5 ms·
Interesting to note that the y-scale on figure 1 is 10^-21 (units of strain). Measurement at that scale is absolutely insane. The power of good engineering, i
by etrautmann 10y ago
Interesting to note that the y-scale on figure 1 is 10^-21 (units of strain). Measurement at that scale is absolutely insane. The power of good engineering, incredible optics, and lots of averaging.
- ISL 10y agoThere's minimal averaging, as the signals are transient.
- antognini 10y agoDepends on what you mean by averaging I suppose, but the signal is a measure of the average path length from several hundred reflections in the cavity. Furthermore, the signals are generated from the average interference of many photons. Even still, shot noise from the limited number of photons in the cavity is a major source of uncertainty.
- ISL 10y agoAll true. To give perspective on where I was coming from: from the (human) perspective of looking at noise in 1/sqrt(Hz) units, the signals are actually less-than-averaged if they're less than a second in duration. It's not like a continuous-wave source where one can integrate for months and hammer down the uncertainty to far lower strain values.
- pdabbadabba 10y agoI suppose one could rely on averaging the raw inputs of a large number of less reliable sensors, but I don't believe that's what the researchers have actually done here.
- etrautmann 10y agoIt's averaging in the sense of a long integration time. The signals of interest are glacial w/r/t speed of light, in the few Hz range, so you can integrate the optical signal over a longer period of time to improve SNR and beat shot noise.
- ahnitz 10y agoTo give you an idea of how crazy this is. It is like measuring the distance from the earth to the sun to an atomic radius.