Spreadsheet, a cute Python hack…

The Python Cookbook has a new entry which I thought was especially clever, and perhaps the only really good use of eval that I’ve ever seen. It is a class which simulates a spreadsheet. It is clever because it uses a class which simulates a dictionary as an environment in which to evaluate expressions. Quite clever, and very short.

Tenet calls for Internet Censor… err.. Security, That’s it!

The Washington Times files this report on a speech by former CIA Director George Tenet. Quoting:

Access to networks like the World Wide Web might need to be limited to those who can show they take security seriously, he said.

Speaking as a citizen of the Internet, I assure you I take security very seriously. It is former CIA Directors that I seem to have difficulty with.

Chilling Effects Clearinghouse

Doc Searle had a link to the Chilling Effects Clearinghouse, an excellent site dealing with many issues related to the chilling effects that laws and practices have on freedom of Speech. I found their treatment of issues surrounding fan fiction to be particularly interesting, but they are also trying to document Cease and Desist letters which are received by ISP and others for distributing content which in some way offends someone who thinks they have some claim to being offended. Good stuff.

Liquid lenses for camera phones | The Register

This story has been making the circuit, but this Register article is the first that I’ve seen which has any real detail. As part of my interest in telescope design, I’ve developed a passing interest in camera lens design, and I was uncertain just how this would work.

Basically the idea is that two different liquids are held inside a conical chamber, usually an oil in the back and water in the front. A charge is applied differentially between the front and the back with the result that as an increasing charge is applied, the oil layer in the back goes from flat to highly convex. Interesting.

Camera lens design is basically a balancing act to control seven or so primary aberrations that can affect final image quality. This lens assembly would seem to be able to control only one degree of freedom (roughly speaking, power of the element: when the charge is off, the assembly is a simple window, when the charge is on, it acts as a lens with some power and significant chromatic aberration). It seems to me that any successful attempt to use such an element in a camera design will likely require more than one of these elements, particularly in a zoom configuration.

Still, very interesting work. I’ll have to do a patent search to see if I can find some real designs based upon this principle.

Addendum: Apparently Phillips has been persuing similar work, and disputes the patents granted to Varioptic for this design. It will be interesting to see how that plays out, possibly in the court system.