This article is also available in Japanese.

In the sequential mode of ZEMAX, the Coordinate Break (CB) surface is used to define a new coordinate system in terms of the current system.  Primarily, these surfaces are used to perform tilts and decenters of surfaces defined in a local coordinate system.  Coordinate Breaks offer great flexibility in positioning and tilting surfaces/elements in your design. 

However, it can be difficult to restore the coordinate system (return to the coordinate system of a prior surface) where many complex nested tilts/decenters are present.  The Coordinate Break return capability of ZEMAX can simplify this problem tremendously. 

The Coordinate Return feature may only be used on Coordinate Break surfaces, and is found underneath the Tilt/Decenter tab of the Surface Properties dialog:



The Coordinate Return is very easy to use.  You simply choose how you would like to restore the coordinate system, and the surface whose coordinate system you want to return to.  Other than “None,” (which disables the Coordinate Return feature), there are three options available for how you want to restore the coordinate system:

Orientation Only:  In this case, only the tilt about x, y and z axes are determined to return the orientation of the coordinate system to the previous surface.  No adjustment is made to the position offset of the surface vertex. 

Orientation XY:  The tilt about x, y, and z axes and the decenters in x and y are determined to return the orientation of the coordinate system.  This will offset the x and y components of the vertex offset to the selected surface, but no adjustment in the z position is made.

Orientation XYZ:  This is identical to Orientation XY, except the z offset is also accounted for.  The z decenter is placed on the thickness parameter of the Coordinate Break surface, and so it is the following surface whose orientation and position are identical to the “To Surf:.”