Fig. 1. Mosaic grating coordinate system and alignment setup for 0-order. (a) Mosaic grating tiling parameters; (b) interferometer setup for 0-order of mosaic grating

Fig. 2. Filtering region of nine-pixel average algorithm

Fig. 3. Interference fringe pattern of mosaic grating G2 with the different misalignments

Fig. 4. A Fourier-transform (FT)-based fringe calculation algorithm of misalignment error in the mosaic grating interferometric technique

Fig. 5. Relationship between misalignment angle Δθ_y and micrometer-head reading in y direction (Δθ_x=0)

Fig. 6. Relationship between misalignment angle Δθ_x and micrometer-head reading in x direction (Δθ_y=0)

Fig. 7. Misalignment angle variation under different micrometer-head readings in the mosaic grating alignment system

Fig. 8. Error analysis of calculated misalignment angle. (a) Comparison of calculated and actual misalignment angles; (b) misalignment angle error distribution

Fig. 9. Interferogram fringe comparisons for slight angle variation. (a)(b) With 0.4 μrad difference of Δθ_x angle error; (c)(d) with 0.946 μrad difference of Δθ_y angle error