Fig. 2.

Quantum dot measurements of laser-induced brain heating. A: Qdot 655 2-photon excited fluorescence emission spectra measured in vitro. Plots show the magnified spectrum in the vicinity of the intensity threshold (80% of maximum) used to identify spectral shifts. Inset shows full spectra. Spectra are red-shifted with increasing solution temperature. B: schematic for in vivo temperature measurements. Qdot 655 nanocrystals were nanoinjected 250 μm below the dura, and a cranial window implanted above (not to scale). C: example 2-photon excited emission spectra measured in vivo at different illumination powers. Inset shows full spectra. D: threshold wavelengths at different illumination powers for the experiment in C. E: measured dependence of steady-state temperature on illumination power for all experiments (N = 4 mice). Shaded region denotes 95% confidence interval for the group mean.