Atmospheric Measurements by Ultra-Light SpEctrometer (AMULSE) Dedicated to Vertical Profile in Situ Measurements of Carbon Dioxide (CO₂) Under Weather Balloons: Instrumental Development and Field Application

Compact, spherical mirror-based dense astigmatic-like pattern multipass cell design aided by a genetic algorithm

We propose a unique way to design multipass cells (MPCs), which combines cost-efficient spherical mirrors with the high-density pattern of astigmatic mirrors. Such functionality was accomplished using at least three standard spherical mirrors appropriately tilted, which breaks the parallelism between them. A genetic algorithm (GA) supported the cell configuration optimization. A 16 m and 23.8 m optical path length (OPL) MPC was developed, practically realized, and proved by a time-of-flight (TOF) experiment to demonstrate the principle. Finally, CO₂ detection at 2004nm obtaining 0.4 ppmv limit of detection (LOD) using wavelength modulation spectroscopy (WMS) with 10 s averaging was performed.

Laser-Based Monitoring of CH₄, CO₂, NH₃, and H₂S in Animal Farming-System Characterization and Initial Demonstration

In this paper, we present a system for sequential detection of multiple gases using laser-based wavelength modulation spectroscopy (WMS) method combined with a Herriot-type multi-pass cell. Concentration of hydrogen sulfide (H₂S), methane (CH₄), carbon dioxide (CO₂), and ammonia (NH₃) are retrieved using three distributed feedback laser diodes operating at 1574.5 nm (H₂S and CO₂), 1651 nm (CH₄), and 1531 nm (NH₃). Careful adjustment of system parameters allows for H₂S sensing at single parts-per-million by volume (ppmv) level with strongly reduced interference from adjacent CO₂ transitions even at atmospheric pressure. System characterization in laboratory conditions is presented and the results from initial tests in real-world application are demonstrated.