Photon counting for the masses

On a sunny day (Thu, 03 May 2012 07:18:53 -0700) it happened John Larkin wrote in :

'single photon' vision is complete bullocks.

Just as a hint, and I predicted that not so long ago, some guys did light measurements on LEDs with super low current, and found the efficiency was > 100%.

Some time before that I pointed out (sci.physics) that theoretically due to thermal and other environmental effects, electrons may just get enough kinetic energy so that they require less than Planck's idea of energy to leave. In the same way electron orbital changes can emit quanta of light when triggered by less energy than your f*cking non existing photon. Lets just say: disturbance of the ether.

In a living being, with high temperature, this effect must be huge. This is totally contradictory to QM ideas of detectors needing to be at close to zero temperatures. Next time I hear somebody use the word 'photon' I .... But you WILL notice it :-)

It's true that people tend to cluster in groups at night for safety, sing around the campfire and such. Even warfare, competition between groups, is mostly conducted by daylight, at least was until radar and night-vision devices were invented.

So, what is the evolutionary payoff? What about our visual system is so improved that it's worth trading away night vision? People here seem to be arguing that night vision is in itself useless or detrimental, and that doesn't make sense.

Possibly high quality color vision is more useful to humans than raw photon sensitivity, and they trade off.

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John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com   

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

That's probably the tradeoff. Weapons, construction of shelter, fire, socialization allow us to cluster and defend ourselves at night. So we can fill our retinas with cones and improve our daytime color vision and resolution at the expense of night vision. So we probably evolved away our photon sensitivity fairlty recently, few hundred thousand years maybe, as we became more human. I wonder if, to this day, some groups around the world are different as ragards this tradeoff. After all, most research is done on Western college students.

Still, single-photon sensitivity would be cool.

You can certainly use a gen-3 image intensifier to see photon-delineated scenes in near-total darkness. And those scenes are sufficiently useful that police and the military pay big bucks for the equipment. Light sure behaves as if it's made of discrete photons.

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John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com   

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

Then why is there a market for night-vision intensifiers? Why can I see a black cat under a desk in a dark room, with my cheap gen-1 Russian intensifier, that I can't see without it?

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John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com   

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

Mainly because you can come badly unstuck moving around in darkness.

Ninja and the like tended to use cover of darkness.

Motion detection - and our night vision is only inferior to the big cats by about a factor of three on retinal sensitivity. They get an extra factor of two from the mirror structure behind their retina (and have to live with the quirks of an asymmetric point spread function from an elongated iris - which allows greater mechanical adaptation).

Yes it does. You don't want the brain overloaded with random shot noise so the does local processing. The human vision threshold is pretty close to the optimum for the eye. Our lateral vision is better at night than looking straight ahead and the eye is optimised for spotting movement at the edge of visual field even at low light levels.

In strong light the utility of the eye is reversed the cones give full colour high resolution imaging but at a fraction of the sensitivity.

No. It is spotting movement either predator or prey in the visual field. You have to tolerate some loss of absolute sensitivity to get reliable detection of movement without too many false positives.

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Regards,
Martin Brown

Because it extends the range of what we can do with the unaided eye. You might just as well ask why we can't see in the thermal band IR - some snakes can and it definitely helps them find warm blooded prey.

Humans evolved in an arms race with their preditors and prey. The eye we ended up with is the one which on average maximises survival. Spotting movement of something you can eat or is intending to eat you is actually more valuable than absolute sensitivity.

I am surprised you can see anything useful though a gen-1 image intensifier they almost all have huge background noise levels of ghoulish green glow. Maybe modern gen-1 gear is better but I doubt it. You would see things a lot better if you had the patience to become dark adapted which takes more than an hour in near total darkness.

Image photon counting came of age in the late 1970's when a combination of microchannel plates, video cameras and fast electronics were used to make image photon counting detectors for astronomy at Imperial College London - the technique still has a few niche uses even today!

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Regards,
Martin Brown

My only patent (7,019,307), which I discovered accidentally some years after it was issued, involves a microchannel plate stack and a 2-d delay-line detector. This can resolve the X-Y-time of single ion or photon hits on a surface. Most people hang a CCD after the MCP stack, but electronically detecting every pulse in real time has uses. Makes you almost want to believe in photons.

