system which provides an eye of a wearer (11 or 49) of a helmet (7 or 35) with a direct view of the scene forward of the wearer (11 or 49) on which is superimposed collimated optical imagery. The system comprises: an eyepiece (1 or 47a, 47b); means (5 or 37a, 37b, 39a, 39b, 41a, 41b, 43a, 43b) operable to develop a bright data representation at a plane (31or 44a, 44b) substantially congruent with the principal focal plane of an element (21 or 46a, 46b) of the eyepiece (1 or 47a, 47b); and, disposed between the means (5 or 37a, 37b, 39a, 39b, 41a, 41b, 43a, 43b) operable and the eyepiece (1or 47a, 47b), a body (3 or 45a, 45b) of light refractive material. The system has a configuration which facilitates improvement in respect of all up weight and/or moments of the system about the helmet wearer's (11 or 49) neck pivot position vis-a-vis known helmet supported optical systems, as above which do not include the body (3 or 45a, 45b) of light refractive material disposed between the means operable (5 or 37a, 37b, 39a, 39b, 41a, 41b, 43a, 43b) and the eyepiece (1 or 47a, 47b).