Advanced Helmet Sight Reticle Assembly (AHRA).

摘要

This report describes the research and development of a 19-month program to develop a helmet display technique that uses the helmet visor as the last optical element in the system. Five techniques were explored for projecting reticle and video imagery without any optical element between the eye and the helmet visor. The single reflecting parabolic approach was selected for fabrication of a prototype helmet mounted visor reticle projection assembly. To complete this design it was necessary to develop parabolic visor fabrication techniques, a miniature lamp, and a thin film dielectric coating for plexiglas visors. It was also recognized early in the program that the double-reflecting symmetrical parabolic visor was the best approach for video projection. The special optical conditions obtained with the symmetrical parabolic approach are the reduction of astigmatism and cancellation of coma. This permits the use of a simple triplet design for the collimation optics which projects collimated light to the parabolic visor. This permits a compact helmet mounted assembly. A fiber optic bundle and relay optics are used to relay video information from a 1-inch CRT mounted at the back of the helmet to the collimation optics. This design approach resulted in a reliable prototype that was assembled and delivered on February 15, 1972. (Author)