In front side, a small Glass is Prism which will work on Total internal reflection and all the display will be shown on this portion only, without any back support actually. Transparent display for this device is possible due to some more factors you will see a bit ahead.
This part where Glass/prism is attached will be even smarter. This projector will project the image/video/screen on the one face of the prism and it will in turn reflect in front of our eyes. It will also have some eye tracking capacity and we can command even trough eyes.