Stereoscopic displays with addressable focus cues

1. A virtual display system with addressable focus cues, comprising:

a microdisplay for providing a virtual image for display to a user;

an eyepiece comprising a reflective optical element configured to reflect optical radiation from the microdisplay to an exit pupil of the system;

a relay lens comprising a refractive active optical element configured to provide a variable optical power, the relay lens disposed along an optical path between the microdisplay and the eyepiece to relay an image from the microdisplay to the eyepiece, the relay lens comprising first and second lens groups disposed along the optical path with the active optical element located therebetween; and

a beamsplitter disposed along the optical path between the microdisplay and the eyepiece, the beamsplitter configured to receive and transmit optical radiation from a source other than the microdisplay to the exit pupil to provide a see-through optical path.

2. The display system of claim 1 , wherein the eyepiece comprises a spherical mirror.

3. The display system of claim 1 , wherein the active optical element comprises a system stop.

4. The display system of claim 1 , wherein the system is telecentric in the microdisplay.

5. The display system of claim 1 , wherein the system comprises an f-number less than 3.

6. The display system of claim 1 , wherein the relay lens comprises a diffractive optical element.