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植保机械科学研究中,雾滴尺寸分布的测定工作,非常繁重,而且不易测得准确。本文简述了激光式雾滴尺寸分布测定仪的工作原理和应用条件。这种仪器是利用平行单色光束照射运动着的雾滴而产生夫琅和费衍射,通过傅里叶透镜将衍射光束会聚在多元光电探测器上,来测定其衍射光能分布,再通过小型计算机,将光能分布翻译成为相应的雾滴尺寸分布。目前仪器所能测定的雾滴尺寸范围为1—1800微米,所测得的雾滴平均直径的误差约为4％。此法的显著特点是测定非常迅速,并不干扰雾流。至于适用的液体种类,雾滴数量和尺寸范围的问题,只要不使入射光的衰减分率达到50％以上,其多次散射的影响是极小的。此项仪器不但可以用来测定气流中的液体雾滴,亦可用于测定气流中的固体微粒,仪器稍加改装,还可测定液流中的固态或液态质点的尺寸分布。因此,这种仪器在其他科研领域亦有多种用途。
Plant protection machinery scientific research, the determination of droplet size distribution, very heavy, but not easy to measure accurately. This article describes the working principle and application conditions of the laser droplet size distribution analyzer. This instrument is the use of parallel monochromatic beam irradiation of moving droplets generated Fraunhofer diffraction, the diffracted beam through the Fourier lens converged on a multi-photodetector to determine the diffracted light energy distribution, and then through the small The computer translates the light energy distribution into the corresponding droplet size distribution. At present, the size of the droplet that can be measured by the instrument ranges from 1-1800 microns, and the measured error of the average droplet diameter is about 4%. The notable feature of this method is that the measurement is very rapid and does not disturb the flow of fog. As for the types of liquids, the number of droplets and the range of sizes, the effect of multiple scattering is extremely small as long as the fraction of incident light that is not attenuated reaches 50% or more. The instrument can not only be used to determine the liquid droplets in the air stream, can also be used to determine the solid particles in the air stream, the instrument slightly modified, but also determine the size of liquid or liquid particle size distribution. Therefore, this instrument also has many uses in other fields of research.