# Material Editor

Material Editor — MC Grating documentation for Modal Collinear and Modal Conical and Modal Crossed and Chandezon Collinear and Chandezon Conical and…

Canonical: https://mcgrating.com/docs/common/material-editor.html


Written by Nikolay M. LyndinLast revised 2017-12-11

This documentation was written for releases up to 2018 and is being revised. Some dialogs have changed since. If something does not match what you see, write to [mc@mcgrating.com](mailto:mc@mcgrating.com).

This dialog window is accessible from the** *[Material Dialog](https://mcgrating.com/docs/common/material.html).* **
 Three models of refraction index wavelength dependence are implemented: *Drude*, *Schott*, *Sellmeier*, *Herzberger*, and *Table*. The *Drude* and *Table* models are complex, the *Schott*, *Sellmeier*, and *Herzberger* models are real valued.
 The *Drude* model requires two parameters. The index of refraction *n* is given as

![equation](https://mcgrating.com/docs/images/f973bb706e.png)

The *Schott*, *Sellmeier*, and *Herzberger* formulas are defined by six parameters. These formulas assume that imagine part of refractive index is identically *0*, and gives *n* according to formulas.

The Schott formula

![equation](https://mcgrating.com/docs/images/0914ed79ca.png)

The Sellmeier formula

![equation](https://mcgrating.com/docs/images/38da0211fd.png)

The Sellmeier coefficients for many common optical materials can be found in the online database of [https://RefractiveIndex.info](https://refractiveindex.info/).

The Herzberger formula

![equation](https://mcgrating.com/docs/images/98d50d6538.png) , where ![equation](https://mcgrating.com/docs/images/000b79ddbc.png).

The *Table* needs at least one data point. For two points in *Table* the linear approximation is used to calculate refractive indexes. If number of points exceeds two the parabolic approximation is used.
 By default the Material Catalog contains the data for calculation of Air refractive index by special formula:

![equation](https://mcgrating.com/docs/images/e98b675124.png)

Coefficients in Material Catalog for all formulas above assume that the wavelength is in micrometers.
 The following dialog window items need explanation:

- ***Minimum*** and ***Maximum*** wavelength edit controls define the wavelength range where the *Table* and formulas are applicable. Outside this range the refractive index will be set to the value at the nearest wavelength limit. For the *Table* the *Minimum* and *Maximum* wavelength controls are disabled and display the minimum and maximum wavelengths in the *Table*.
- ***Convert*** button allows the user to convert a *Table* data into a new Material Catalog record of formula presentation.
 For *Drude* formula the *Table* should contain at list one point and coefficients are calculated for every *Table* point between *Minimum *and *Maximum* wavelengths followed by an averaging.
 The *Schott*, *Sellmeier*, and *Herzberger* formula coefficients are calculated assuming minimum square deviation of formula and *Table* refractive index values between *Minimum *and *Maximum* wavelengths. In this case the *Table *should contain at list six points.
- ***Ok*** applies all changes in this dialog and closes it.
 The *Table* data will be automatically sorted in wavelength ascending order.
- ***Cancel*** abolishes all changes in this dialog and closes it.

This dialog was used in composition of the main materials catalog and the following sources were used to retrieve some refractive index values:

1. From the reference book Physical values, ENERGOATOMIZDAT, Moscow (1991)
 Reference in catalog: (Table Ru) and (Schott Ru).
2. From GratingSolver 4.20 Demo, [http://www.gsolver.com](http://www.gsolver.com)
 Reference in catalog: (Table GS) and (Drude GS).
3. From the website [http://www.luxpop.com/#index%20of%20refraction%A0](http://www.luxpop.com/#index%20of%20refraction%A0)
 Reference in catalog: (Table).
4. From the paper in Applied Optics Vol. 32 No. 28 p.5587 (1993)
 Reference in catalog: Film (Table).
5. From the website [https://RefractiveIndex.info](https://refractiveindex.info/)
 Reference in catalog: (Sellmeier).

From the in-application help of Modal Collinear and Modal Conical, documented through 2018. If you publish results computed with MC Grating, see [how to cite it](https://mcgrating.com/references.html#cite).