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Thread: Thermal pile

  1. #31
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    I dont suppose that you could use a black NTC for a basic power measuring device could you? Are thermopiles temerature based only or do they sense wavelength?

  2. #32
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    mixedgas is offline Creaky Old Award Winning Bastard Technologist
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    Quote Originally Posted by steve-o View Post
    I dont suppose that you could use a black NTC for a basic power measuring device could you? Are thermopiles temerature based only or do they sense wavelength?
    put a matched pair of them in a wheatstone bridge, and yes, you'd have a very good PM. paint it black with carbon black in clear nail polish.

    Steve

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    Lightbulb Here's a cool idea for a cheap power meter!

    Here's an interesting little gadget: A thermal power meter based on a meat thermometer! (Ok, it's a bit more accurate than a meat thermometer, but still...)

    Have a look at these pics in the gallery that I just uploaded. It's a power meter that was sent to me by mistake. (Was supposed to go to some dude with a large CO2 laser, but the labels got mixed up and it ended up on my doorstep.)

    It's a pretty cool idea, though it's only really practical for larger lasers. (You need to be able to generate enough heat to warm up the sensor block.)

    I took some pictures of the thing before I sent it on to the rightful owner. I thought you guys might find it interesting...

    Adam

  4. #34
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    So laser power meters are nothing more than temperature measurement devices with several settings to compensate for different wavelengths?

  5. #35
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    The lasercheck doesn't measure temperature. It doesn't rely on the light heating something up, but measures the light directly.

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    With what kind of medium: silicon, cadmium. ..?

  7. #37
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    I don't know for sure. It wont be CdS. Probably a Silicon or Gallium photodiode.

  8. #38
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    OK, has anybody analyzed their lasercheks? What's in that window???

  9. #39
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    I just checked the Coherent website. They say it's Silicon.

  10. #40
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    Cool

    Quote Originally Posted by steve-o View Post
    So laser power meters are nothing more than temperature measurement devices with several settings to compensate for different wavelengths?
    The broadband thermal probes work by sensing a change in temperature, yes. Though the really good ones use a TEC rather than just a thermometer.

    Smaller power meters like the lasercheck (or the light detector on an Ion laser) use photoresistors like pixpop mentioned.

    Adam

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