Compact, Robust, and Single-Side Installable Tunable-Diode-Laser-Absorption-Spectroscopy Sensor for Real-Time Gas Diagnosis

This study presents design concepts and performance validation of a tunable diode laser absorption spectroscopy sensor considering compactness, easy installation, and robustness for real-time gas diagnosis in a harsh environment, including mechanical vibration and thermal load. Optical parts are designed to make the sensor compact and reliable for vibration and temperature increase. A triangular-spiral-shaped laser beam path is configured in the sensor for signal amplification and vibrational robustness. Signal postprocessing is designed not only to improve measurement accuracy but also to make the sensor output signal stable in vibration. To reduce sensor complexity, a single absorption line is utilized for gas diagnosis, and a real-time gas property measurement procedure analyzing a single absorption line is applied. The performance of the sensor is examined through three tests: a vibration test, a gas property measurement test, and a real-time gas analyzing test. The vibration test is performed to validate the sensor’s robustness in harsh environments. The gas property measurement test is conducted using a gas chamber generating air conditions with a pressure range and temperature range of 10–110 kPa and 300–500 K, respectively. A real-time gas analyzing test is performed to verify the sensor usability in a flow passage.