The Raman scattered light is emitted by the stimulation of the electric field of the incident light. Therefore, the direction of the vibration of the electric field, or polarization direction, of the scattered light might be expected to be the same as that of the incident light. In reality, however, some fraction of the Raman scattered light has a polarization direction that is perpendicular to that of the incident light. This component is called the perpendicular component. Naturally, the component of the Raman scattered light whose polarization direction is parallel to that of the incident light is called the parallel component, and the Raman scattered light consists of the parallel component and the perpendicular component.