Ask an Engineer: STAR module for STOP analysis

Dear all,

on one site the import of FEA data into the STAR Module via textfiles is quite “universal”, but it also requires a preprocessor (Ansys, FEMAP, Hypermesh) which automates the export of deformations considering which FE-nodes are placed on which optical surface. For Ansys Mechanical a dedicated script was already made available (see “FEA data export from Ansys”. However, users of FEMAP and Hypermesh are still excluded from the simplified workflow and space-industry is (still) dominated by Nastran users. They will feel somewhat irritated that their beloved *.op2 or *.pch format is not directly supported. Unless FEMAP, Hyperworks and hundreds of other Nastran-Preprocessors provide a similar script for the export of data, all Nastran users will need an additional/intermediate MATLAB tool to import Nastran results, then assign the surface nodes and export into STAR-Module format.

Are there any plans in future releases to import native results file from Nastran (*.op2, *.pch) or Ansys (*.rst) or Abaqus, etc.  and assign the FEA surface node numbers to the optical surface within the STAR-Module?

If the answer is “yes, planned in one of the next releases” do you have any idea when this will happen?

Hi @ERT 

Thank you for posting your inquiry on this thread! Yes, your understanding is correct. The motivation behind STAR accepting text format as input is to make sure the module is not limited to one specific FEA software, but rather it can take the structural and thermal data saved in a general text format coming from any FEA software. Our developers have published an extension that helps automate the data export from Ansys Mechanical. I’m not sure such scripts are being considered for other FEA software you have mentioned here. I agree there are two possible ways for us to move forward and help users ease their time and effort spent on FEA data export. One is to create a collection of customized extensions for common FEA software in the market; the other is to have STAR directly accept native data format used by the FEA software. I will provide your valuable feedback to our Product and Development team and have them evaluate the possibility of implementing such capabilities in STAR. New features and new capabilities are constantly being investigated for STAR since our goal is to make STAR as powerful and useful as possible. 

2. FAQ on STAR data format

STAR currently only exists in OpticStudio Sequential mode. It can take in structural deformation data and thermal temperature gradient data defined in a text file format.

For structural deformation, STAR converts the deformed surface internally to a surface type similar to Grid Sag. The main difference is that the native Grid Sag requires uniform mesh while STAR supports any non-uniform mesh as defined originally in the FEA software. This significantly improves the fitting quality and enables STAR to accurately capture the structural deformation of each surface.

For thermal gradient, STAR takes in the temperature cloud and converts it internally to a surface type similar to Grid Gradient so the index variation due to temperature can be captured.

STAR streamlines the process and makes it much easier to bring the FEA results into OpticStudio. 

4. STAR future development

STAR module is constantly under development for new features and new capabilities. When STAR was first released, it can only handle single wavelength operation. Since OS22.1 we have added multiple wavelength capability so dispersion effect can be properly accounted for. This is particularly important for designing systems operating in a range of wavelengths, for example camera systems working in the visible range. STAR in OS22.1 has also added two important GUI tools, Index vs Temp plot and Inspect FEA data tool. The Index vs Temperature plot allows you to view the glass index change as temperature varies. The Inspect FEA tool provides a closer look of the FEA data set within the OS GUI by reporting the Max, Min and Median of the data points in your FEA data set.  

Currently STAR supports modeling of structural deformation and thermal gradient index effect. However, many customers have also expressed interests in modeling stress induced birefringence effect, or for STAR to support Non-Sequential mode operation. These are all great ideas. If you would like to see certain features added to STAR or certain GUI tools developed for STAR to make it easier for user to visualize and analyze FEA data, please feel free to share it with us. It will help us brainstorm and make STAR a better and more powerful tool.

A side note to complete today’s session, in February OpticStudio STAR module has won the highly esteemed SPIE Prism Award in Software. The STAR team at Zemax is very proud and honored to receive this award and will continue to work hard and make STAR a better tool in the future!

Dear Hui Chen,

thank you for answering my question. If there’s any feedback of your Product and Development team pleas let me know.

Have a nice day!

This thread is now closed. Thank you to @Hui Chen for an informative event :). 

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