A widely used polarizer in the IR is the wire-grid polarizer. Wire-gri
d polarizers with a typical minimal wire spacing of similar to 0.25 mu
m perform well in the middle IR and the far IR, but in the near IR th
e performance deteriorates as the wavelength approaches the wire spaci
ng. A possibility for improving this performance is to put two wire gr
ids in tandem with their transmission axes parallel. Starting with the
extended Mueller matrix description for a single wire grid, we presen
t a mathematical treatment of this tandem polarizer showing that perfo
rmance improves quadratically; e.g., a single polarizer extinction rat
io of 100 increases to a tandem extinction of 10,000. The improved per
formance is also verified experimentally.