Vertical prism disparity in aircraft windshields

A current method of quantifying optical distortion in F/FB-111 aircraft windshields is by a technique of displacement grading. It has been hypothesized that varying magnitudes of displacement grading result in corresponding magnitudes of vertical prism disparity, potentially inducing binocular stress. In order to test this hypothesis, three F/FB-111 windshields of varying displacement grading values were evaluated for vertical prism disparity. The hypothesis was borne out by the results. If a binocular design specification for U.S. military aircraft windshields is appropriate, a maximum vertical prism disparity value would appear to be most meaningful.