Surface definition
mm
–
mm
Coefficients in mm1−2i (standard lens-design convention, sag in mm with r in mm).
Scientific notation accepted, e.g.
-2.0e-9. Set R = 0 for a plano-base polynomial surface.Sag table export
mm
Columns: r, sag, slope, local curvature, departure from LSQ best-fit sphere.
Surface metrics
Metrology & tolerancing advanced
nm
λ/N
What this means
Surface profile & best-fit sphere
Aspheric departure (vs LSQ BFS)
Surface slope
Best-fit sphere: found by golden-section minimization of the area-weighted RMS sag
difference over the clear aperture (annular weighting ∝ r). The vertex–edge sphere (through both the vertex and
the edge point) is also reported — it is the common choice for generating the closest starting sphere.
Testability: fringe count assumes a null-less interferometric test against the BFS at 633 nm
(2 fringes per λ of mechanical departure); gradients beyond ~1 fringe/mm typically need stitching, CGH or
profilometry.