ISO 12005:2003 specifies a method for determining the polarization status and, whenever possible, the degree of polarization of the beam from a continuous wave (cw) laser. It can also be applied to repetitively pulsed lasers, if their electric field vector orientation does not change from pulse to pulse.ISO 12005:2003 also specifies the method for determining the direction of the plane of oscillation in the case of linearly polarized (totally or partially) laser beams. It is assumed that the laser radiation is quasi-monochromatic and sufficiently stable for the purpose of the measurement.The knowledge of the polarization status can be very important for some applications of lasers with a high divergence angle, for instance when the beam of such a laser shall be coupled with polarization dependent devices (e.g. polarization maintaining fibres). ISO 12005:2003 also specifies a method for the determination of the state of polarization of highly divergent laser beams, as well as for the measurement of beams with large apertures.