Near to Eye Display Using a Laser Scanner and a Pancake Lens Relay
A pancake lens is used to relay the scan mirror to the eyebox.
All the pancake surfaces are concentric with either the scan mirror or the eyebox thus this relay has no off-axis aberrations. The input beam is focused by the beam shaper and objective shown so that the scanned beams are focused onto a curved pupil expander. The PBS is used so that the scanning mirror is operating about a normal incidence angle. While the scan mirror is small at about 1 mm, the eyebox due to the beam expander is 8 mm in this example. The curved pupil expander shown, expands the numerical aperture of the beams to create the large eyebox.
The field of view is 41° x 20°. The system is compact.