Fig. 1. Schematic diagram of DPP

Fig. 2. Mould of DPP

Fig. 3. Preparation process. (a) Basic plate; (b) basic plate with non-abrasive layer; (c) adding abrasive layer and putting it into the mold; (d) demoulding forming

Fig. 4. Two test pads. (a) DPP; (b) GGP

Fig. 5. Morphologies of the workpiece processed by two kinds of pads. (a) Surface morphology of the workpiece processed by GGP; (b) surface morphology of the workpiece processed by GGP

Fig. 6. Extraction of surface defects on the workpiece. (a) Original morphology of workpiece; (b) morphology of workpiece after defect extraction

Fig. 7. Surface roughness of sapphire substrate polished by different pads. (a) Influence of rotational speed ratio on surface roughness; (b) influence of pressure on surface roughness

Fig. 8. PV of sapphire substrate polished by different pads. (a) Effect of rotational speed ratio on PV; (b) effect of pressure on PV

Fig. 9. Material removal under different polishing parameters. (a) Effect of rotational speed ratio on material removal rate; (b) effect of pressure on material removal rate

Fig. 10. Removal thickness distribution of GGP and DPP. (a) Removal thickness distribution of GGP; (b) removal thickness distribution of DPP

Fig. 11. Surface morphologies of the two pads. (a) Surface morphologies of GGP; (b) surface morphologies of DPP

Fig. 12. Morphology of the FAP. (A) Original morphology of the FAP; (b) extraction of debris from the FAP

Fig. 13. Schematic diagram of abrasive debris flow in two kinds of groove plates. (a) Schematic diagram of abrasive debris flow in GPP; (b) schematic diagram of abrasive flow in DPP