Measurement Technique Based On Mie Light Scattering Theory Of Bubbles

After comparing several methods the studying of scattering light is chosen for studying character of ship wake. The character of ship wake is decided by the mount moving bubbles in it. So the character of scattering light of single bubble is researched in Mie scattering theory. First the scattering model of single bubble is built in computer, and it is found out that the character of scattering light of single bubble is related with its radius and refraction index. In the base of scattering model of single bubble, the character of scattering light of multi-bubbles are researched. It is found out the scattering light of multi-bubbles are the linear sum of single bubble if the scattering is non-related. Using the scattering model of multi-bubbles, the speed and radius and density of multi-bubbles can be calculated by the scattering Light of ship wake in lab. They are the key variables of ship wake.The ship wake is simulated in lab. The Fourier optical system and CMOS image sensor are used first to collect scattering light signal. In the lab the laser atλ=532nm is collimated by collimation lens and then goes thought the total reflect mirror into the bubbles. The scattering light is reflected by the total reflect mirror into the Fourier optical system. The signals collected by CMOS are save in computer by the image collecting card.The methods of dynamic and static scattering light are used in the date process. The scattering light signals are changing quickly for the mount of moving hubbies. In the method of dynamic scattering light the signals are changed from time into frequency by Fast Fourier Transform. The image of spectrum of signals is found out. The key frequencies are found out in the spectrum. And these frequencies are related with the speed of bubble. So the speed of bubble can be got out by the study of dynamic scattering light. The method of static scattering light is studying of one frame of the collection images. The intensity of scattering light in different angles are got out by filtering the frame and linear rings. And then the radius and density of bubbles can be calculated by inversion method. It is found out the speed of bubbles is linear with the radius of bubbles at the radius is less than 1mm and the intensity of back-scattering light is max at 180 degrees. It is feasibly that detecting ship wake by back-scattering light from the studying of theory and experiment.