Development of a stereo video see-through HMD for AR systems

Geometrical studies and experiments were carried out in order to specify requirements for the imaging and display systems of a stereo video see-through head-mounted display (HMD) for augmented reality (AR) systems. It was found that it was necessary to set the left and right optical axes of the stereoscopic imaging system to be parallel to one another, and likewise for the display system. It was also found that, for AR applications handling real spaces at short distances, it was necessary to align the optical axes of the imaging system with the optical axes of the display system in order to avoid spatial perception errors. We refer to this as a 'parallax-free' system. Based on these studies and experiments, a parallax-free stereo video see-through HMD with a wide field of view was developed. It was also confirmed experimentally that a small displacement of the entrance pupils of the imaging system along the axes to the exit pupils of the display system does not cause serious spatial perception errors. By displacing the position of the entrance pupils of the imaging system by 30 mm, we have downsized the HMD to a thickness of 36 mm and lightened it to 340 g. The HMD was then applied to an actual AR system and its usefulness was verified.