Transmittance filters

GOLD provides transmittance filters with these features:

• Peak wavelength can be selected at wavelengths of 120 nm and longer.
• Bandwidth can be selected with FWHM of ~ 10 nm and wider
• Long-wavelength rejection can be selected up to the range of ~ 10^-6.

The filters are made with multilayers of Al/MgF₂ or Al/AlF₃.

The transmittance at the peak wavelength is very dependent on the long-wavelength rejection and on the bandwidth. A larger rejection of the long wavelengths results in a smaller peak transmittance. A narrower band often results in a smaller peak transmittance, but also in a larger long-wavelength rejection.

Here are two examples of filters with a strong rejection of the visible.

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