Fig. 1. Schematic of intensity distribution characteristics of Gaussian beam propagation

Fig. 2. Schematic of spatial positions of initial propagation surface and target plane

Fig. 3. Schematic of laser propagation area classification

Fig. 4. Schematic of light-field distribution at target plane

Fig. 5. Schematic of a new set of light-field distribution at target plane

Fig. 6. Schematic of optical path for beam quality measurement by non-equidistant and bidirectional propagation

Fig. 7. Diagrams of light-field information at initial plane. (a) Intensity information; (b) phase information

Fig. 8. Fitting maps of laser propagation profile curves. (a) Initial propagation curve; (b) second propagation curve; (c) third propagation curve; (d) final propagation curve

Fig. 9. Fitting maps of laser propagation profile curves with different scaling factors of propagation step. (a) ε=1.2; (b) ε=1.3; (c) ε=1.4; (d) ε=1.5; (e) ε=1.6; (f) ε=2.0