Design of an off-axis helmet-mounted display with freeform surface described by radial basis functions

An off-axis optical system with a freeform surface described by Gaussian radial basis functions for a see-through wide field of view helmet-mounted display (HMD) is presented. By using a freeform surface, an off-axis see-through HMD system with one tilted freeform combiner and four relay optical lenses is designed. An off-axis see-through wide field of view HMD system with a 100 mm eye relief, 15 mm pupil, 45°×32° FOV, and 60° combiner tilt angle is achieved. For the purpose of comparison, two other off-axis see-through HMDs which have the same specifications, but different surface type of combiner and different use count of relay lenses are designed too. One of the two contributions in this paper is the application of radial basis functions to describe optical freeform surface in a wide field of view off-axis helmet-mounted displays, and the other is a way used to determine a starting point of optimization quickly while designing.