So, can collimated optics be used in a glider? Anybody know if it is physically possible?


With the right lenses (in a fairly compact arrangement), it's perfectly feasible to make a HUD image seem like it's at infinite distance or fairly close to it. Try looking through a (straight refractor) telescope with one eye and keeping the other open - if you adjust the focus you'll find a point where both images are clear.

It's then the brain's job to make sense of the overlapping and contradictory images i.e. which image is more important, so you can still suffer from 'object blindness'.

HH
DH