Figure 1: Aβ plaque birefringence and PS-OCT. | Scientific Reports

Figure 1: Aβ plaque birefringence and PS-OCT.

From: Visualization of neuritic plaques in Alzheimer’s disease by polarization-sensitive optical coherence microscopy

Figure 1

(A) Neuritic plaques (NP) are extracellular deposits of Aβ around cortical neurons. Their fibrous substructure causes birefringence. (B) Birefringent fibers produce a phase retardation between orthogonally polarized light components. (C) Sketch of spectral domain PS-OCT device. The sample arm incorporates scan optics and an objective. The OCT signal is detected by two identical spectrometers (SP), one each for an orthogonal polarization state. SLD superluminescent diode, ISO optical isolator, POL polarizer, 2 × 2 fiber coupler, PBS polarizing beam splitter. (D) Photo (left, GM: grey matter, WM: white matter) and exemplary PS-OCT images of a formalin-fixed brain sample. The sample structure can be observed in the reflectivity image. Birefringent WM and polarization preserving GM can be distinguished in the phase retardation image extracted 50 μm below the tissue surface in greenish and blue hue, respectively. Different fiber orientations give rise to rainbow-like color changes in the axis orientation image.

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