Four Years of Night Vision Goggle Diopter Eyepiece Research and Field Studies with AFSOC Aircrew (2000-2004)

摘要

United States Air Force aircrews are some of the most skilled and highly experienced night vision goggle (NVG) users in the world. Beginning in the 1990s, the use of AN/AVS-9 (F4949) allowed aircrews to have continuously adjustable eyepiece diopter settings. However, continuously adjustable eyepiece settings are not in the design of the newest NVG that is in the transition phase of being fielded. The Panoramic Night Vision Goggle (PNVG) has a 95-degree horizontal field-of-view, achieved with two channels per ocular with an image intensifier each. The first three studies reported on in this publication were performed to help determine what fixed diopter setting of the eyepiece would work for most aircrew. The surveys were conducted with AFSOC aircrew members at several Special Operations Squadrons in Ft. Walton Beach, Florida. The first study surveyed 95 aircrew to determine the range of diopter settings they were using. A second study addressed how consistent 18 highly trained aircrew were at preflight setting of their goggles. The third study addressed how 90 aircrew would tolerate a fixed-focus eyepiece set at either -1.0D or -0.50D. In another study, aircrew members gave a favorable response to the use of snap-on lenses, so the authors proceeded to examine how many snap-on lenses would be necessary for the majority of the user population. It was determined that the majority of aircrew could work with a total of 3 diopter settings: -0.25D, -1.0D, and -2.0D. It also was determined that custom snap-on lenses could be made for the few crew members who could not work with the three choices. For some of these individuals, the lenses needed to be refracted. A final study was designed to evaluate NVG visual acuity and subjective ratings for a range of diopter settings, including user-selected and three fixed settings of -0.25D, -1D, and - 2D. The median user-selected setting was -1.25D and ranged from +0.5D to -3.5D. (multiple tables, figures, and refs.).