Abstract
Real-time quantitative phase imaging has tremendous potential in investigating live biological specimens in vitro. Here we report on a wideband sensitivity-enhanced interferometric microscopy for quantitative phase imaging in real time by employing two quadriwave lateral shearing interferometers based on randomly encoded hybrid gratings with different lateral shears. Theoretical framework to analyze the measurement sensitivity is firstly proposed, from which the optimal lateral shear pair for sensitivity enhancement is also derived. To accelerate the phase retrieval algorithm for real-time visualization, we develop a fully vectorized path-independent differential leveling phase unwrapping algorithm ready for parallel computing, and the framerate for retrieving the phase from each pair of two 4 mega pixel interferograms is able to reach 47.85 frames per second. Experiment results demonstrate that the wideband sensitivity-enhanced interferometric microscopy is capable of eliminating all the periodical error caused by spectral leaking problem and reducing the temporal standard deviation to the half level compared with phase directly retrieved by the interferogram. Due to its high adaptability, the wideband sensitivity-enhanced interferometric microscopy is promising in retrofitting existing microscopes to quantitative phase microscopes with high measurement precision and real-time visualization.
Highlights
Error of the reconstructed phase image will decrease to 12%12
We describe a novel wideband sensitivity-enhanced interferometric microscopy (WSEIM) based on quadriwave lateral shearing interferometry by employing two randomly encoded hybrid grating (REHG) with different lateral shears to enhance its measurement sensitivity and the signal noise ratio (SNR) (Fig. 1)
We have presented wideband sensitivity-enhanced interferometric microscopy (WSEIM) based on quadriwave lateral shearing interferometry (QWLSI) for real-time quantitative phase imaging
Summary
Error of the reconstructed phase image will decrease to 12%12. its accuracy still need to be improved if compared with interferometric methods like diffraction phase microscope (DPM)[1, 13,14,15], digital holographic microscope (DHM)[16,17,18,19,20,21] and the off-axis τ interferometer[22, 23]. Most of the interferometric microscopes, including the DHM, the DPM and the off-axis τ interferometer, are based on Mach-Zehnder interferometry (MZI) or point diffraction interferometry (PDI), in which the interferograms are obtained due to the interference between the reference beam and the sample beam. The precision of these interferometers is of significant relevance to the flatness of the reference wavefront in MZI or the fabrication quality and the actual position and orientation of the pinhole in PDI. The WSEIM is highly adaptable for a plenty of potential applications, including quantitative phase imaging for microfluidic and biomedical research
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