Polarimetry for the Gemini telescopes

Polarimeters at optical and near-IR wavelengths are increasingly available as part of facility instruments at major observatories, and are used for a large number of astronomical programs, ranging form nearby star-forming regions to high-redshift galaxies. Polarimetry is used in both imaging and spectroscopic modes and at both low and high spectral resolutions. As degrees of polarization are usually low a large collecting area is needed to get the high signal to noise required for accurate polarimetry. Thus polarimetry can take particular advantage of the new generation 8m telescopes such as Gemini. Techniques for obtaining high precision measurements used for IR polarimeters on UKIRT and on the AAT, together with the performance achieved for both imagers and spectrometers are presented. The implementation of the same techniques proposed for Gemini instruments is described.