Abstract
The objective of the present study is to quantitatively analyze optical signals obtained from a Single-Tip Optical fiber Probe (S-TOP), and to improve the accuracy in a bubble/droplet measurement. The complicated probing signals were evaluated through the newly developed 3D simulator. Based on this simulator, two characteristic peaks (pre-signal in the bubble measurement and post-signal in the droplet measurement) were observed before the S-TOP pierced the gas-liquid interface. Analyzing rays contributing to these peaks, the generation mechanisms of the peaks were clarified. In addition, we found that the pre/post-signal intensively appears when the S-TOP touches a bubble/droplet at the center region. By using these characteristics, we finally established a new threshold-method for detection of a touched- position by the S-TOP on the bubble/droplet surface. In the practical measurement with the threshold-method, a standard deviation of results of the S-TOP was significantly decreased.
