The Ultra-high Speed Infrared Spectra Measured Method Based On Phtotelastic Effect

Measurements of Infrared Spectra have a wide range of value application in the fields ofenvironmental monitoring and control, aviation and space, safety, military field and so on.The new FTIR (fourier Transform Infrared Spectroscope), which based on photoelasticmodulator-PEM, has many advantages such as ultra-speed, high sensitivity, wide spectralrange and vibration-proof. In this thesis, the design approaches had been studied, andsimulated and analyzed by finite-element method based on basic principles of phtotelastic.Then the result has been proved by the experiment, and it has been provided that a newarithmetic applied to spectrum recovery for PEM’s interferogram.By the analyzing of principles of photoelastic modulation and in according withtechnology indicators of national science fund, the basic plans of phtotelastic modulator hasbeen designed, determining geometry dimensions and materials of each part of the device hasbeen determined, and the resonance frequency can be calculated.With Comsol Mutiphiscs, the designed device has been simulated and analyzed by thefinite element method. The result at the field of study of resonance frequency and timedomain has been obtained, and it is in accordance with the designed object and reaches thetarget of project. The simulation and analysis method of photoelastic modulator by finiteelement method and suggest the study process has been summarized.The nonlinear optic path difference is existed in photoelastic modulator processing,which made classical FFT be ineffective in spectrum recovery of nonlinear optic pathdifference interferogram. If direct computations as the first step, which will bring excessiveconsume and cannot fit hardware actualization, new method is required. The practicability, ofadopting nonuniform Fast Fourier Transform to spectrum recovery of nonlinear optic pathdifference interferogram is designed in this paper, and the algorithm simulation is alsofinished. Fast and high precision spectrum recovery in photoelestic modulator is achieved andmet the requirement of project.