Particle size distribution measurement is indispensable for pharmaceutical industry, material manufacturing, food industry, microbiological industry, health-friendly environmental support, etc. In particular, it is very important to visualize dust particle distribution in real time in order to reliably and intuitively ensure the steady-state operation of a dust filtration system for high quality filtration.
Optical measurement techniques with laser light sources of excellent optical properties such as laser diffraction metrology, phase Doppler metrology, photon correlation spectroscopy, laser-induced fluorescence method, light extinction method, etc. have been developed and used in the field of particle size distribution measurement for short measurement time, real-time measurement, remote measurement, etc.
However, above optical dust measurement methods are independent of the visualization of dust particle distribution in the measurement area of interest.
With the recent development of high-resolution, high-sensitivity and high-speed digital cameras which are easy to control automatically, there has been a growing interest in determining particle velocity, size, and shape while visualizing particle distribution using direct imaging of particles. At present, however, the direct imaging method by digital cameras is limited to spherical particles of relatively large size (50㎛).
The size of dust particles that are particularly detrimental to human body is in the range of 0.3~5㎛, so in general cases, such digital camera optical system cannot separate dust particles from the imaging plane.
Ri Chol Man, a researcher at the Faculty of Physical Engineering, has theoretically and experimentally investigated the possibility of magnification of the particle images by introducing intense light irradiation to the imaging system, and based on the results, he has constructed a particle size distribution measurement apparatus and confirmed its usefulness.
The results demonstrate that the proposed method can be used instead of the light scattering particulate counting method, which is widely used in portable applications for measuring dust particles in the size range harmful to human body.
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