The Hypespectral Image is the complex file to generate for this equipment.
There are 2 possible file types:
- Raw files, with extension *.gsf
- Spectra files, with extension *.txt
It is the least processed file for equipment, so it is necessary to do the entire mathematical process. There are benefits to this approach, as in this case you can have access to all measurements. In some cases, it can be important to access SNR from all points, so with raw files you can do this.
How to open?
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To open these files you need to have 3 files in the same folder, for example to open the second harmonic (O2)
- "file name" O2A raw.gsf → Interferogram of amplitude
- "file name" O2P raw.gsf → Interferogram of phase
- "file name" .html → File with measurement information
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Open with Multifile, when selecting the file "[...] O2A raw.gsf" or "[...] O2P raw.gsf" you need to select a specific reader, to raw files, needs to be "NeaSPEC raw files (*. gsf) ", and the software will take care of finding the other 2 files, if they are in the same folder
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After opening the interferogram files, it is necessary to apply a Fast Fourier Transform (FFT), for that it is necessary to use the Interferogram to Spectrum widget, there are some settings available to users, such as Zero fill factor and what type of apodization you want to use. But you can just live by default if you don't want to change.
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The result of FFT is two files, "O2A" amplitude spectrum and "O2P" phase spectrum, this two files need to be splipted, for you can use them. For this you will use the Select Rows widget. Input the data from Interferogram to Spectrum in Select Rows, open Select Rows and in Conditions add channel and type or select O2A, now you have only amplitude spectrum in output. Put another Select Rows in data from Interferogram to Spectrum and in Conditions add channel and type or select O2P, now you have only phase spectrum on another output.
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Now you have two diferent files, Phase Spectrum and Amplitude Spectrum.
It is the file generate for the equipament after Fourier Transform. In this file isn't necessary to do Fourier transform
How to open, second harmonic?
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To open these files you need to have a unique *.txt file.
- "file name" Spectra.txt → File with all harmonic data
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Open with Multifile, when selecting the file "[...] Spectra.txt" you need to select a specific reader, to Spectra .txt files, needs to be "NeaSPEC(*. nea *. txt) ".
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In Multifile you need to change in column: name, line: channel type to categorical. It is almost the last line of the file.
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After opening the files, you need to separate the data, for you can use them. For this you will use the Select Rows widget. Input the data from Multifile in Select Rows, open Select Rows and in Conditions add channel and type or select O2A, now you have only amplitude spectrum in output. Put another Select Rows in data from Multifile and in Conditions add channel and type or select O2P, now you have only phase spectrum on another output.
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Open the reference file following the procedure described above.
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For normalization it is necessary to use the Preprocess Spectra widget. Input the experimental data from Select Rows in Preprocess Spectra, and conect another input from reference data.
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Open Preprocess Spectra and click in Add preprocessor, select Normalize Spectra and check the box Normalize by Reference for Amplitude and Normalize by Reference (Complex phase) for phase.
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In this case you need to use the HyperSpectra widget.
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Conect the data from Preprocess Spectra in HyperSpectra.
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Open the HyperSpectra and now you can visualized the normalized data.
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In this case you need to use the Spectra widget.
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Conect the data from HyperSpectra in Spectra.
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Open the HyperSpectra and click in the position of interest.
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Open the Spectra and now you can visualized the selected data.