# High-tech thermometer. How does it work? **URL:** \ **Category:** Factual Questions\ **Created:** [July 20, 2003, 9:53am UTC](https://boards.straightdope.com/t/high-tech-thermometer-how-does-it-work/189721 "2003-07-20T09:53:29Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Aankh](https://avatars.discourse-cdn.com/v4/letter/a/ebca7d/32.png) [@Aankh](https://boards.straightdope.com/u/Aankh)\ **Post date:** [July 20, 2003, 9:53am UTC](https://boards.straightdope.com/t/high-tech-thermometer-how-does-it-work/189721/1 "2003-07-20T09:53:29Z")
The SARS situation has meant that your temperature is checked pretty much anywhere you go. A friend of mine had his temperature checked by a rather nifty device recently. Apparently, the checker just waved the instrument a foot or so away from his body and it managed to register his temperature accurately. Am I being kidded or does such a thermometer actually exist? If so, how does it work? I really hope I’m not overlooking some extremely obvious answer here. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [July 20, 2003, 1:56pm UTC](https://boards.straightdope.com/t/high-tech-thermometer-how-does-it-work/189721/2 "2003-07-20T13:56:39Z")
They only way I can possibly imagine such a thing _might_ work is via infrared. But I have a non-contact IR thermometer, and no matter where I point it at me, it doesn’t resgister my body’s core temperature. Only if I actually stick it _in_ an orifice (my mouth, you dirty-minded Dopers) does it register anything like an accur4ate body temperature reading. I can’t say such a thing _doesn’t_ exist, but to me it seems unlikely, in my experience. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [July 20, 2003, 2:27pm UTC](https://boards.straightdope.com/t/high-tech-thermometer-how-does-it-work/189721/3 "2003-07-20T14:27:21Z")
Likely some variant on [this device](http://www.sensorsmag.com/articles/0801/10/main.shtml) which uses multiple readings, and software to deduce the actual temperature. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [July 20, 2003, 3:08pm UTC](https://boards.straightdope.com/t/high-tech-thermometer-how-does-it-work/189721/4 "2003-07-20T15:08:40Z")
I’ve been scanned by one of those devices too. It was set up on a tripod in an airport just before the immigration checkpoint. Passengers were asked (but not required) to walk slowly past the camera in single file. I agree it has to be infrared. I didn’t get to see the screen but I think it’s just a regular [infrared thermal imager](http://www.howstuffworks.com/nightvision2.htm), probably with the color scale set to highlight areas which is at or slightly above body temperature. The skin wouldn’t be at core temperature, but the skin of a person with a high fever is still higher temperature than a normal person. ---
**Author:** ![Zenster](https://avatars.discourse-cdn.com/v4/letter/z/cdc98d/32.png) [@Zenster](https://boards.straightdope.com/u/Zenster)\ **Post date:** [July 20, 2003, 5:39pm UTC](https://boards.straightdope.com/t/high-tech-thermometer-how-does-it-work/189721/5 "2003-07-20T17:39:47Z")
Infra red thermography has proven useful in a wide variety of applications. Not all of them are medical. Some of the more amazing medical uses include the ability to detect and verify pain. By monitoring localized micro-heating of tissues, increased bloodflow to injured tissue sites can help establish that a patient is still suffering from pain long after the physical trauma has supposedly healed. This has proven useful in pain-and-suffering court cases. The same application also helps to identify soft tissue injuries that will only show up on more expensive MRI or CAT scans. Thermography is also used to detect localized heating non-uniformities in special materials and semiconductor process components. This method can also detect cracks and other structural defects in materials, due to the inability of voids and flaws to conduct heat as well as a contiguous piece. ---
**Author:** ![Mort\_Furd](https://avatars.discourse-cdn.com/v4/letter/m/8e8cbc/32.png) [@Mort\_Furd](https://boards.straightdope.com/u/Mort_Furd)\ **Post date:** [July 20, 2003, 5:40pm UTC](https://boards.straightdope.com/t/high-tech-thermometer-how-does-it-work/189721/6 "2003-07-20T17:40:43Z")
I agree with the above suggestions - thermal imager with some kick-ass software.