Laser sensors

Researchers at

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have successfully used laser-based sensors to detect the presence of specific gases in concentrations in the range of parts per billion to (ppb) parts per trillion (ppt).

The Rice researchers’ method is based on Tunable Diode Laser Absorption Spectroscopy (TDLAS), which uses a semiconductor laser as the excitation light source for absorption spectroscopic measurement. Different types of molecule absorb light at different wavelengths, and the amount of light absorbed depends on the number of molecules in the light’s path. The device measures the change in the light intensity as it resonates with molecules’ absorption wavelengths.

Inside the laser, a Texas Instruments 32-bit TMS320F2812 DSP controller performs calibration, filtering and numeric processing to precisely detect these intensity changes in real time. A technician can then monitor the concentration of molecules encountered in a person’s breath or in the air to detect the presence of a particular gas.