Fig. 1. Three-dimensional model of table structure

Fig. 2. Optical path for measurement

Fig. 3. Schematic of revising on error of grooves

Fig. 4. Schematic of measuring system in y direction

Fig. 5. Schematic of Abbe error

Fig. 6. Measuring optical path with a function of Abbe error measurement. (a) Top view; (b) side view

Fig. 7. Schematic of measuring angle αi

Fig. 8. Abbe error of indexing system

Fig. 9. Impact of Abbe error on grating wavefront quality of different groove densities. (a) 600 groove/mm; (b) 79 groove/mm; (c) 6000 groove/mm

Fig. 10. Wavefront quality of the grating measured by Zygo interferometer. (a) Before revising Abbe error; (b) after revising Abbe error