In an ATR experiment, the sample interacts with a field rather than with a wave. This field is made up from three compounds; one of these is perpendicular to the interfacial plane, the two others are parallel to this and, additionally, parallel or perpendicular to the plane of reflection, respectively. Commonly, one deals with the individual amplitudes of the oscillating compounds only neglecting their mutual phase correlation. However, when taking these into account, one finds that within the sample, the electric vector rotates and its tip describes an ellipse. The orientation of the ellipse with respect to the three constituing field compounds and the ratio of its axes are determined by the angle of reflection and the ratio of the refractive indices of the crystal and the sample, respectively. Possible states of the field and their experimental use will be discussed.