Criterion Function

The Optimization procedure objective is the minimum mean-square deviation of the user defined values assigned in the Criterion Function from the calculated values. The user can construct this function in the form of a number of (Number of Points) completely independent criterion points. The Point control provides the possibility to select the criterion point index. By clicking the mouse right button at this control the user activates the Popup Menu for editing the criterion points.
There are two types of Criterion Function i.e. one for the diffraction efficiencies and one for the angular resonance positions of the modes of the structure. The choice depends on the state of the Optimization Type control (available only in collinear versions).
In the first type of Criterion Function every criterion point targets the assigned power of the given diffraction order (edit control Value) with the Weighting Factor of this criterion point within the whole criterion function and its characteristics (Diffraction Order and Cover/Substrate propagation). In the conical mount version there is an additional criterion point characteristic – Output Polarizer and its orientation (edit control Angle). All these characteristics are placed in the Criterion Diffraction Order Power panel. The right hand Criterion Arguments panel contains other parameters. These arguments are: the polarization type, the incident conditions (Angle or Normal Angle and Plane Angle in the conical mount version) and the Wavelength and the grating Period. The edit controls of the corresponding Variable parameters are inactive.

During the Optimization process these two panels are inactive, but at the bottom of the left panel under the label Current Power Value the user can see the updated every second power of the appropriate diffracted wave. In addition this information will be updated every time the user changes the criterion Point index.
In the second type of Criterion Function every criterion point targets a set of assigned angular resonance positions (the latter corresponds to the maximum resonant reflection in the cover or to the maximum mode excitation). The cover refractive index in the Criterion Arguments panel is an additional parameter for this type of Criterion Function.

Note During the Optimization process the asterisk may appear at the right of the Point label. This means that for this point an iteration number in resonance position search exceeds the limit. In that case the advice is to try for this criterion point an alternative Resonance Type search.