Nonzero-mean light off-axis phase imaging based on light intensity correlation.

Ghost imaging (GI) is a technique for indirectly obtaining object images through the second-order intensity correlation and has been extensively documented. However, it is typically limited to intensity imaging, and phase retrieval requires the introduction of supplementary methods such as interferometers or phase-shifting techniques. Here, a technique is proposed that reconstructs the phase of objects based on the second-order intensity correlation without the supplementary methods. By substituting the zero-mean thermal light in conventional GI with non-zero mean light and employing a point detector to detect the object's higher-order Fourier spectrum, the second-order intensity correlation generates an off-axis hologram, thereby reconstructing the object's phase. This technique eliminates the need for additional methods and demonstrates the feasibility of using solely the second-order intensity correlation for phase imaging, which may contribute to advancing the theory and application of GI in phase imaging.