Complex polarimeters have been designed for optical and near-infrared polarimetry. Many involve a combination of half-wave and quarter-wave plates, polarizers, analysers, retarders, prisms, and collimating lenses. Various types of optical polarimeters have been described by Serkowski (1974).
Evocative names have started to appear, such as "Beauty (computer section) and the Beast (polarimeter section)" (Manset & Bastien 1995), "TNTCAM" = Ten aNd Twenty micron CAMera (Klebe et al. 1996), "PIREX" =Polarimetric InfraRed EXplorer (Clemens 1996).
4.1. Cataclysmic Binary Objects (~ 105 km) (~ 106 Gauss) and Polars (~ 6 × 107 Gauss)
Cataclysmic variable objects consist of two stars orbiting each other in a few hours up to a few days. The primary star is a white dwarf star. The secondary could be a red dwarf star. Mass transfer occurs, from the extended secondary star to the environment of the smaller primary white dwarf.
In some cataclysmic variables, magnetic fields from the white dwarf star then guide the mass transfer through funnels of gas, toward shocked accretion sites on the stellar surface of the white dwarf star (e.g., Wickramasinghe 1988). The size of the overall system is about 60 white dwarf radii, or 1 × 105 km, and the circumstellar magnetic field is about 106 Gauss.
In other cataclysmic variables, the mass transfer falls first onto an accretion disk around the white dwarf, and later joins the white dwarf itself (e.g., Lamb & Melia 1988). These binary star accretion disks are considered to be thin, and are fed by a stream of gas originating from the secondary star. To remove excess angular momentum, disk magnetic fields have been proposed. Small-scale "magnetic cells" in the disk have been envisioned, as well as a large-scale poloidal field; both may require a disk dynamo (e.g., ch. 11 in Campbell 1997).
"Polars" are defined as two stars in a closed binary system, one being a red M dwarf secondary and the other being a white dwarf primary, with the white dwarf having an accretion disk and a strong magnetic field which can range from ~ 10 million Gauss up to 230 million Gauss, with an average near 60 million Gauss. They are also called AM Herculis-type binaries (e.g., Burwitz et al. 1997). Polars are thus high-magnetic field cataclysmic variables.