The Didymium glass filter 666-F7A is made from material specially manufactured by Schott AG. The didymium glass filter’s absorbance behavior in the ultraviolet range also makes it suitable for use as an absorbance filter.

Didymium glass filters are suitable for checking wavelength accuracy (F7W) in the UV-Vis range and photometric accuracy in the UV range.

Absorbance behavior in the UV range can be checked at 270 nm, 280 nm, 297 nm, 321 nm, and 342 nm. Filters are routinely set at a thickness that produces a nominal optical density of 0.5 Abs at 342 nm. This results in increasingly higher absorbances the shorter the wavelengths become.