Angular compounding by full-channel B-scan modulation encoding for optical coherence tomography speckle reduction.

We describe an angular compounding method by full-channel B-scan modulation encoding for speckle reduction in optical coherence tomography. The complex-valued spectral interferogram (SI) is reconstructed by removing one of the conjugate terms in the depth space. Fourier transform of the complex SI along the lateral direction enables a full-channel (with both negative and positive Fourier space) for B-scan modulation in the spatial frequency (ν) domain. A full-size probe beam, determined by the scanning mirror size, is centered on the mirror pivot, which allows the negative and positive half-channels working in parallel. Compared with the existing method, where only a half-channel (negative or positive) works alone, the proposed full-channel method offers more than twice the performance in speckle reduction. The feasibility of the proposed full-space approach is validated through both the phantom and in vivo human thumbnail experiments.