SCATMECH > Example Programs

Example Programs

The following provides examples of how the SCATMECH library can be used in a variety of types of calculations. Since each example has its own main(), each is expected to be linked separately.

BRDFProg -- Polarized light scattering model evaluator
RCWProg -- Reflection or transmission from a grating
ReflectProg -- Thin film reflectance
MieProg -- Mie scattering

Notice that all four examples contain a try/catch block, so that any errors are handled and messages written to the standard error stream (cerr).

BRDFProg

The following example (found in BRDFProg.cpp) asks the user for an incident angle, a range of incident polar and azimuthal angles, and a BRDF model. The program writes to the standard output the principal angle of the polarization, the various degrees of polarizations, and the intensity.


#include "brdf.h"

using namespace std;        // Use unqualified names for Standard C++ library
using namespace SCATMECH;   // Use unqualified names for SCATMECH library

int main(int argv,char** argc)
{
    try {

        // Query user for scattering angles and ranges...
        double thetai = AskUser("Incident Angle ",45.)*deg;

        double thetas_1 = AskUser("Initial Scattering Angle ",45.)*deg;
        double thetas_2 = AskUser("Final Scattering Angle ",45.)*deg;
        double thetas_3 = AskUser("Step Scattering Angle ",1.)*deg;

        double phis_1 = AskUser("Initial Azimuthal Angle ",0.)*deg;
        double phis_2 = AskUser("Final Azimuthal Angle ",180.)*deg;
        double phis_3 = AskUser("Step Azimuthal Angle ",2.)*deg;

        // Get an instance of BRDF_Model...
        BRDF_Model_Ptr model = Get_Model_Ptr();

        // Query user for model parameters...
        model->AskUser();

        // Loop through scattering geometries...
        for (double thetas=thetas_1; thetas<=thetas_2; thetas+=thetas_3) {
            for (double phis=phis_1; phis<=phis_2; phis+=phis_3) {

                // Get the Mueller matrix for scattering...
                MuellerMatrix m=model->Mueller(thetai,thetas,phis,0.);

                // Calculate the Stokes vector for p-polarized incident light...
                StokesVector s=m*StokesVectorUnitP();

                // Print out various light scattering parameters...
                cout << thetas/deg << tab   // Scattering angle (theta)
                     << phis/deg << tab     // Scattering angle (phi)
                     << s.eta()/deg << tab  // Principal angle of polarization
                     << s.DOLP() << tab     // Degree of linear polarization
                     << s.DOCP() << tab     // Degree of circular polarization
                     << s.DOP() << tab      // Degree of polarization
                     << s.I() << endl;      // The intensity (BRDF)
            }
        }

    } catch (exception& e) {

        cerr << e.what() << endl;

    }

    return 0;
}

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RCWProg

The following program (found in RCWProg.cpp) demonstrates how one can use the rigorous coupled-wave (RCW) solution for diffraction from a grating. In this case, it calculates ellipsometric parameters for the normal (specular) reflection or transmission from the grating as a function of wavelength and writes the results to the standard output.

#include "rcw.h"

using namespace std;
using namespace SCATMECH;

int main()
{
    try {

        // Create object...
        RCW_Model RCW;

        // Query user for parameters...
        RCW.AskUser();

        // This keeps RCW from being verbose...
        RCW.set_quiet(1);

        // Display all of the available parameters...
        cerr << endl << "Available parameters:" << endl << endl;
        RCW.print_parameters(cerr);
        cerr << endl;

        // Get parameter to vary, its limits, and its range...
        string parameter=AskUser("Parameter to vary",string("lambda"));
        double begin=AskUser("Initial value",0.200);
        double end=AskUser("Final value",0.800);
        double step=AskUser("Step value",0.005);

        // Output file header...
        cout << parameter << tab << "alpha" << tab << "beta" << endl;

        // Scan parameter...
        for (double value = begin; value <= end; value += step) {

            // Set the parameter...
            RCW.set_parameter(parameter,value);

            // Get the Mueller matrix intensity of the specular (0 order) reflection...
            MuellerMatrix M = RCW.GetIntensity(0);

            // Get the Stokes vector for 45 deg polarized incident light...
            StokesVector S = M*StokesVectorUnitLinear(45.*deg);

            // Output the normalized Stokes parameters measured by a rotating analyzer ellipsometer...
            cout << value << tab << S[1]/S[0] << tab << S[2]/S[0] << endl;
        }

    } catch (exception& e) {

        cerr << e.what() << endl;

    }
    return 0;
}

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ReflectProg

The following program (found in ReflectProg.cpp) demonstrates how one can use the thin film classes to characterize the reflection from a stack of dielectric films.

#include "filmtran.h"

using namespace std;    // Use unqualified names for Standard C++ library
using namespace SCATMECH;


int main()
{
    try {

        // Query user for wavelength...
        double lambda = AskUser("Wavelength",0.633);

        // Query user for substrate...
        dielectric_function substrate =
            dielectric_function::AskUser("Substrate",optical_constant(1.5,0));

        // Query user for films...
        dielectric_stack stack = dielectric_stack::AskUser("Stack","");

        // Loop through angles...
        for (double theta=0; theta<90; theta+=1) {

            // Print out s- and p-polarized reflectances...
            cout << theta << tab
                 << norm(stack.rp12(theta*deg,lambda,vacuum,substrate)) << tab
                 << norm(stack.rs12(theta*deg,lambda,vacuum,substrate)) << endl;
        }

    } catch (exception& e) {

        cerr << e.what() << endl;

    }

    return 0;
}

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MieProg

The following program (found in MieProg.cpp) is a simple Mie scattering program, demonstrating the use of the MieScatterer class.

#include "miescat.h"

using namespace std;        // Use unqualified names for Standard C++ library
using namespace SCATMECH;   // Use unqualified names for the SCATMECH library

int main(int argv,char** argc)
{
    try {

        // Query user for angle and wavelength...
        double dtheta = AskUser("Step angle",1.)*deg;

        // Create a Mie scatterer...
        MieScatterer mie;

        // Query user for parameters...
        mie.AskUser();

        // Output scattering efficiencies...
        cout << "Qsca = " << mie.Qsca()
             << "  Qext = " << mie.Qext()
             << "  Qback = " << mie.Qback() << endl;

        // Output column header...
        cout << endl
             << "Angle" << tab << "S11" << tab << "Pol" << tab << "S33" << tab << "S34" << endl;

        // Get normalization factor at zero angle...
        double m00= MuellerMatrix(mie.s(0.0))[0][0];

        // Loop through angles...
        for (double theta=0.; theta<180.*deg; theta+=dtheta) {

            // Evaluate scattering matrix...
            MuellerMatrix m = mie.s(theta);

            // Output unique elements of normalized Mueller matrix...
            cout << theta/deg << tab
                 << m[0][0]/m00 << tab
                 << m[0][1]/m[0][0] << tab
                 << m[2][2]/m[0][0] << tab
                 << m[2][3]/m[0][0] << endl;
        }

    } catch (exception& e) {

        cerr << e.what() << endl;

    }

    return 0;
}

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Current SCATMECH version: 7.22 (April 2021)