A swept-source OCT system that comprises the following: - means (32, 48, 52) for generating an electronic sweep control signal for operating a tunable light source in such a way that the tunable light source carries out wavelength sweeps with a repetition rate f sweep that is dependent on the frequency of the sweep control signal in response to the sweep control signal, and - a detection device for the time-resolved detection of an interference signal of a sample beam and a reference beam with the aid of a detection clock signal, wherein • the sweep control signal and the detection clock signal are phase-locked, wherein the fixed phase relation between the sweep control signal and the detection clock signal is realized in that means (46, 48) are provided for deriving one of the signals from the other signal or for deriving both signals (30, 38) from a common source signal, or • means are provided for generating a signal or a signal sequence that is respectively characteristic for the frequency ratio and/or the relative phase position of the sweep control signal and the detection clock signal, characterized in that the tunable light source is a buffered light source, by means of which successive wavelength sweeps can be essentially carried out without time gap, wherein the system is designed for generating - a data frame consisting of the detection data of a plurality of wavelength sweeps, or - a data volume consisting of a plurality of data frames in a continuous data stream, without separate trigger for every individual depth scan. - means (32, 48, 52) for generating an electronic sweep control signal for operating a tunable light source in such a way that the tunable light source carries out wavelength sweeps with a repetition rate f sweep that is dependent on the frequency of the sweep control signal in response to the sweep control signal, and - a detection device for the time-resolved detection of an interference signal of a sample beam and a reference beam with the aid of a detection clock signal, wherein • the sweep control signal and the detection clock signal are phase-locked, wherein the fixed phase relation between the sweep control signal and the detection clock signal is realized in that means (46, 48) are provided for deriving one of the signals from the other signal or for deriving both signals (30, 38) from a common source signal, or • means are provided for generating a signal or a signal sequence that is respectively characteristic for the frequency ratio and/or the relative phase position of the sweep control signal and the detection clock signal, • the sweep control signal and the detection clock signal are phase-locked, wherein the fixed phase relation between the sweep control signal and the detection clock signal is realized in that means (46, 48) are provided for deriving one of the signals from the other signal or for deriving both signals (30, 38) from a common source signal, or • means are provided for generating a signal or a signal sequence that is respectively characteristic for the frequency ratio and/or the relative phase position of the sweep control signal and the detection clock signal, - a data frame consisting of the detection data of a plurality of wavelength sweeps, or - a data volume consisting of a plurality of data frames in a continuous data stream, without separate trigger for every individual depth scan.