Patent ID: 8300511

Claim:
A holographic memory apparatus that causes interference between a reference beam and a signal beam, records an obtained interference fringe on a holographic recording medium as page data, and reproduces the recorded page data, said holographic memory apparatus comprising: first phase modulator that adds phase information to each pixel of the signal beam to generate page data at recording time; oscillator light generation means that generates an oscillator light that is superimposed on, and interferes with, a diffracted light from the holographic recording medium at reproduction time; second phase modulator that adds phase information to the oscillator light; and light detector that detects an interference light generated by superimposing the oscillator light and the diffracted light from the holographic recording medium wherein said second phase modulation means adds at least four different phases to the oscillator light, said light detection means has pixels arranged in such a way that at least four pixels are used to oversample each pixel of the page data, the oscillator light, to which at least four different phases are added, irradiates on each of the at least four pixels and is superimposed on the diffracted light from said holographic recording medium, and the phase information added to the pixels of the signal beam is detected based on the principle of a fringe scan method.