Hi Jaren,

Yes, as you discovered, pythonnet is only supported up to 3.8 (https://github.com/pythonnet/pythonnet); when pythonnet upgrades to 3.10 then you can also upgrade to the latest version of Python and still access the ZOS-API.

As for adding references via pythonnet, you need import clr and clr.AddReference() methods (I’m not sure where NET.AddReference is coming from).  When you first download the file, make sure you unblock the file so you can actually access it via Python (by default, Windows will block the execution of code from unsigned sources).  After downloading & extracting the ZIP file, you will need to right click on it, select Properties and then check the Unblock option at the bottom of the General tab:

As for sample Python code, refer to the below code for running a Normalized Unpolarized raytrace (it traces the 4 marginal rays at full field for the Double Gauss 28 degree field sample file):

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import zosapi
from System import Enum, Int32, Double

# add the raytrace.dll from the current directory
import clr, os
dll = os.path.join(os.path.dirname(os.path.realpath(__file__)), r'RayTrace.dll')

clr.AddReference(dll);

# import the raytrace namespace
import BatchRayTrace;

# load the double gauss
zos = zosapi.App()
TheSystem = zos.TheSystem
ZOSAPI = zos.ZOSAPI
TheSystem.LoadFile(os.path.join(zos.TheApplication.SamplesDir, r'Sequential\Objectives\Double Gauss 28 degree field.zmx'), False)

# check to make sure the file was loaded
if TheSystem.LDE.NumberOfSurfaces < 4:
    print('did not load the file properly')
    exit()

# run a sequential ray trace
maxrays = 4;        # let's trace the 4 marginal rays
tool = TheSystem.Tools.OpenBatchRayTrace();
normUnpol = tool.CreateNormUnpol(maxrays, ZOSAPI.Tools.RayTrace.RaysType.Real, TheSystem.LDE.NumberOfSurfaces - 1)

# pass raytracer to dll
reader = BatchRayTrace.ReadNormUnpolData(tool, normUnpol)
reader.ClearData();

# initialize the output (the number of indices in the output array is maxseg*maxseg
maxseg = 2;
rays = reader.InitializeOutput(maxseg);

# add the 4 full field marginal rays
reader.AddRay(2, 
    [0, 0, 0, 0], 
    [1, 1, 1, 1], 
    [1, -1, 0, 0], 
    [0, 0, 1, -1], Enum.Parse(ZOSAPI.Tools.RayTrace.OPDMode, 'None'));

# read the segments (array length is maxsegs * max segs)
isfinished = False
while not isfinished:
    segments = reader.ReadNextBlock(rays)
    if segments == 0:
        isfinished = True

# print the rays
print(list(rays.X))
print(list(rays.Y))

# always close your tools
tool.Close();