22 May 2015 Visual fatigue induced by optical misalignment in binocular devices: application to night vision binocular devices
Author Affiliations +
Abstract
The additional and perhaps unnatural eye-movements required to fuse misaligned binocular images can lead to visual fatigue and decreased task performance. The eyes have some tolerance to optical misalignment. However, a survey of the scientific literature reveals a wide range of recommended tolerances but offers little supporting experimental evidence. Most experimental studies are based on small numbers of participants exposed to brief periods of optical misalignment. Therefore, these published tolerance limits might have limited relevance for long-duration exposure to misaligned binocular devices. Prolonged use of binocular devices may cause visual fatigue irrespective of binocular alignment especially for complex tasks such as night vision flying. This study attempts to identify measures most sensitive to misalignment in order to establish relevant tolerance limits for in-service binocular night vision devices. Firstly, we developed a rugged and deployable test bench that can measure binocular alignment with a reproducibility error of less than 1 arcmin. The bench was used to identify and investigate major factors affecting the stability of the optical misalignment over time. Our results indicated that the optical misalignment of a given device changed over time as a function of the in-service usage and thermal history of the device. Secondly, participants were exposed to experimentally controlled levels of optical misalignment typical of those measured on in-service binocular night vision devices. The visual fatigue of each participant was assessed via a set of oculomotor parameters. The oculomotor parameters showing high sensitivity to optical misalignment were compared for subjects exposed to extended periods of misalignment in a baseline reading task and a task using an actual night vision device.
© (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Maria Gavrilescu, Josephine Battista, Michael R. Ibbotson, Peter Gibbs, "Visual fatigue induced by optical misalignment in binocular devices: application to night vision binocular devices", Proc. SPIE 9470, Display Technologies and Applications for Defense, Security, and Avionics IX; and Head- and Helmet-Mounted Displays XX, 947010 (22 May 2015); doi: 10.1117/12.2176530; https://doi.org/10.1117/12.2176530
PROCEEDINGS
15 PAGES


SHARE
RELATED CONTENT

Space focusing mirror assembly with flexure hinges
Proceedings of SPIE (August 21 2014)
Visual just noticeable differences
Proceedings of SPIE (February 19 2018)
Biocular image misalignment tolerance
Proceedings of SPIE (September 08 2003)
Making The Qualitative Quantitative A Discussion Of The...
Proceedings of SPIE (September 07 1979)

Back to Top