AR / VR Science Note 001: HMD Optics
Optics within a head-mounted display serve three general purposes:
Collimation of light such that an image source appears at a distance greater than its physical distance from the wearer’s eyes;
Magnification of the image source such that an image appears larger than the actual source;
Relay of light patterns from an image source, sometimes located off axis, to the wearer’s eyes (Melzer et al., 2009).
There are a variety of imaging and display technologies employed within head-mounted viewing devices. Each separate implementation requires its own specific optical design, whether it is to enable users to focus on a flat panel array positioned within inches of their eyes, or to relay imagery generated by a microdisplay in an off-axis position such as the side of a display device. In many ways optics are the greatest challenge, and often the limiting factor, in the design of head-mounted viewing devices. Each optical element added to a system means an increase in size and mass of the overall display.
Melzer, James E. Head-Mounted Displays: Designing for the User. McGraw-Hill Professional, 1997.
This AR / VR Science Note is based on content drawn from the book Practical Augmented Reality: A Guide to the Technologies, Applications and Human Factors for AR and VR (Pearson / Addison Wesley Professional, Fall, 2016).
Reproduced by the author with permission from Pearson © 2017.
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