Skulls in the Stars

Some technology is so pervasive and mundane in modern society that it is hard to comprehend what a seismic shift its introduction caused in civilization. Examples I can think of are refrigerators and air conditioning, but in science an example that I hadn’t really appreciated until recently is the humble polarizer — in particular, the inexpensive sheet polarizers that form the basis for almost every practical polarizer used today.

Not long ago I wrote a blog post about the curious history of the crystal herapathite, one of the first truly effective polarizing materials. It was discovered in 1852 by accident, but didn’t really become a practical polarizing material for some 75 years, mainly due to the extreme difficulty in growing crystals large enough to be used for optical devices. In 1929, however, Edwin Land took a very different strategy: he used a magnetic field to align a solution of microscopic herapathite crystals, and then dipped a sheet of plastic into the solution to capture the crystals. The result was a thin material that produced nearly perfect polarization over the entire visible spectrum of light, and one that could be produced in large quantities inexpensively. This material, dubbed Polaroid, become the basis of the Polaroid company that later created the Polaroid instant camera (no relation to polarizers).

How big a deal was the creation of Polaroid? Well, in 1938 an article appeared in the Journal of Applied Physics titled, “Polarized light enters the world of everyday life.” The purpose of the article was the lay out all the new technologies, and possible technologies, that could now be implemented thanks to Polaroid and similar polarizers. In this blog post, I thought I would give an overview of this paper and the applications it covered, to show how inexpensive mundane polarizers really did change the world!