Fig. 1. (a) Schematic diagram of a typical laser-based interception velocimetry setup; (b) Configuration of a single-source multi-channel terahertz interception velocimetry system

Fig. 2. Variation of terahertz beam radius with propagation distance

Fig. 3. Numerical simulation of detector voltage response as a function of target parameters

Fig. 4. Interrupted-zone velocimetry simulation. (a) Voltage response of 1×21 linear array detector to moving targets; (b) Poisson spot extraction from channels 1 and 21

Fig. 5. (a) Diagram of experimental system link; (b) Diagram of experimental system setup

Fig. 6. Terahertz beam propagation in free space. (a) Radial plane light intensity distribution at Z₂=1 m; (b) Formula fitting for beam radius and peak light intensity

Fig. 7. Simulation of linear array interception velocimetry. (a) Data acquisition: Response voltage of a 50-pixel linear array monitoring the target passage; (b) Signal preprocessing: Extraction and filtering of single-pixel response voltage curves; (c) Poisson point extraction: Identification of minimum-value interval S and calculation of Poisson point timing; (d) Velocity fitting: Linear regression of pixel positions versus Poisson point timing to derive slope-based velocity