Southwest Sciences Inc

Wavelength modulated photoacoustic spectrometer

U. S. patents 6,552,792, 6,608,683 and 6,618,148

Photoacoustic spectroscopy indirectly detects the absorption of light by measuring the sound wave that is produced when the light energy is converted to heat. This technique dates back to Thomas Edison. In conventional photoacoustic spectroscopy, the light beam is chopped on and off at an acoustic frequency, beacuse the sound wave is generated from time-varying heating of the sample. Southwest Sciences has explored the use of wavelength modulation with photoacoustic spectroscopy using rugged, low-cost diode lasers. The wavelength emitted by a diode laser can be tuned by changing the injection current. Because the sound wave is generated by the difference in absorption as the wavelength is tuned, the narrow spectral features of gases are efficiently detected. Broadband absorption by windows or walls of the cell, which can limit conventional photoacoustic detction, leads to constant heating and no photoacoustic signal.

These patents improve the signal to noise and stability of photoacoustic spectroscopy, by providing improved modulation waveforms and means to lock the modulation frequency to the acoustic resonance of the spectrometer.


Contact Information

Southwest Sciences, Inc.
1570 Pacheco St., Suite E-11, Santa Fe, NM 87505
tel. (505) 984-1322/ fax (505) 988-9230



[Home]   [Meet Our People]   [Products&Services]   [Research]   [Technology]   [Commercial Partnerships]   [News]  [Contact]