OpenFilters: open-source software for the design, optimization, and synthesis of optical filters

Abstract

The design of optical filters relies on powerful computer-assisted methods. Many of these methods are provided by commercial programs, but, in order to adapt and improve them, or to develop new methods, one needs to create his own software. To help people interested in such a process, we decided to release our in-house software, called OpenFilters, under the GNU General Public License, an open-source license. It is programmed in Python and C++, and the graphical user interface is implemented with wxPython. It allows creation of multilayer and graded-index filters and calculation of reflection, transmission, absorption, phase, group delay, group delay dispersion, color, ellipsometric variables, admittance diagram, circle diagram, electric field distribution, and generation of reflection, transmission, and ellipsometric monitoring curves. It also provides the refinement, needle, step, and Fourier transform methods.

Cold mirror based on High-Low-High refractive index dielectric materials

“…The open filter uses transfer matrix method to analyze the transmission and reflection of light from layers based on thickness and type of materials. Designs are optimized to maximum the transmission required at wavelengths using needle synthesis method (addition of thin layers called needle and analyze transmission till the best results obtained) [11]. The thicknesses of the layers for cold mirror based on TiO2 68 13 TiO2 72 14 MgF2 130 14 SiO2 123 15 TiO2 48 15 TiO2 54 16 MgF2 118 16 SiO2 106 17 TiO2 87 17 TiO2 93 18 MgF2 54 18 SiO2 53 19 TiO2 79 19 TiO2 80 20 MgF2 228 20 SiO2 218 Total thickness 1639 Total thickness 1669 Fig.…”

A photodiode-based neutral particle bolometer for characterizing charge-exchanged fast-ion behavior

“…In order to attenuate photon energies in the visible to EUV range we chose a tungsten filter coating for its low transmittance up to ∼80 eV, according to available transmittance data. 12,13 Using this data and the Stopping and Range of Ions in Matter (SRIM) code 14 we determined that a 40 nm coating should provide sufficient attenuation of photons and remain sensitive to neutrals with energy >5 keV, for the possible detection of the E/3 component of neutral beam injected fast ions.…”

Multilayer dielectric stack Notch filter for 450-700 nm wavelength spectrum

“…Open filter calculates optical properties of filters. It uses transfer matrix method to calculate the transmission and reflection properties of filters based on the absorption and materials refractive indices [9]. Optimization techniques are available in this software like needle synthesis (Adding an extra layer to give targeted transmission).…”