Tilted Cat Helmet Mounted Display

Honeywell has developed a new helmet mounted display (HMD) with a 60° field of view (FOV) by using a unique Tilted Cat (Catadioptric) Combiner. The Tilted Cat display concept allows a wide FOV display to be designed: with a 3:1 display brightness improvement over the conventional folded catadioptric approach; provides a similar improvement in combiner see through transmissions; and only requires a small tilt on the optically powered combiner which minimizes the complexity of the optics. Large FOV HMD's with see through capability require tilted optically powered surfaces with complex optical systems for the display projection and relay. The optical performance of a tilted powered element becomes more asymetric as the tilt increases, and to maintain a resultant well resolved symmetric display image, additional non-symmetric, tilted, decentered lens elements are required. The Tilted Cat combiner permitted a practical display optical system to be defined for a 60° FOV. The high resolution performance levels of the smaller FOV displays was obtained, with the resolution limited only by the CRT's resolution. A summary of the design considerations, the development of, and the demonstrated performance data for the 60° Tilted Cat HMD will be presented.