Fig. 2.

Amyloid-beta ($\mathrm{A}\text{-}\beta$) plaques were investigated using visible light OCM at three different magnifications. (a)–(c) OCM en-face projection images taken with $4\times$, $10\times$, and $20\times$ magnification objectives, respectively in a 51-week-old mouse. (d) Immunohistochemically and hematoxylin stained tissue section of a plaque-rich region. Plaques appear brown. (e) Depth intensity projection over $200\mu \mathrm{m}$ in a plaque-rich region in a 51-weeks-old mouse brain cortex. (f)–(h) Representative OCM B-scans taken with $4\times$, $10\times$, and $20\times$ magnification objectives, respectively. (i)–(k) OCM en-face projections over $20\mu \mathrm{m}$ for different depth positions (40 to $100\mu \mathrm{m}$) of a 64-weeks-old mouse brain. Plaques appear at different depths in the brain tissue. (l) OCM en-face projection image taken with the $10\times$ magnification water immersion objective of a 64-weeks-old mouse brain. (m) Attenuation image of (l). For all en-face projections, the intensity over the first $50\mu \mathrm{m}$ underneath the tissue surface were averaged. In all images, representative $\mathrm{A}\text{-}\beta$ plaques are marked with red and white arrows.