Figure 1. Cross section optical-coherence tomography (OCT) image from the skin on the human finger tip. Image obtained in 0.5 s using a superluminescent diode of central wavelength 793 nm and delivering 600 µW optical power to skin. Depth resolution is 15 µm.
Figure 3. Comparison between the photodetector output in Figure 2 when an ideal laser (top) or a broadband source (bottom) is used. OPD, optical path difference.
Figure 5. Photodetected optical-coherence tomography signal (middle) for an object made of two interfaces (top) and the rectified output (bottom). Moving the reference mirror with velocity v, generates a time varying signal with frequency f=2v/, where is the central wavelength of the optical source.
Figure 6. Relative orientation of the axial scan (A-scan), en face scan (T-scan), longitudinal slice (B-scan) and en face or transverse slice (C-scan).
Figure 9. Spectra (left) and the temporal evolution (right) obtained with the set-up in Figure 8 from a mirror as target [16]. If the beam is shifted by 3 mm from the rotation axis (bottom), higher frequency oscillations are generated, concentrated around a carrier, as shown in the left bottom figure [17]. a.u. represents arbitrary units for the strength of the photodetected signal.
Figure 10. 3D display of in vivo optical-coherence tomography image of normal human skin from a volunteer's finger tip, [19]. Volume size: 5 mm x 4 mm x 1 mm (depth measured in air). The arrow ED shows the direction of exploration of the 3D reconstructed volume made from 40 en face slices acquired at 25 µm depth interval.
Figure 11. (a) C-scan images of the fovea [20] obtained with the dual channel optical-coherence tomography (OCT)/confocal instrument in the C-scan imaging regimen. CSO: confocal scanning ophthalmoscopy image produced by the confocal channel; all the other images were provided by the OCT channel at depths shown below each image. Lateral size: 3 mm x 3 mm. (b) Large angle pair of images produced with the OCT/confocal instrument in the B-scan imaging regimen, showing the fovea and the optic nerve. 28° lateral size (peak to peak angular extension of the fan of scanned rays at the pupil). Top: CSO image; Bottom: B-scan OCT image (depth 2 mm in air). RNFL, retinal nerve fibre layer; PL, photoreceptor layer; RPE, retinal pigment epithelium [21]. Depth resolution in the OCT images: 12 µm.
Figure 12. Simultaneous indocyanine green (ICG) (left) and en-face optical-coherence tomography (right) image from an healthy eye. Lateral size: 26°. Images collected at 40 s after ICG was released into the body [22]. RPE, retinal pigment epithelium.
Figure 13. En face polarization sensitive optical-coherence tomography images of an extracted human tooth: linear output images of the V and H channels (top), net reflectivity and birefringence retardation images (bottom). The size of each image was 2 mm x 2 mm. The images were acquired from a depth corresponding to a 300 µm optical path in dental tissue and their thickness is less than 15 µm.
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