Hey James,

This error message would imply that the GERMANIUM material in the AGF catalog does not have Thermal Coefficients defined.  The default germanium in the INFRARED.AGF catalog only has D0 (linear dn/dT) but doesn’t have any higher order values:

I’m not sure if all 6 Thermal Coefficients are needed for STAR but I would guess you won’t get accurate index values if you don’t have all 6 values defined.

Since this data is provided by the vendors themselves and is not verified by Zemax, I think you’ll have to work with your vendor to provide these values.  The Thermal Coefficients are empirical values which fit the Schott thermal model.

Yes, that does appear to be the issue.  If I switch the material to N-BK7, that “error” goes away.  I shall add this to the list of STAR module disappointments.    Thanks for the guidance!

Hi @James.Fry and @MichaelH ! Thank you for reporting this.  

Yes a restriction was added on the material catalog. To load thermal datasets, all 6 coefficients need to be defined. But since it is becoming an issue for our customers as they don’t always have access to those coefficients, the product team has decided to roll back the restriction so that if D0 is defined, temperature data can be applied in STAR and will be accepted. It is something that will be available in a coming release. Thank you for your patience.