Charlie Sorrel of Wired describes Julius von Bismarck as The Brains Behind the Image Fulgurator:
But first, about that name: According to von Bismarck, ‘Image Fulgurator’ comes from the Latin for ‘lightning’ (fulgur) and means ‘Flash Thrower’.First, let us make clear that von Bismarck has applied for a patent for the Fulgurator. He stressed this point. Of course, anyone with the requisite skills can make one of their own, but Julius wants to keep some degree of control over commercial use.
To see why, consider how it works. The device is a modified camera — in this case, an old manual Minolta SLR. A flashgun fires through the camera in reverse, from the back. The flash picks up the image of a slide inside and projects it out through the lens and onto any surface.
The trick is in the triggering. The Fulgurator lies in wait until an unsuspecting photographer takes a picture using a flash. When the device’s sensor sees this flash, it fires its own unit, throwing up an image which is captured by the hapless photographer’s camera while remaining unseen by the naked eye.