Ghost imaging

The topic of ghost imaging (GI) has attracted noteworthy attention in recent years [1-26]. Invented by Klyshko many years ago [1] with the idea of exploiting the quantum entanglement in photon pairs generated by Parametric Down-Conversion (PDC), this technique was also called entangled (two-photon) imaging until recently [1-11]. It is by now clear that appropriate classically correlated beams also can be used to implement such a technique [12-25]; the interesting relation between the two kinds of approaches will be discussed in the last two sections of this chapter. © 2007 Springer.