Real-time phase measurement of optical vortex via digital holography

Real-time phase measurement is of great value to study the evolution of optical vortex. However, it cannot be recorded in real time due to the limitation of the exposure time of the recording device in the experiment. Therefore, based on the temporal and spatial evolution correlation of the optical phase, a real-time phase measurement method of optical vortex generated by an acoustically induced fiber grating is proposed based on digital holographic reconstruction algorithm. First, a series of holograms are continuously recorded using a low frame rate CCD. Then, the evolution of optical vortex over time is translated into changes in transmission distance. Furthermore, the unrecorded vortex phase distributions are calculated using diffraction theory. By serializing these phase maps over time, the propagation and evolution of spiral phase structure of the vortex beam can be demonstrated in real time.