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Fastest Timer
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raptor1956:

--- Quote from: nctnico on June 16, 2021, 11:58:52 am ---At picosecond precision levels the refractive index, wavelength and temperature coefficient of air are going to influence the result.

--- End quote ---

Yes, quite true, in fact common Total Stations have inputs for temperature etc to help account for these effect.  Of course, doing this in a vacuum would obviate those problems. 


Brian
raptor1956:

--- Quote from: daqq on June 16, 2021, 05:44:35 am ---This is commercial off the shelf-ish stuff. I've read about ASICs that CERN uses, others will have something similar. A quick google search shows some tens of femtoseconds resolution stuff being possible.

No idea of higher resolutions, probably could achieve more by interpolation, averaging and other sorcery?

Not this is the way to go when measuring 1e-18m kinds of distances.

--- End quote ---

I'd guess NIST and other such institutions around the world would have some pretty high end tech for this -- would love to know what they have and its capabilities.


Brian
5065AGuru:
Brian,

If your light pulses can be at a 1Mhz rate a DMTD unit and any 8 digit counter would provide 1us full scale and a resolution of 1X10-14th and close to 1 picosecond "realizable" resolution.

So your 667 nanosecond reading would be 0.667XXXZZ Microseconds with the ZZ digits mostly noise.

Cheers,

Corby
RoGeorge:
For very small time differences, other techniques are implied than using a start/stop timer.

The most advanced resolution in measure timing is probably done at LIGO, thought in an indirect way.
https://en.wikipedia.org/wiki/LIGO

--- Quote ---At its most sensitive state, LIGO will be able to detect a change in distance between its mirrors 1/10,000th the width of a proton! This is equivalent to measuring the distance to the nearest star (some 4.2 light years away) to an accuracy smaller than the width of a human hair.
--- End quote ---
Source:  https://www.ligo.caltech.edu/page/facts

Overall LIGO measures the time difference in light traveling through the arms of an interferometer, and that corresponds to 1/10000 of the width of a proton, which proton is about 1.7 femtometers, so dividing that with the speed of light would be about 5 x 10-24 seconds.

Or else said 5 yoctoseconds, or 5 trillionth's of a trillionth's of a second, or 5 billionth's of a millionth's of a nanosecond.   ;D

As a side note, the minimum possible quanta of time would be about 5 x 10-44 seconds.
Source:  https://www.quora.com/Is-there-a-minimum-length-of-time


raptor1956:

--- Quote from: RoGeorge on June 17, 2021, 04:25:44 am ---For very small time differences, other techniques are implied than using a start/stop timer.

The most advanced resolution in measure timing is probably done at LIGO, thought in an indirect way.
https://en.wikipedia.org/wiki/LIGO

--- Quote ---At its most sensitive state, LIGO will be able to detect a change in distance between its mirrors 1/10,000th the width of a proton! This is equivalent to measuring the distance to the nearest star (some 4.2 light years away) to an accuracy smaller than the width of a human hair.
--- End quote ---
Source:  https://www.ligo.caltech.edu/page/facts

Overall LIGO measures the time difference in light traveling through the arms of an interferometer, and that corresponds to 1/10000 of the width of a proton, which proton is about 1.7 femtometers, so dividing that with the speed of light would be about 5 x 10-24 seconds.

Or else said 5 yoctoseconds, or 5 trillionth's of a trillionth's of a second, or 5 billionth's of a millionth's of a nanosecond.   ;D

As a side note, the minimum possible quanta of time would be about 5 x 10-44 seconds.
Source:  https://www.quora.com/Is-there-a-minimum-length-of-time

--- End quote ---

Yeah, I mentioned in a prior about the incredible sensitivity of the LIGO instrument as a baseline for the kind of resolution I'd like to see in a timing system.  What LIGO does using interferometry isn't exactly like timing as it's more of a differential (relative) thing than an absolute thing.  Getting down to the LIGO level of sensitivity in timing would still be many many orders of magnitude away from Planck Time.


Brian
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