http://people.csail.mit.edu/jaffer/FreeSnell
	The FreeSnell Thin-Film Optical Simulator
	Current Version Released Terms 1c4 2020-02-20 GPL 3.0

FreeSnell is a program to compute optical properties of multilayer thin-film coatings.

FreeSnell is an application of the SCM Scheme implementation and the WB B-tree database package.

News

FreeSnell-1c4 is a minor release. Details at http://cvs.savannah.gnu.org/viewvc/*checkout*/freesnell/freesnell/ChangeLog

• usercat: Removed "../FreeSnell/" from paths.

x86 MS-Windows Installation

• Obtain slib-3c1-1.exe (1.1.MB) and run.
• Obtain scm-5f4-1.exe (475.kB) and run.
• Obtain FreeSnell-1c4-1.exe (700.kB) and run.

x86_64 GNU/Linux with RPM Installation

• Obtain SLIB, SCM, WB, and FreeSnell:

        #! /bin/sh
        wget http://groups.csail.mit.edu/mac/ftpdir/scm/slib-3c1-1.noarch.rpm
        wget http://groups.csail.mit.edu/mac/ftpdir/scm/scm-5f4-1.x86_64.rpm
        wget http://groups.csail.mit.edu/mac/ftpdir/scm/wb-2b4-1.x86_64.rpm
        rpm -U slib-3c1-1.noarch.rpm scm-5f4-1.x86_64.rpm wb-2b4-1.x86_64.rpm
        wget http://groups.csail.mit.edu/mac/ftpdir/scm/FreeSnell-1c4.zip
        unzip FreeSnell-1c4.zip
        (cd FreeSnell; ./configure --prefix=/usr/local/; make install)
    

Unix (Including GNU/Linux) Installation

• Obtain SLIB, SCM, WB, and FreeSnell:

        #! /bin/sh
        wget http://groups.csail.mit.edu/mac/ftpdir/scm/slib-3c1.zip
        wget http://groups.csail.mit.edu/mac/ftpdir/scm/scm-5f4.zip
        wget http://groups.csail.mit.edu/mac/ftpdir/scm/wb-2b4.zip
        wget http://groups.csail.mit.edu/mac/ftpdir/scm/FreeSnell-1c4.zip
        unzip -o slib-3c1.zip
        unzip -o scm-5f4.zip
        unzip -o wb-2b4.zip
        unzip -o FreeSnell-1c4.zip
        (cd slib; ./configure --prefix=/usr/local/; make install)
        (cd scm; ./configure --prefix=/usr/local/; make all; make wbscm.so; make install)
        (cd FreeSnell; ./configure --prefix=/usr/local/; make install)
    

Viewing Graphs

FreeSnell generates (encapsulated) PostScript graphs for output. If you have ImageMagick and GhostScript installed, then FreeSnell will use the ImageMagick convert program to translate these .eps files to other graphics formats:

• ImageMagick: Install from Binary Distribution
• Ghostscript, Ghostview and GSview

You can view the PostScript .eps files with GhostView (Unix gv) or GSview (MS-Windows).

Running

To run FreeSnell in MS-Windows from the C:\Program Files\FreeSnell diretory, click on the FreeSnell desktop icon. In Unix, from the FreeSnell directory run scm.

You can then type expressions to the SCM interpreter. To run FreeSnell's regression suites type:

  (load "dielectric.scm")
  (dielectric)
  (load "metallic.scm")
  (metallic)
  (load "granular.scm")
  (granular)
  (load "coherence.scm")
  (coherence)
  (load "polyethylene.scm")
  (polyethylene)

To exit SCM type (exit).

Documentation

• Online FreeSnell Manual or FreeSnell.pdf

The validation source files are a good source for design examples.

	Refractive Index Spectra. Parametric Data Tabular Data The nk Spectral Database Management Script Wedged Databases Building Refractive-Index Databases
	Validation suite of dielectric filters; generated from "dielectric.scm". Bandpass Filter Polarizers Anti-Reflection Coatings Dielectric Mirrors
	Validation of metallic films; generated from "metallic.scm". Thick Reflective Metal Thin Metal Films Matching Measured Data Colors of Zinc Sulfide
	Validation of granular films; generated from "granular.scm". Maxwell Garnett Theory Gold Ruby Glass IRG-II GranFilm The Colors of Silver and Gold Films
	How thick films work in FreeSnell; generated from "coherence.scm". Coherence Incoherence Gaussian Filtering Huge Layers
	Characterizing Polyethylene; generated from "polyethylene.scm". Background Emissivity Absorption Lines Thin HDPE Films Thick HDPE Films Short Wavelengths

FreeSnell Development

• Savannah: CVS Repository freesnell/freesnell
• Development Snapshot FreeSnell.zip (760.kB)
• FreeSnell discussion mailing list

Volunteer opportunities

• Implement reading and writing of designs in Optical-Thin-Film-Exchange format.
  Click to join otfe.
  
• Another potential source of refractive-index spectra is http://www.rpi.edu/~schubert/Educational resources/Materials - refractive index and extinction coefficient.pdf, although the PDF does not facilitate easy extraction of the data.
• The Stony Brook Optical Constant Database has spectral infrared n and k values (in separate files) for over 20 minerals.

Related Software

FreeSnell and SimRoof were originally written to support Radiative Cooling in Hot Humid Climates, which employs infrared-transparent cold mirror roof panels.

Another Free-Software thin-film program is OpenFilters:

OpenFilters offers multiple tools for the design and optimization of optical interference coatings, including refinement, the needle method, the step method, the Fourier transform method and multiband rugates. It has the ability to optimize a stack to match a target response.