Apparatus for interferometric distance measurement, having - a multiple-wavelength light source , which provides a beam (S) 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 (S) into a measurement beam (M) and a reference beam (R) and comprises a measurement reflector and a stationary reference reflector , wherein the measurement beam (M) propagates in a measurement arm in the direction of the measurement reflector and undergoes a back reflection there and the reference beam (R) 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 superpose in an interfering manner to form an interference beam (IF), - a detection unit , via which the interference beam (IF) 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 (L) 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 (S) 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 (S) into a measurement beam (M) and a reference beam (R) and comprises a measurement reflector and a stationary reference reflector , wherein the measurement beam (M) propagates in a measurement arm in the direction of the measurement reflector and undergoes a back reflection there and the reference beam (R) 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 superpose in an interfering manner to form an interference beam (IF), - a detection unit , via which the interference beam (IF) 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 (L) 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 ). <EOS>