Fig. 1

FONT set-up. (a) The imaged sample is placed in the vicinity of the geometrical center of a custom-made spherical ultrasound detection array. Light illumination of the entire object is provided via an optical fiber bundle. The generated optoacoustic signals are acquired by the array transducer, whereas the induced fluorescence is simultaneously recorded by the high-speed sCMOS camera. (b) Spectral dependence of the absorbance on calcium-bound versus calcium-free GCaMP5G (reproduced from Ref. 12). (c) Optoacoustic images of a 5-day-old HuC:GCAMP5G larva acquired at 488 and 530 nm (maximal intensity projection views through volumetric reconstructions are shown). Whereas the pigmented eyes are strongly absorbing at both wavelengths, GCaMP5G is hardly absorbing at 530 nm; thus, neural tissue is much more visible at 488 nm (scale bar=250 μm).