We are using two HD USB camera for the 3D image. The cameras are mounted on the robot head. The robot head can be moved freely at 3 axis.
For the good field of view we put fish eye lenses on the cameras. It's more than what you can see in the HMD, but it's needed for the correct depth perception. Without the high FOV lenses everything feels lot closer than in reality.
It will be better if the eyes of the robot can be upgraded with high FPS (frame per second) capable cameras for more realistic feeling. The higher FPS rate is achievable with higher image compression, but it will need more powerful computing on the robot.