New Scientist Invention blog: "Ever tried to read a car's maintenance manual while looking inside the engine for the right greasy bolt to unscrew? Then you'll appreciate an idea being patented by US defence contractor Northrop Grumman.

The patent covers a handheld device similar to a torch that contains a miniature mirror chip like the one used in a conventional video projector. The device beams a prerecorded image onto a surface as a maintenance guide."