A Sampled Material uses a table of wavelengths and refractive indices to define a material. The refractive index can have real and imaginary parts (i.e., for metals) and the table can be entered by hand, read from a simple text file, or entered using the Digitization tool. The default materials Air, Vacuum, and Standard Glass are all defined as Sampled Materials. Once created, a material Type (i.e. Sampled Material or Model Material) cannot be changed.
This feature can be accessed in the following ways: •Open a materials dialog and select "Sampled Material" as the type
The imaginary component of the refractive index is directly proportional to the absorption (or gain) coefficient at the associated wavelength via the following formula: a = ( 4p * k / l ) where a is the absorption coefficient, l is the wavelength and k is the imaginary part of the refractive index at that wavelength. Absorption is specified with a positive value, no absorption is specified with a value of zero, and gain may be specified with a negative value.
FRED linearly interpolates refractive index data between sampled wavelengths. If the source wavelength lies outside the minimum or maximum sampled wavelengths, then the interpolated refractive index equal to that of the nearest sampled wavelength.
A report of all materials currently contained in the Materials folder can be printed to the output window by right mouse clicking on the materials folder and selecting either "Summary Report" for a brief summary or "Detailed Report" for a complete listing of all the materials defined in the FRED document.
The summary report option prints the name and description of all defined materials.
The detailed report option prints all information relevant to the material including any coefficient specifications, real and imaginary refractive indices and absorption specifications. The wavelengths at which each material is evaluated is generated by searching through all the existing sources for unique wavelengths regardless of whether the source is designated Traceable or Not Traceable.
A material can be applied to a surface via drag and drop onto that surface.
Material wavelengths can be added, deleted, inserted or appended by right mouse clicking in the spreadsheet area and selecting "Add Wavelength", "Delete Wavelength", "Insert Wavelength" or "Append All Source Wavelengths" from the list menu. The last option, "Append All Source Wavelengths", adds a new row to the list for each unique wavelength defined by the sources of the FRED document.
Importing refractive index data from file An alternative to manually entering data is to import the wavelength and refractive index values from an ASCII text file. The file should have on each row: wavelength (in microns), refractive index, and imaginary refractive index delimited by any combination of spaces, commas, or tabs. Right mouse click in the spreadsheet area and select "Replace With Data From a File" from the list menu to open a dialog allowing file selection. The file type must be ASCII text, but the extension is not important (*.txt, *.dat, etc.).
An example of acceptable formatting is shown below.
0.45 1.465 0.0 0.48 1.463 0.0 0.50 1.462 0.0 0.53 1.461 0.0
The file name of the last file accessed can be displayed by right mouse clicking in the spreadsheet area and selecting "Show Last Accessed Filename" from the list menu.
Material data can be specified using FRED's digitization tool by right mouse clicking in the spreadsheet area and selecting "Digitize Material Index" from the list menu. The file input should be an image (*.bmp, etc.) so that the user can select the ordinates, scaling and data points. There is no limit on the number of data points that can be extracted.
All wavelength and index data can be exported to an ASCII text file by right mouse clicking in the spreadsheet area and selecting "Export Data to a File" from the list menu. Use the file dialog to save the data exactly as it is shown; Wavelength, Refractive Index, Imaginary Refractive Index.
|
|||||||||||||||||||||||||||||||||||||||||||||