FEA, SigFit & ZEMAX: coordinate system orientation

  • 21 August 2019
  • 1 reply


The standard method for defining the direction of the Z-axis is that positive is towards the image plane. This is opposite to what my team's FEA & CAD team has been doing and prefers. We are looking at integrating SigFit for thermo-optical analysis.

For implementation of SigFit the coordinate systems need to align.  

Does anyone have any experience in changing the Z-axis orientation? The CAD & FEA team prefers that we first investigate just changing the definition of positive Z in ZEMAX. Or will it be a better procedure for the FEA & CAD to default to the ZEMAX optical system Z-orientation (positive towards the image plane)?



1 reply

Userlevel 4
Badge +1
Hi Dalene,


Coordinate break surface can be used to adjust axis orientation. If you would like to flip the Z axis 180 degrees, you can insert a Coordinate break surface, and set its Tilt Y to 180 degrees. So instead of going from left to right, Z axis will now point from right to left and away from the image plane. To show how this works, I’ve created a simple system as shown below. I inserted a CB surface in front of the image plane. After the Coordinate break surface, the positive Z direction is reversed and now going from right to left. That’s why I need to set the thickness on surface 4 to a negative value to place the image plane to the right of the lens, as shown below.