linescan

Linescan Examples

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There are 2 possible file types:

• Raw files, with extension *.gsf
• Spectra files, with extension *.txt

How to open these files?

1. RAW files

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?

• 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

• 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

• 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.

• 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.

• Now you have two diferent files, Phase Spectrum and Amplitude Spectrum.

2. Spectra files

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?

• To open these files you need to have a unique *.txt file.

  • "file name" Spectra.txt → File with all harmonic data

• 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) ".

• In Multifile you need to change in column: name, line: channel type to categorical. It is almost the last line of the file.

• 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.

How to normalized these files using a reference spectrum?

• Open the reference file following the procedure described above.

• 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.

• 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.

How to visualize?

1. Colormaps by position

• In this case you need to use the Spectral Series widget.

• Conect the data from Preprocess Spectra in Spectral Series.

• Open the Spectral Series and now you can visualized the normalized data.

2. Individual spectra by position

• In this case you need to use the Spectra widget.

• Conect the data from Spectral Series in Spectra.

• Open the Spectral Series and click in the position of interest.

• Open the Spectra and now you can visualized the selected data.

3. Colormaps by Wavenumber

• In this case before you use the Spectral Series widget. It is necessary made a transpose of de data.

• Conect the data from Preprocess Spectra in Transpose.

  • Open Transpose and From variable column.

  • Conect a Edit Domain change de Feature name to type: Numeric.

  • If you want, it is possible to change de name to Wavenumber.

• Conect the data from Edit Domain in Spectral Series.

• Open the Spectral Series and now you can visualized the transpose data.

2. Individual spectra by Wavenumber

• In this case you need to use the Spectra widget.

  • Conect a Edit Domain change de Feature name to type: Numeric.

• Conect the data from Edit Domain in Spectra.

• Open the Spectral Series and click in the Wavenumber of interest.

• Open the Spectra and now you can visualized the selected data.