Grid Sag Surface
The Grid Sag Surface is an object whose shape is defined by a rectangular array of points listed in a file. This surface shape is similar to the sequential Grid Sag surface, although no Zernike terms are supported. For a detailed description of the sequential Grid Sag surface shape, see " Grid Sag " .
Grid Sag Surface objects use the following parameters:
| Parameter # | Description | Face Name | Face # |
| 1 | Interpolate: Use 0 for bicubic, and 1 for linear. See "Bicubic spline vs. linear interpolation" . | All Faces | 0 |
| 2 | The radius of curvature in lens units. | All Faces | 0 |
| 3 | The conic constant. | All Faces | 0 |
| 4-11 | The αi aspheric coefficients. | All Faces | 0 |
| 12-13 | The X- and Y-decenter values in lens units. This is the decenter of the grid data relative to the aspheric substrate. The decenter values are added to any decenter values defined in the GRD file, described below. | All Faces | 0 |
The actual point by point sag data is defined by placing the data in a properly formatted file ending in the extension GRD. The file format is defined in "Importing grid data" . The grid data file must be placed in the <objects>\Grid Files folder (see "Folders" ). The file name, without the path, is then placed in the comment column of the NSC Editor.
Face Numbers: The entire face is Face 0.
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