# Research on High Performance Methane Gas Concentration Sensor Based on Pyramid Beam Splitter Matrix

## TL;DR

This paper presents a high-performance methane gas sensor using a pyramid beam splitter matrix to improve accuracy and reliability in harsh environments.

## Contribution

A novel optical path design using a pyramid beam splitter matrix for enhanced methane detection.

## Key findings

- The sensor achieves a reliability level of 0.01 ppm at the lower explosive limit of methane.
- It maintains ppm-level detection under extreme conditions like high humidity and dust.
- The sensor enables full-range methane measurement with improved sensitivity and robustness.

## Abstract

Methane gas concentration detection faces the challenges of increasing accuracy and sensitivity, as well as high reliability in harsh environments. The special design of the optical path structure of the sensitive element provides an opportunity to improve methane gas concentration detection. In this study, the optical path structure of the sensitive element was newly designed based on the Pyramidal beam splitter matrix. The infrared light source was modulated by multi-frequency point-signal superimposed modulation technology. At the same time, concentration detection results and confidence levels were calculated using the four-channel methane gas concentration detection algorithm based on spectral refinement. Through the experiment, it was found that the sensor enables the full-range measurement of CH4; at the lower explosive limit (LEL, CH4 LEL of 5%), the reliability level is 0.01 parts-per-million (PPM), and the limit of detection is 0.5 ppm. The sensor is still capable of achieving PPM-level detections under extreme conditions in which the sensor’s optical window is covered by two-thirds and humidity is 85% or dust concentration is 100 mg/m3. Those improve the sensitivity, robustness, reliability, and accuracy of the sensor.