# fresnel

Example of input parameters to run `start` using Fresnel data.

## Contents

- Syntax and Example
- Input Arguments
- References
- See Also
- Code

## Syntax and Example

    inseti = 'fresnel';
    start

- General information about using `inseti` are in example.html
- Make sure that the experimental data from Institute Fresnel are in the correct folder, in this case: `inexpdata/fresnel_opus_1/twodielTM_8f.exp`.
- Real-world data from Institute Fresnel are not part of this package. You have to download them separately, see readRAWData.html.

## Input Arguments

Specific input arguments to use the computational framework with data from Institute Fresnel:

- seti.expData = 'fresnel'; : in general to use experimental data from Institute Fresnel (currently no other data is available).
- seti.nuMax : 2*nuMax+1 coefficients are computed for polynomial approximation, see matchIncField.html for details.
- seti.ampCalc : method to compute coefficients, we recommend 1, see matchIncField.html for details.
- seti.fresnelFreq : Frequency in Hz (make sure that data for this frequency is available, see [1] and [2])
- seti.fresnelFile : Path to *.exp-file with data from Institute Fresnel

For other fields in struct `seti` see setiRef.html.

## References

- [1] Kamal Belkebir and Marc Saillard. Special section on testing inversion algorithms against experimental data. Inverse Problems, 17(6):1565-1571, 2001. URL: https://doi.org/10.1088/0266-5611/17/6/301.
- [2] Jean-Michel Geffrin, Pierre Sabouroux, and Christelle Eyraud. Free space experimental scattering database continuation: experimental set-up and measurement precision. Inverse Problems, 21(6):S117, 2005. URL: https://doi.org/10.1088/0266-5611/21/6/s09.

## See Also

- example.html
- readRAWData.html
- matchIncField.html
- setiRef.html

## Code

    % -- setGrid
    seti.dim = 2;
    seti.rCD = 0.2;
    seti.nCD = 256;

    % -- setKernel
    seti.model = 'helmholtz';

    % -- setExpData
    seti.expData = 'fresnel';
    seti.nuMax = 10;
    seti.ampCalc = 1;

    % -- reconstruction
    seti.beta = 1E-5;
    seti.alpha = 500;
    seti.tau = 1.6;

    seti.physBounds = [-1,3,0,1];

    seti.nOut = 20;
    seti.useDis = 1;

    seti.pdaStepsize = 'fix';
    seti.pdaN = 10;

    % -- figures and files
    seti.usecbarlim = 1;
    seti.cbarlim = [-0.40,2.40];

    seti.plotPublish = 1;
    seti.plotFreq = 10;
    seti.plotFreqiPda = 0;
    seti.savedata = 0;

    % -- Fresnel: 2 dielectrics with 5 GHz
    seti.delta = 0.25;
    seti.fresnelFreq = 5*1E9;
    seti.fresnelFile = 'inexpdata/fresnel_opus_1/twodielTM_8f.exp';