The Theory Anlysis And The Experiment Study Of Acousto－Optic Tunable Filter

Spectrum application technology ,combined with light dispersion method and Chemometrics,is now one of the best choices in measuring elements on line,for it has many advantages of fast,multi-elements and no contacting measure ect. And acousto-optic tunable filter(AOTF) is the chief instrument in this measuring method. Transfer function is one of the basic theory which noninvasive glucose measument depend on. As the chief instrument of noninvasive glucose measument,AOTF is the improtant part of the noninvasive glucose measument's transfer function.We figure out the AOTF's characteristic by matrix through analyzing AOTF's theory for the first time,and we get the matrix of AOTF's transfer function.We call this matrix as Characteristic matrix. Orthogonal polarizing method which could be used in the spectrum analyzer such as noninvasive glucose measument can improve the spectrum SNR. Based on Characteristic matrix, we work out mathematic expression of the orthogonal polarizing method, and we verify it through experiment.The spectrum analyzer must have very good spectrum resolving power and SNR,because feeble information will be picked up from the spectrum in the noninvasive glucose measument. Reducing sidelobe can improve the spectrum purity, thereby improving the spectrum SNR. We analysed this problem on the basis of coustics at the first time. by calculating the acoustic intensity distribution of different transducers, we analysed that different acoustic intensity distributions induced different sideband. According to the result, we designed some acousto-optic tunable filters(AOTF) with different transducers. Through the experiment, we find sideband can be reduced by changing the transducer geometry and the Spectrum SNR get improved.