Single-shot 4-phase shifting optical coherence microscopy

One limitation of phase shifting optical coherence microscopy (OCM) is that any changes in imaging conditions, caused by either system-level instability or movement of dynamic samples, will inevitably lead to reduction in image quality. Here we present a novel implementation of OCM which permits accurate measurements of phase and intensity, by simultaneously capturing four phase-shifted images on a single camera sensor. Uniquely, our approach enables probing the sample with unpolarized light, producing four phase-shifted interferograms, separated by Ïin two orthogonally polarized detection channel pairs. The proposed set-up is compatible with spatially incoherent illumination sources, enabling high resolution imaging due to its inherently reduced susceptibility to speckle noise. By simultaneously capturing the four phase-shifted images on a single CCD camera chip we demonstrate the capacity to acquire stable phase recordings with a phase sensitivity of 0.1 nm rms error at 500 Hz frame rates, a field-of-view of 250x250 μm, and 1μm lateral resolution. Instantaneous, coherence-gated, phase-sensitive imaging at high frame rates enables observations of the dynamics in cells and tissues, providing instant feedback on metabolic activity and tissue states. We present the novel design and methodology that enables ultrasensitive label-free coherence-gated measurements of intracellular dynamics in cells and cellular networks.