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When the first femtosecond laser pulses were reported I calculated the length of the pulse and noted it was on a scale less than 1/2 wavelenght (uncertainty broadening neglected). An explanation I heard that was reasonable was that it was simply a breakdown in the wave-nature description of light (there's also a particle nature).
For those of you who need a easy frame of reference:
Light travels 1 foot (30cm) in a nano-second (10^-9 = 1 billionth)Even in the mid 1970's I was able to resolve a split laser pulse that took two paths, one longer than the other.As shown in the video, due to the Heisenberg Uncertainty Principle, such a short pulse must have a very uncertain wavelenght (hence the rainbow) ΔtΔν > ℏ = hc/λ [edit] Note that Δν is proportional to ΔE, so equation is OK.[/edit]
| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "As far as we know, our computer has never had an undetected error." - Weisert | | "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
modified 21-Jan-16 15:13pm.
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I also enjoyed the part where he explained the perspective between watching light in slow motion vs. watching the bullet through the apple in slow motion.
To watch the bullet go through the apple at the same frame rate as the light it would take about 1 year to see it.
It's amazing we can work with such incredibly small values.
There are only 10 types of people in the world, those who understand binary and those who don't.
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In the late 1980's I worked with laser range gating and intensified cameras (cameras with a photomultiplier between the lens and the CCD). At that time we were able to gate the intensifier on and off at around 5 nanoseconds, so we could adjust the depth of field down to about five feet. We could also range when the sensor was open to the reflected light. This allowed us to do some interesting things, such as see through sandstorms.
Marc
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I recall seeing that video a while ago (I'm assuming it's the one with the pulse of light shown travelling through a room and a p.e.t coke bottle)
Having been absolutely stupefied at the prospect of a camera that could shoot that many frames a second, I immediately recalled the gas-turbine powered high-speed cameras that needed some serious horse-power to turn the rotating mirror head and run the film fast enough to get in the order of a million frames a second. I mean, c'mon - a gas turbine powered camera - talk about a boy's toy!
As it turns out, the technique shown in the TedTalks video I saw actually isn't shooting anywhere near a million times as fast as the turbine cameras - the exposure time is astonishingly short, but the continuous frame rate vastly slower. The trick to the technique used was to stitch together using software a series of single frames from many, many, many videos - all offset in time by a small amount. If you could shoot 10 million frames a second continuously, you'd only need to do 100,000 captures to get a second worth of video.
Since they used a Hamamatsu streak camera model C5680[^] that has a maximum sweep frequency of 20Mhz, one can see that even then - an awful lot of videos were stitched together to create the stunning video of the "light bullet"
I find the field of computer reconstructed imaging fascinating and am really looking forward to the advances that may come in our lifetime, particularly with reference to the software reconstructions that allow an image to be formed from around a corner by 'simply' capturing the diffuse reflections from materials generally not considered to be useful mirrors.
More here: The amazing camera that can see around corners[^]
Thanks for the reminder!
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So as I watched an electrician install a new electrical outlet I asked him "Wire you doing that?"
| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "As far as we know, our computer has never had an undetected error." - Weisert | | "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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In the states, it is a wonder you did not get a union grievance against you. [:whistle innocently]
Mongo: Mongo only pawn... in game of life.
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He did turn and gave me a shocked look.*
* This reply was done because you implicitly demanded it.
| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "As far as we know, our computer has never had an undetected error." - Weisert | | "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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Did that spark a conversation?
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment
"Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst
"I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
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I am sure he was well grounded.
Mongo: Mongo only pawn... in game of life.
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Sometimes it's good to be neutral.
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment
"Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst
"I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
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Well, aren't you a live wire!
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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I alternate.
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment
"Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst
"I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
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That's very direct.
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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I can be short.
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment
"Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst
"I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
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I sense a bit of resistance.
Cheers,
Mike Fidler
"I intend to live forever - so far, so good." Steven Wright
"I almost had a psychic girlfriend but she left me before we met." Also Steven Wright
"I'm addicted to placebos. I could quit, but it wouldn't matter." Steven Wright yet again.
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Calm down and repeat after me... "ohm....".
/ravi
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I don't understand watt you are all talking about.
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Well, isn't that the usual with current affairs ...
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I'm still alternating in my opinion, but with reluctance, I accept that there's no hysteria.
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Good thread for this electron season.
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