A new 50° x 60° field of view helmet-mounted display (HMD) with
a tilted catadioptric combiner has been designed, fabricated, and tested.
The tilted cat display concept allows a wide-FOV display to be designed
that has a 3:1 display brightness improvement over the conventional folded
catadioptric approach, provides a similar improvement in combiner seethrough
transmissions, and requires only a small tilt on the optically powered
combiner that minimizes the complexity of the optics. Large-FOV
HMDs 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, optically powered element becomes
more asymmetric as the tilt increases, and to maintain a resultant wellresolved
symmetric display image, additional nonsymmetric, tilted, decentered
lens elements are required. The tilted cat combiner permits a
practical display optical system to be defined for a 60° FOV. The highresolution
performance levels of the smaller FOV displays were obtained,
with the resolution limited only by the CRT's resolution. A summary of
the design considerations, development process, and demonstrated performance
data for the 60° tilted cat HMD are presented.