# newAD2 - optical characterization software

This web page was created in the FRMU project no. 1350/2015 to serve as a learning material for courses F8130 - Advanced dispersion models in thin film optics, F8542 - Experimental methods and special laboratory and F8120 - Optics of thin films.

newAD2 is software for optical characterization which can model optical quantities by various models and it can fit these quantities to measured data by the method of least squares. It is linux software supporting parallel calculations distributed by pvm, primary intended for use at heterogeneous servers. It can be installed on personal computers as well, however, a longer computing time must be expected for numerically demanding models.

Realistic models
newAD2 is able to model the main sample non-idealities manifested in optical measurements. These namely include roughness of the sample interfaces which can besides others be modeled by RRT (Rayleighr-Rice Theory), vertical inhomogeneity, i.e. profile of dispersion parameters, planar non-uniformity in any parameter and transitional layers.

Physical models of instruments
Apart from dispersion and structural parameters also correction parameters of individual experimental instruments can be fitted on basis of physical models of the instrument non-idealities.

Wide spectral range
Optical constants in newAD2 can be modeled in wide spectral range from far infra-red region up to vacuum UV or synchrotron radiation. For that, numerous dispersion models can be used - ranging from simple, empiric or classical models to very complicated models based on recent findings if condensed matter physics.

Multisample methods
newAD2 enables to simultaneously fit experimental data of different samples with some common properties, which allows to reduce correlations between parameters.

Data from multiple instruments
It is possible to fit data from different instruments simultaneously.

Multiple physical quantities
It is possible to simultaneously fit multiple physical quantities, for example transmission, reflectances from the both sides, ellipsometric quantities etc.

Difference and relative data
It is possible to fit difference and relative data, for example differences of ellipsometric quantities of ratio of reflectances.

Tabulated data
Tabulated data are a bit special in newAD2. Dielectric response of known materials cannot be modeled directly by using tabulated values, but it has to be modeled by suitable dispersion model together with experimental data.

User interfaces
newAD2 can be by controlled by graphical user interface or by command line. Text interface is convenient for writing scripts for automatic batch processing.