On May 24, 10:24*am, (Richard Harrison)
wrote:
Cecil Moore, W5DXP wrote:
"It has been demonstrated that light-sensitive cells in your eye (rod
cells) are able to detect single photons."

From Navy lectures on night vision in WW-2, I remember that cone cells
are used for day vision and rods are used at night.

The cones cannot detect single photons. It takes many photons to
activate the cones. It only takes one photon to activate a rod.
Unfortunately, the rod is more sensitive than the rest of the path to
the brain so it takes about 9 photons to result in an impulse to the
brain.
--
73, Cecil, w5dxp.com