Apparatus for interferometric distance measurement, having - a multiple-wavelength light source, which provides a beam with at least three different wavelengths (λ 1, λ 2, λ 3) and is designed as a fibre laser comprising at least three different Bragg gratings (13.1_λ 1, 13.1_λ 2, 13.1_λ 3; 113.1_λ 1, 113.1_λ 2, 113.1_λ 3; 213.1_λ 1, 213.1_λ 2, 213.1_λ 3; 313.1_λ 1, 313.1_λ 2, 313.1_λ 3), the grating constants (d 1, d 2, d 3) of which are tuned to the generated wavelengths (λ 1, λ 2, λ 3), - an interferometer unit, which splits the beam into a measurement beam and a reference beam and comprises a measurement reflector and a stationary reference reflector, wherein the measurement beam propagates in a measurement arm in the direction of the measurement reflector and undergoes a back reflection there and the reference beam propagates in a reference arm in the direction of the stationary reference reflector and undergoes a back reflection there, wherein the measurement and reference beams (M, R) that are back-reflected by the measurement and reference reflectors (33, 34) superpose in an interfering manner to form an interference beam, - a detection unit, via which the interference beam is split in a manner such that in each case a plurality of phase-shifted partial interference signals (S λ1_ 90, S λ1_210, S λ1_330, S λ2_90, S λ2_210, S λ2_330, S λ3_90, S λ3_210, S λ3_330) result per wavelength (λ 1, λ 2, λ 3), and - a signal processing unit, which is configured to determine a piece of absolute position information with respect to the measurement reflector from the partial interference signals (S λ1_90, S λ1_210, S λ1__330, S λ2_90, S λ2_210, S λ2_330, S λ3_90, S λ3_210, S λ3_330) of different wavelengths (λ 1, λ 2, λ 3). - a multiple-wavelength light source, which provides a beam with at least three different wavelengths (λ 1, λ 2, λ 3) and is designed as a fibre laser comprising at least three different Bragg gratings (13.1_λ 1, 13.1_λ 2, 13.1_λ 3; 113.1_λ 1, 113.1_λ 2, 113.1_λ 3; 213.1_λ 1, 213.1_λ 2, 213.1_λ 3; 313.1_λ 1, 313.1_λ 2, 313.1_λ 3), the grating constants (d 1, d 2, d 3) of which are tuned to the generated wavelengths (λ 1, λ 2, λ 3), - an interferometer unit, which splits the beam into a measurement beam and a reference beam and comprises a measurement reflector and a stationary reference reflector, wherein the measurement beam propagates in a measurement arm in the direction of the measurement reflector and undergoes a back reflection there and the reference beam propagates in a reference arm in the direction of the stationary reference reflector and undergoes a back reflection there, wherein the measurement and reference beams (M, R) that are back-reflected by the measurement and reference reflectors (33, 34) superpose in an interfering manner to form an interference beam, - a detection unit, via which the interference beam is split in a manner such that in each case a plurality of phase-shifted partial interference signals (S λ1_ 90, S λ1_210, S λ1_330, S λ2_90, S λ2_210, S λ2_330, S λ3_90, S λ3_210, S λ3_330) result per wavelength (λ 1, λ 2, λ 3), and - a signal processing unit, which is configured to determine a piece of absolute position information with respect to the measurement reflector from the partial interference signals (S λ1_90, S λ1_210, S λ1__330, S λ2_90, S λ2_210, S λ2_330, S λ3_90, S λ3_210, S λ3_330) of different wavelengths (λ 1, λ 2, λ 3).