Another feature of modern polarimeters is the Faraday modulator. The detectors are mass-produced coherent correlation polarimeters. In biquartz polarimeters, a biquartz plate is used. Today, semi-automatic polarimeters are available. Most automatic polarimeters make this calculation automatically, given input on variables from the user. Polarimeters may therefore be applied for concentration measurements of enantiomer-pure samples. Groups such as ZIMPOL/CHEOPS and PlanetPol are currently using polarimeters to search for extrasolar planets.