Aiming at the existing problems such as weak environmental adaptability,low analytic efficiency and poor measuring repeatability in the traditional spectral oil analyzers,the present paper designed a portable mid-infrared rapid analyzer for oil con-centration in water.To reduce the volume of the instrument,the non-symmetrical folding M-type Czerny-Turner optical struc-ture was adopted in the core optical path.With a periodically rotating chopper,controlled by digital PID algorithm,applied for infrared light modulation,the modulating accuracy reached ±0. 5%.Different from traditional grating-scanning spectrophotome-ters,this instrument used a fixed grating for light dispersion and avoided rotating error in the course of the measuring proce-dures.A new-type MEMS infrared linear sensor array was applied for modulated spectral signals detection,which improved the measuring efficiency remarkably.Optical simulation and experimental results indicate that the spectral range is 2 800~3 200 cm-1 ,the spectral resolution is 6 cm-1 (@3 130 cm-1 ),and the signal to noise ratio is up to 5 200∶1.The acquisition time is 13 milliseconds per spectrogram,and the standard deviation of absorbance is less than 3 ×10-3 .These performances meet the standards of oil concentration measurements perfectly.Compared with traditional infrared spectral analyzers for oil concentra-tion,the instrument demonstrated in this paper has many advantages such as smaller size,more efficiency,higher precision,and stronger vibration&moisture isolation.In addition,the proposed instrument is especially suitable for the environmental monito-ring departments to implement real-time measurements in the field for oil concentration in water,hence it has broad prospects of application in the field of water quality monitoring.%针对传统光谱测油仪存在的环境适应能力弱、分析速度慢、测量重复性差等问题，研制了一种便携式中红外水中油浓度速测仪。其核心光路采用典型的非对称折叠式 M型 Czerny-Turner 光学结构，有效缩小仪器体积；使用周期性转动的斩光器调制红外光源，并对斩光器转速进行数字PID控制，调制精度达到±0．5％；采用固定光栅作为分光元件，无需光栅扫描装置且不存在转动误差；利用新型 ME MS红外线传感器阵列探测调制后的光谱信号，显著提高光谱采集速度。光学仿真及实验结果表明仪器光谱范围为2800～3200 cm-1，光谱分辨率达到6 cm-1（＠3130 cm-1），信噪比达到5200∶1，谱图采集速度为13 ms·幅-1，吸光度标准偏差优于3×10-3，满足了水中油测定国家标准要求。与已有红外光谱测油仪相比，该仪器小型便携，分析速度快，测量精度高，抗震防潮性能好，特别适用于环境监测部门对水中油浓度的现场实时测量，因此在水质监测领域具有广阔的应用前景。
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