Passive stereo is realized by the polarization of light. Two kinds of light polarization to internal and external methods.
Linear polarization was earlier using passive stereoscopic solution, its principle is the light from the projector along x and y axis of polarization, and glasses of the x and y direction corresponds to the grating, so as to achieve stereoscopic images. Circular polarization is a new way of polarization. The principle is: light travels perpendicular to the propagation direction of 360 degrees has optical vibration transmission. Direction of polarization of the light is actually using a particular principle of optical display. The principle of circular polarization is polarization can be rotated in the direction of the light changes, rotating in the opposite direction of the left and right eyes see light. Based on circular polarization technology, head of the observer can be free, because the change does not affect the display of light.