A spectroscopic system for determining a property of a fluid flowing through a volume of interest underneath the surface of the skin of a patient is described. The spectroscopic system comprises: a probe head having an objective for directing an excitation beam into the volume of interest and for collecting return radiation from the volume of interest; a base station having a spectroscopic analysis unit and a power supply; and a cable connecting the probe head and the base station for transmission of the return radiation from the probe head to the base station and for providing the probe head with power from the power supply of the base station.