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Thread: home made laser power meter

  1. #21
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    Because then you have too much of the Laser's beam reflect off of a
    non coated TEC's ceramic plate and no way to control the reflectiveness.

    Jerry
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  2. #22
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    The nice thing about this non coated plate is in fact the smooth,, regular reflectivity.

    The surface is matte and does not add the variability of an organic that is applied by the user. I agree that the spill into the room is much greater, but then I'm usually using goggles. I agree with one of your older posts about the variability of the power readings depending where a beam strikes one of my high end, Ophir meters. These seem to have much less of that variability, presumably due to the distribution of heat as it traverses the much thicker alumina plate. Also, when you are metering much higher power lasers the uncoated ceramic works well. I have been able to meter a high power Q switched YAG that burned a few spots onto my expensive Ophir.

    Why not have several TEC's? Use a large, non coated for high power and a small coated with a high V/degree response for maximum sensitivity and speed.

  3. #23
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    on the non coated TEC the reflected beam on white ceramic is quite bright and i would too think it would effect accuracy a bit as you want to heat that side of the TEC and keep the other cool so you develop the temp difference needed to make a measurable voltage
    Remember Remember The 8th of November, When No One Stood, but Kneel, In Surrender
    In a popular government when the laws have ceased to be executed, as this can come only from the corruption of the republic, the state is already lost. Montesquieu

  4. #24
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    The sensitivity will be much lower. Probably 5-10 x lower, but the accuracy should be higher without the variability of the coating. This is not just theoretical. I use a power meter that is uncoated. It works well.

  5. #25
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    ok, once i build the amp i will try that, the only reference i have was done on a LaserBee I just wish i could find the thinner TEC that laserbee uses for his units. using this amp what would be the safe upper limit? I set my reference laser at 1.2 watts, the one unit i own my self is a Sper Scientific "pocket laser power meter" it's max range is 40mw and does not have a liner response but they have the correction curve numbers on the inside of the outer door, it has served fairly well for about 10 years now, the dang things still cost around 200 bucks but at that time i never thought i would need anything higher then 40mw, with the higher power lasers now is i use a mirror that passes a few percent of the beam hitting the mirror, the other way i used it was with a standard prism but that turned out to not be as accurate as a hoped for.

    Also I want to give a shout out for laserbee helping us in this project, when i can afford it i will diffidently buy one from him, this shows how professional he is, i am diffidently impressed
    Remember Remember The 8th of November, When No One Stood, but Kneel, In Surrender
    In a popular government when the laws have ceased to be executed, as this can come only from the corruption of the republic, the state is already lost. Montesquieu

  6. #26
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    one quick question, do these types of power meters respond the same to different wavelengths of lasers?
    Remember Remember The 8th of November, When No One Stood, but Kneel, In Surrender
    In a popular government when the laws have ceased to be executed, as this can come only from the corruption of the republic, the state is already lost. Montesquieu

  7. #27
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    Yes they do. The high end ones will add a correction factor for major changes such as <650nm, <1064nm ect. The white alumina and the black coated surfaces with several blackening treatments have relatively broad band flat response, but there is a need to adjust for extremely broad wavelength changes.

  8. #28
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    Quote Originally Posted by Draco View Post
    ok, once i build the amp i will try that, the only reference i have was done on a LaserBee I just wish i could find the thinner TEC that laserbee uses for his units.
    Also I want to give a shout out for laserbee helping us in this project, when i can afford it i will diffidently buy one from him, this shows how professional he is, i am diffidently impressed
    We have the small fast response time TECs for the discontinued LaserBee I and
    in stock LaserBee II LPMs made for us to our specs. To say the least.. they are
    quite expensive.
    Thanks for the kind words.

    As to if coated and non coated TECs respond the same way.. I have no idea.
    I would imagine that the uncoated TEC would not be broadband.
    We will probably test this in the near future.
    See the LaserBee II and all other LaserBee LPM products here....
    All LaserBee Laser Power Meter Products

    New 3.2Watt RS232/USB LaserBee II LPM REVIEW


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