Highly sensitive cantilever-enhanced photoacoustic detection of hydrogen cyanide and methane in the mid-infrared region is demonstrated. A mid-infrared continuous-wave frequency tunable optical parametric oscillator was used as a light source in the experimental setup. Noise equivalent detection limits of 190 ppt (1 s) and 65 ppt (30 s) were achieved for HCN and CH4, respectively. The normalized noise equivalent absorption coefficient is 1.8 × 10−9 W cm−1 Hz−1/2.
- parametric oscillators
- laser sensors