It appears to me that you have run the POP simulation starting at surface 1 and ending at surface 2, with save the beam on all surfaces checked. The three files are:

4158_10_none_NKT_007.ZBF The beam on the final surface, which is 2

4158_10_none_NKT_007_1.ZBF The beam on surface 1

4158_10_none_NKT_007_2.ZBF The beam on surface 2

This is the way OpticStudio saves surface beam files. The final surface file has no _N suffix. All surfaces have file with a _N suffix, where N is the surface number.

Kind regards,

David

When polarization is ticked, OpticStudio will save 3 files per surface.

If “Use Polarization” has been selected under the General Tab and the input beam is unpolarized (i.e. no specific polarization state has been provided in the  ” Polarization (system explorer)” input of the System Explorer), then individual surface beam files will be provided for each of two orthogonal beams that are propagated to model the unpolarized beam, and an additional suffix will be added to the file name to differentiate between the two beams.

For example, if “Use Polarization” has been selected and no specific polarization state has been specified in the System Explorer, then in the above case two files would be generated on surface 12, named “MyBeamData_0012_1.ZBF” and “MyBeamData_0012_2.ZBF”. ZBF files are stored in the folder (see  Folders).