Fig. 2.

Correlation of in vivo fluorescence contrast with water absorptance. Brain vasculature of a mouse was fluorescently labeled with a broadly emitting InAs-based quantum dot mixture and imaged through ∼1 mm to 2 mm of intact skin and skull (12) with 50-nm-bandwidth band-pass filters centered in 50 nm spacing between 950 nm and 1,600 nm (SI Appendix, Fig. S5). (A) We show here images taken with 1,000-, 1,200-, 1,450-, and 1,600-nm filters and their respective intensity profiles in counts per second (cps) across a line of interest (yellow line in Insets) used to calculate the contrast (Eq. 1) of a vessel. Images are scaled to fill the maximum number of displayable intensities. (B) The contrast (black line) of the vessel plotted against band-pass center wavelength mimics the water absorptance spectrum (blue line).