The opposite of visual persistence time...

[Externet]

The time for visual persistence is typically taken as 1/30th of a second; what is the minimal time a light should be on to recognize its brief presence ?

Example, a high speed mechanical shutter wheel in front of a light source.  (Or a pulse on LED)  The light passes a slot to the eye for one millisecond.  Probable visible.  What if one microsecond ?  Would that time be long enough to be detected by the eye ?   

Is there a name for that 'time sensitivity' ?

[swansont]

It’s going to depend on how bright the light is, since this is related to how many photons you need to collect to see it.

[Externet]

Thank you.

Found some reading on the photons subject.  Believe there is no such thing as half a photon, right ?

----> https://math.ucr.edu/home/baez/physics/Quantum/see_a_photon.html#:~:text=Since only about 10% of,actually required at the receptors.