Fig. 1. Structure block diagram of four-light coherent mixing detection system

Fig. 2. Variation curves of frequency of four-light coherent mixing signal with movement speed

Fig. 3. Schematic diagram of receiving plane beam relationship in four-light coherent mixing

Fig. 4. Variation curves of the SNR of the four-light coherent mixing system with the local light radius. (a) ρ_s1=5D; (b) ρ_s1=2D; (c) ρ_s1=D; (d) ρ_s1=0.5D

Fig. 5. SNRs corresponding to different mismatch angles

Fig. 6. Variation curves of SNR with mismatch angle under different receiving apertures. (a) ρ_s1=1 m; (b) ρ_s1=0.2 m