The only solid lead given ingame to us is via the NPC in and around the altruist camp and its the spectrometer The use of triangle is clearly evident in the game not to mention the beams. Either through a triangular crystal or with the help of water a spectrum can be obtained. A beam through an object that might produce the spectrum casted over to a particular object might open up somethin ? I cant think of a triangular figure or a proper beam to project through.
Like i said before, its what the NPC said, it might be a device or a location where we need to project the light from.
There is a triangle/pyramid on top of the FIB building. Which also looks like a eye from above, but we all knew that.
Maybe its a hint at the black light needed for the limited edition map?