Fig. 1. Measurement optical path for surface defects of ICF capsule using Linnik type white light null micro-interference

Fig. 2. Step surface with bat-wing effect and corrected step surface. (a) Ideal step surface; (b) step surface with bat-wing effect; (c) step surface obtained by bat-wing correction algorithm

Fig. 3. Flowchart of white light phase-shifting interference algorithm

Fig. 4. Experimental devices. (a) Measurement device of white light null micro-interference; (b) measurement device of laser micro-interference

Fig. 5. White light interferograms of seven-step phase-shifting

Fig. 6. Intensity and modulation of white light interference. (a) Interference fringe intensity; (b) interference fringe modulation

Fig. 7. Surface morphology of ICF capsule obtained by white light interferometry. (a) Three-dimensional image; (b) isolated defect

Fig. 8. Surface morphology of ICF capsule when bat-wing effect is eliminated. (a) Three-dimensional image; (b) isolated defect

Fig. 9. Laser interferograms of four-step phase-shifting. (a) 0; (b) π/2; (c) π; (d) 3π/2

Fig. 10. Surface morphology of ICF capsule by laser interferometry. (a) Three-dimensional image; (b) isolated defect

Fig. 11. Height profiles of ICF capsule defect in different directions measured by white light interferometry. (a) X-direction; (b) Y-direction

Fig. 12. Height profiles in different directions of ICF capsule defect measured by laser interferometry. (a) X-direction; (b) Y-direction