Ultra-high sensitive photoacoustic gas detector based on differential multi-pass cell

Multi-mechanism collaboration enhanced photoacoustic analyzer for trace H2S detection

“…When the gas to be measured is excited, part of the photons will be absorbed and transition to a high-energy state. The non-radiative transition of gas molecules releases part of the absorbed light energy in the form of heat [11] . When the excitation source is modulated, periodic thermal expansion of the gas produces photoacoustic signals [12] , [13] .…”

Multi-pass Differential Photoacoustic Sensor for Real-Time Measurement of SF6Decomposition Component H2S at the ppb Level

“…The two PA signals in the differential photoacoustic cell (DPAC) are processed differentially, doubling the amplitude of the perceived signal and effectively eliminating the flow noise. , In the field of dynamic monitoring, the DPAC improves the detection accuracy and real-time performance of the sensing device from the perspective of acoustic resonance enhancement. In 2017, Yin et al achieved an MDL of 109 ppb for H 2 S in the SF 6 background gas using a DPAC and a DFB laser with the central wavelength of 1582 nm .…”

Flexible Hollow Core Fiber Photoacoustic Gas Sensor Based on Embedded Acoustic Resonant Structure

“…Nevertheless, the design of metallic resonant PA cells might be faced with some difficulties. For example, the transmitted light beams should avoid being reflected by the cell wall, of which the reflectivity is relatively low. − The inner diameter of metallic resonant PA cells is usually more than 6 mm consequently. However, the amplitude of the PA pressure signal is inversely proportional to the inner diameter of the large core PA cell .…”