| 摘要 |
PURPOSE:To enable measurement of a liquid surface without being influenced by the kind of a liquid and atmosphere by providing a light projector and photodetectors disposed in such a way that light can be projected and detected from and to each other to the outside of a vessel and detecting the light by utilizing the total reflecting effect of the liquid surface. CONSTITUTION:Light is passed through the glass window 5 of a protecting tank 3 and a vessel 2 consisting of a quartz material to the inside of a liquid 1 in the stage of projecting the light from a light projector 4 toward the liquid surface 1b. The light is totally reflected by the surface 1b owing to the light refractive index of the liquid 1, advances diagonally downward at the reflection angle corresponding to the incident angle and is made incident through the vessel 2 on the opposite side and the glass window 7 of the tank 3 to a photodetector 6b. The existing of the present liquid level at 1b is thereby detected. Other liquid surfaces 1a, 1c are similarly detected and measured by photodetectors 6a, 6b. The highly reliable measurement of the liquid level by an indirect measuring method is thus made possible. |
