Apparatus for measuring water content

Claim 1

An apparatus for measuring the water content of an object to be measured comprising in combination: a pair of optical filters for obtaining from the same source light a reference light having a wavelength not easily absorbed in said object and a measuring light having a wavelength easily absorbable in said object; an optical system for irradiating said object with said reference and measuring lights extracted through said optical filters; an photoelectric converter for converting said reference and measuring lights incident from said object to electrical signals; a temperature detector for detecting the temperature of said optical filters; a humidity detector for detecting the humidity of optical paths for said reference and measuring lights, extending from said optical system to said object; and water content-measuring circuit for finding the quantity of water contained in said object on the basis of output signals produced from said photoelectric converter, said temperature detector and said humidity detector, said water content-measuring circuit including: means for calculating a temperature correction factor from a linear equation involving as the variable a detected temperature given by the output signal from said temperature detector; means for calculating a humidity correction factor from a linear equation involving as the variable a detected humidity given by the output signal form said humidity detector; means for calculating the rate of the quantity of said measuring light absorbed in said object with respect to the quantity of said reference light absorbed in said object from a linear equation involving as the variable a value obtained by multiplying the ratio of the intensities of said reference and measuring lights indicated by the output signals from said photoelectric converter by said temperature and humidity correction factors; means for calculating the quantity of water contained in said object from a linear equation involving as the variable the absorbance of the measuring light calculated; and means for determining the equations for calculating said temperature and humidity correction factors, using the output signals from said temperature and humidity detectors which are obtained under the conditions where both the temperature of said optical filters and the humidity of said optical path are varied.

Claim 2

An apparatus for measuring the water content of an object to be measured comprising in combination: a pair of optical filters for obtaining from the same source light a reference light having a wavelength not easily absorbed in said object and a measuring light having a wavelength easily absorbable in said object; an optical system for irradiating said object with said reference and measuring lights extracted through said optical filters; an photoelectric converter for converting said reference and measuring lights incident from said object to electrical signals; a temperature detector for detecting the temperature of said optical filters; a humidity detector for detecting the humidity of optical paths for said reference and measuring lights, extending from said optical system to said object; and water content-measuring circuit for finding the quantity of water contained in said object on the basis of output signals produced from said photoelectric converter, said temperature detector and said humidity detector, said water content-measuring circuit including: means for calculating a temperature correction factor from a linear equation involving as the variable a detected temperature given by the output signal from said temperature detector; means for calculating a humidity correction factor from a linear equation involving as the variable a detected humidity given by the output signal form said humidity detector; means for calculating the rate of the quantity of said measuring light absorbed in said object with respect to the quantity of said reference light absorbed in said object from a linear equation involving as the variable a value obtained by multiplying the ratio of the intensities of said reference and measuring lights indicated by the output signals from said photoelectric converter by said temperature and humidity correction factors; means for calculating the quantity of water contained in said object from a linear equation involving as the variable the absorbance of the measuring light calculated; and means for determining the equations for calculating said temperature and humidity correction factors, using the output signals from said temperature and humidity detectors which are obtained under the conditions where both the temperature of said optical filters and the humidity of said optical path are varied.