[time-nuts] temperature sensor
cfharris at erols.com
Sun Jul 20 21:45:46 EDT 2014
That sounds sort of like what they must have been doing.
But, they were quite clear that it was a "Quartz" thermometry
unit, and that the crystals were quartz.
And, this was before solid state IR laser diodes, around 1982.
Each temperature measuring module was plug in, and about 3/4 inch
by 5 inches, by 8 inches in size... maybe a little smaller.
Whatever they did was stable, needed no alignment when the plugins
were moved in the chassis, and had no external adjustments.
Attila Kinali wrote:
> On Sun, 20 Jul 2014 15:57:24 -0400
> Chuck Harris <cfharris at erols.com> wrote:
>> I initially thought that it might be a transmission sort of effect, where
>> the light intensity changed with temperature, but its total lack of sensitivity
>> to being in a liquid, kind of makes that unlikely.
> Nope, it's a path length difference system.
> There is a small, temperature dependend crystal at the tip.
> The device measures the optical length of this crystal.
> See: http://www.emeraldinsight.com/content_images/fig/0870260309013.png
> I'm sure there are other ways as well, like using distributed fiber
> gratings (a change in length means a change in "resonant" frequency/wavelength)
> but i have no references for such (though, i haven't searched either)
> Attila Kinali
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