What is portable monitor? It was researched by the German Institute for optical microsystems. Its shape like a pair of glasses, but it shows images by receiving instruction from people eyes' activities. All the mystery is inside the chip on monitor, so you can read the various data directly on the glasses.
How does portable monitor work as one kind of multi touch monitor? Actually it works through a set of optical systems, mainly precision optical lens ultrastructure, to enlarged image on the panel. It projects the image on the retina and then presents to the eye of the beholder. In another words, you can take a magnifying glass to see the enlarged virtual object image.