Encuentro de Ciencia y Tecnología – ECITEC 2016
Línea de I+D UNI
Abner Velazco Torrejón
Facultad de Ciencias (UNI)
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Título de la conferencia
Light scattering measurements from small dielectric particles
Scattering of light is the result of the interaction between a beam of light and a particle, which size is comparable to the wavelength of the incident light. Mie theory  is used in order to calculate the intensity of scattering from spherical particles of any size.
In this work we describe the design and construction of a system to measure the angular scattering distribution from small dielectric spheres suspended in water. The work also covers the development of a detection system to improve the signal to noise ratio. We report experimental measurements of laser light scattering from a dilute suspension of latex spheres with diameters of 0.49±0,02 and 1.03±0,03 μm. Two wavelength were used, 632.8 and 532.0 nm, to observe the variation of the angular scattering distribution and size parameter, χ [1,2]. Oscillatory behavior and angular position of the minimums of the angular light scattering distribution was used for particle sizing. Experimental results were compared with angular scattering distributions from Mie theory and it was possible to determine the size of the particles with a relative accuracy less than 7%.
New activities have been focused on automatization and improvement of the detection system. Measurements of the angular scattering distribution from latex spheres with diameters of 1.03±0,03 and 2.5±0.23 and a wavelength of 632.8 nm were made, the results show good repeatability and reproducibility.
Theoretical and experimental angular light scattering distribution from particles with nominal diameter of 1.03 μm and different size parameters.
Abner Velazco Torrejón (a), Abel Gutarra Espinoza (a)
a) Facultad de Ciencias. Universidad Nacional de Ingeniería, Av. Túpac Amaru s/n, Rímac, Lima 25, Perú.
 Craig F. Bohren and Donald R.Huffman, Absorption and Scattering of Light by Small Particles (Wiley, New York, 1983).
 I. Weiner, M. Rust, and T. D. Donnelly, Particle size determination: An undergraduate lab in Mie scattering, Am. J. Phys. 69 (2), 129 – 136 (2001).