Particle size in polarizing filters

[RogerInHawaii]

I know that light can be polarized by passing through a medium that has linear particles all oriented in the same direction. But what size particles are necessary to do that?

 

[Andy Resnick]

I couldn't find information about the size of of herapathite molecules (used in polarizer film), but infrared polarizers often consist of wires spaced apart around 1/4 the wavelength:

http://www.specac.com/products/infrared-polarizer/wire-grid-infrared-polarizer/654
http://www.internationalcrystal.net/icl59a.htm