Non see-through, monocular helmet mounted displays (HMDs) provide warfighters with unprecedented amounts of information at a glance. The US Air Force recognizes their usefulness, and has included such an HMD as part of a kit for ground-based, Battlefield Airmen. Despite their many advantages, non see-through HMDs occlude a large portion of the visual field when worn as designed, directly in front of the eye. To address this limitation, operators have chosen to wear it just above the cheek, angled up toward the eye. However, wearing the HMD in this position exposes the display to glare, causing a potential viewing problem. In order to address this problem, we tested several film and HMD hood applications for their effect on glare. The first experiment objectively examined the amount of light reflected off the display with each application in a controlled environment. The second experiment used human participants to subjectively evaluate display readability/legibility with each film and HMD hood covering under normal office lighting and under a simulated sunlight condition. In this test paradigm, participants had to correctly identify different icons on a map and different words on a white background. Our results indicate that though some applications do reduce glare, they do not significantly improve the HMD's readability/legibility compared with an uncovered screen. This suggests that these post-production modifications will not completely solve this problem and underscores the importance of employing a user-centered approach early in the design cycle to determine an operator's use-case before manufacturing an HMD for a particular user community.
