Surface Curvature
Displays the tangential, sagittal, x, or y curvature of a surface as a 2D color or contour map, or as a 3D surface plot.
Sampling The size of the grid used. The sampling may be 33x33, 65x65, etc.
Contour Format The contour format string. This option will only appear when "Contour" is selected under "Show As". For a discussion of the contour format string syntax, see "The Contour Format String". The contours are defined in lens units.
Surface The surface number at which the curvature will be computed.
Data Choose tangential. sagittal, x, or y curvature or Modulus. Modulus is defined as the maximum length of the curvature vector.
Show As Choose surface plot, contour map, grey scale, or false color map as the display option.
Off-Axis Coordinates If checked, the plot will consider any apertures defined in the Surface Properties of the surface. The coordinate system for the sag computation will have an origin at the vertex of the off-axis part.
Valid apertures for this option will be: Circular Aperture, Rectangular Aperture, Elliptical Aperture, User Aperture, and Floating Aperture.
Remove The Remove selection gives the option to remove "None", "Base Radius", "Best Fit Sphere", "Base Sag" or "Composite Sag".
If "Base Radius" is selected, the base radius of curvature of the surface will be subtracted from the current curvature, and the difference will be reported.
If "Best Fit Sphere" is selected another option will appear labelled "Criterion" The Criterion section will explain the options for Remove Bet Fit Sphere.
If "Base Sag" is selected, the analysis displays:
- in case STAR data is applied to the surface, the sag difference between the surface with STAR effects applied and the original surface. This is useful to visualize small changes in sag due to the FEA data.
- in case the surface is a Composite Base or Add-on, the sum of sag profiles of any composite Add-on surfaces up to and including the surface above the one considered. This is useful to visualize Composite Add-on profiles that are added to the Composite Base.
If "Composite Sag" is selected, the analysis displays the sag profile of the surface being considered, ignoring any Composite Add-on surfaces added to it.
Criterion The Criterion selection appears when Remove Best Fit Sphere is selected and gives the option to select "Minimum Volume", "RMS, no offset", "RMS, with offset". When "Minimum Volume" is selected, another checkbox with the title "Reverse Direction" will appear. Reverse direction changes the sign on the radius of curvature of the best-fit sphere. This results in fitting, for example, a concave best fit sphere instead of a convex best fit sphere. These selections indicate where the Best Fit Sphere will be subtracted from the surface.
The diagram below shows this more clearly:
Discussion This feature accounts for the size and shape of any aperture present on the surface; even if the aperture is decentered.
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