In designing remote vision systems for human operators, two different features of the human eye should be considered: (1) the very wide field of view of the eye permits secure and rapid orientation and the avoiding of obstacles; (2) the high central (foveal) acuity of the eye permits fine discrimination. A capable head-mounted display will not limit either of these human eye features more than absolutely necessary. LCDs show promise for reasonable cost and weight, but the small number of pixels available now and in the foreseeable future means a necessary limitation of the field of view or of the central acuity, or of both, if only one LCD is used per eye. The best available compromise using only one LCD is embodied in the LEEP optics, which use a radial compression format to provide a very wide field with minimum loss of resolution at the center. LEEP Systems, Inc. has undertaken two developments. The first simply increases the lateral field of view by twenty-five degrees (the CYBERFACE2). The second adds an optical high-resolution insert. Because the insert is added optically in the head- mount, the smaller the insert, the sharper its detail.
Eric M. Howlett,
"High-resolution inserts in wide-angle head-mounted stereoscopic displays", Proc. SPIE 1669, Stereoscopic Displays and Applications III, (30 June 1992); doi: 10.1117/12.60427; https://doi.org/10.1117/12.60427