The
paintings of Georges Seurat consist of closely spaced small dots
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Solution: Click For PDF Version Because of diffraction effects, dots of 2 mm diameter will cease to be resolved by eyes, if viewed from a distance beyond the Rayleigh’s criterion limit.The
Rayleigh’s criterion is that two objects when viewed by a lens
of aperture d using
light of wavelength
For the problem the data are
and
Therefore, dots separated by 2 mm will cease to remain resolved when viewed from a distance l given by the following relation:
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of pure pigment, as indicated in the figure.
The illusion of colour mixing occurs because
the pupils of the observer’s eyes diffract light entering them.
We have to calculate the minimum distance an
observer must stand from such a painting to achieve the desired
blending of colour. We
may take the wavelength of the light to be 475
nm and the diameter of the pupil to be
4.4 mm.
will cease to be resolvable if their angular
separation is less than
:
,
.