Fig. 1. Overall research framework of grating interference precision nanometer measurement technology

Fig. 2. Schematic diagram of grating interferometer

Fig. 3. Grating scales produced by HEIDENHAIN

Fig. 4. Absolute single degree of freedom grating interferometer^［35］

Fig. 5. Absolute two degree of freedom grating interferometer^［41］

Fig. 6. Nano-resolution three-axis sensor developed by Tohoku University^［42］

Fig. 7. Subnanometer three-axis surface encoder with short-period planar grating for platform motion measurement^［43-44］

Fig. 8. Three-degree-of-freedom measurement system with expanded Z-axis range^［46］

Fig. 9. Three-degree-of-freedom grating encoder based on quadrilateral pyramid prism^［47］

Fig. 10. Six degrees of freedom homodyne grating interferometer^［54］

Fig. 11. Dual-channel six-degree-of-freedom grating encoder^［56］

Fig. 12. Four degrees of freedom absolute grating encoder ^［57］

Fig. 13. Frequency-stabilized light sources based on MTS systems^［58］

Fig. 14. Dual frequency stable laser system^［69］

Fig. 15. Heterodyne two-degree-of-freedom system^［62］

Fig. 16. Two-dimensional grating encoder based on dual-space heterodyne optical path^［65］

Fig. 17. Heterodyne three-degree-of-freedom grating interferometer^［69］

Fig. 18. Multi-reading head six-degree-of-freedom model^［73］

Fig. 19. Technology spatially separated heterodyne optical interferometer^［93］

Fig. 20. Heterodyne grating encoder based on quasi-common optical path^［94］

Fig. 21. Six-degree-of-freedom measurement system based on four two-degree-of-freedom readheads proposed by ASML^［97-98］

Fig. 22. Multi-degree-of-freedom measurement readhead model^［101］