Virtual or augmented reality headsets having adjustable interpupillary distance

A virtual or augmented reality headset, comprising:

• a frame including opposing arm members, a bridge positioned intermediate the opposing arm members, and a plurality of linear rails, at least one linear rail provided at each of opposing sides of the frame defined by a central reference plane;
• a pair of virtual or augmented reality eyepieces each having an optical center, the pair of virtual or augmented reality eyepieces movably coupled to the plurality of linear rails to enable adjustment of an interpupillary distance between the optical centers;
• and
• an adjustment mechanism coupled to both of the pair of virtual or augmented reality eyepieces and operable to simultaneously move the pair of virtual or augmented reality eyepieces in adjustment directions aligned with the plurality of linear rails to adjust the interpupillary distance.