Study on broadening the size range in laser particle size measurement by combined spectrum technology

摘要

In laser particle size measurement, the instrument based on traditional Fourier transform structure is disadvantaged in the narrow measurable dynamic size range. So it is hardly to be used to measure broadly distributed particle. The presented technology is based on Fresnel diffraction theory. The formula of combined spectrum technology by detecting signals on coaxial focal planes is educed. In the proposed method, the two lenses are set coaxially and signals are detected on the back focal plane of the first lens and the combined back focal plane of the two lenses. The detected signals are then combined. The data are processed with a no-model algorithm. Thus, the measurable dynamic range can be broadened as no component of the sizer is changed. Experimental results of some samples show that the particulate in the size range of 5 ～ 3500 μm can be measured simultaneously.