In this manuscript the application of a novel technique for axial resolution improvement in Fourier Domain Optical
Coherence Tomography (FDOCT) is demonstrated. Axial resolution in FDOCT can be improved by ~7x without the
need for a broader bandwidth light source using modulated deconvolution. In FDOCT the real part of FFT of each
interferofram is modulated by a frequency which depends on the position of the interferogram. If an interferogram is
shifted slightly, the frequency of the real part of the FFT changes. By adding two shifted interferograms, beating can be
appeared in the OCT A-Scans. Subsequently deconvolution with suitable kernels can produce a significant resolution
improvement in the FDOCT image.
This manuscript presents a novel technique for axial resolution improvement in Fourier Domain Optical Coherence
Tomography (FDOCT). The technique is based on the modulated deconvolution of OCT signals which results in a
resolution improvement by a factor of ~ 7 without the need for a broader bandwidth light source. This method relies on a
combination of two basic properties: beating, which appears when adding two signals of slightly different frequencies,
and the resolution improvement, achieved by deconvolution of an OCT image with the encoded source autocorrelation
function. In FDOCT the real part of the FFT of the interferogram is modulated by a frequency which depends on the shift
in position of the interferogram. A slightly shifted interferogram will, therefore, result in an A-Scan which will have a
different modulation frequency. Beating will appear when two such A-Scans, with an appropriately selected amount of
shift, are added. Deconvolution of the resulting signal, using suitable kernels, results in a narrower resolution width.
A novel technique for axial resolution improvement of Optical Coherence Tomography (OCT) systems is presented. The
technique is based on step-frequency encoding of the OCT signal, using frequency shifting. A resolution improvement
by a factor of ~ 7 is achieved without the need for a broader bandwidth light source. This method exploits a combination
of two basic principles: the appearance of beating, when adding two signals of slightly different carrier frequencies, and
the resolution improvement of OCT images by deconvolution of the interferogram with the encoded source
autocorrelation function. In OCT, step-frequency encoding can be implemented by performing two A-scans, with
different carrier frequencies and subsequently adding them to create the encoded signal. Deconvolution of the resulting
interferogram, using appropriate kernels, results in a narrower resolution width when the frequency steps are appropriately selected.
We present an experimental study of the depolarization of circularly polarized (CP) light backscattered from random
media. We employ a polarization sensitive OCT, capable of producing intensity profiles for two orthogonal polarization
channels simultaneously. For CP light backscattered from polystyrene solutions containing spherical particles of sizes
larger than the radiation wavelength, the phenomenon of polarization memory is observed. The degree of circular
polarization (DOCP) as a function of the path the light travels in the medium depends on the scatterers' size. In the case
of scatterers larger than the wavelength, the DOCP exhibits a minimum indicating a helicity cross-over. The copolarized
light then exceeds the intensity of cross-polarized light of backscattered radiation, a phenomenon predicted
theoretically but not observed experimentally so far. The helicity cross-over is observed in the DOCP curves for large
scatterers at small and large concentrations.