Fig. 3.
Linear effect at low mean power may be related to water absorption and tissue heating. (a) Linear slope SL of the HBR relative variation of mCherry labeled zebrafish hearts (N = 27 embryos) depending on the laser pulse frequency f = 1/T. Black line indicates mean value < SL> = 0.177 ± 0.017%.mW-1). (b) SL as a function of the relative position of the fish heart and illumination beam focus in the x-direction at f = 10 MHz (N = 3 embryos per position). Black line indicates mean SL value. (c) SL at f = 80 MHz depending laser wavelength. (d) Water absorption spectrum in the 1000-1200 nm wavelength range.