To reduce the influences of laser power variation, laser focus position shift and quartz tuning fork (QTF) resonant frequency shift, and improve the robustness of light-induced thermoelastic spectroscopy (LITES) sensor system, a self-correlated heterodyne-based light-induced thermoelastic spectroscopy (SC-HLITES) was proposed for near-infrared methane (CH₄) sensing by exploring the correlations in the time-domain heterodyne response of the QTF. The first correlation between the HLITES signal and the baseline signal was investigated, and a normalized HLITES signal was used to correct measurement errors caused by laser power variation and focus position shift. Also, the correlation between the normalized HLITES signal and frequency offset was utilized to compensate for the measurement error by QTF resonant frequency shift. The SC-HLITES technique shows a minimum detectable normalized noise equivalent absorption (NNEA) coefficient of 5.37 × 10⁻¹⁰ cm⁻¹ WHz^−1/2 with a 1 ms integration time in CH₄ measurement. The enhancement in the robustness of the SC-HLITES sensor system was experimentally confirmed under the influences of the above three factors. In addition to a similar level in detection sensitivity with other reported QTF-based sensors, the proposed two correlations and measurement correction scheme enable good stability of a LITES sensor system in field applications.

为了减少激光功率变化、激光焦点位置偏移和石英音叉 (QTF) 共振频率偏移的影响，并提高光致热弹性光谱 (LITES) 传感器系统的鲁棒性，一种基于自相关外差的光致提出了用于近红外甲烷（CH ₄) 通过探索 QTF 的时域外差响应中的相关性来感知。研究了HLITES信号与基线信号之间的第一个相关性，并使用归一化的HLITES信号来校正由激光功率变化和焦点位置偏移引起的测量误差。此外，归一化 HLITES 信号和频率偏移之间的相关性被用来补偿 QTF 谐振频移引起的测量误差。SC-HLITES 技术显示最小可检测归一化噪声等效吸收 (NNEA) 系数为 5.37 × 10 ^-10 cm ^-1 WH ^{-1/2 ，在 CH} ₄中积分时间为 1 ms测量。在上述三个因素的影响下，实验证实了 SC-HLITES 传感器系统鲁棒性的增强。除了与其他报告的基于 QTF 的传感器具有相似水平的检测灵敏度外，所提出的两种相关性和测量校正方案使 LITES 传感器系统在现场应用中具有良好的稳定性。