Dispersion Staining, Becke' Line
Becke' Line Dispersion Staining was first documented in
1911 by F. E. Wright in Publication #158 by
the Carnegie Institute. He noted that when a particle and a liquid matched
refractive indices for some
wavelength in the visible range but they had different dispersion curves
then two Becke' lines would
be formed on defocusing the particle. The Becke' line for the blue end of
the spectrum would move
into the material with the steepest dispersion curve and the Becke'line for
the red end of the
spectrum would move into the material with the flatest dispersion curve.
The first two images below show a refractive index match at 589 nanometers
wavelength
Test with Interference Filters
Match at 590 nanometers wavelength
Match at 530 nanometers wavelength
Match at 550 nanometers wavelength
Match at 460 nanometers wavelength
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