초록 ▼

In a spectrophotometer for measuring the concentration of a specific substance, a pulsating (modulated) source of radiation gives rise to an alternating current component, a direct current component and a dark signal component in a measurement signal. The response time for changes in the concentrati

In a spectrophotometer for measuring the concentration of a specific substance, a pulsating (modulated) source of radiation gives rise to an alternating current component, a direct current component and a dark signal component in a measurement signal. The response time for changes in the concentration of the specific substance is reduced while the measurement signal\s signal-to-noise ratio is simultaneously improved when the pulsation frequency is from 50 to 1000 Hz, and the direct current component in the measurement signal is filtered out for normalization by a reference signal in a signal analyzer so the concentration of the specific substance can be calculated.

대표청구항 ▼

A spectrophotometric method for determining the concentration of a substance, comprising the steps of: directing radiation having a selected degree of intensity modulation through a substance whose concentration is to be determined, said radiation including radiation at a wavelength absorbed by said

A spectrophotometric method for determining the concentration of a substance, comprising the steps of: directing radiation having a selected degree of intensity modulation through a substance whose concentration is to be determined, said radiation including radiation at a wavelength absorbed by said substance and other radiation; detecting said radiation, after passing through said substance, at said wavelength absorbed by said substance with a first detector and generating a measurement signal corresponding thereto; detecting said other radiation after passing through said substance with a second detector and generating a reference signal corresponding thereto, each of said measurement signal and said reference signal consisting of a dark signal component corresponding to respective signals generated by said detectors with no radiation incident thereon, a direct current component and an alternating current component corresponding to respective signals generated by said detectors when said modulated radiation is incident thereon, said alternating current component and said direct current component having a ratio which is independent of the concentration of said substance and which is known from said degree of intensity modulation; filtering out said alternating current component from said measurement signal; determining said direct current component of said measurement signal from the filtered-out alternating current component and said known ratio; normalizing said direct current component of said measurement signal with said reference signal; and determining the concentration of said substance from the normalized direct current component.