Trace gas measurement has a wide range of applications needed in industrial, medical, and environmental protection. With the evolution of time, the demand for real-time, sensitivity, and accuracy of gas detection has been increasingly heightened. Off-axis integrated cavity output spectroscopy (OA-ICOS) is an effective method for the high-sensitivity detection of trace gases. It uses an integrated cavity with two highly reflective mirrors to provide a long optical path, which guarantees its high sensitivity. However, as the reflectivity of the mirrors increases, the intensity of the output light decreases, and the signal-to-noise ratio decreases. This contradiction makes it difficult to achieve a long optical path and a high signal-to-noise ratio together. To combat this issue, this paper proposes a type of integrated cavity using a direct-injection method. This structure, under equivalent mirror conditions, can maintain an effective absorption optical path very close to the original off-axis integrated cavity while increasing the output light intensity hundreds of times. This enhancement increases the sensitivity of OA-ICOS.

The hyperspectral full-waveform LiDAR (HSL) system based on the supercontinuum laser can obtain spatial and spectral information of the target synchronously and outperform traditional LiDAR or imaging spectrometers in target classification and other applications. However, low detection efficiency caused by the detection of useless background points (ULBG) hinders its practical applications, especially when the target is small compared with the large field of view (FOV) of the HSL system. A novel vision-aided hyperspectral full-waveform LiDAR system (V-HSL) was proposed to solve the problem and improve detection efficiency. First, we established the framework and developed preliminary algorithms for the V-HSL system. Next, we experimentally compared the performance of the V-HSL system with the HSL system. The results revealed that the proposed V-HSL system could reduce the detection of ULBG points and improve detection efficiency with enhanced detection performance. The V-HSL system is a promising development direction, and the study results will help researchers and engineers develop and optimize their design of the HSL system and ensure high detection efficiency of spatial and spectral information of the target.