Fig. 3.

Time course of the optical path length changes $\mathrm{\Delta }\ell$ for different stimuli. (A–D) Response to a 50-ms stimulus; a small negative response after about 17 ms (B) converts to a strong positive stimulation (C and D). (E and F) Time course, averaged over the stimulated area. The black line (E) is the average of seven individual measurements (gray lines). Dashed lines (E) are a control evaluation showing $\mathrm{\Delta }\ell$ between two different layers in the nerve fiber bundle. (G–J) Response to a permanent stimulus. An increasing response is observed, finally leading to phase wrapping. (K) Response to different flash intensities attenuated by OD 0.3 and OD 1.3, respectively. (L) Response for 50-, 500-, and 3,000-ms stimuli with 10 μW. The strong signal at about $t=-0.5\hspace{0.17em}\text{s}$ in the blue curve is caused by rapid eye movement that could not be corrected for. Dashed black lines, start of the stimulus at $t=0$ (E, F, K, and L); green areas (E, F, and K), duration of the stimuli. The center wavelength ${\lambda }_0$ of the OCT was 841 nm. (Scale bars, 200 μm.)