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- How to Measure the Sag of an NSC Object
How to Measure the Sag of an NSC Object
- By Sanjay Gangadhara
- Published 23 November 2007
- ZPL , Objects
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Introduction
There are many situations in which it is necessary to know the surface sag of an object in ZEMAX. This information can be easily obtained in sequential mode using the SAGG operand, or by clicking under Analysis > Surface > Surface Sag.
In non-sequential mode things are more complex. Sequential surfaces are defined by a single equation referenced to a surface vertex, but non-sequential objects are three-dimensional objects which can be arbitrarily complex. Objects may be viewed using the Object Viewer, but sag data depends on the viewing point.
The surface sag of an object may be easily determined by the use of the NSRA operand. This operand can be used to determine the intersection point (along the local z-axis) of a source ray with the object surface. By varying the coordinates of the source ray, the full surface of the object may be mapped out.
In non-sequential mode things are more complex. Sequential surfaces are defined by a single equation referenced to a surface vertex, but non-sequential objects are three-dimensional objects which can be arbitrarily complex. Objects may be viewed using the Object Viewer, but sag data depends on the viewing point.
The surface sag of an object may be easily determined by the use of the NSRA operand. This operand can be used to determine the intersection point (along the local z-axis) of a source ray with the object surface. By varying the coordinates of the source ray, the full surface of the object may be mapped out.