Fig. 1. Gear involute artifact with single base circle from DLUT

Fig. 2. Gear involute artifacts with single base circle from NGML and PTB^［18-19］

Fig. 3. Involute corrugation artifact from PTB^［20］

Fig. 4. Gear involute artifact with rollers from NMIJ^［22］

Fig. 5. Gear involute artifact with double design base circles from BelGIM^［25］

Fig. 6. Micro-gear involute artifact with multi-modular internal teeth from PTB^［27］

Fig. 7. Gear involute artifact with three design base circles from DLUT^［30］

Fig. 8. Workpiece gear artifact^［31］

Fig. 9. Class-1 master gear from DLUT

Fig. 10. Large involute gear segment measurement standard from PTB^［34］

Fig. 11. Large ring gear measurement standard from PTB^［36］

Fig. 12. Double ball artifact from NMIJ^［39-40］

Fig. 13. Double-axis arc-shaped large-size involute artifact from BJUT^［45］

Fig. 14. Micro gear artifacts^［46］

Fig. 15. Involute measurement based on rolling generation

Fig. 16. Gear measuring center（GMC） and its measuring principles^［37］

Fig. 17. CMM form PTB（5 m×4 m×2 m）^［35］

Fig. 18. Large standard gear with multi-parameters

Fig. 19. Large gear involute artifact assembled with mandrel

Fig. 20. Comparison of evaluation ranges of gear involute artifacts with those of standard gears