Optical System Design for a Head-up Display through Analysis of Distortion and Biocular Parallax

In this study, we present methods to quantitatively analyze and correct the distortions and biocular parallaxes in a head-up display (HUD). To analyze asymmetrical distortions, five kinds of distortions are proposed and evaluated at five eye positions of an eyebox. The differences between distortions evaluated at the four corners of the eyebox and that at the center are defined as the relative distortions, which occur due to head motion of the driver. We also define the convergence and divergence parallaxes at six biocular positions in the eyebox to quantitatively analyze them. Using these analytical methods, we constrain the degree of biocular parallaxes and distortion changes with eye position to be small, so that an optical system nearly free from them can be obtained by optimization design for HUD optics