Designers of visual systems need information regarding the human eye. There are entire books on this subject, but most of the information is not relevant for optical engineers. Here are a few relevant bits of information.
One characteristic of human vision is the binocular field, shown in Figure 1. Fully immersive displays must subtend an angle greater than ±90° horizontally and +60°/-70° vertically, although this angle is limited to 65° on the nose side for each eye. Within this range, binocular vision is limited to a “T” shaped region subtending a bit over ±60°. Virtual reality displays typically cover slightly more than the binocular region while augmented reality glasses are currently limited to significantly less.
Resolution is another characteristic of the human eye that is important to display testing. Figure 2 shows a labeled picture of the region of the human eye surrounding the fovea (the area of highest resolution vision) and Figure 3 shows the resolution of the human eye as a function of distance from the center of the fovea.
It is important to note that the eye normally scans up to ±25°, so the angular resolution required of a display device needs to be on the order of 30 cycles/deg over this entire range of angles. Outside of this, the resolution requirement drops significantly.
[1] Photograph: Danny Hope from Brighton & Hove, UK; Diagram: User:Zyxwv99; License:
https://creativecommons.org/licenses/by/2.0/deed.en
[2] Bernard Kress, “Optical Technologies and Architectures for Virtual Reality (VR), Augmented Reality (AR) and
Mixed Reality (MR) Head-Mounted Displays (HMDs)”, SPIE Short Course SC1218, 2024
[3] Steve Eckhardt and Karly Lunda, “Digital Age Sees New Demand for the Venerable Conoscope”, Photonics Spectra,
September 2020, pp. 56-59
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