Fig. 1. Principle diagram of Ronchi lateral interferometer setup used for wavefront aberration test of projection lens

Fig. 2. Area used in tilt coefficients measurement

Fig. 3. Geometrical paths of interfering rays at detector when image-plane grating is placed at focus of optics under test

Fig. 4. Geometrical paths of interfering rays at detector when image-plane grating is placed behind focus of optics under test

Fig. 5. Measurement process of lens NA based on Ronchi lateral shearing interferometry

Fig. 6. Schematic of tilt coefficients c2 and c3 varying with axial position

Fig. 7. Error of NA measurement versus wavelength shift (central wavelength is 532 nm)

Fig. 8. Error of NA measurement versus axial positioning error

Fig. 9. Error of NA measurement versus axial distance δz when positioning error is set to be 6 nm

Fig. 10. Error of NA measurement versus image-plane grating period error

Fig. 11. Error of NA measurement for different image-plane grating periods

Fig. 12. Error of NA measurement versus c₂ or c₃ measurement error

Fig. 13. Experimental setup of double-grating Ronchi LSI system

Fig. 14. Shearing interferograms in X direction and Y direction when image-plane grating is located at different axial positions. (a) X direction shearing interferogram near focal plane; (b) Y direction shearing interferogram near focal plane; (c) X direction shearing interferogram with about 50 μm defocusing; (d) Y direction shearing interferogram with about 50 μm defocusing

Fig. 15. Measurement results of c2 and c3 when image-plane grating is moved along axial direction

Fig. 16. Geometrical model of beam radius at detector

Fig. 17. Measurement results of beam radius when CCD is moved along axial direction

Fig. 18. Relative RMS error of reconstructed wavefront versus relative shearing error