Coherence and diffraction limited resolution in microscopic oct by a unified approach for the correction of dispersion and aberrations

© 2018 SPIE.Optical coherence tomography (OCT) images scattering tissues with 5 to 15 andmu;m resolution. This is usually not sufficient for a distinction of cellular and subcellular structures. Increasing axial and lateral resolution and compensation of artifacts caused by dispersion and aberrations is required to achieve cellular and subcellular resolution. This includes defocus which limit the usable dep of field at high lateral resolution. OCT gives access the phase of the scattered light and hence correction of dispersion and aberrations is possible by numerical algorims. Here we present a unified dispersion/aberration correction which is based on a polynomial parameterization of the phase error and an optimization of the image quality using Shannon's entropy. For validation, a supercontinuum light sources and a costume-made spectrometer with 400 nm bandwid were combined with a high NA microscope objective in a setup for tissue and small animal imaging. Using is setup and computation corrections, volumetric imaging at 1.5 andmu;m resolution is possible. Cellular and near cellular resolution is demonstrated in porcine cornea and the drosophila larva, when computational correction of dispersion and aberrations is used. Due to the excellent correction of the used microscope objective, defocus was the main contribution to the aberrations. In addition, higher aberrations caused by the sample itself were successfully corrected. Dispersion and aberrations are closely related artifacts in microscopic OCT imaging. Hence ey can be corrected in the same way by optimization of the image quality. This way microscopic resolution is easily achieved in OCT imaging of static biological tissues.