Patent ID: 7248905

Claim:
A concentration measuring apparatus comprising: a linearly polarized light supplier that supplies linearly polarized light; an optical rotation angle modulator that modulates an optical rotation angle of the linearly polarized light to obtain modulated light; a light intensity detector that detects an intensity of light coming out of an inspection object when the modulated light is passed through the inspection object, wherein an optically active substance in the inspection object optically rotates the modulated light when the modulated light passes through the inspection object; a variation calculator that calculates a variation in the optical rotation angle of the light coming out of the inspection object based on an angle to which the optical rotation angle modulator has modulated the linearly polarized light and the intensity of the light detected by the light intensity detector, wherein the optical rotation angle of the light coming out of the inspection object varies in response to a pulsation of a pulsing component of the inspection object; and a concentration calculator that calculates a concentration of the optically active substance based on the variation in the optical rotation angle, wherein said variation calculator comprises a sampler that samples two optical rotation angles and a difference calculator that determines a difference of the two angles as the variation in the optical rotation angle.