The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 27, 1999
Filed:
Mar. 27, 1997
Yoji Higashi, Higashiyamato, JP;
Japan Radio Co., Ltd., Tokyo, JP;
Abstract
The light absorption spectrum of carbon isotopes .sup.12 CO.sub.2 and .sup.13 CO.sub.2 is measured highly accurately within a short period of time to determine a carbon isotopic abundance ratio highly accurately and reliably. Laser light emitted from a laser diode, which has been slightly modulated with a frequency f and swept in wavelength, passes through a specimen cell and is applied to a photodetector, which produces an electric signal converted from the detected laser light. 2f components of .sup.12 CO.sub.2 and .sup.13 CO.sub.2 of the light absorption spectrum are detected by a lock-in amplifier, and 3f components of .sup.12 CO.sub.2 and .sup.13 CO.sub.2 of the light absorption spectrum are detected by a lock-in amplifier. Spectral intensities of .sup.12 CO.sub.2 and .sup.13 CO.sub.2, which correspond to zero-cross points of the 3f components, are determined from peak values at three points of each of the 2f components, and a carbon isotopic abundance ratio of .sup.12 CO.sub.2 and .sup.13 CO.sub.2 is determined from a ratio of the spectral intensities.