Near-eye display device and methods with coaxial eye imaging

A near-eye display device, with coaxial eye imaging, for mounting in field of view of an eye of a user, comprising:

• a display unit for displaying a display image;
• a viewing unit for (i) presenting the display image to the eye based upon polarized visible light received from the display unit and (ii) transmitting ambient light from an ambient scene toward the eye;
• and
• an eye imaging unit including
• an illumination module for generating infrared light,
• a first polarizing beamsplitter interface, disposed between the display unit and the viewing unit, for (i) merging a polarized infrared component of the infrared light with the polarized visible light and (ii) separating from the polarized visible light a portion of the polarized infrared component reflected by the eye, and
• a camera for forming an image of the eye based upon the portion;
• wherein the viewing unit includes:
• an imaging objective for focusing the polarized visible light to present the display image to the eye,
• a second polarizing beam splitter interface configured for (i) transmitting the polarized visible light received from the display unit and (ii) reflecting toward the ambient scene the polarized infrared component received from the first polarizing beamsplitter interface,
• an infrared-band mirror disposed between the second polarizing beamsplitter interface and the ambient scene for retro-reflecting the polarized infrared component reflected toward the ambient scene by the second polarizing beamsplitter interface, and
• an infrared-band quarter-wave plate for rotating polarization of the polarized infrared component to form, in cooperation with the infrared-band mirror, orthogonally polarized infrared light to be transmitted by the second polarizing beamsplitter interface toward the eye.