Fig. 3.

(a) The absorption coefficients of water and lipids versus wavelength. Three peaks of positive contrast for lipids occur at 910 nm, 1210 nm, and 1720 nm. (b) The pulse energy of the laser measured at each wavelength. (c) The normalized contrast-to-noise ratio as a function of wavelength estimated for several depths: 0, 400, 800, and 1200 μm.