Concentration measuring device and a method of controlling the concentration measuring device

A concentration measuring device measuring a concentration of a first constituent of an object to be examined, the concentration measuring device comprising:

• a light source irradiating light toward the object to be examined which includes water, the first constituent having optical rotation and absorbency, and a second constituent having optical rotation and absorbency, such that the light transmits through the object to be examined;
• a light detector receiving transmitted light transmitted through the object to be examined and outputting output signals;
• a memory storing first measurement data and second measurement data, the first measurement data including at least a first optical rotation coefficient that is predetermined corresponding to a first wavelength and a first absorbance coefficient that is predetermined corresponding to a second wavelength different from the first wavelength, the first optical rotation coefficient and the first absorbance coefficient being related to a first aqueous solution containing water and the first constituent, the second measurement data including at least a second optical rotation coefficient that is predetermined corresponding to the first wavelength and a second absorbance coefficient that is predetermined corresponding to the second wavelength, the second optical rotation coefficient and the second absorbance coefficient being related to a second aqueous solution containing water and the second constituent;
• and
• a processor controlling the light source and calculating the concentration of the first constituent, the processor
• selecting the first wavelength and the second wavelength from a wavelength region in which an absorbance coefficient of water is substantially zero,
• controlling the light source to irradiate a first measuring light with the first wavelength to the object to be examined,
• controlling the light source to irradiate a second measuring light with the second wavelength to the object to be examined,
• calculating an optical rotation value of the first measuring light, which has passed through the object to be examined, based on a first signal of the output signals from the light detector,
• calculating an absorbance value of the second measuring light, which has passed through the object to be examined, based on a second signal of the output signals from the light detector,
• obtaining, from the memory, at least the first optical rotation coefficient, the second optical rotation coefficient, the first absorbance coefficient, and the second absorbance coefficient, and
• calculating the concentration of the first constituent based on at least first and second liner combinations each of which is a linear combination of the concentration of the first constituent and a concentration of the second constituent, the first liner combination including only at least one product of the first optical rotation coefficient and the concentration of the first constituent and at least one product of the second optical rotation coefficient and the concentration of the second constituent, the second liner combination including only at least one product of the first absorbance coefficient and the concentration of the first constituent and at least one product of the second absorbance coefficient and the concentration of the second constituent.