Optical parametric oscillator-based photoacoustic detection of hydrogen cyanide for biomedical applications

A versatile, continuous wave, optical parametric oscillator is used in combination with photoacoustic spectroscopy for long-term trace gas experiments of volatile compounds emitted by biological samples. The optical parametric oscillator-based spectrometer (wavelength near 3 μm, 8-MHz linewidth, output power ∼1 W) is suc- cessfully tested for the detection of hydrogen cyanide (HCN) emission from clover leaves, and Pseudomonas bac- teria; in addition, the presence of HCN in exhaled human breath is measured. For specific experiments, the spectrometer is operated continuously up to 10 days and has a detection limit of 0.4 parts-per-billion volume of HCN in air over 10 s, using the P8 rotational line in the ν3 vibrational band of HCN at 3287.25 cm −1 . This results in an overall sensitivity of the system of 2.5 × 10 −9 cm −1 Hz −1∕2 . © 2013 Society of Photo-Optical Instrumentation