Best merit function to use for minimize RMS spot size

Question

Hi there, I am pretty new on Zemax and I am trying to understand how to optimize some values. I have some issues on that.

I am using a lens from the lens catalogs and I want to minimize the Spot radius on the image plane by moving the object in Z. Which is the best merit function I could use to do that?

I put the operand variable on the the thickness of the object and I am not sure of the best suitable merit function for that.

Thanks in advance for your support.

Gianluca

icon

Best answer by David.Nguyen 20 June 2022, 12:52

View original

David.Nguyen · Accepted Answer

Hi Gianluca,Assuming you want to optimize the last thickness value before the image plane such that the RMS spot size is minimized. You could use theOptimize..Quick Focusfeature with theSpot Size Radialcriterion (this is the RMS spot radius).You can decide to use the Centroid (as shown in the screenshot) or the chief ray landing position to compute the RMS spot radius. For this particular feature, you don’t even need to set the last thickness as a variable.Alternatively, underOptimize..Optimization Wizard. You can generate a default Merit Function with an Image Quality:Spotand Type: RMS. That would optimize your variable to minimize the RMS spot size in your image. As shown in my screenshot below.I also strongly suggest browsing the getting started articles here(OpticStudio is the third column).Hope this helps.Take care,David

David.Nguyen · Answer

Dear Gianluca,If you open theField Data Editor, by double-clicking onSetup..System Exporer..Fields. You get your list of fields with a column namedWeight. The default should be a value of 1.00 for all your field. You can increase the weight of the field you are interested in to 10.00 for example.When you then use the Quick Focus, OpticStudio will take into consideration the higher weight on your field of interested.Example with all weights at 1.00Same example with weight of 10.00 for the Field 1Let me know if it works for you.David