Standoff LITES Sensor Based on a Frequency‐Stabilized Encased Quartz Tuning Fork

ABSTRACT We propose and demonstrate a standoff light‐induced thermoelastic spectroscopy (standoff‐LITES) sensor for the first time. An encased quartz tuning fork (QTF) was employed in the standoff‐LITES sensor to improve the frequency stability. The QTF operating temperature was optimized to be ∼0°C. A distributed feedback (DFB) interband cascade laser (ICL) emitting at 3.27 µm was employed, whose emission wavenumber range of 3056.8–3058.1 cm −1 covers the absorption lines of water (H 2 O) and methane (CH 4 ). For the standoff gas sensing concept demonstration, the sensor employed an off‐axis parabolic mirror and a cooperative target positioned 5 m away from the mirror, creating a 10‐meter absorption path. The…

• NN
  National Natural Science Foundation of China

  Awards: 62405078, 62275065, 62335006, 62505066, 624B2050, 62022032
• CP
  China Postdoctoral Science Foundation

  Award: 2024M764172
• NS
  Natural Science Foundation of Heilongjiang Province

  Awards: LBH-Z23144, LH2024F031, 62022032
• HP
  Heilongjiang Provincial Postdoctoral Science Foundation

  Awards: LBH‐Z24155, LBH‐Z23144
• FR
  Fundamental Research Funds for the Central Universities

  Awards: HIT.NSFJG202463, 62022032