Holoscopy is a new imaging approach combining digital holography and full-field Fourier-domain optical coherence tomography. The interference pattern between light scattered by a sample and a defined reference wave is recorded and processed numerically. During reconstruction numerical refocusing is applied, overcoming the limitation of the focal depth and thus a uniform, diffraction limited lateral resolution over the whole measurement depth can be obtained. The advantage of numerical refocusing becomes especially significant for imaging at high numerical apertures (NAs). We use a high-resolution setup based on a Mach-Zehnder interferometer with an high-resolution microscope objective (NA = 0.75). For reliable reconstruction of a sample volume the Rayleigh length of the microscope objective and the axial resolution, given by the spectral range of the light source, need to be matched. For a 0.75 NA objective a tunable light source with a sweeping range of ! 300nm is required. Here we present as a first step a tunable Ti:sapphire laser with a tuning range of 187 nm. By characterizing the spectral properties of the Ti:sapphire laser and determining the axial point spread function we demonstrate the feasibility of this light source for high-resolution holoscopy.
Holoscopy is a new imaging approach combining Digital Holography and Full-field Fourier-domain Optical Coherence
Tomography. The interference pattern between the light scattered by a sample and a defined reference
wave is recorded digitally. By numerical processing of the recorded interference pattern, the back-scattering field
of the sample is reconstructed with a diffraction limited lateral resolution over the whole measurement depth
since numerical refocusing overcomes the limitation of the focal depth. We present two setup configurations - a
low resolution setup based on a Michelson interferometer and a high resolution setup based on a Mach-Zehnder
interferometer. Successful measurements were demonstrated with a numerical aperture (NA) of 0.05 and 0.14,
respectively and will be presented. Additionally, the effects of filtering spatial frequencies in terms of separating
sample signals from artifacts caused by setup reflections is discussed and its improvement on the image quality
is shown.
We demonstrate Holoscopy -- a combination of full-field swept-source optical coherence tomography and digital holography. By using a simple Michelson interferometer setup, a rapidly tunable laser and combining scalar diffraction theory with standard Fourier-domain OCT signal processing we obtain depth invariant imaging quality.
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