Fig. 1. Schematic of Gauss beam

Fig. 2. Schematic of interference of double Gauss beams

Fig. 3. Nonlinear error of interference field with different waist radii in ideal condition. (a) 0.5 mm; (b) 1.0 mm; (c) 2.0 mm; (d) 5.0 mm

Fig. 4. Nonlinear error of interference fringe with misalignment of 20 μm. (a) 0.5 mm; (b) 1.0 mm; (c) 2.0 mm; (d) 5.0 mm

Fig. 5. Nonlinear error of interference fringe with misalignment of 100 μm. (a) 0.5 mm; (b) 1.0 mm; (c) 2.0 mm; (d) 5.0 mm

Fig. 6. Variation of grating line error with waist radius of interference field

Fig. 7. Variation of exposure contrast with (a) step interval and (b) waist radius of interference field at certain period error

Fig. 8. Schematic diagram of lens distribution distance

Fig. 9. Morphologies of left and right exposure spots. (a) Left side; (b) right side

Fig. 10. Schematic of interference fringe phase measurement

Fig. 11. Interference patterns of five-step phase shifting. (a) 0; (b) π/2; (c) π; (d) 3π/2; (e) 2π

Fig. 12. Nonlinear error distributions of interference fringe phase. (a) Two-dimensional figure; (b) three-dimensional figure