| Spectrum,one of the basic properties of substances,is called ’fingerprint of substances’.Spectrometer is a common optical detection device,which can analyze the composition,structure and chemical properties of a substance by obtaining spectral information of the substance.Among them,near-infrared spectroscopy is the most widely used spectral band,which has been widely used in food safety,medical analysis,agricultural production,aerospace manufacturing,resource detection,military reconnaissance and other fields.The micro near-infrared spectrometer has the advantages of small size,low cost,convenient detection,online analysis and convenient secondary development.Based on the analysis of the development of micro near infrared spectrometer at home and abroad,this paper designs a portable near infrared spectrometer based on digital micromirror devices(DMD)and hadamard transform(HT)technology to solve the problems of complex structure,large size,expensive price and inconvenient carrying of traditional spectrometer.The main work and research contents are as follows:Firstly,based on the overall design scheme of portable near-infrared spectrometer,this paper focuses on the principles of near-infrared spectroscopy analysis technology,Hadamard coding and decoding,DMD drive control,spectral data acquisition and other related principles,and introduces the basic theory,technical process,analysis method of nearinfrared spectroscopy analysis technology,as well as the development principle of Android system in detail.Secondly,the hardware unit and client application program of portable near-infrared spectrometer are designed.The main hardware unit includes DMD driving and controlling module,spectral signal acquisition module,signal filtering and digital-to-analog conversion module.In order to further improve the application convenience of the system,based on the realization of wireless data communication between the main hardware unit and mobile terminals such as mobile phones,an Android application is designed to complete the functions of spectral scanning,data display and storage,and spectral data analysis.Finally,in order to verify the comprehensive performance of portable near-infrared spectrometer,the working wavelength range,spectral resolution,wavelength repeatability and other performance index are tested under natural conditions.The quantitative analysis experiment of wool polyester blended fabric is carried out,and the corresponding analysis model is established,and this model is used to dectect fiber content detection experiments to verify its practicality.The test results show that:The portable near-infrared spectrometer designed in this paper has a working wavelength range of 900-1700nm,spectral resolution of 10nm,standard deviation of characteristic peak within 0.1%,correlation coefficient of quantitative analysis model of textile samples up to 0.97,and root-mean-square error of prediction within 0.5%,which meets the design requirements.It has strong practical application value in the fields of material identification,quality control and process analysis. |
