Fig. 6: Principle of depth measurement.
a Lattice light field generated by a micro-axial conical mirror array, with the tracking point (yellow circle) monitoring Y-direction variations. b Color-coded 3 × 3 lattice field (white box in a), highlighting intensity distribution; 3 × 3 points marked by red dashed circles. c SEM-characterized trench array sample 1# (depth: 111 μm, width: 1.91 μm, aspect ratio: 58.12); experimental objective focused on trench base. d Color-mapped intensity contrast between trench top/bottom (white box in c), e Schematic of microscopic imaging setup, f Lattice light interaction with trench array, g Geometric principles for depth calculation. h Video-derived Y-coordinate evolution (frames 1–600); i–k Maximum Y-coordinate case for sample 1#: peak intensity pixel at (474, 1014) (j); intensity profile along line A1(k). l–n Minimum Y-coordinate case: peak intensity pixel at (478, 1005) (m); corresponding profile (n). o The extracted 4 × 5 lattice light field array. p Case with a unique maximum-intensity pixel. q Case with non-unique maximum-intensity pixels; r The coordinate variations of light spots at different wafer positions
