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?
Pay attention now:
No matter how much you know or learn about syntax, grammar, or rhetoric,
This small internal quaver, this inner disturbance,
Is the most useful evidence you'll ever get.
Someday, you'll be able to articulate what causes it.
But for now, what's important is to notice it.
Noticing is always the goal.
...the faint vertigo caused by an ambiguity you can't quite detect.
What matter is what it points to.
Find out what's causing it and fix it
Even if you're not sure how.