Online measurement of nanoparticle size distribution in flowing Brownian motion system using laser diode self-mixing interferometry

Abstract

application. Thanks to these advantages, this technique has been successfully applied to measuring many physical parameters [2][3][4]. However, little attention is paid to the measurement of particle size or particle size distribution [5]. have demonstrated that the quick evaluation of the submicron particle size in solution by using highly sensitive laser-diode-pumped thin-slice solidstate laser self-mixing interferometry and the self-mixing photon correlation spectroscopy of particle size distributions has been also discussed. Liu et al. [9] have theoretically analyzed the possibility of measuring the nanoparticle size in solution by using erbium-doped fiber ring laser selfmixing interferometry. Zakian et al. [10,11] have applied the laser diode self-mixing interferometry to measuring the nanoparticle size in solution, and the size has been retrieved on basis of the dependence of the full width at half maximum (FWHM) of power spectral density on the nanoparticle size. Wang and Shen [12] have further applied the laser diode self-mixing interferometry to measuring the nanoparticle size distribution in solution, and the size distribution has been retrieved from power spectral density by a modified inversion algorithm.In a flowing Brownian motion system, Sudo et al.[13] have demonstrated that the power spectral density can be reproduced by a single q Gaussian distribution function in which q depends on the diffusion constant of colloidal particles. Thus, by fitting the q parameter of the Gaussian distribution function to the measured power spectrum, the particle size can be easily deduced from the diffusion constant using the Stokes-Einstein relation. Recently, Wang and Shen [14] have developed a quick laser diode self-mixing interferometry for measuring the nanoparticle size distribution. The quick measurement technique is promising to be applied to the online measurement of the nanoparticle size distribution in the flowing Brownian motion system. As far Abstract Laser diode self-mixing interferometry, which is characterized by self-alignment, compactness, low cost and few additional optical elements required, is promising to be applied to the online measurement of the particle size distribution in a flowing Brownian motion system. In this paper, the online measurement is realized by the laser diode self-mixing interferometry with a quick signal processing technique and a quick inversion algorithm. The total power spectrum of the self-mixing signal is achieved, and the impact of particle motions on the total power spectrum is researched. A method is proposed for retrieving the particle size distribution, which is validated by experimental tests.