Results from the Alcator C-Mod Polarimeter Prototype and Plans for an FIR System

A single chord CO$_{2}$ polarimeter channel has been installed on the existing Two-Color Interferometer (TCI) on Alcator C-Mod. The measured rotation ranged from 0.1-0.3 degrees in magnitude depending on plasma density, current, and configuration.~ Empirical results are comparable to predicted values from model density profiles and Efit reconstructions.~ Experimental techniques developed to optimize signal quality and minimize drifts will be discussed.~ This work is in support of an FIR system with poloidally viewing chords to be installed on C-Mod in FY08.~ Some aspects of the FIR design will also be discussed.