Simultaneous Detection of Major Greenhouse Gases with Multiresonator Photoacoustic Spectroscopy.

Greenhouse gas (GHG) detection plays an important role in climate change research and industry applications. A novel photoacoustic spectroscopy (PAS) sensor based on multiple resonators has been developed for the detection of GHGs. The major GHGs CO, CH, and NO were measured simultaneously using only one acoustic sensor by coupling three acoustic resonators into a photoacoustic cell.

Neural Network Based Aliasing Spectral Decoupling Algorithm for Precise Mid-Infrared Multicomponent Gases Sensing.

Owing to the overlapping and cross-interference of absorption lines in multicomponent gases, the simultaneous measurement of such gases via laser absorption spectroscopy frequently necessitates the use of supplementary pressure sensors to distinguish the spectral lines. Alternatively, it requires multiple lasers combined with time-division multiplexing to independently scan the absorption peaks of each gas, thereby preventing interference from other gases. This inevitably escalates both the cost of the system and the complexity of the gas pathway.

Pressure sensing with two-color laser absorption spectroscopy for combustion diagnostics.

Pressure is an important parameter in assessing combustion performance that is typically measured using contact sensors. However, contact sensors usually disturb combustion flows and suffer from the temperature tolerance limit of sensor materials. In this Letter, an innovative noncontact two-color pressure sensing method based on tunable diode laser absorption spectroscopy (TDLAS) is proposed.

Portable TDLAS Sensor for Online Monitoring of CO and HO Using a Miniaturized Multi-Pass Cell.

We designed a tunable diode laser absorption spectroscopy (TDLAS) sensor for the online monitoring of CO and HO concentrations. It comprised a small self-design multi-pass cell, home-made laser drive circuits, and a data acquisition circuit. The optical and electrical parts and the gas circuit were integrated into a portable carrying case (height = 134 mm, length = 388 mm, and width = 290 mm).

Double-enhanced multipass cell-based wavelength modulation spectroscopy CH sensor for ecological applications.

A novel CH sensor based on wavelength modulation spectroscopy with a multipass cell was developed for the soil respiration measurement of CH. A home-made double-enhanced Herriot-type multipass cell with an effective absorption length of 73.926 m and a fiber-coupled distributed feedback diode laser emission at 1653.

Open-path anti-pollution multi-pass cell-based TDLAS sensor for the online measurement of atmospheric HO and CO fluxes.

We report an open-path and anti-pollution multi-pass cell based tunable diode laser absorption spectroscopy (TDLAS) sensor, which was designed for online measurement of atmospheric HO and CO fluxes. It is mainly composed of two plano-convex mirrors coated on a convex surface, which makes it different from traditional multi-pass cells. This design does not allow a direct contact between the coating layer of the lens and air, thereby realizing the anti-pollution effect of the coating layer.

Simultaneous Sensitive Determination of C, O, and O in Human Breath CO Based on ICL Direct Absorption Spectroscopy.

Previous research revealed that isotopes C and O of exhaled CO have the potential link with ; however, the O isotope has received very little attention. We developed a sensitive spectroscopic sensor for simultaneous C, O, and O analysis of human breath CO based on mid-infrared laser direct absorption spectroscopy with an interband cascade laser (ICL) at 4.33 μm.

A Dual-Laser Sensor Based on Off-Axis Integrated Cavity Output Spectroscopy and Time-Division Multiplexing Method.

In this article, a compact dual-laser sensor based on an off-axis integrated-cavity output spectroscopy and time-division multiplexing method is reported. A complete dual-channel optical structure is developed and integrated on an optical cavity, which allows two distributed feedback (DFB) lasers operating at wavelengths of 1603 nm and 1651 nm to measure the concentration of CO and CH, simultaneously. Performances of the dual-laser sensor are experimentally evaluated by using standard air (with a mixture of CO and CH).

Laser frequency locking and intensity normalization in wavelength modulation spectroscopy for sensitive gas sensing.

A novel method for laser frequency locking and intensity normalization in wavelength modulation spectroscopy (WMS)-based gas sensor system is reported. The center spacing between two second harmonic peaks demodulated from the rising and falling edges of a scanning triangular wave (for wavelength scan) is employed as a frequency locking reference. Amplitude of the directly acquired sine signal (for wavelength modulation) in the spectral region far away from the absorption feature is employed as an intensity normalization reference.

Dual-Gas Sensor of CH₄/C₂H₆ Based on Wavelength Modulation Spectroscopy Coupled to a Home-Made Compact Dense-Pattern Multipass Cell.

A sensitive dual-gas sensor for the detection of CH₄ and C₂H₆ is demonstrated. Two tunable semiconductor lasers operating at 1.653 μm (for CH₄ monitoring) and 1.