Study On The Dispersion And Compensation Of Edible Oil Based On Optical Coherence

The safety detection of edible oil is an urgent problem.The detection system involves the physical and chemical properties of the edible oil,the chromatogram of the edible oil,the nuclear magnetic resonance signal and the spectral information,etc.,and except the dispersion characteristics of the edible oil.Mastering more information about oils provides the basis for the accuracy of edible oil detection.Optical Coherence Tomography?OCT?is widely used in people's real life and in other related research fields.It is also of great practical significance to explore and study the OCT.Because most of the optical components and biological tissues have dispersive properties in the optical imaging system,the resolution of the system will decrease.On the basis of improving OCT resolution,this paper attempts to obtain dispersion information of edible oil.Aiming at the research contents of refractive index of edible oil,high order dispersion information,dispersion compensation and so on,using ultraviolet spectrophotometer and Frequency Domain Optical Coherence Tomography?FDOCT?and other experimental systems,the research results of edible oil and OCT imaging system are used for reference.Taking five different edible oils as research objects,the refractive index of oil is measured and calculated by transmission spectrum method,and the influence of dispersion characteristics on OCT signal is deduced theoretically,and the method of deep dispersion compensation is tried to compensate the dispersion.The purpose of this paper is to obtain the dispersion information of various oils and to improve the axial resolution of OCT.1.In the experiment of measuring the refractive index of oil products by transmission spectrum method,the transmission spectrum curve of samples was measured by ultravioletspectrophoto-meter,the refractive index of odd extreme point was deduced by analysis.The refractive index and wavelength are fitted by 1st Opt software and compared with the fitting method of MATLAB toolbox.The optimum fitting curve formula is reasonably determined and selected.After five kinds of oil products are treated with the same method,the formula of refractive index of five kinds of oil wavelength is obtained.And in the interval of 0.95 0.97 with complex correlation coefficient,the fitting formula of five kinds of oil products is n???=p₁+p₂?^0.5+p₃?+p₄?^1.5+p₅?²+p₆?^2.5.2.In the study of the influence of dispersion on OCT signal,firstly,the influence of sample dispersion on envelope width of OCT signal is deduced theoretically,and the envelope width of the same sample is different under different light sources.Secondly,the second-order dispersion and third-order dispersion curves of each sample are simulated by MATLAB numerical method.The comparison and analysis show that the third-order dispersion is very small and can be ignored.The influence of second-order dispersion on OCT signal is mainly studied.Therefore,in this study,only second-order dispersion compensation is used to correct the image.3.On the basis of considering only second-order dispersion,dispersion compensation is mainly used to eliminate the second-order dispersion phase in interference signal.In this paper,using the method of deep dispersion compensation to simulate the numerical compensation of double-layer glass by MATLAB.And the relationship between the second-order compensation coefficient and the depth is obtained,that is a₂=-1.176113×10^-8d³+7.56984×10^-5d²-0.0511285d+13.9887.The feasibility of the compensation method is verified.The experiment is carried out with FDOCT.The data can be obtained by Origin software.The results show that?1?The oil can only detect the information on the surface of the liquid surface;?2?The width of half peak of the compensated signal is smaller than that of before compensation,and the resolution of the tomography is improved;?3?The compensation coefficient of different oil products is obtained.They are rapeseed oil: 29?A.U.?,peanut oil: 27?a.u.?,blend oil: 19?a.u.?,sesame oil: 23?a.u.?,waste cooking oil: 35?a.u.?.The main conclusions are: the refractive index of oil under different wavelength and high order dispersion can be used as the basis for detecting oil.The three order dispersion process of dispersion compensation is negligible in the oil,and then through the depth of the dispersion compensation method can obtain compensation coefficient of different oils,and effectively improve the high resolution of OCT.