Abstract: In analogy with the amplitude modulation-demodulation of the signal, we demonstrate the laser ho-lography from the modulation and demodulation of the information angle. We use this analogy to describe the infor-mation of the optical path difference modulated by the two-beam interference and the slit width information demodu-lated by the optical diffraction pattern.

Key words: nterference, diffraction, modulation, demodulation, laser holography