Category Archives: Computing and fitting spectra

Thickness fits: Automatic slider range

Starting with object generation 4.77 you can generate low and high limits for fit parameters automatically when you generate them – at least for thickness values. In the fit options dialog (File/Options/Fit) you can set a percentage (lower right corner) which is used to compute the low and high limit of the available thickness range. The reference value is the thickness value at the time the new fit parameter is generated.

Note that the automatically generated range is also the range of parameter sliders that are based on fit parameters.

Note also that you can automatically generate thin film thickness values as fit parameters by drag&drop of a layer stack to the list of fit parameters in the treeview. If the list of fit parameters is shown in a view this is certainly the fastest way of generating thickness sliders.

Here is an example showing sliders with limits of +/-5% that have been generated automatically:

Batch import using Excel files

If you have used the option to export measured spectra in CODE using Excel format you can now import these spectra in batch mode.

There is a restriction, however: The spectra must be stored in the first worksheet of the Excel document, with the first wavelength in cell A1.

The number of the file format to be used in the batch control sheet is 27.

This feature is available starting with object generation 4.48.

 

Difference spectra

How can I display the difference of simulated and measured spectra?

Sometimes it is advantageous to inspect the difference of simulated and measured spectra in order to find out about appropriate model extensions. Please read the instructions below to activate the drawing of difference spectra.

Open the spectrum for which you want to see the difference with a right-click in the treeview. Select the local menu command File/Options/Difference/Show to turn on the difference display. This menu item is a checked property: Clicking on it changes its status from checked to unchecked or vice-versa.

The additional menu commands File/Options/Difference/Pen and File/Options/Difference/Line mode are used to control the appearance of the difference curve. Use these settings to clearly separate the difference curve from the simulated and measured spectra. You can use, for example, pen 3 (green by default) and line mode 3 (dashed).