DIY infrared thermometer?

Everything starts with an idea...

So here's my latest idea :

Has anyone tried to build an IR thermometer from the ground up? The technology doesn't seem too difficult; kind of like focusing a laser, only in the reverse direction.

Using something like this (although there are probably better ones for this task):
http://www.melexis.com/Infrared-Thermometer-Sensors/Infrared-Thermometer-Sensors/MLX90614-615.aspx

Since the digital thermopiles handle most of the difficult parts of this idea, it seems that we would only need to add a host and focusing lens and work out some way of displaying the temperature reading.
Since we are able to make lasers which far outperform the cheap Chinese lasers, it seems reasonable that we would be able to make a thermometer that outperforms the cheap Chinese ones (which are being sold on ebay for practically nothing).
Other than the basic concepts of IR thermometry, I don't know a lot about the inner working of these things.

Does anyone have input here?

What would be the benefit over something like this...

Pocket IR Infrared Non-Contact LCD Digital Thermometer | eBay

With stated specs of...

* Size: 8.0 x 5.0 x 2.35 cm
* Weight: 45 grams
* Temp Range: -50C to 300C
* Accuracy: +/- 2%
* Repeatability: 1%
* Response time: 0.8 sec

Price $9.17 with shipping included...


Jerry

I don't know, why do we build lasers rather than buy this one?:3000mw 532nm green laser pointer burst balloon for sale
Haha, I couldn't resist

There are much more expensive ones that are able to measure temperatures to a much greater degree of accuracy, and also a lot that are able to point more accurately at objects or measure objects which are further away. The distance:spot size ration on that cheap one is 2:1.
This one is 60:1, but its A LOT more expensive: http://www.tequipment.net/Fluke572.html

I don't know why I would ever need a super accurate measurement other than scientific studies (but I couldn't publish results taken from a DIY thermometer anyway). I might use the extra accuracy (spacial accuracy, not measurement) or range of a greater distance:spot ratio, but probably not all that often.

I think we could do a better job for less money than the really expensive ones, and I think there might be applications for customizable thermometers.

Maybe a very fine focusing close range therm. for checking temps of electronic components on circuit boards? (Maybe that already exists...)

Or maybe I want to measure the temperature of my 2nd story windows in the winter to see how much heat is being lost.

I think it's an interesting idea that might be worth looking into a little bit, although it might turn out too expensive or difficult to really make it worth it.



*I just found this: http://www.dehnes.com/4/2010/02/03/building-your-own-ir-thermometer-part1/
He uses the same sensor that I found... It still doesn't look too difficult, although it would need to be shrunk down to hand size.

I can't think of many examples where you need to measure the temperature of something from across the room and cannot get close to it. 2:1 is good enough for me.

It's just optics, so you could try adding a lens or two (beam-expander style) to an existing thermometer. The problem is the lenses that pass mid-IR are already more money than a higher end thermometer.

Dogs Best Friend said:

maybe I want to measure the temperature of my 2nd story windows in the winter to see how much heat is being lost.

Click to expand...

Tape a regular thermometer to the outside.

Dogs Best Friend said:

Maybe a very fine focusing close range therm. for checking temps of electronic components on circuit boards? (Maybe that already exists...)

Click to expand...

You can just bring it close to the sensor.

There's FLIR, but that's NOT cheap. Pangolin's FB3 at idle:



DX buck LED driver:


As you can see, the temperature doesn't vary too much at scales this small*. That's because of conduction. That also means you can get "close enough" with a $10 IR thermometer. If you need high accuracy, a thermistor arrangement is a better solution.

*The darker specks are solder joints or other metal parts. Metal has lower emissivity than other materials, and it tricks IR equipment into reading a lower temperature.

Dogs Best Friend said:

I think it's an interesting idea that might be worth looking into a little bit, although it might turn out too expensive or difficult to really make it worth it.



*I just found this: Building your own IR Thermometer Part 1 | Sebastian Dehne's Blog
He uses the same sensor that I found... It still doesn't look too difficult, although it would need to be shrunk down to hand size.

Click to expand...

Well there you go.... Let us know the total costs and specs
compared to the $9.00 one I linked to when it's completed.

I'd like to see if the effort to build and test it and/or the specs
are much better...:beer:


Jerry

I'm not suggesting building one of these so that I don't have to shell out $9 for one. I'm positive I couldn't make it for less than that. I was just suggesting it as maybe an interesting project.

At any rate, I probably won't be doing this any time soon. I don't NEED one of these, I'm pretty sure the cheap model would suit 99% of my uses as well. When I see a $1000 gadget with a $9 Chinese counterpart however, I have to wonder what makes one worth $981 more than the other (and also if I could build something comparable).

Thanks for the input though :beer:

Dogs Best Friend said:

I'm not suggesting building one of these so that I don't have to shell out $9 for one. I'm positive I couldn't make it for less than that. I was just suggesting it as maybe an interesting project.

At any rate, I probably won't be doing this any time soon. I don't NEED one of these, I'm pretty sure the cheap model would suit 99% of my uses as well. When I see a $1000 gadget with a $9 Chinese counterpart however, I have to wonder what makes one worth $981 more than the other (and also if I could build something comparable).

Thanks for the input though :beer:

Click to expand...

Where did you see a $9 IR thermometer counterpart selling for $1000...:thinking:

Jerry

By "counterpart", I am referring to "another IR thermometer", not anything very similar to the $9 ebay version.

Thermometer, Infrared - Infrared Thermometers - Temperature and Humidity Measuring - 5YB28 : Grainger Industrial Supply
Amazon.com: FLUKE-572: Home Improvement

Obviously, there are lots of bells and whistles on the expensive one, but they are basically the same thing... an IR thermometer.

I would assume that they use better sensors and optics to get a faster, more accurate reading in addition to features like data logging, humidity etc. (I would hope it would be VERY accurate at that price).

The huge price difference just makes me wonder how much better the components really are.

ive got a fluke ir thermometer, it works really well, not as good as the flir imaging one tho :drool:

Thanks for the link Jerry. I was looking for a cheap one much better than building one

The sensor array used in the FLIR, will cost you a very very pretty penny. Looking at $200-300 for a low quality array 160x120pixels... if memory serves me correct. These sensors are properly referred to as micro-bolometers (I'm pretty sure spark fun had them for sale at one time?). The larger ones used by fluke are nearly 10x this price.

No CCD sensor array can detect far IR, that is a fact.