Hi Asuku,

The diffraction limited data will be stored as the first DataSerie in the result interface.

Here is a simple example that demonstrates how to plot FFT MTF data (this is inspired from Example 23 in the Syntax Help File), this file is also attached to my reply:

Here is the Python code to reproduce a similar plot (only with the tangential component) in an Interactive Extension:

import numpy as np
import matplotlib.pyplot as plt


# Open FFT MTF
my_fft_mtf = TheSystem.Analyses.New_FftMtf()

# Get FFT MTF settings
fft_mtf_settings = my_fft_mtf.GetSettings()

# Show diffraction limit
fft_mtf_settings.ShowDiffractionLimit = True

# Run FFT MTF
my_fft_mtf.ApplyAndWaitForCompletion()

# Get FFT MTF results
fft_mtf_results = my_fft_mtf.GetResults()

# Check how many data series are available
print('Number of data series = ' + str(fft_mtf_results.NumberOfDataSeries))

# First data serie: diffraction limit
data_1 = fft_mtf_results.GetDataSeries(0)

x_1 = np.asarray(tuple(data_1.XData.Data))
y_1 = np.asarray(tuple(data_1.YData.Data))
# Side note: this splits between tangential and sagittal data series
y_1 = y_1.reshape(data_1.YData.Data.GetLength(0), data_1.YData.Data.GetLength(1))

# Second data serie: actual FFT MTF
data_2 = fft_mtf_results.GetDataSeries(1)

y_2 = np.asarray(tuple(data_2.YData.Data))
y_2 = y_2.reshape(data_2.YData.Data.GetLength(0), data_2.YData.Data.GetLength(1))

# Plot data series (only tangential)
plt.figure()
plt.plot(x_1, y_1 :, 0], 'r', label='Diffraction limit')
plt.plot(x_1, y_2 :, 0], 'c', label='FFT MTF')
plt.legend()
plt.show()

# Close FFT MTF
my_fft_mtf.Close()

This is what it plots:

I did not double-check that I was indeed plotting the tangential and not sagittal data so better double-check, but I think you get the idea.

Take care,

David

Hello David,

Thanks for advice. I tried to run your code on the zos file you provided. However, I don’t see any data series for diffraction limit even though fft_mtf_settings.ShowDiffractionLimit = True

As you can see below, data_1 contains the actual Field == 1 data only (see plot below which shows Field ==1 data instead of diffraction limit data).

Also note that data_2 array = empty.

fft_mtf_results.NumberOfDataSeries == 1 (this shows that there is only one MTF series output) 

Note: I am running Zemax 22.2.1

Thanks - A

Hi Asuku,

What is your version of Pythonnet? If it is after 2.5.2, can you try 2.5.2 to see if it makes a difference? I’ve seen quite some strange issues lately with people using Pythonnet 3.0.0 and above.

Take care,

David

yes, it was > 2.5.2.

pythonnet → 3.0.0.post1 

I downgraded to:

pythonnet → 2.5.2

Now I am able to replicate your process successfully without errors. Are there any other problems caused by pythonnet that I need to be aware of when developing on ZOS-API Python?

Thanks a lot for your help.

Best - Auku

Hey Asuku,

I never had any issues with 2.5.2 before. I think it is only an issue with more recent versions of Pythonnet.

Take care,

David