An example of "tangible interaction" is pressing this checkbox in this video:

https://www.youtube.com/watch?t=100&v=AoWi10YVmfE

In terms of what the projection feels like, this article explains that to some people the laser feels like sandpaper, and to some people it feels like a static shock:

http://www.popsci.com/secret-interactive-holograms-plasma-an...