Fig. 4.

Aberration measurement on fixed mouse hippocampus mounted in PBS. (a) and Media 4 ^{(1.5MB, AVI)} , endogenous 2PEF image at a depth of 80μm. (b), corresponding total aberration map, and (c) superposition of (a) and (b). (d)–(f), aberration coefficient maps for (d) astigmatism (z=5), (e) coma (z=8) and (f) spherical aberration (z=11). The 3 maps share the same colour scale. (g) and Media 5 ^{(1.8MB, AVI)} , region of the tissue modelled for aberration simulation (top), corresponding to the yellow bow in (a). Dotted circle, limit of the excitation cone at the surface of the tissue. Arrow, line along which aberrations were calculated. bottom, model used for the 3D refractive index map. Left, xy image 10μm below the surface of the tissue; right, xz reslice. Scale bars, 100μm.(h)–(j), experimental (blue) and simulated aberration profile with (purple) and without (green) index variation within the tissue at a depth of 80μm. (h), astigmatism; (i), coma; (j), spherical aberration. (k), residual aberration profile at the same depth after correction of 0 (black), 11 (red) and 32 (orange) Zernike modes.