In Fourier transform infrared spectrometer (FTIR), the optical path difference of laser metrology is applied to increase
spectrum measure precision. However, due to the characteristics of laser single frequency and steady frequency, the
uneven speed of moving mirror, circuit delay etc. cause the deviation of sampling point. In this paper, based on the
interference theory of spectrometer, according to the Fourier contrary transform and methods of error analysis, the theory
model between relative error of spectrum measure and the deviation of sampling point is established. Some simulation
computations of the model have been done, the result indicates that, as a theory basis, the model can be applied in
analyzing the sampling error of spectrometer and correction algorithm.