Efficient speckle noise reduction by aperture phase modulation in adaptive optics: optical coherence topography (APM-AO-OCT) (Conference Presentation)

Speckle in optical coherence tomography (OCT) is a consequence of coherent detection scheme and is often considered as a noise submerging the micro-structures of biological tissue. In this work we present a novel method to suppress the speckle in OCT by introducing random phase shifts using a fully controlled segmented deformable mirror (DM) conjugated with imaging system pupil plane, allowing dynamic control of Point Spread Function (PSF) in the sample. These PSF modulations allow different set of scatters contribute to generation of un-correlated speckles, allowing for efficient suppression of speckle contrast by averaging multiple images. The speckle contrast suppression by the random shapes of deformable mirror was investigated in detail. We further present that the degradation of image intensity and resolution can be mitigated by using only the selected mirror shapes that correspond to the brighter OCT images, while maintains similar speckle suppression effect. Finally, the in vivo mouse retina imaging results demonstrate the capabilities of our method to enhance the visibility of subcellular micro-structures previously hidden behind the speckles.