Just call me "et al"

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John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com   

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

Interesting paper, thanks. I need to build a test gizmo to see how fast I can turn off a LED by applying a honking reverse bias, and using an avalanche transistor would be fun. I have a bunch of NOS metal-can

2N2369s that I've been wanting to try out for avalanching.

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203 Briarcliff Manor NY 10510 845-480-2058

hobbs at electrooptical dot net

Good point. It may be that tigers do better with "false positives." Or perhaps they use other senses (smell, hearing) to confirm what their eyes are seeing.

But, different animals, different dietary needs, different modes of behavior, different diurnal cycle - different heredity. What works for tigers may simply be useless or even a hindrance to us.

Back in the olden days, we slept at night and did our hunting, gathering, farming, and other stuff during the day. AFAIK, this was a worldwide phenomenon across all ancient peoples - and still is among those who lack artificial lighting. I am unaware of any cultures that operated at night, before the invention of artificial illumination. That being the case, there wasn't a great need for night vision. We were sleeping.

Nocturnal creatures do need such enhancements. Some of these are actually blind in ordinary daylight. Cats have versatile pupils that can stop down enough to allow them to see. But at night they can open up completely, and their reflective retinas add to their ability to see in very low light.

But they hunt at night.

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You have a massage (from the Swedish prime minister).

A friend took a ton of photos in Kruger recently, and as he's a B&W aficionado they were reproduced in B&W. Predators are a LOT better camouflaged in monochrome. If that's the trade-off, I think I'll take high-def color vision.

Over-unity, perpetual motion at last!

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John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro   acquisition and simulation

It certainly help for PCB layout.

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John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro   acquisition and simulation

_Photodetection_ behaves as though light were discrete photons. Essentially no other process does, at least not in the 0-5 eV range. Even where the idea of photons helps the bookkeeping, e.g. in figuring out the frequency shift in an acousto-optic cell, there are wave ways to do the calculations.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

If wave-particle duality was that simple, they should have said so 100 years ago.

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Reply in group, but if emailing add one more
zero, and remove the last word.

On a sunny day (Thu, 03 May 2012 08:32:48 -0700) it happened John Larkin wrote in :

Our ability to make tools (that can, among other things, make us see at night) helps us survive. I agree with you that the ability to see at night is important to some extent, for example for warfare or perhaps even hunting.

I do not see any conflict in that, last week I did read some article on more and more 'bionic', oops, no it was a German science TV program, limbs coming, some better than our original limbs from flesh and blood as far as performance in some fields is concerned (they showed this runner who had 2 artificial legs, he was excluded from the Olympics because he was faster with his artificial legs). So maybe in a couple of hundred or thousand years we will be half man and half machine. They also showed somebody with a chip implant that generated a feeling of happiness... Where does it go? Sure if we evolve and learn to make these things we will become a very different looking 'species'. But is not that what evolution was doing in the first place? Creating ever different species, adapted to ever different environments. Maybe we will travel space that way, as a brain supported by machines, And then at one point transfer our awareness to a sort of electronic or chemical or quantum stuff net. Would be interesting to time warp a thousand years ahead. It is also possible that we do not make it and dinos are our example.

On a sunny day (Thu, 03 May 2012 11:22:57 -0700) it happened John Larkin wrote in :

Well, you have google, of COURSE it was not really >100%, but the light output was > then the electric energy put in at those low elves. I think the article is at physicsworld.com:

If you google sci.phycis you can see I predicted it, those guys tested it. And this works both ways.

Heck, if I heat an LED to 135C, I can get it to emit infrared energy with no electrical input.

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John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro   acquisition and simulation

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How else do we know about E&M radiation if not by detection? I thought the heralded photon experiments pretty much required the 'photon' picture. "There's this much energy at this wavelength at it will arrive at your detector at this time." Still you need a detector.

George H. (agnostic when it comes to the existence or non-existence of photons)

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That's exactly right. But when people talk about light being "made up" of photons, it assumes two things that aren't true:

1. a photon is a thing like an electron or a billiard ball
2. a photon has a definite location.

If you start thinking of little billiard balls bouncing around, you _never_ get the right answer.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net