Measurement of formaldehyde H2CO concentration in air using diode vertical-cavity lasers

A two-channel gas-analysing spectrometer is developed using a vertical-cavity surface-emitting laser (VCSEL) (λ=1.79 μm) and a multi-pass cell (total optical length 39 m) for studying the absorption spectra and measuring the background concentration of formaldehyde. High-resolution absorption spectra of formaldehyde are obtained within the VCSEL frequency tuning range (λ~1.79 μm). Changing the background concentration of H₂CO, the sensitivity limit of the gas analyser is estimated.