Talk:Optical autocorrelation

I do not exactly know what to do to tell the author about the error; it is not easy to correct it as it would involve amending the figure. Namely, on the first figure (field autocorrelation, http://upload.wikimedia.org/wikipedia/en/thumb/d/d6/Optical-field-autocorrelation-setup.png/400px-Optical-field-autocorrelation-setup.png), the beamsplitter is reflecting the beam the wrong way; it should reflect it towards the scanning mirror first rather than to the detector. So, what author should do about it is rotate the beamsplitter 90 degrees. Just it. Lukkor 19:56, 19 November 2006 (UTC)

I have just noticed the same problem about the next setup figure. --Lukkor 20:52, 19 November 2006 (UTC)

There is another thing: the author creates the impression that second-order autocorrelation called here "intensity" or "interferometric" autocorrelation must be measured with a nonlinear crystal; it is wrong - a two-photon photodiode is sufficient and the experimental setup is just identical, with a different kind of a photodiode, that is detector. I do not really know how to include this into the article as there are many remarks about these measurements being more difficult. --Lukkor 21:36, 19 November 2006 (UTC)

There should be no distinction between "field", "interferometric" and "intensity" autocorrelation; instead, there should be "first order" and "second order" autocorrelation. The "second order" coming in two flavours, "intensity" or "interferometric" what depends on the speed of scanning and presence of beams overlap. The first order, field autocorrelation is always "interferometric". --Lukkor 21:36, 19 November 2006 (UTC)

A bit late, but I'll do it. I was going to redo the 3D figure with some real software anyway (the original was made with gmax as I didn't know any better by then, I use Blender now). I'll talk to my brother (Pgabolde) about the nonlinear crystal. Fgabolde 09:27, 19 June 2007 (UTC) Done. Would anyone please check it again ? Fgabolde 17:35, 26 June 2007 (UTC)

According to Trebino (Frequency Resolved Optical Gating: The Measurement of Ultrashort Pulses, pg 62 & 84) Field Autocorrelation is also called the Interferrogram and Interferometric autocorrelation is also called Fringe-Resolved Autocorrelation (FRAC) — Preceding unsigned comment added by 141.34.3.183 (talk) 16:41, 16 January 2020 (UTC)

Interferometric Autocorrelation

The autocorrelation signals governed by this formula


 * $$I_M(\tau) = \int_{-\infty}^{+\infty}|(E(t)+E(t-\tau))^2|^2dt$$

do not have an amplitude range of 0 to 8. They need to be normalized. Is that correct? —Preceding unsigned comment added by 84.173.171.50 (talk) 15:48, 26 September 2010 (UTC)

In reference to Lukkor's comment I've added a chart clarifying the different types of ACs. This avoids confusion about the differences of all the different kinds of ACs for people who are not familiar with ACs. --Lukie.80 (talk) 20:04, 12 September 2011 (UTC)

Photodiode and Oscilloscope Response Tmes
Photodiode and oscilloscope response times are listed as "at best ... 200 femtoseconds." I think that has to be wrong. It's unlikely photodiodes can be faster than about 20 picoseconds and oscilloscopes faster than about 200 picoseconds.157.185.95.28 (talk) 20:24, 9 July 2014 (UTC)mjd

autocorrelation schematic
I did this recently and it seemed to me it would fit here. if anyone thinks this would be an improvement to the article feel free to use it. Not quite as fancy as the 3D figures though. ; ) WeeGodzilla (talk) 00:51, 30 December 2015 (UTC)