[10a-A33-1~13] 3.7 Optical measurement, instrumentation, and sensor

10:00 AM - 10:15 AM JST(1:00 AM - 1:15 AM UTC)Presentation by Applicant for JSAP Young Scientists Presentation Award

[10a-A33-5] ppb-Level Sensing by 3-μm-Band Mid-Infrared Absorption Spectroscopy with Simultaneous Reference Measurement

〇(M2)Luxiang Wang¹, Tsubasa Endo¹, Kotaro Nakagawa¹, Katsunori Danno², Kenji Yoshida², Osamu Komeda², Hiroaki Saito², Yohei Kobayashi¹ (1.ISSP, Univ. Tokyo, 2.Toyota Motor Corp.)

Keywords:

Mid-infrared spectroscopy,Breath diagnosis,Simultaneous reference measurement

Mid-infrared spectroscopy in the fingerprint region is promising for real-time breath monitoring. We extended our cross-dispersed mid-infrared spectroscopy system using an ultra-high-order Ge immersion grating (EGIG) to trace component measurement in gas mixtures containing water vapor for breath diagnosis. Overlapping absorption lines of coexisting H₂O limit accuracy in trace CH₄ estimation based on single peaks. To resolve this, we performed simultaneous H₂O/CH₄ fitting based on the HITRAN database using the broadband, high-resolution spectrum from the EGIG, separating close absorption features. Simultaneous measurement of signal and reference beams compensated for common noise from source fluctuations and environmental changes. Consequently, a 6-ppb detection sensitivity was achieved for trace CH₄ in air at atmospheric pressure with an integration time of 0.3 s, demonstrating ppb-level methane evaluation in humid mixtures.