The technology provides for adjusting a see-through, near-eye, mixed reality display device for alignment with an inter-pupillary distance (IPD) of a user by different examples of display adjustment mechanisms. The see-through, near-eye, mixed reality system includes for each eye a display optical system having an optical axis. Each display optical system is positioned to be seen through by a respective eye, and is supported on a respective movable support structure. A display adjustment mechanism attached to the display device also connects with each movable support structure for moving the structure. A determination is automatically made as to whether the display device is aligned with an IPD of a user. If not aligned, one or more adjustment values for a position of at least one of the display optical systems is automatically determined. The display adjustment mechanism moves the at least one display optical system in accordance with the adjustment values.