| As a very important characteristic spectrum of molecule, infrared spectrum holds the balance in physics and chemistry field.In a long time, domestic FTIR instrumentation market in China is occupied by couple of instrument companies from Europe, America, Japan and Russia.There isn’t any FTIR spectrometer product in China has an independent intelligent property right of our own.This dissertation, as the critical part of a 10th Five Years Key Programs for Science and Technology Development of China, which is named the research and development of Infrared and Laser Raman Spectrum analysis instrument (2004BA210A02), was mainly focused on the exploring and research of core technologies of FTIR spectrometer. Some latest optical, mechanical and electronic methods were adopted to build up the Michelson Interferometer system. Until the accomplishment of this project, this is the first FTIR spectrometer in domestic, which has an independent intelligent property right. Meanwhile, a novel portable FTIR spectrometer was designed with the application of researched technologies and a patent of it was applied.In the dissertation, some core technologies of FTIR were researched and two types of FTIR instrument were accomplished. The research work is mainly as following:1. According to the fundamental theory of FTIR spectroscopy, some theoretical problems in spectrometer design were discussed. The instrument function and apodization were talked over in this work, and some factors which may result in deduction of resolution, and several issues in interferogram acquisition, and the generation of phase error in single side interferogram Fourier transformation and the way to correct this kind of error were mentioned in this dissertation too.2. The construction of Michelson interferometer in the FTIR spectrometer was specifically described. Referring to the principle of induced magnetic force, we built up a kinetic model of magnetic coil, with the help of the model the mechanic system and electronic control system of linear motor were made to drive the moving mirror scan to and fro. The magnetic suspending technology was used in linear motor mechanic system to reduce friction force and DSP was used as control unit to execute new PID arithmetic which realizes the high precision of motion. The detailed information on mechanic system design, controlling arithmetic, hardware and software system design was put forward in thesis. The experiment result showed that the speed accuracy of linear motor is better than 5%, it was as good as we expected.3. According to the fundamental theory of FTIR spectroscopy, the mathematic model of interferometer was built up and the reason of interferometer misalignment was analyzed. Based on the model analysis, a dynamic alignment system of fixed mirror which is based on the electrical magnetic driving was proposed. This system can track the tilt of movable mirror to the fixed mirror in real-time, and keep movable mirror perpendicular to fixed mirrors. The principle, structure design, hardware and algorithm of controlling of dynamic alignment system were discussed in the dissertation. The experiment result showed that the modulation rate of spectrometer was improved, and the speed accuracy was enhanced too.4. A set of hardware and software for data acquisition system with electronic filter was proposed. A fast design method of electronic filter based on OrCAD simulation tool was put forward. Through comparing to the output of frequency scanner, it was proved that this way of design analog filter is fast, correct and effective. Referring to related test criterion, our data acquisition system had a high capacity, and adequate to the requirement of FTIR instrument. On the other hand, we connected the moving mirror driving system and data acquisition system together to build up a set of real-time data acquisition system which can automatically finish a number of interferometer acquisition, get the average of them, do the Fourier transformation and display the spectra. This helped to increase the efficiency and convenience of our software. Experiment result proved that, by this data acquisition system, the SNR of spectrum is almost 20000:1, and approach to our expectation.5. While our researching and developing the FTIR spectrometer for laboratory usage, we reviewed the features of large scaled FTIR spectrometers and optical parts in advanced spectrometer. A kind of small scaled FTIR apparatus was proposed. We applied corner-cube mirror in the optical system to get rid of the dynamic alignment system which would take more room and add too much weight to the spectrometer system. So the size and weight of the interferometer were reduced. This small instrument was applied as an oil testing machine which was used to in-field measure mineral oil mixed in water. In this thesis, the principle of the apparatus, the optic structure and a linear motor driving system suit to minimized Michelson interferometer were proposed. Experiment result turned out that the capacity parameters of this instrument were much higher than we have thought. |
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