Solution Concentration and Temperature Measurements by Long-path Optical Coherence Tomography

Long path time domain OCT was developed and applied to evaluate a certain solution under the consideration of concentration and temperature. Long path TD-OCT has the measurement range of 100mm and the resolution of position decision of 1m. Optical characteristics of the solution is represented as group refractive index by Long path TD-OCT, and it depends on solution concentration and temperature. In this study, the experimental result of the diluted alcohol solution was compared with the plural theoretical models. As a result, the measurement accuracy was confirmed with the refractive index error of less than 0.0001. Long path TD-OCT has potential to evaluate the target solution with volume, and the experiment was proceeded to monitor the spatial fluctuation process. As a result, the unique phenomenon was observed in the model experiment of partially different refractive index sample. The OCT signal had the change of knife-edge effect at the boundary of refractive index. More fundamental experiment was conducted to observe the phenomenon precisely. Now the theoretical approach was started to understand the phenomenon.