Learning Forum

[Ali]

I have a segmented telescope model, which is using non-sequential components to represent the segments. The issue arises with the DENC and GENC operands, which return incorrect values when I introduce disturbances to the segments(for example, center and clocking). The encircled energy value I observe in the plot differs from what GENC and DENC report after I apply any clocking or decentering adjustments to a segment. However, in the nominal model—where no disturbances are applied to the segments—the GENC and DENC values are accurate. I have used different sampling does effect DENC but not GENC

[Niki Papachristou]

Hi Ali,

Thank you for reaching out to us! May I confirm with on what you are repoting here? You are observing different values reported on the Merit function operands compared to the graph, is that correct. 

In this case it woud be much easier if I had your design file to work on your case. Hence, may I ask you whether you have support with us?

Kind Regards,

Niki

[Elham Sarbazi]

Hi Ali,

The GENC operand in the MFE should provide the exact same results as computed by the Geometric Encircled Energy tool, as long as you set them up with the exact same parameters. 
If the system is a mixed mode system with NSC component embedded in a sequential model, then, many of the wavefront-based analysis tools may no longer work properly. So you’ll need to use geometric ray based analysis. And for the geometric encircled energy, you should not check “Multiply by Diffraction Limit”. 
In addition, because the GENC operand listed in the Merit function Editor does not provide a setting for the “Maximum Distance” computed, you’ll sometime see a small discrepancy. However, if you set the sampling very high, the discrepancy should be a very small.

[Ali]

Hi Elham, thanks for the reply. 

I thought that would be the case, but unfortunately, it seems like the GENC operand does not work effectively for hybrid models. This is the case even when I leave "Multiply by Diffraction Limit" unchecked and use very high sampling, particularly when I introduce disturbances to the segments.

My goal is to perform a sensitivity analysis (tolerancing) on our segmented telescope design to evaluate how sensitive Encircled Energy is to parameters like tilt, decenter, and radius of curvature (ROC). While the DENC operand provides results that are close, I’m uncertain about the reliability of the diffraction-based Encircled Energy results in mixed mode.