| abstract |
A system for detecting volatile components in a vapor, e.g., alcohol, in the breath of a human subject. A ray of frequencymodulated and collimated light of suitable near infrared wavelength from a source such as a laser or a quartz-halogen lamp, collimated with quartz lenses and appropriate optical interference filters passes through the vapor sample via a path of fixed length and free from light losses except those caused by the volatile components being detected, and strikes a radiant energy detector, setting up an electrical signal which is amplified, electronically processed, filtered, and displayed. The concentration of alcohol or other test vapor affects the amount of energy able to pass through the sample to the detector. The detector determines the energy absorbed by the sample and transmits the result to a readout device, meter, or permanent recording means. The sample can be collected by taking an alveolar (deep lung) sample of the subject''s breath. The system determines, through Henry''s law, the blood content of alcohol, ketones, aldehydes, various anesthesias and the like. This system is also applicable to determine combustible gases, for example, in coal mines. |