Design of freeform surface optical component in helmet mounted display

Abstract

Helmet display (HMD) is the core hardware of virtual display technology. It is a small display device mounted on the helmet to produce visual images for the user. The MHD system mainly consists of an image source, optical, and support system. Still, the traditional optical subsystem cannot achieve the functions of the ideal optical system, such as being light-weight, small in size, and having an extensive field angle. This paper established the proper initial model, and the optimal control conditions and surface upgrade strategy were determined. Herein, the design scheme of the free-form prism with good performance was obtained. We solve the feature of large volume and complicated structure of optical components of helmet display and describe the design idea of free-form prism in detail. In this paper, the system resolution we designed is 800 × 600, the Modulation transfer function (MTF) value of the prism is more significant than 0.1 at the spatial resolution of 30 lp/mm, and the distortion is less than 5%. The exit pupil diameter of the system is 8 mm, and the field angle is 26°×20°.