Optical see-through free-form head-mounted display

A free-form prism-lens for use in an optical see-through head-mounted display, comprising:

• a first free-form surface configured to receive light from a micro-display and configured to transmit the received light into the body of the prism-lens;
• a second free-form surface configured to receive the light transmitted into the body of the prism-lens from the first free-form surface and configured to totally internally reflect the received light at the second surface;
• and
• a third free-form surface configured to receive the light reflected by the second free-form surface and configured to reflect the light out of the prism-lens,
• wherein the prism-lens has an f-number less than 3.5 and an effective focal length of 21 mm or less, wherein the exit pupil diameter is at least 6 mm.