Near field optical microscope for acquiring spectra

Device for the near-field optical measurement of a sample comprising

• a. a probe (1),
• b. a wavelength-tunable monochromatic light source (2) with tuning mechanism for changing the wavelength λ provided by the light source, and
• c. an interferometer integrated in the optical path of the light source (2), comprising a beam splitter (3) splitting the light of the light source into two optical light paths, the reference light path (4) and the signal light path (5),
• wherein the reference light path (4) does not contain the probe, and the signal light path (5) comprises the probe (1), and the reference and the signal light paths (4,5) are superimposed at the detector (6), characterized in that the difference of the lengths of the two optical paths (4) and (5) can be adjusted to be at most 1000 μm.