In optics, a caustic is the envelope of light rays reflected or refracted by a curved surface or object, or the projection of that envelope of rays on another surface. The caustic is a curve or surface to which each of the light rays is tangent, defining a boundary of an envelope of rays as a curve of concentrated light.
A piece of milled plexiglass acting as a projecting lens; via the Computer Graphics and Geometry Lab at the École Polytechnique Fédérale de Lausanne
New milling techniques applied to glass and plexiglass panels could be used to “create windows that are also cryptic projectors, summoning ghostly images from sunlight.”
[Pauly and Bompas] hope that the technique will be used in architectural design, to create windows that mould sunlight and throw images or patterns onto walls or floors,” which, if timed, milled, and manipulated just right, could produce a slowly animated sequence of images being projected by an otherwise empty window during different times of day.
To control the shape of a caustic pattern generated by a specular or refractive surface, we need to solve the inverse problem: how can we change the surface geometry, such that incident light is redirected to produce a desired caustic image?
I cannot perceive for you. I can conceive for you and we can then in a sense hold a general agreement about quality of conception and we may all operate under it and that's what is known as a common agreement. But the area of perceiving as such is totally individual, there's no way that we carry it in that sense.
This is not an antisocial gesture; it is in fact a highly ethical one, since trying to get another person to see what and how you see has the potential to become a violation of the other's own autonomy:
There is nothing more unethical than having ambitions for someone else's mind.