| 摘要 |
PURPOSE:To exclude the influence due to elements other than moisture, by a method wherein light is irradiated to the predetermined part of a porous member contacting with a measuring part and the change in a reflection level is detected to carry out the indirect measurement of a water content ratio. CONSTITUTION:Light with predetermined intensity is sent into the optical fiber 1 of a sensor mechanism part 6 having a porous member 2 contacting with a measuring part from a light source 7 and a part of reflected light from a bottom surface 2B is sent to a compensation circuit 9 through an end surface 1B, the fiber 1 and a light receiving element 8B. On the other hand, a part of the output of the light source 7 is sent to the circuit 9 through a light receiving element 8A and the drift of the light source 7 is detected to compensate the drift of reflected light as well as to be displayed by a display part 11 through an amplifier 10. By this method, the water content ratio in soil can be measured as the reflection level of light. |
