Fig. 1. Schematic diagram of Wolter-I

Fig. 2. Measurement device for surface profile of mandrel（Probe 1 measures the surface profile of the mandrel and probe 2 measures the surface profile of the reference mirror）

Fig. 3. Mandrel test process

Fig. 4. Decomposition of measurement errors

Fig. 5. Schematic diagram of spectral confocal probe

Fig. 6. Schematic diagram of assembly error correction

Fig. 7. Measurement system of mandrel

Fig. 8. Variation of repeatability with sampling frequency

Fig. 9. Surface shape and repeatability of reference surface

Fig. 10. Mandrel roundness fitting

Fig. 11. Taper error correction results

Fig. 12. Temperature and humidity monitoring data

Fig. 13. Result of environmental error correction experiment

Fig. 14. Comparison of reference surface corrections

Fig. 15. CGH measurement experiment

Fig. 16. Verification experiment of optical probe and CGH

Fig. 17. Two-dimensional surfaces