Research On Observation Technology Of Transient Bubble Plumes Based On Optical Fiber Probe

Air-sea flux is an important parameter to describe character of large scale atmos-phere dynamics in air-sea interaction.Its an important research contents in marine biology,marine chemistry and physical oceanography.During the process of air-sea exchange,bubble plumes entrained by the breaking waves plays a vital role.In order to accurately observe the parameter of bubble plumes,an Optical Fiber Probe Sensor Observation Sys-tem and algorithm of extracting parameter of bubble plumes are designed by this project.Preliminary work about collecting parameter of bubble plumes based on Single-tip Opti-cal Fiber Probe has been accomplished.Firstly,in order to make the probe tip of the optical fiber probe more suitable to the marine environment,optimum design to the structure of the probe is done based on Ze-max according to total power and peak irradiance.The result shows that the optimum de-sign of optical fiber probe tip is conical sapphire tip of cone angle with 35 degrees.Then,single-fiber transmission and twin-fiber transmission are compared about their pros and cons.Single-tip with twin-fiber transmission structure is finally established due to exper-imental performance and operational feasibility.Secondly,the method of using grinding machine to manufacture optical fiber probe is introduced.The technical process is mainly divided into two parts—grinding and polish-ing.Then,we continue to do simulation test about transmission efficiency on actually fabricated optical fiber probe whose tip is inclined structure of inclination angle with 35 degrees based on Zemax.The result shows that the transmission efficiency of the optical fiber probe reaches the highest when the wavelength is 940 nm as well as the matching mode of the two probe tips is ‘face to face'.After that,an Optical Fiber Probe Sensor Ob-servation System is designed based on C8051f020 singlechip and OPT101 photoelectric sensor.We utilize this system demonstrate the feasibility of probe method.Last but not the least,counting test of bubble plumes is carried out.The result shows that with the rate of air blast decreases,counting accuracy is promoted.And the effect of the method of trigger as rising edge is better than that of trigger as voltage.Then,image method and probe method are used respectively to observe parameter of bubble plumes.The algorithm of extracting parameter of bubble plumes of these two method are put for-ward.Image method extracts the bubble boundary information through edge detection af-ter removing the background using thresholding,filtering noise-elimination and morpho-logical processing.Correspondingly,probe method obtain the parameter of bubble plumes through curve fitting after preprocessing.Finally,the bubble equivalent size which ob-tained by probe method is compared with that of image method and calibration equation is calculated.