Beamsplitter wire-grid polarizer

An example of a Martin-Puplett interferometer is schematically illustrated in Figure 19.1. The important characteristic of the Martin-Puplett interferometer lies in its use of a wire-grid polarizer (WGP) as the beamsplitter this is free from the effects of interference arising from multiple internal reflections occurring inside a PET film. The WGP used for the Martin-Puplett interferometer is an array of parallel metallic wires, each having a diameter of about 10 pm and separated by intervals of about 12.5 pm. A beam of far-infrared radiation incident on the WGP is divided into two orthogonal polarized components that is, a component with its plane of polarization parallel to the wires, which is reflected, and a component with its plane of polarization perpendicular to the wires, which is transmitted. Thus, the WGP performs the role of a beamsplitter. 

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