High numerical aperture fall-field optical coherence tomography with space-invariant resolution without scanning the focus

In high-numerical-aperture optical coherence tomography, the depth-of-field is usually quite short and therefore the focus is scanned through the object to form a well-resolved image of the entire volume. However, this may be inconvenient for in vivo scanning when precision placement is not easily achieved between the object and the focusing objective. We show that by scanning the illumination wavelength, and using novel inverse scattering methods on the detected interferograms, features outside of the focus can be resolved and therefore the focus does not need to be scanned.