Fig. 1. Flow chart of the calculation process of beam quality parameters based on complex amplitude reconstructed

Fig. 2. Schematic diagram of optical path of large aperture off-axis beam quality measurement system

Fig. 3. Schematic diagrams of the off-axis collimator optical path. (a) Optical system; (b) spots distribution

Fig. 4. Schematic diagrams of the field tracing process of Gaussian beam

Fig. 5. Schematic diagrams of the reconstructed phase compared to the true phase and phase error. (a) The schematic diagram of reconstructed phase; (b) schematic diagram of true phase; (c) schematic diagram of phase error

Fig. 6. Experimental setup of beam quality measurement

Fig. 7. Captured intensity and reconstructed complex amplitude with 1550 nm wavelength. (a) (b) Captured intensity in different locations; (c) the schematic diagram of reconstructed phase; (d) the schematic diagram of reconstructed intensity

Fig. 8. Curve fitting results of the relationship between beam width and transmission distance. (a) Method based on ISO11146; (b) method based on TIE