#PhysicsFactlet
Usually to form an image you illuminate your object uniformly and then collect the light with a pixellated camera. But since Maxwell equations are reciprocal, we can swap the role of the camera with the illumination, and use a patterned illumination, and a detector without any spatial resolution.
This technique is called "ghost imaging" and it is mostly useful in those cases when pixellated cameras are hard to come by (e.g. for THZ radiation).
#Physics #Optics #Visualization