We have performed photoluminescence (PL) measurements on III - V semiconductor materials. InP and related compounds, used in fiber-optic communication. The PL radiation is excited with an argon laser ((lambda) equals 488 nm) and collected by a liquid nitrogen cooled Ge detector (spectral range 5800 - 15000 cm-1). The sampling of the PL signal, using a He-Ne reference laser, occurs every (Delta) d equals (lambda) REF/2 equals 316.4 nm of the optical path difference (OPD) due to the displacement of the movable mirror; the maximum wavenumber detectable, without aliasing problems, is (sigma) M equals 1/2 (Delta) d 15803 (cm-1). In a real instrument, considering the possibility of small errors in the position of the movable mirror, the value of the OPD dj in the sampled points is given by dj equals -L + j(Delta) d + (epsilon) (d), j equals 0,1,2,...N - 1, where L is the maximum displacement of the movable mirror, N is the number of sampled points and (epsilon) (d) is the error in the value of the OPD caused by an erroneous position of the movable mirror.