Ppm-level photoacoustic oxygen gas sensor with a 3W red diode laser

Oxygen (O₂) detection is of vital importance for life safety, medical monitoring, environmental monitoring, and industrial process control. It is a key technical support for preventing asphyxiation, assessing ecological health, and ensuring production safety. However, the existing O₂ sensors are unable to perform real-time online detection and highly sensitive detection. A trace laser photoacoustic gas sensor based on red light diode laser was developed for ppm-level O₂ sensing. This sensor utilizes resonant photoacoustic spectroscopy technology, combined with a high-sensitivity microphone and light power intensity modulation technology, to achieve highly selective and low-concentration detection of specific target gases (O₂). The core of the system adopts a red light band semiconductor laser with a high output power of 3W as the excitation source, fully leveraging the advantage that the detection excitation laser power of photoacoustic spectroscopy is proportional to the detection sensitivity, effectively reducing the system cost and volume while maintaining excellent detection performance. Experiments show that the detection limit of this sensor for O₂ can reach the ppm (parts per million) level. The detection limit of photoacoustic spectroscopy is enhanced by replacing the long optical path with high-power laser excitation. It demonstrates broad application potential in non-invasive medical diagnosis of human breathing, environmental air monitoring, and industrial process safety control. This research provides an effective technical solution for the development of high-performance, low-cost, and portable trace gas analysis instruments.