Research On PCS Nanoparticle Size Analyzer

Nanoparticles have been widely used in many fields of the national economy with its special characters in electrics, magnetic, mechanics, photics and acoustics. Measurement of nanoparticles is significant because the characteristics of nanoparticles are closely related to particle size distribution parameters. Photon Correlation Spectroscopy (PCS) which is based on the particle Brownian motion is the main measurement method. This dissertation studied nanoparticle size analyzer which is based on PCS, the main contents are as following:1. Based on Photon Correlation Spectroscopy Theory, proposing the scheme of nanoparticle size analyzer.2. A photon counter including PMT, amplifier, discriminator and pulse counter was developed for very weak scattering intensity.3. A exponential Photon correlator was implemented using FPGA and DSP to overcome the conflict of dynamic range and resolution in linear Photon correlator. The task of FPGA is to complete high-speed pulse-counting and the operation of linear correlation channel, DSP is to complete the operation of exponential correlation channel.4. Based on the analysis of structural parameters, the apparatus of nanoparticle size analyzer was developed. The main work consists of the choice of laser and the design of optical system and mechanical structure.5. We studied the inversion algorithm of particle size distribution. Used the constraint i’ikhonov regularization algorithm in the PCS nanoparticle size analyzer for the shortage of a negative solution in Tikhonov regularization algorithm. The inversion results showed that the inversion peak of constrained Tikhonov regularization algorithm was better than the inversion peak of unconstrained Tikhonov regularization algorithm.6. Five types of standard particles with diameters of 60,100,200,300,450nm are respectively measured by PCS nanoparticle size analyzer. The results showed that the repeatability of measured results was less than 5% and the relative error less than 3%. Various (?)actors including sample preparation, sample concentration, noise, vibration, etc were analyzed which may affect the measurement results and proposing.the corresponding solutions.Developing high performance nanoparticle size analyzer has an important economic and social benefit with the widely application of the nanoparticle size analyzer. The domestic PCS nanoparticle size analyzer is still fall behind the developed countries, the work carried out in this paper will improve the performance of domestic nanoparticle measuring instruments.