Analysis Of Mirror-Tilting And Sampling Errors In Fourier Transform Spectrometry And Design Of Simulation Software

The Fourier Transform Spectrometer develops very quickly,while the functionand performance of the spectrometer is constantly improved,so the spectrometer isused in more and more area. The Fourier transform spectrometer measurementdepends on the quality of interferogram and the interferogram sampling. The movingmirror is required to move at a constant speed in a straight line and keepperpendicular to the fixed mirror during a scan, and the sampling interval for theinterferogram is required to be equivalent.The Michelson interferometer is the optical core of the Fourier TransformSpectrometer. The performance of the Fourier Transform Spectrometer is related tothe mechanical characteristics of the moving mirror’s driving mechanism. In fact,there are tilting errors caused by the vibration of the moving mirror and otherfactors,which causes the change of the optical path difference, and thus have animpact on the interferogram and spectrum. In order to obtain the spectrum, one needsto sample the interferogram and then Fourier transforms it. If sampling theinterferogram is not in strict equal OPDs, because of the electrical delays and so on,there are sampling errors that affect the sampled interferogram.The causes of the moving mirror’s tilt error and the sampling error and the errors’classification is analyzed in the article.The article takes the static tilt error as anexample to establish the interferometer model.The function of the interferogram withstatic tilt error is deduced, and the effect of the parameters (such as the wave number,the tilt angle of the moving mirror, the beam’s aperture size) on the interferogram withtilt error is analyzed.Due to the errors having different characteristics, they may cause loss of thedetected radiation or change of the measured frequency. To quantify the effects of the different errors on the output spectrum, one needs to take into account manyinterrelated factors, some of which are not easily quantifiable. The models of thedifferent errors are given in this article. The effects of the tilt error and the samplingerror on the interferogram and the spectrum are simulated by the MATLAB,which haspowerful data processing and calculating ability.In order to simulate the effects of the different errors on the spectrum, it isnecessary to design the error’s simulation software because the errors have differentparameters and there is not an simulation software now. According to the actual needs,the error’s simulation software is designed in the article, so the user can observe theeffects of different errors on the spectrum conveniently.Through simulating the effects of the different errors on the spectrum andmaking comparison with the ideal spectrum, it is convenient for the users to adjust thespectrometer. The performance of the spectrometer can also be improved according tothe results of the simulation, so the spectrometer can have high precision and smallerror.