Fig. 1. Coordinate definition of grating mosaic error

Fig. 2. PSF variation under different piston errors

Fig. 3. Interference of monochromatic light and white light under different mosaic errors. (a) x-axis tilt error of monochromatic light; (b) y-axis tilt error of monochromatic light; (c) piston error of monochromatic light; (d) x-axis tilt error of white light; (e) y-axis tilt error of white light; (f) piston error of white light

Fig. 4. Adjustment of piston error of mosaic grating by two-step method. (a) White light interferogram when Δz=1μm; (b) two-wavelength interferogram when ∆z=240 nm; (c) single-wavelength interferogram when ∆z=10 nm

Fig. 5. Design of experiment setup

Fig. 6. Schematic diagram of Fourier analysis piston calculation by interference fringes

Fig. 7. Relationship between control piston of PI nano-translation stage and calculated piston value. (a) Piston calculation accuracy analysis; (b) analysis of piston change caused by environment

Fig. 8. Schematic diagram of fringe alignment under white light interference.（a）Interference fringes and intensity comparison diagram of tungsten-halogen light source with wavelength of 360-2600 nm; (b) interference fringes and intensity comparison diagram at bandwidth of 50 nm and wavelength of 607-657 nm; (c) interference fringes and intensity comparison diagram at bandwidth of 10 nm and wavelength of 627-637 nm

Fig. 9. Piston precision adjustment detection results. (a) Interference fringe and wavefront fitting at wavelength of 532 nm;(b) interference fringe and wavefront fitting at wavelength of 632.8 nm