The reason why we see depth is because of the stereoscopic effect of the eyes. We get two views of the same object by the two eyes and when these are superimposed, we get the idea about the depth. (In fact a clear idea about the depth coordinates cannot be got if only one eye is functional). The same can be used even in the case of computer displays. How exactly can we show two images differ? Either two different screens showing slightly displayed images of the same object can be shown or the same screen can be used to alternate the two views at more than 20 times per second. The method of polarized glasses is of a recent origin
