To provide a concentration measuring method with which the concentration of a predetermined chemical component can be accurately, quickly, and nondestructively measured down to a concentration range of an extremely small amount with a simple means, and to provide a concentration measuring method with which the concentration of a chemical component in an object to be measured can be accurately and quickly measured down to a concentration range of a nano-order extremely small amount in real time, the method having universality, i.e., the ability to be embodied in various forms and modes. Light having a first wavelength and light having a second wavelength, which have different light absorptances with respect to an object to be measured, are each radiated onto the object to be measured using a time-sharing method; the light having the first wavelength and the light having the second wavelength, optically passing through the object to be measured as a result of the irradiation with the light having the first and second wavelengths, are received with a common light receiving sensor; a differential signal between a signal related to the light having the first wavelength and a signal related to the light having the second wavelength to be output from the light receiving sensor according to the received light is formed; and the concentration of a chemical component in the object to be measured is derived on the basis of the differential signal.

A concentration measurement method accurately, quickly, and non-destructively measures the concentration of a predetermined chemical component within an object to a nano-order trace concentration level in real time. A time sharing method irradiates the object light of a first wavelength and light of a second wavelength having different light absorption rates with respect to the object to be measured. Light of both wavelengths that arrives optically through the object is received by a shared light reception sensor, and signals respectively relating to light of the first and second wavelengths are output from the light reception sensor in accordance with the received light. A differential signal of these signals is formed, and the concentration of a chemical component in the object to be measured is derived on the basis of the differential signal.

To provide a concentration measuring method with which the concentration of a predetermined chemical component can be accurately, quickly, and nondestructively measured down to a concentration range of an extremely small amount with a simple means, and to provide a concentration measuring method with which the concentration of a chemical component in an object to be measured can be accurately and quickly measured down to a concentration range of a nano-order extremely small amount in real time, the method having universality, i.e., the ability to be embodied in various forms and modes. Light having a first wavelength and light having a second wavelength, which have different light absorptances with respect to an object to be measured, are each radiated onto the object to be measured using a time-sharing method; the light having the first wavelength and the light having the second wavelength, optically passing through the object to be measured as a result of the irradiation with the light having the first and second wavelengths, are received with a common light receiving sensor; a differential signal between a signal related to the light having the first wavelength and a signal related to the light having the second wavelength to be output from the light receiving sensor according to the received light is formed; and the concentration of a chemical component in the object to be measured is derived on the basis of the differential signal.

NDIR is used to determine a concentration of a chosen molecule M in a liquid sample which contains one or more interfering molecules M.sub.J which absorb radiation at the signal wavelength used in the NDIR process by addition of an interference source. M is calculated by electronics which use R.sub.ave(t) from a pulsed signal and reference channel output and a calibration curve which is validated by use of R.sub.Jave(t.sub.2) from a pulsed interference and reference channel output. Signal, interference and reference sources are pulsed at a frequency which is sufficiently fast so that a given molecule of M or M.sub.J will not pass in and out of the liquid sampling matrix within the pulsing frequency.

A concentration of glucose in a blood sample is determined through use of a signal channel output/reference channel ratio obtained by use of an NDIR absorption technique in which scattering noise attributable to the liquid phase is reduced by alternately and successively pulsing infrared radiation from signal and reference sources which are multiplexed and collimated into a pulsed beam directed through the sample space containing the liquid phase and the pulse frequency is sufficiently fast so that a given molecule of glucose will not pass in and out of the sample space within the pulse frequency.

A composition sensor for measuring composition of fluid mixtures is presented. The composition sensor includes a plurality of high-brightness emission sources having respective spectrally narrow wavelength emission bands in the infrared region. The wavelength emission bands overlap absorption wavelength bands of the composition. The wavelength emission bands are wavelength multiplexed and time multiplexed prior to emission through a fluid mixture. A single optical detector senses the emitted light. The composition sensor includes arms that can rotate to measure composition at different angular position of a pipe in a lateral section of an oil well. Rotation of the arms is provided by rotation of an element of a mobile vessel to which the arm is rigidly coupled. The rotation of the arms is provided by a rotation of a nose of the mobile vessel that rotates independently from a main body of the mobile vessel.

A concentration of a chosen molecule in a liquid phase in a sample space is determined through use of a signal channel output/reference channel ratio obtained by use of an NDIR absorption technique in which scattering noise attributable to the liquid phase is reduced by alternately and successively pulsing infrared radiation from signal and reference sources which are multiplexed and collimated into a pulsed beam directed through the sample space containing the liquid phase and the pulse frequency is sufficiently fast so that a given molecule of the chosen molecule will not pass in and out of the sample space within the pulse frequency.