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Laser Thermometer - morfizm


May. 12th, 2011 12:13 am Laser Thermometer

I told grocery store clerk my funny story about broken refrigerator, and he, in exchange, told me something unbelievable: you can get a toy called "laser thermometer". Basically, you can point it to the wall on the other side of the street and it will give you temperature of that specific point. And... it's very affordable, I can see the cheapest model goes from $20.

Super cool toy! Wow! Now you can determine from distance if a girl is actually hot ;)
I wonder how this technology works.

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Comments:

From:_m_e_
Date:May 12th, 2011 07:20 am (UTC)
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i would call it "infrared thermometer", although sometimes they do come with laser pointer just to get an idea of the point where they measure temperature (the spot is usually pretty big - the cheapest have 1 radian angle - i.e. at 1 meter distance they measure "spot" of 1 meter diameter; better ones around 0.1 radian).
From:morfizm
Date:May 12th, 2011 07:24 am (UTC)
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Hm... the clerk told me that the one he has is actually quite like a laser. He can point somewhere, like using a laser pointer. He can point through the window and distinguish the temperature of someone's motorcycle engine from the seat. Probably we need to go for a more expensive model. I'll try to check with him again on what exactly is the model he uses.
From:_m_e_
Date:May 12th, 2011 07:35 am (UTC)
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I researched them for locating thermo-leaks to insulate house, did not see any with distance-to-spot ratio better than 12.

So if the distance from engine to seat is 30 cm - you can measure them more or less accurately from about 4 meters. Of course you can "distinguish" from bigger distance, but it will just show that engine is hotter than stuff around it, temperature reading will be full B.S.
From:morfizm
Date:May 12th, 2011 07:42 am (UTC)
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Got it. Okay, forget about long-distance hot girl spotting :)

Can you tell me what is the name/price of at least one good model (which has over 10 distance-to-spot ratio?)
From:_m_e_
Date:May 12th, 2011 07:47 am (UTC)
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I did not buy anything that time, did not have time to use it :)
The second in your list claims ratio 12:
http://www.amazon.com/IRT0421-Non-Contact-Infrared-Thermometer-Targeting/dp/B0017L9Q9C/ref=sr_1_2?ie=UTF8&qid=1305186361&sr=8-2
From:morfizm
Date:May 12th, 2011 07:51 am (UTC)
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Now I see. Cool! I've actually added it to wishlist :)
From:dennyrolling
Date:May 12th, 2011 04:00 pm (UTC)
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oh that's the model I have
From:_m_e_
Date:May 12th, 2011 06:41 pm (UTC)
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как работает?
в плане нахождения утечек тепла в доме удобен?
From:dennyrolling
Date:May 12th, 2011 10:11 pm (UTC)
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я его в плане готовки использую - очень удобно, единственное он не может измерять у блестящей кастрюли снаружи температуру правильно. а в плане нахождения утечек тепла я ничего сделать не могу, мне стены не принадлежат (ну и в основном стены это окна).
From:archaicos
Date:May 12th, 2011 08:32 am (UTC)
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http://en.wikipedia.org/wiki/Infrared_thermometer

My dad's making similar equipment, except it's precise and costs thousands of bucks. :)

http://en.wikipedia.org/wiki/Pyrometer describes his implementation in general:
"...To get around these difficulties, the ratio or two-color pyrometer was developed. They rely on the fact that Planck's Law, which relates temperature to the intensity of radiation emitted at individual wavelengths, can be solved for temperature if Planck’s statement of the intensities at two different wavelengths is divided. This solution assumes that the emissivity is the same at both wavelengths [2] and cancels out in the division. This is known as the gray body assumption." And there're some know-hows, of course. It only looks simple to the end-user or the uninitiated, but there's a lot of physics to account for. :) But, I agree, it's pretty cool to aim at something and read back the temperature with great precision.
From:dennyrolling
Date:May 12th, 2011 03:53 pm (UTC)
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infrared thermometer is one of four types of thermometers I have in my kitchen. very useful to get quick pasta or frying pan temp reading.
From:miris_rants
Date:May 12th, 2011 05:11 pm (UTC)
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Oooh can't wait till u share the results! :))