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post in: Health, Video Date:29 Sep 2017, 04:23 views:2191
Laser photo-acoustic spectrometer based on optical parametric oscillator for medical gas ysis is presented.
Designed spectrometer allows yzing the absorption spectra of the twenty gaseous biomarkers in real time in the spectral range from.5.7. The spectrometer capabilities for medical diagnostics of some bronchopulmonary diseases of different etiologies are demonstrated.
P hoto-acoustic spectroscopy (PAS) is one of the most intensively developing types of spectroscopy. The method is based on photo-acoustic phenomena primarily discovered. . Bell in 1880.
The effect consists in appearance of acoustic peribronchial waves when gas is undergone by electromagnetic radiation modulated at acoustic frequencies in the spectral range from UV to IR and corresponding to the absorption bands of the gas. Application of photo-acoustic effect for ysis of gas mixtures is simple and reliable.
Also it possesses high selectivity and allows obtaining results in real-time.
Beside that the method has very large dynamic range for concentration sensitivity. This makes possible detection of gases in concentrations differing in tens of thousand times in one sample. It was found in first experiments on studying photo-acoustic effect that photo-acoustic signal amplification can be caused by acoustic resonance phenomena.
Different variants of photo-acoustic cell design were developed. And efficiency of this method was demonstrated with use of them.
But due to absence of convenient components like light sources, microphones and electronic PA phenomena was forgotten for more than a half of a century. Only in 1938. .
Viengerov suggested PA system based on "black body" radiation source and microphone for gas mixture ysis.
In 1960th an important result was obtained when a laser was used as a radiations source for PA gas ysis.