Part accuracy in Solidworks and export

I want to design a micro-optical component in SW and then export it as STEP or parasolid for ray tracing in an optics design program. For this I need a STEP model with geometry accuracy better than 1um, preferrable 100nm. How can I achieve this accurate export to STEP, and what is the accuracy to STEP or X_T files? Is there a setting to increase the model accuracy? Thank you for helping!