Patent ID: 8665449

Claim:
A system for optical coherence tomography comprising: an interferometer which has a beam splitter and at least one reflector, the optical distance of which from the beam splitter can be changed at a speed, light being injected into the interferometer and light being emitted by the interferometer with which a specimen is irradiated, wherein the intensity of the light injected into the interferometer or the intensity of the light emitted by the interferometer is modulated with a modulation frequency which is not equal to the Doppler frequency, the Doppler frequency being given by twice the ratio of the speed of the change of the optical distance between the reflector and the beam splitter to the average wavelength of the injected light, and a low-frequency beat frequency signal resulting from a superposition between the modulated intensity of the light injected into or emitted by the interferometer, respectively, and a high-frequency interference pattern is obtained, wherein the interference pattern is produced upon superposition of light reflected by the specimen with light reflected by the reflector, a detector for recording said beat frequency signal independently of the phase position of the modulation of the intensity of the light injected into or emitted by the interferometer, respectively, and of the interference pattern, and a control unit for demodulating the beat frequency signal independently of the phase, wherein an envelope of the beat frequency signal is determined.