We offer interference filters, especially suited for colorimetric applications.
Made with non-hydroscopic materials, these filters have much improved longevity in harsh environments compared to standard “off the shelf” soft hydroscopic film filters, which begin to degrade after as little as one year. Our Interference Filters have an anticipated working life of five years.
The center wavelength of the filter will shift toward shorter (blue) wavelengths as the angle of incidence increases; the greater the angle the greater the shift. This is known as blue shifting.
A thin silver spacer is placed between colour glass plates, multiple reflections and interference can be used to select a narrow frequency band, producing an interference 
filter.
If the spacer is properly selected for the desired wavelength, then other wavelengths will be attenuated by destructive interference and choice of colour glasses. These devices are designed for normal incidence, and shift in wavelength to shorter wavelengths if tilted.
Made with non-hydroscopic materials, these filters have much improved longevity in harsh environments compared to standard “off the shelf” soft hydroscopic film filters, which begin to degrade after as little as one year. Our Interference Filters have an anticipated working life of five years.
The center wavelength of the filter will shift toward shorter (blue) wavelengths as the angle of incidence increases; the greater the angle the greater the shift. This is known as blue shifting.
Available band pass (@ FWHM) 30 nm +/- 5 nm Available center wavelengths 380 nm, 430 nm, 490 nm, 520 nm, 540 nm, 590 nm, 630 nm, 660 nm, 700 nm, 750 nm, 815 nm, 880 nm. Center wavelength tolerances +/- 5 nm
Dimensions
Diameter : 20 mm. Thickness: depending on the wavelength the filter thicknesses are from 4 mm to 9 mm.