实时声光红外汽车尾气检测技术及图象信息系统的研究

Along with developing of economy, possession quantity of car is more and more great, at the same time; urban atmospheric environment pollution from end gas of car is more and more serious. So fast and conveniently determining component and content of end gas of car has significance for controlling end gas drain quantity and improving urban atmospheric environment..Traditional equipments for detecting end gas of car use non-dispersive infrared analysis for gas content. This measuring method has the advantage of high detection accuracy. Its disadvantage is poor operation flexibility..The new infrared detecting system for end gas of car is developed. This system, which uses AOTF (Acousto-Optic Tunable Filter) as dispersive element and uses on-line infrared spectra analysis, on-line detects end gas drain quantity of car. Using AOTF technique, system realizes infrared dispersion. AOTF has advantages of large aperture and easy interfacing with computer; therefore it is suitable for on-line fast detecting end gas of car. The detecting system consists of three parts: infrared monochromatic radiating system, spectral receiving system and computer controlling system. Completed design and debug works include: infrared beam collimating system; DDS frequency scan circuit under control of single-chip computer; AOTF power driving circuit with VDMOSFET; infrared sphere focusing system; HgCdTe infrared signal detecting circuit; autocorrelation detecting circuit and spectral signal processing system. The integrated detecting system for end gas of car is completed. Experiments show that the wavelength region of the system is 2.5~5.0 um, spectral resolution is 15nm. In this wavelength region, all CO、CO2、CH、NO2 of end gas have selective absorptions. .Innovations in this detecting system are:.1..Using AOTF technology generates monochromatic infrared, feature of the monochromatic system is no mechanical moving device, and so measuring error is decreased..2..Complex sample collecting and pre-processing devices are not needed. The system is suitable for on-line detecting..3..Using autocorrelation detecting technology and error compensating technology improves accuracy of the system..4..Using DDS technology increases wavelength scan speed and improves frequency stability.

随着人类文明的提高，汽车保有量越来越大。汽车尾气对环境和人类健康的影响晶趋严重。传统的尾气检测方法采用不分光的滤波气室分析方法。其缺点是不能实现实时检测。本课题综合采用声光红外分析技术与图象信息处理相结合的方法，实时分析汽车尾气的成分及含量，通过摄象器件和计算机组成的图象系统记录有关汽车的特征，为环保部门提供检测信据。