Wyniki wyszukiwania - BazTech

1

Ultrasensitive laser spectroscopy for breath analysis

Wojtas J., Bielecki Z., Stacewicz T., Mikołajczyk J., Nowakowski M.

Opto-Electronics Review

|

2012

|

Vol. 20, No. 1

26-39

EN

At present there are many reasons for seeking new methods and technologies that aim to develop new and more perfect sensors for different chemical compounds. However, the main reasons are safety ensuring and health care. In the paper, recent advances in the human breath analysis by the use of different techniques are presented. We have selected non-invasive ones ensuring detection of pathogenic changes at a molecular level. The presence of certain molecules in the human breath is used as an indicator of a specific disease. Thus, the analysis of the human breath is very useful for health monitoring. We have shown some examples of diseases' biomarkers and various methods capable of detecting them. Described methods have been divided into non-optical and optical methods. The former ones are the following: gas chromatography, flame ionization detection, mass spectrometry, ion mobility spectrometry, proton transfer reaction mass spectrometry, selected ion flow tube mass spectrometry. In recent twenty years, the optical methods have become more popular, especially the laser techniques. They have a great potential for detection and monitoring of the components in the gas phase. These methods are characterized by high sensitivity and good selectivity. The spectroscopic sensors provide the opportunity to detect specific gases and to measure their concentration either in a sampling place or a remote one. Multipass spectroscopy, cavity ring-down spectroscopy, and photo-acoustic spectroscopy were characterised in the paper as well.

2

Cavity ring down spectroscopy : detection of trace amounts of substance

Stacewicz T., Wojtas J., Bielecki Z., Nowakowski M., Mikołajczyk J., Mędrzycki R., Rutecka B.

Opto-Electronics Review

|

2012

|

Vol. 20, No. 1

53-60

EN

We describe several applications of cavity ring-down spectroscopy (CRDS) for trace matter detection. NO₂ sensor was constructed in our team using this technique and blue-violet lasers (395–440 nm). Its sensitivity is better than single ppb. CRDS at 627 nm was used for detection of NO₃. Successful monitoring of N₂O in air requires high precision mid-infrared spectroscopy. These sensors might be used for atmospheric purity monitoring as well as for explosives detection. Here, the spectroscopy on sharp vibronic molecular resonances is performed. Therefore the single mode lasers which can be tuned to selected molecular lines are used. Similarly, the spectroscopy at 936 nm was used for sensitive water vapour detection. The opportunity of construction of H₂O sensor reaching the sensitivity about 10 ppb is also discussed.

3

Blue laser diodes for trace matter detection

Holc K., Bielecki Z., Wojtas J., Perlin P., Goss J., Czyżewski A., Magryta P., Stacewicz T.

Optica Applicata

|

2010

|

Vol. 40, nr 3

641--651

EN

We present spectroscopic applications of GaN-based laser diodes (LDs), fabricated and developed at the Institute of High Pressure Physics and its spin-off company TopGaN. LDs were manufactured using MOCVD technology. For spectroscopic applications we applied pulsed operated lasers generating the radiation in 395–430 nm spectral range reaching the power of 200 mW within the light pulses of 30–150 ns at the repetition rates of 10 kHz. These LDs were successfully applied to the detection of nitrogen dioxide in free atmosphere using cavity ring down spectroscopy (CRDS) sensor. Cw operated lasers generating within the spectral range of 385–420 nm and reaching powers up to 300 mW were adapted for atomic spectroscopy. Using external cavity tuning with diffraction grating in Littrow configuration, we obtained the stability of single mode generation better than 100 MHz within the periods of 30 minutes without any additional frequency stabilization feedback.