Adaptive beamforming for optical coherence tomography of biological tissues

Coherent noise in images of highly scattering tissues acquired by optical coherence tomography (OCT) reduces the visibility of microscopic features. Incoherent summation of interference signals from multiple array elements has been shown previously to improve the signal-to-noise ratio of OCT images at the expense of resolution loss. This study demonstrates the improvement in image quality that can be achieved without loss of resolution by applying adaptive beamforming techniques. The authors built and tested a prototype four-detector OCT scanner and tested it performance on particle-in-gelatin phantoms and living tissue. The weighting vector applied to the array signals before summation was calculated from the inverse of the 4×4 convariance matrix measured for each A-line. Compared to the images formed from the single-channel and coherently added signals, the processed images were found to be substantially sharper and less noisy