PURPOSE: To measure humidity accurately even under existence of an infrared ray absorptive gas without being influenced by electromagnetic noise by securing a porous body bearing a moisture-sensitive color-changing substance to the tip of an optical fiber.
CONSTITUTION: A visible ray 6 led through an optical fiber 4 is cast onto a porous body which bears a moisture-sensitive color-changing substance 2 secured to the tip of an optical fiber with a clear adhesive 3, and the reflected visible ray 7 is sent to the body of a measuring device upon passing through the optical fiber 4. The substance 2 absorbs part of the cast-on visible ray 6 and reflects the ray 7 not absorbed, when the color of the substance 2 will change with adsorption and separation of the moisture in the air, and therefore, the wavelength of the absorbed visible ray differs depending upon the ambient humidity and also the wavelength of the ray 7 reflected differs accordingly. Because of possibility of using visible rays, the optical loss in the course of optical fiber 4 is lesser to enable measuring in the distance.
MORIMOTO ATSUO
MIYAJI AKIHIRO
ITO TOYOJI
KANSAI ELECTRIC POWER CO