HAN KAN

–Key Laboratory of Opto-electronics Information Technology (Tianjin University), under instruction of Prof.LU QIENI

1. Introduction

Interferometric Particle Imaging(IPI) is a technology which is used to measuring the size, velocity and distribution of the spray. The basic setup of IPI is showed in Fig.1. According to Lorenz-Mie scattering and Debye Series(see Fig.2), we got a specific scattering angle to get better focused images and interference images. My work in IPI can be divided into two parts, simulation and image processing. During this work I have completed two papers.

IPI原理图

Fig.1. Basic Setup of IPI

Mie理论 Debye级数

Fig.2. Lorenz-Mie scattering(left) and Debye Series(right)

2. Simulation

Based on Fourier Optics, I build a optical field distribution(see Fig.3) which can take detail parameter like the characteristics of particles, imaging lens and the position of image plane into concern. And it can describe the optical distribution everywhere in the setup(Fig.4). By using it I calculate the center deviation in IPI(Figue.5).

Fourier Optics

Fig.3. Setup of IPI for Fourier Optics Simulation

SimulResult

Fig.4. Simulation Result

Center Deviation

Fig.5. Center Deviation

3. Image Processing:

For the density of the particls in spray is quite high. By adding aperture, we can change the round fringe into line fringe in order to reduce overlap(Fig.5). In this case we use some algorithm to locate each fringe in the dense spray(see the red point in Fig.6), and now the accuracy is much higher. And also we find a algorithm named Improved Rife Algorithm to improve the accuracy in extracting the frequency in each fringe(see Fig.7).

Image Processing

Fig.5. Line Fringe

IPResult

Fig.6. Location Result in Dense Field

Rife Algorithm

Fig.7. Improved Rife Algorithm