The unified imaging condition of Fourier-transform ghost imaging in the far field

Abstract

In general, the unequal distance between the two detectors and the thermal light source can lead to poor imaging quality in the Fourier-transform ghost diffraction (FGD) system, while the rule does not hold in the far field. Based on the numerical simulations and experimental results, the imaging condition of the FGD pattern is analyzed in the far field. It is shown that the condition is quite different from that in the near field. When the difference between the distance from the light source to the reference detector and the one from the object to the light source are in the far field, the better diffraction pattern can also be kept when the equivalent distance from the object to the test detector is in the far field, although the lengths of the test path and the reference path are not equal.