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damitr
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What is the lowest intensity of light that generates any stimulus in the human eye? In what wave length range?
IIRC you can actualy see single photon events with the eye rod system.damitr said:What is the lowest intensity of light that generates any stimulus in the human eye? In what wave length range?
... neural filters only allow a signal to pass to the brain to trigger a conscious response when at least about five to nine (photons) arrive within less than 100 ms. If we could consciously see single photons we would experience too much visual "noise" in very low light, so this filter is a necessary adaptation...
At any given instant, the retina can resolve a contrast ratio of around 100:1 (about 6 1/2 stops). As soon as your eye moves (saccades) it re-adjusts its exposure both chemically and by adjusting the iris. Initial dark adaptation takes place in approximately four seconds of profound, uninterrupted darkness; full adaptation through adjustments in retinal chemistry (the Purkinje effect) are mostly complete in thirty minutes. Hence, over time, a contrast ratio of about 1,000,000:1 (about 20 stops) can be resolved. The process is nonlinear and multifaceted, so an interruption by light nearly starts the adaptation process over again. Full adaptation is dependent on good blood flow; thus dark adaptation may be hampered by poor circulation, and vasoconstrictors like alcohol or tobacco.
A light-adapted eye typically has its maximum sensitivity at around 555 nm, in the green region of the optical spectrum
The lowest light intensity that can stimulate the human eye is approximately 0.000001 lux, which is equivalent to the light of a single candle from about 30 miles away.
The wavelengths of light that can stimulate the human eye at the lowest intensity are between 400-700 nanometers, which is the visible light spectrum.
The human eye responds to low light intensity by activating the rods in the retina, which are sensitive to dim light. This allows us to see in low light conditions.
Prolonged exposure to low light intensity does not typically cause damage to the human eye. However, it can cause eyestrain and fatigue, as the eye has to work harder to see in low light conditions.
Exposing the human eye to low light intensity can have some health benefits, such as improving night vision and reducing the risk of nearsightedness. However, it is important to maintain a balance and not expose the eyes to excessively low light levels.