| 摘要 |
[Problem] To avoid measuring light which has passed over an optical path diagonally traversing a tube in the direction of extension thereof, to thereby measure with high accuracy the concentration of a fluid, such as blood or a drug solution, flowing within a resin tube or other tube having a tube wall that is light transmissive and deformable. [Solution] A device for measuring the concentration of a fluid flowing within a tube having a tube wall that is light transmissive and deformable, provided with: a light source for supplying light to the tube interior from a light supply position on the surface of the tube; a photoreceptor element situated at a light reception position located to the opposite side from the light supply position in the a diametrical direction of the tube, for receiving the supplied light having passed through the tube wall of the tube and the fluid inside the tube, and outputting a signal indicating the intensity of the light; an optical path distance setting means for setting a plurality of optical path distances between the light supply position and the light reception position; and fluid concentration output means that, on the basis of the Lambert-Beer law, calculates from the intensity of the light at the light reception position at each of the plurality of optical path distances, a plurality of relational expressions indicating a relationship between fluid concentration and light intensity when light from the light supply position is received at the light reception position at each optical path distance, and that on the basis of the relational expressions for the plurality of optical path distances, outputs the fluid concentration calculated from the light intensity at the light reception position. |
