Talk:Fibre optic gyroscope

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Copyright problem?[edit]

Sorry, but i can't see any copyright problem. Maybe the link is going to the wrong page? I could not find one sentence which was copied. At the first look, i could find only one part which was indeed very similar, but wouldn't call it a copy:

http://www.kvh.com/Press/pr.asp?id=146&category=FIBEROPTIC: "FOGs provide extremely precise rotational rate information by measuring the phase difference between two paths of light traveling in opposite directions through the optical fiber. Their precision results in part because of their lack of cross-axis sensitivity to vibration, acceleration, and shock."

Wikipedia Article: "FOGs provide extremely precise rotational rate information, in part because of their lack of cross-axis sensitivity to vibration, acceleration, and shock,and are designed both on open-loop and closed-loop technology."

-- DeQuibbler 17:19, 24 February 2006 (UTC)

I agree, couldn't find anything in the provided link that made this look like a copyvio; a quick search didn't produce any other online source, so I'm removing the tag. .:.Jareth.:. babelfish 15:14, 6 March 2006 (UTC)

Xilliah (talk) 09:52, 3 February 2008 (UTC) Can anyone explain/link "higher drift and worse scale factor performance"? I really don't get it. I know this isn't a tutorial website, but it can't be a huge problem to link to another article that explains these terms.

Performance of FOG greatly exagerated?[edit]

I question much of what is claimed in the last few paragraphs of the article in terms of performance, as this conflicts with my understanding of the technical problems and the state of the art. Admittedly my familiarity in this regard is from a few decades ago, however the poorer performance of the FOG in relation to the RLG seems borne out by the failure of this device to find applications beyond the one I'll mention where it does (for a different reason) succeed.

According to the current text: "A FOG provides extremely precise rotational rate information" The supposed precision isn't specified and I can't find any reference stating that it is superior to other technologies.

"Because of their intrinsic reliability, FOG are used for high performance space applications." The only such application I know of is ballistic missles, and the reason it is suited for that case is because they take off and return to earth in less than an hour, thus their drift does not have a chance to accumulate.

"The FOG typically shows a higher resolution than a ring laser gyroscope" I see no backing for this statement. It isn't clear whether "resolution" refers to the rotational RATE (which is what it directly measures) or accumulated rotation (more important). If it were better in the latter respect, then I don't understand why it hasn't come into use.

".... used to have less stable bias and worse scale factor performance until the end of the 90's. Since the beginning of the century, high performance FOG have demonstrated better bias stability than the most accurate ring laser gyroscopes[citation needed]" <<<< Yes a citation is needed, and I don't think there are any. I wonder if this originated as advertising from a company involved in this business.

"FOGs are used in surveying, stabilization...." which are obviously applications having lower performance demands.

"and inertial navigation tasks" Again, only for ballistic missles (as far as I know) whose flights are over within an hour.

In short, I challenge the author(s) of these portions to supply references and better (quantitative) figures to back up the claims. Interferometrist (talk) 20:59, 9 September 2010 (UTC)

I agree the language is vague and does sound like it was written by a fan of the FOG technology. The only disadvantage of the RLG that I know of is the "lock-in" phenomenon (at low rotation rates, the counter-propagating frequencies lock together, forcing the detected rotation to be zero). Perhaps that is what the "higher resolution" claim refers to. Spiel496 (talk) 22:09, 9 September 2010 (UTC)
Right. I removed one such claim and added some more tags. If any of the original authors are still listening, please add citations or at least leave a message here in regards to the tracts in question. Interferometrist (talk) 17:42, 21 March 2011 (UTC)
And actually the fourth reference I just added pretty much contradicts some of these performance claims, so I expect that the "needed" citations won't exist. But I'm giving it a few days for someone else to prove me (and that author) wrong.... Interferometrist (talk) 18:39, 21 March 2011 (UTC)

Actual configuration?[edit]

The diagram in this article is severely over-simplified, I suspect. I worked with fiber-optic gyroscopes in a laboratory setting 20 years ago, so my experience is not with field-deployed devices. However, the diagrams in this article leave out features essential to ideal operation, namely dual beam splitters (couplers) and what my colleagues called "active biasing". I'll not go into all the details here, but the configuration can be seen here and is described here and here. I do know that these features eliminate the need for "zeroing" (in contrast to a comment in the "disadvantage" section). What I do not know is the design of current commercial or military FOGs. Can anyone help out on this? Spiel496 (talk) 05:52, 15 August 2012 (UTC)