Let’s use the third option on the previous page to demonstrate the effectiveness of Coordinate Return.  As mentioned earlier, S2 (which is Surface 5 in the LDE) has been decentered in Y due to the Z propagation in the tilted coordinate system of S1.  We wish to restore this offset so that S3 is in the same coordinate system as OBJ space.  Surface 1 in the LDE is also in this coordinate system.  Since our object is at INFINITY, we will use Surface 1 as our “To Surf.” 

Insert a surface just before the IMA plane, and change the surface type to Coordinate Break.  Select OK.  Prior to applying the Coordinate Return, we must first make some adjustments to the thicknesses of Surfaces 5 & 6.  We would like S3 to be 20 lens units away from S2.  But we would first like to restore the offset created by the z propagation in the coordinate system of S1.

Thus, place the thickness from Surface 5 to Surface 6, so that the thicknesses are as follows:

Open the Surface Properties dialog for Surface 6 and select the Tilt/Decenter tab.

In this case, we want to restore the x, y, z rotations and the x and y decenters (if any).  We do NOT want ZEMAX to co-locate our new coordinate system with Surface 1 in the z axis.  Therefore, change the “Coordinate Return” option to Orientation, XY (which does not consider the z offset) and change the “To Surf” to 1. 

Select OK to close the Surface Properties dialog, and note the changes made the CB parameters of Surface 6.  The letter “R” indicates that the parameter is controlled by a Coordinate Return, and acts very similarly to a solve.  Any time a Coordinate Return is used, it will overrule any other solve, variable or multi-configuration status on any data controlled by the Coordinate Return.



In this example, only the Decenter Y needed to be controlled to restore the coordinate system to match that of Surface 1.  Note that this is effectively 20*sin(20) = 6.8404.