http://people.csail.mit.edu/jaffer/FreeSnell/dielectric.html

FreeSnell: All-Dielectric Optics


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

This validation suite is from "dielectric.scm", part of the FreeSnell package. "dielectric.log" is the text generated by running dielectric.scm:

scm -l dielectric.scm > dielectric.log

Bandpass Filter

Lets start with some all-dielectric filters simulated with constant (not wavelength dependent) indexes of refraction.

Here is a 47-layer Wide Infrared Bandpass Filter produced by Software Spectra, Inc.'s TFCalc program, which incrementally optimized its design.

TFCalc
FreeSnell

Polarizers

In "Immersed Wide-Angle Polarizer" the blue region is the envelope of many wavelengths swept over angle of incidence.

TFCalc
FreeSnell

In "New Thin Film Polarizing Beamsplitter" looks at angles from 65 to 75 degrees while sweeping over wavelength.

TFCalc
FreeSnell

Anti-Reflection Coatings

There are two "6-layer antireflection coatings" in "Basics of Optics of Multilayer Systems" from OptiLayer Thin Film Software

OptiLayer
FreeSnell

This "8-layer antireflection coating" is from "Basics of Optics of Multilayer Systems" from OptiLayer Thin Film Software

OptiLayer
FreeSnell

"Growing an Antireflection Coating" from Software Spectra, Inc. does not exactly match; but is close.

TFCalc
FreeSnell

Dielectric Mirrors

"(HL)7H on glass" is an example of "Dielectric Multilayers" from JK Consulting.

JK Consulting
FreeSnell

"Cold Mirror" from JK Consulting is a stack:

G 1.2(.5H L .5H)5 1.0(.5H L .5H)5 0.8(.5H L .5H)5 2L

where:

Although it acts as a mirror, this design is composed entirely of dielectric materials.

JK Consulting
FreeSnell

The FreeSnell stack is written:

(optical-stack (substrate 1)
               (nominal nom)
               (layer SiO2 1/2)
               (nominal (* 0.8 nom))
               (repeat 5
                       (layer TiO2 1/8)
                       (layer SiO2 1/4)
                       (layer TiO2 1/8))
               (nominal (* 1.0 nom))
               (repeat 5
                       (layer TiO2 1/8)
                       (layer SiO2 1/4)
                       (layer TiO2 1/8))
               (nominal (* 1.2 nom))
               (repeat 5
                       (layer TiO2 1/8)
                       (layer SiO2 1/4)
                       (layer TiO2 1/8))
               (substrate glass))

"Cold Mirror" from Software Spectra, Inc.'s TFCalc program.

TFCalc
FreeSnell
TFCalc
FreeSnell

"Broadband High-Reflection Coating at 50 Degrees" from Software Spectra, Inc.'s TFCalc program.

TFCalc
FreeSnell

"Dielectric Omnidirectional Reflector" from Software Spectra, Inc.'s TFCalc program treats the metal Tellurium as a dielectric with a fixed index of refraction. FreeSnell matches well midband; less so elsewhere.

TFCalc
FreeSnell

The next section tests FreeSnell's modeling of metal films.


Copyright © 2003, 2004, 2005, 2006, 2012 Aubrey Jaffer

I am a guest and not a member of the MIT Computer Science and Artificial Intelligence Laboratory.  My actions and comments do not reflect in any way on MIT.
FreeSnell
agj @ alum.mit.edu
Go Figure!