Research gives crystal clear temperature readings from toughest environments

Sep 06, 2011

Researchers at the University of Warwick and Oxford University have developed a form of crystal that can deliver highly accurate temperature readings, down to individual milli-kelvins, over a very broad range of temperatures: -120 to +680 degrees centigrade.

The researchers used a “birefringent” crystal which splits light passing through it into two separate rays. Research has already shown that the size of the effect will increase or decrease in proportion to the of the crystal. Therefore, in theory, you could calibrate such crystals to be highly accurate temperature gauges.

However, the use of birefringence in this way has significant problems in practice. This temperature measuring ability of highly birefringent crystals is badly compromised by changes in the thickness and orientation of the crystal. This adds expense to the manufacture and calibration of such crystals and makes them almost unusable in situations where, for example, vibration could alter the orientation of the crystal.

However the Warwick and Oxford researchers have developed a reproducible a and low-cost method of modifying the properties of crystalline lithium tantalate so that its birefringence is virtually independent of the crystal’s thickness and position making it resistant to vibration and cheaper to manufacture. In fact, they have made the birefringence almost zero in magnitude in all directions (the material is close to being optically isotropic just like ordinary glass). However, the slightest temperature change induces a rapid increase in birefringence in these materials, making this a reliable, robust and very sensitive method for measuring temperature. The inventors have named their device a Zero-Birefringence Optical Temperature Sensor (Z-BotS) and are currently seeking follow-on funding to develop the device from the bench-top proof-of-concept to a miniaturized commercially-viable package.

Professor Pam Thomas of the University of Warwick said: “This advance, which has come out of research funded by EPSRC, allows us to create a new generation of robust reliable birefringent crystal based temperature sensing equipment which will be particularly valuable in electromagnetic, radio frequency and high voltage environments, where other types of sensor are subject to large errors due to interference. Examples are temperature measurement within the vicinity of MRI scanners in hospitals, industrial microwave dryers and the human body.”

Professor Mike Glazer of the University of Oxford said, “This opens new possibilities for remote temperature sensing of challenging environments. As the birefringence changes detection in these crystals can actually be operated remotely as only the crystal itself needs to be in the environment. All the other components: light source, measurement and processing electronics can be situated remotely.”

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User comments : 2

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1.8 / 5 (5) Sep 06, 2011
That's great news!

Now get the devises (with back-up recordings of actual temperatures) to climatologists who are now at war over data manipulation that was exposed in Nov 2009 Climategate documents and e-mail messages!

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo
1 / 5 (1) Sep 06, 2011
omatumr, you are on a hiding to nowhere. If you don't like the thought of climate change though, you could start taking serious notice of ocean acidity. Yes we are still talking about CO2! Anthropogenic CO2 that is, but you can relax a little because we are only talking about 30% of it, which I read recently should mean [to keep you happy] we only have a bit less than 3 gigatonnes per year to deal with. As luck would have it, I [yep little ol' me] know how to fix it [fix being another spelling of sequester :-]. We just have to grow more seaweed and I figure I know how to do that. Google "ocean cities acidification seaweed" and you should be able to find it.

But remember, dey who spend too long in denial, will end up eaten by de crocodails.

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