# Algorithm for the Simultaneous Measurement of Multiple Parameters Based on Wavelength Modulation Spectroscopy

## TL;DR

This paper introduces a new algorithm using laser spectroscopy to simultaneously measure gas concentrations, temperature, and pressure in confined spaces, improving safety monitoring.

## Contribution

A novel multi-parameter inversion algorithm integrating L-M fitting and spectral separation for accurate TDLAS-based monitoring in confined spaces.

## Key findings

- Simultaneous inversion of H2O, CO2, CO, and O2 concentrations, temperature, and pressure was successfully achieved.
- Simulation results showed the algorithm's measurement accuracy meets practical requirements for confined space monitoring.

## Abstract

To ensure personnel safety and prevent serious accidents, it is crucial to monitor parameters such as temperature, pressure, and gas composition concentrations in confined spaces. This study proposes a multi-parameter simultaneous inversion algorithm based on tunable diode laser absorption spectroscopy (TDLAS). The algorithm integrates the Levenberg–Marquardt (L-M) fitting method, single-line thermometry and manometry methods, spectral separation, and alternating iteration techniques, with an adaptive feedback mechanism adding to enhance convergence stability. Through this approach, simultaneous inversion of H2O, CO2, CO, and O2 concentrations, temperature, and pressure was successfully achieved. Simulation results demonstrated that the measurement accuracy meets practical requirements. This study provides an effective monitoring method for multi-parameter detection in confined spaces within conventional environments and lays a foundation for expanding the application scope of TDLAS technology.