newAD2 - optical characterization software

Yeh matrices

Yeh matrices represent boundary systems and can be used to construct the structural models using the Yeh matrix formalism. There are available boundary and transfer matrices as well as more complicated constructs that can be used to define complicated systems.

Boundary matrices

Simple boundary matrix
```
B(left_medium, right_medium[, roughness_RMS, roughness_correlation_length])
```
This is a simple boundary matrix used to model the boundary between two media. The first two parameters are the corresponding definitions from the media section. Optional roughness_RMS and roughness_correlation_length describe the boundary roughness. If they are omitted, a flat boundary model will be used. If only roughness_RMS is added, a simple Drude model will be used for roughness. If both are specified, the roughness will be modeled using the Rayleigh-Rice theory.

Transfer matrices

Simple transfer matrix
```
T(medium, thickness_parameter[, right_medium])
```
This is a simple transfer matrix through a film described by medium, with thickness thickness_parameter. If the optional right_medium is specified, the linear inhomogeneous model will be used, modeling a linear interpolation of the optical constants between the left and right media over the film thickness.

Advanced matrices

Scalar Diffraction Theory (SDT)
```
BSDT(left_medium, Boundary1, right_medium, sigma[, tau])
```
Roughness is modeled using the Scalar Diffraction Theory (SDT). The Boundary1 parameter can be set to any of the other boundary matrices, so you can use this, for example, to combine SDT with RRT to model a surface with both long- and short-range roughness. BSDT can also be used to model layer roughness from both sides. Use the following syntax:
```
BSDT(left_medium, Boundary1, right_medium, Boundary2, middle_medium, d, sigma1[, tau1])
```
In this case the SDT will be applied on both sides of the medium middle_medium with thickness d. To model correlated roughness with different RMS values, use:
```
BSDT(left_medium, Boundary1, right_medium, Boundary2, middle_medium, d, sigma1, sigma2, C12)
```
where C12 is the cross-correlation coefficient of the top and bottom boundaries.
Identical rough layer
```
BIRL(left_medium, middle_medium, right_medium, sigma, tau[, tau2, eta])
```
This is the advanced matrix for the special case of a rough boundary, a film, and a second rough boundary with identical roughness parameters.

Examples of model construction using the Yeh matrix formalism

Flat boundary:

B(ambient_medium, substrate_medium)

Flat thin film:

B(ambient_medium, film_medium)*T(film_medium, thickness_parameter)*B(film_medium, substrate_medium)