Introduction. Proper fitting and left to right eye ocular alignment is necessary to maintain user performance and comfort with the use of binocular head-worn displays (HWDs). Towards that objective, measuring alignment of binocular HWDs for performance was investigated. Methods. A new, deployable, ruggedized Helmet-Mounted Display Binocular Alignment measurement tool (HMD BAMT) was developed that provides accurate alignment measurements to 15 microns. The tool was developed for measurement of any HWD/HMD in use in the field. Validation of the tool was accomplished using a commercially available binocular HMD. The HMD was provided to the U.S. Army C5ISR Center Research and Technology Integration Directorate at Fort Belvoir, VA for additional validation against the Near-Eye Display Test Station (NDTS), a much larger and more expensive system designed for laboratory measurement of HWDs. Results. Measurements showed the BAMT has very good accuracy and repeatability (i.e. milliradian accuracy). The BAMT capability and comparison to the NDTS measurements are described in this paper. Discussion. Further development of the alignment tool is ongoing and expanding the capability to include other measurements such as but not limited to uniformity, contrast, modulation transfer function (MTF) and distortion. The tool has been ruggedized for field support of binocular displays. The tool design updates have 3-axis capability and will provide fast, automated testing capability for production rate measurements. The new alignment tool will enable measurements to characterize quality of alignment of binocular HWDs in use in the field which will, in turn, support research concerning individual tolerance to representative levels of misalignment.
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