| 摘要 |
<p>PURPOSE:To make it possible to trace an accurate and highly sensitive isotope ratio by using a compact, highly reliable semiconductor laser in a near infrared region as a variable wavelength light source, and measuring the spectrums of a plurality of isotopes having the same vibration and wave number in rotating mode. CONSTITUTION:The isotope ratio of a body under test wherein a plurality of isotopes are mixed is detected based on the intensity ratio of light absorbing spectrums. At this time, the light having the wavelengths of spectrums which are absorbed with a plurality of the isotopes at the same vibration and rotating state is emitted form a semiconductor laser 10 in a near infrared region. The laser 10 undergoes frequency modulation with an oscillator 13 as a frequency modulating means. A photodetector 16 detects the laser light which has passed through the body under test, wherein a plurality of the isotopes are missed, in a sample cell 2 from the laser 10. In a lock-in amplifier 19, the modulating frequency from the oscillator 13 is matched with the signal frequency of the laser light detected in the photodetector 16, and the matching is detected. The intensity ratio of the light absorbing spectrum of the material under test is detected based on the signal having the matching property.</p> |
