This is a high power incandescent lamp for movie/TV studio or on-stage theater lighting projectors. Its filament has the classic flat shape for this use. The power rating of this particular lamp is unknow for me, but I gues it must be at least 1.5 kW.
I ignore the actual purpose of that "curious" mesh grid placed near the filament, but I guess it must be for taking a lot of the vaporised tungsten pushed by convection towards the upper side of the globe when the lamp works upright but slightly lifted, avoiding in some degree the glass blackening of that part.
Perhaps someone could give you a broad info about this beautiful lamp.