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Photodiode -- measure power

  1. May 16, 2016 #1
    Hello, I would like to measure power from a photodiode. How do I go about doing this? What would the circuit look like?
  2. jcsd
  3. May 16, 2016 #2
    I would like to measure the power of a laser through a photodiode, i mean.
  4. May 16, 2016 #3


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    Staff: Mentor

    The traditional circuit is a current-to-voltage converter with an opamp:

  5. May 16, 2016 #4


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    Science Advisor

    The circuit given above operates the LED as a photodiode at zero voltage and so measures the short circuit current. Short circuit current is a measure of the flux of photons being received. That current can be converted to power if the wavelength (colour) of the photons is known. You will need to calibrate the system. You may need to use an optical attenuator for higher output lasers.

    For better answers more information is needed.
    Why do you want to measure the power ?
    What is the laser wavelength or colour ?
    What is the power supply for the laser ?
    Does the laser have a manufacturers part number ?
    What sort of photodiode did you plan to use ?
  6. May 20, 2016 #5
    I successfully hooked up my photodiode to an oscilloscope and got a good reading. Is there a way to measure noise, or SNR?
  7. May 20, 2016 #6
    or should i use an optical spectrum analyzer?
  8. May 20, 2016 #7


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    Science Advisor

    I am not a mind reader. Why do you not answer questions?
    What type of laser are you using?
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