Multifocal spectral-domain optical coherence tomography based on Bessel beam for extended imaging depth.

To advance the practical application of optical coherence tomography (OCT) in the field of biomedical imaging, the imaging depth must be extended without sacrificing resolution while maintaining sufficient sensitivity. However, there is an inherent trade-off between lateral resolution and depth of field (DOF) in OCT. To address this shortcoming, this article proposes a multifocal Bessel beam spectral-domain optical coherence tomography (MBSDOCT) capable of increasing the DOF with unchanged lateral resolution and a high signal-to-noise ratio. The proposed technique is demonstrated by simulation and experiment. A three-focal MBSDOCT with an axicon lens theoretically achieved a DOF of ∼6  mm with a lateral resolution of ∼13  μm. In imaging experiments performed on the acinar cells of orange tissue, a measured DOF of ∼4  mm was demonstrated with a sensitivity penalty of ∼18.1  dB, relative to the Gaussian beam spectral-domain OCT, with a 9-mW light source.