Fig. 1. Schematic diagram of scanning beam interference lithography system

Fig. 2. Schematic diagram of dual-frequency laser interferometry system

Fig. 3. Schematic diagram of dead path error

Fig. 4. Air refractive index’s curve variation with different temperatures and pressures

Fig. 5. The impact of roll angle on laser interferometers measurement accuracy. (a) The position of measuring point Q when the workbench is not rotating. (b) Workbench rotates α at origin O. (c) Workbench rotates α around point Q

Fig. 6. Workbench roll angle error diagram

Fig. 7. Measurement axis offset vs. measurement error at different rotation angles

Fig. 8. Principle diagram of nonlinear error measurement

Fig. 9. Nonlinear error

Fig. 10. Test results of Zygo interferometer

Fig. 11. Mirror shape curve measured at working height

Fig. 12. Changes in the laboratory environment during a three hour period

Fig. 13. Comparison of wavelength tracker data and environmental data

Fig. 14. Stability test device diagram

Fig. 15. Comparative stability of the laser interferometer and grating interferometer

Fig. 16. Spectrum analysis of the difference between the grating interferometer and laser interferometer

Fig. 17. Measuring principle of table roll angle

Fig. 18. Test results of table roll angle

Fig. 19. Grating diffraction wavefront

Fig. 20. Real picture of 200 mm×200 mm×20 mm grating