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purpleoctopuppy t1_ixtgxg3 wrote

Going off this, nine photons in 100 ms at 510 nm is sufficient for people to see, which is 90 photons per second, or 3.5e-17 W. Pupil is about 8 mm across, so that's 5e-5 square metres, so on the order of e-12 W/square metre at the lower end.

Keep in mind our sensitivity to different wavelengths is different, so it's important that this is at 510 nm, and not generalisable beyond that.

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Bbrhuft t1_ixtmeue wrote

Researchers a few years ago discovered that humans can see single photons.

>Here we report that humans can detect a single-photon incident on the cornea with a probability significantly above chance. This was achieved by implementing a combination of a psychophysics procedure with a quantum light source that can generate single-photon states of light. We further discover that the probability of reporting a single photon is modulated by the presence of an earlier photon, suggesting a priming process that temporarily enhances the effective gain of the visual system on the timescale of seconds.

Tinsley, J.N., Molodtsov, M.I., Prevedel, R., Wartmann, D., Espigulé-Pons, J., Lauwers, M. and Vaziri, A., 2016. Direct detection of a single photon by humans. Nature communications, 7(1), pp.1-9.

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purpleoctopuppy t1_ixtmrws wrote

Oh cool! Last I read is that our eyes could detect a single photon, but our brain would filter it out, good to know there's been progress in this! Being a single-photon detector is a cool flex.

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[deleted] t1_ixvk435 wrote

[removed]

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Bbrhuft t1_ixvwxhc wrote

The energy carried by a single photon of 500 nm light is 4.0 × 10^−19 J.

The approximate conversion is 1 Lux = 0.0079 W/m^2 for sunlight that has a peak at 500 nm.

3.16 × 10^21 lux.

The brightness at noon at the equator is 111,000 lux, of which (albedo) for bright sand is 0.4. So sand in desert at the equator at noon, will be around 44,000 lux.

Which is a dynamic range of approximately 1.4 × 10^25 .

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DeismAccountant OP t1_ixvzbjf wrote

Wait is this maximum or minimum?

Thank you so much but I’m sorry I’m so confused. Unless one is minimum and the other maximum.

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DeismAccountant OP t1_ixtilm5 wrote

So 10^-12 as the minimum? Thanks!

Now how to make that apply to 1,000,000nm and 10nm respectively 😅

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ozspook t1_ixu1u4f wrote

>1,000,000nm

is radio, specifically 240GHz millimeter band which would be radar, basically.

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DeismAccountant OP t1_ixvjoqy wrote

It’s the peak/maximum of infrared too though? It equals 1mm, and is where infrared and radio meet?

Edit: Microwaves before Radio.

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ozspook t1_ixx9sae wrote

It's around the high end of the red-shifted Cosmic Microwave Background, your usual sensors for such are MEMS radiometer arrays or graphene bolometers cooled to near absolute zero.

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DeismAccountant OP t1_ixxk2zz wrote

What would you propose as an alternative maximum to infrared then? 300,000nm? 20,000nm?

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