Optics: measuring and testing – For light transmission or absorption
Reexamination Certificate
1998-07-07
2001-03-13
Pham, Hoa Q. (Department: 2877)
Optics: measuring and testing
For light transmission or absorption
C356S436000, C356S039000
Reexamination Certificate
active
06201606
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method and an apparatus for processing a spectrum of transmitted light or reflected light obtained by projecting light on an object to be measured by spectral measurement.
BACKGROUND ART
Noise exists in an energy spectrum obtained in spectral measurement irrespective of the measured energy value. For a wavelength where the energy level is relatively close to noise due to the optical characteristics of a light source, the sensitivity characteristics of a detector, a high absorption of an object to be measured, or the like, the noise is greatly amplified when the energy spectrum is converted into an absorbance spectrum. As a result, the noise becomes greater than the original absorption information, causing the inconvenience of failing to provide a correct quantitative analysis.
The existence of noise greater than the original absorption information is also inconvenient for the processing of the absorbance spectrum. The reason is that the large amount of noise makes it impossible to use an automatic axial alignment function, for example, which is inconvenient.
In multivariate analysis, measured values for multiple wavelengths are used for calculation. In such calculation, also, the existence of large amounts of noise is inconvenient. The reason is that the large amounts of noise makes it impossible to perform correct quantitative analysis.
Conventionally, in spectral measurement, a multi-scanning averaging method and a moving average smoothing method are known as methods for reducing noise included in a spectrum. Quantitative analysis is not conventionally available for a wavelength having an excessively large amount of noise.
In spectral measurement, noise included in an energy spectrum is substantially constant irrespective of the energy value. However, noise included in an absorbance spectrum becomes greater as the original energy level becomes smaller.
In the multi-scanning averaging method, it takes a considerably long time to obtain absorption information. Moreover, the level of noise reduction is limited.
In the moving average smoothing method, it is impossible to reduce noise greater than the original absorption information. Moreover, there is even a possibility of deleting absorption information in a wavelength range where noise is small.
The object of the present invention is to provide a method and an apparatus capable of reducing noise included in an absorbance spectrum in spectral measurement.
SUMMARY OF THE INVENTION
The method of the present invention is a method for processing a spectrum in spectral measurement, including the steps of: measuring an energy spectrum of light for measurement from an object to be measured; adding a predetermined value to the energy spectrum of the light for measurement; and obtaining an absorbance spectrum with reduced noise by effecting absorbance conversion of the energy spectrum of the light for measurement with the addition of the predetermined value, whereby the above object is attained.
The predetermined value may be variable for a wavelength range of the energy spectrum of the light for measurement.
The method may further include the step of conducting quantitative analysis of a component contained in the object to be measured based on the absorbance spectrum with reduced noise.
The quantitative analysis may be conducted based on a multivariate analysis method.
The apparatus of the present invention is an apparatus for processing a spectrum in spectral measurement, including: a measurement section for measuring an energy spectrum of light for measurement from an object to be measured; an addition section for adding a predetermined value to the energy spectrum of the light for measurement; and a conversion section for obtaining an absorbance spectrum with reduced noise by effecting absorbance conversion of the energy spectrum of the light for measurement with the addition of the predetermined value, whereby the above object is attained.
The predetermined value may be variable for a wavelength range of the energy spectrum of the light for measurement.
The apparatus may further include a quantitative analysis section for conducting quantitative analysis of a component contained in the object to be measured based on the absorbance spectrum with reduced noise.
The quantitative analysis may be conducted based on a multivariate analysis method.
Hereinbelow, the function will be described.
According to the present invention, an absorbance spectrum with reduced noise can be obtained by adding a predetermined value or a predetermined spectrum to the energy spectrum of light for measurement and converting the energy spectrum of the light for measurement with the addition of the predetermined value or the predetermined spectrum into the absorbance spectrum.
The precision of quantitative analysis can be improved by conducting the quantitative analysis using the absorbance spectrum with reduced noise.
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Kyoto Dai-ichi Kagaku Co. Ltd.
Pham Hoa Q.
Sterne Kessler Goldstein & Fox PLLC
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