Real-time quantitative phase reconstruction in off-axis digital holography using multiplexing

Wepresent a new approach for obtaining significant speedup in the digital processing of extracting unwrapped phase profiles from off-axis digital holograms. The new technique digitally multiplexes two orthogonal off-axis holograms, where the digital reconstruction, including spatial filtering and two-dimensional phase unwrapping on a decreased number of pixels, can be performed on both holograms together, without redundant operations. Using this technique, wewereable to reconstruct, for the first time to ourknowledge, unwrappedphaseprofiles fromoff-axisholograms with 1 megapixel in more than 30 frames per second using a standard single-core personal computer on a MATLAB platform, without using graphic-processing-unit programming or parallel computing. Thisnewtechnique is important for real-time quantitative visualizationandmeasurements of highlydynamic samplesandis applicable for a widerange of applications, including rapid biological cell imaging and real-time nondestructive testing. After comparing the speedups obtained by the new technique for holograms of various sizes, we present experimental results of real-time quantitative phase visualization of cells flowing rapidly through a microchannel.