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Description
Optical resolution photoacoustic microscopy (OR-PAM) is a powerful technology for high-resolution imaging of biological tissues. The integration of optical ultrasound detectors enables highly sensitive and broadband detection of photoacoustic waves up to the high-frequency range (>100 MHz), while maintaining a small detector size. This facilitates high axial and lateral resolution. This work utilizes planar Fabry-Pérot sensors in a coaxial excitation and detection geometry to minimize the distance between source and detector, thereby maximizing the signal-to-noise ratio (SNR). Additionally, a fiber-based Raman excitation laser with a high repetition rate (>100 kHz) was employed to achieve high imaging speeds (>1 Hz, volume = 1 mm³). Time-resolved photoacoustic signals were acquired using both raster scanning and, for higher speeds, continuous scanning modes. For functional imaging of phantoms, two wavelengths were used. A potential application of this highly sophisticated technology in clinical studies is envisaged, for instance in functional imaging of oxygen transport in post-COVID patients.