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In this problem, you will use the ``night-time speckle effect'' and
then use that effect to make an arm-chair estimate of the value of
Planck's constant h.
When we observe objects at low illuminations we see ``static'' similar
to what one might see on a television set. In this question we
investigate the issue of whether this might be due to the randomness in the
arrival of photons, so called ``photon shot noise.''
We will use the following rough observations about the human eye,
which you could make yourself.
- The ``response/sampling'' time for the human eye is
somewhere between the imperceptible cycle time of fluorescent lighting
and the noticeable flicker of old-time movies at 15 frames per second,
- The resolution of the human eye is
(the angle of a
single pixel on a
CRT at a viewing distance about 30 cm). This
corresponds to a solid viewing angle of each receptor of about
st. rad. - The radius of the pupil (the aperture through which light
enters the eye) is 0.4 cm making the total area over which it
gathers light
- The human eye can perceive fluctuations in brightness on the
order of about f=3% of the power received. (8 bits is more than
enough to digitally encode black and white pictures.)
Prof. Tomas Alberto Arias
Thu Feb 6 11:34:49 EST 1997