We have developed a Near-to-Eye Display (NED) technology based on diffractive optics. Thin and highly transparent
plastic light guides enable a light-weight and ergonomic see-through NED design. We have previously reported of a
compact NED with an integrated gaze tracker. Eye gaze tracker can detect the user's focus point in the displayed image.
We have now made advances to further increase the level of integration as well as to enable the optical see-through.
Originally, three separate light guides were used: two for the display (red, green/blue) and one for infrared light of the
gaze tracker. To reduce weight and the system complexity, a shared light guide is now used for transmitting red (~630
nm, display) and infrared (~850 nm, gaze tracker) wavelengths. In addition, shared output gratings are used for outcoupling
the light. Light guide plates have been characterized by measuring their modulation transfer functions.
Measurements show that the deterioration of the NED's resolution, caused by the light guides, is reduced with improved
manufacturing techniques. Also, it has been verified that the additional gratings for infrared (light in-coupling and
expansion areas) do not have a notable effect on the display resolution.