Polarimetry is the measurement and analysis of the polarization of electromagnetic radiation. Polarization can indicate and quantify gravitational lensing and magnetism and other phenomena. It is of particular interest in the study of cosmic microwave background and cosmology. An instrument detecting polarity is termed a polarimeter.
Dust polarimetry, i.e., using polarization of dust clouds, is useful for detecting and mapping their magnetic fields, e.g., for clouds, and disks such as protoplanetary disks.