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?
Keep your contact information in a prominent location.
Write for yourself and for posterity.
Write pertinent field information with every new entry. You should enter the date, time, and location at the top of every page.
Add information on your location.
Record your methods.
Make backup copies.
If you use abbreviations, make sure there is a key in your field notebook.
Don’t leave home without it.
Form a writing habit. Thomas Jefferson was such an inveterate chronicler of daily events in his notebooks that he even took the time to record the weather four times on the day he helped write the Declaration of Independence. So unless you have something far more pressing than writing the Declaration of Independence, you have no excuse for avoiding your field notebook!
Set up a structure for your field notebook.
Create an index.
Treat your field notebook like a scrapbook. You should view your field notebook as a central clearinghouse for miscellaneous information that is relevant to your research project. If there are related bits of information that you will find useful later on, sketch them, write them down, photocopy them, and staple or tape them in your notebook.