Cantilever enhanced photoacoustic detection of carbon dioxide using a tunable diode laser source

摘要

Recently introduced cantilever enhanced photoacoustic sensing has been applied to the tunable diode laser-based trace gas detection. The pressure variations due to the photoacoustic signal are detected with a miniature silicon cantilever, whose displacement is measured with a compact Michelson type laser interferometer. The system has been used to detect carbon dioxide (CO_2) at 1572 nm with a distributed feedback diode laser. With a new photoacoustic cell, that was optimized for the laser sources, a normalized noise equivalent sensitivity of 1.7 × 10~(-10) cm~(-1) W/(Hz)~(1/2) at atmospheric pressure was realized. The result obtained in the non-resonant operation mode is at least.10 times better than in previous reports. The future improvements of the technique are also discussed.