We mainly study on hardware design and implementation of multiplexing photon correlator based on FPGA and the graphical user interface programmed by LabView to control it, and its application in submicron particle size analyzer. The study is based on the verification of the principle of sampling correlation calculation, the implementation of the multiplexing correlation operation, the hardware design of FPGA, and etc. Multiplexing photon correlator can calculate the auto-correlation function of multiplexing photon signals that were received by a single PMT at different times. Multiplexing photon correlator mainly composes of signal control module, photon counter module, shift register module, multiplier-accumulator module, communication module, etc. With appropriate optical set-up, it will change from the traditional measurement of the single point to the 2D or 3D measurement using a single photon detector, greatly expands the application range of photon correlation spectroscopy.
Dynamic Light Scattering is used for measuring particle size distribution of nano-particle under Brownian motion. Signal is detected through a photomultiplier and processed by correlation analysis, and results are inverted at last. Method by using CCD camera can record the procedure of motion. However, there are several weaknesses such as low refresh speed and noise from CCD camera, and this method depends on particle size and detecting angle. A simulation of nano-particle under Brownian motion is proposed to record dynamic images, studies contrast of dynamic images which can represent speed of diffusion, and its characteristic under different conditions. The results show that through contrast of dynamic images diffusion coefficient can be obtained, which is independent on density of scattering volume.