The Study On Herriott Photo-elastic Modulator

The spectrum technology and its instruments with high speed, high sensitivity, highresolution and widest range of spectra has a wide range of applications in geoscience,cosmology, aerospace, military, etc..According to the disadvantage of low spectral resolution and narrow spectral range ofstatic Fourier transform spectrometer, and under the support by the International S&TCooperation Projects of China, the paper reference the photo-elastic modulator’s inherentadvantage of high speed, high sensitivity, wide spectrum range and anti vibration, etc. AHerriott photo-elastic modulator was proposed in order to solve the problem of insufficientspectrum resolution of current photo-elastic modulator-based Fourier transform spectroscopy.Based on the Herriott photo-elastic modulator interferometer structure, we carried out relatedtheoretical analysis, design and development works. This particular Herriott photo-elasticmodulator structure utilizes the characteristics of simple and easy to be combined with ofHerriott multipass cell. The purpose of superpose optical path difference has been achieved bymultiple and effective reflection in the crystal. It breakthroughs the limitation of maximumoptical path difference in one photo-elastic crystal, increasing the permission scope ofincident light and improving the utilization rate of light energy at the same time. In order tofurther improve the optical path difference, a method for measuring resonant frequency of thephoto-elastic crystal has been proposed based on the theory of mechanical vibration. TakingHerriott photo-elastic modulator as an example, the resonant frequency and the Q value ofzinc selenide has been precisely measurement using the method above. In this way, themodulator achieves better frequency matching.Finally, Herriott Photo-Elastic Modulator designed above has been taken trial productionand performance verification. The results shows that, the resonant frequency is50033.73Hz,and the maximum optical path difference of this modulator is about14.5times that ofordinary one’s. In summary, the feasibility of Herriott photo-elastic modulator has beenverified by simulation and experiment.