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    How to they calculated resolution of the photodiode

    Thorlabs photodiode s150c. They have mentioned a resolution of 10 pW. how do they calculated it?.

    I want to know the resolution of this photodiode op560c op560c.

    kindly help

    - - - Updated - - -

    if i connected in 10k series resistance with phe photodarlington and measure the voltage reading when I shine 0.03 mW green light (530 nm).
    Last edited by 4tuty; 7th June 2019 at 14:14.

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    Re: How to they calculated resolution of the photodiode

    Thorlabs S150C is a Fiber Photodiode Power Sensor

    https://www.thorlabs.com/newgrouppag...&pn=S150C#6035

    footnote b says : Measured with PM100D console in low bandwidth setting.

    the PM100D console is a Compact Power and Energy Meter Console (i.e a bench top machine for measuring optical power and energy)
    https://www.thorlabs.com/newgrouppag...3341&pn=PM100D

    the S150C is a sensor that connects with the PM100D



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    Re: How to they calculated resolution of the photodiode

    Quote Originally Posted by wwfeldman View Post
    Thorlabs S150C is a Fiber Photodiode Power Sensor

    https://www.thorlabs.com/newgrouppag...&pn=S150C#6035

    footnote b says : Measured with PM100D console in low bandwidth setting.

    the PM100D console is a Compact Power and Energy Meter Console (i.e a bench top machine for measuring optical power and energy)
    https://www.thorlabs.com/newgrouppag...3341&pn=PM100D

    the S150C is a sensor that connects with the PM100D
    Thank you for the reply.

    I want to measure the resolution of this photodiode op560c when it connected to the 16 bit ADC (NI-DAQ), if I connected in 10k series resistance with the photodarlington and measure the voltage reading across it when I shine 0.03 mW green light (530 nm).

    Is it the correct way of doing it?



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    Re: How to they calculated resolution of the photodiode

    Hi,

    It seems you want to measure SNR.
    Define the bandwidth of interest...use an appropriate filter.

    Instead of the 10k series resistor (which will degrade AC performance) I'd use a TIA combined with filter.
    This gives more defined results especially regarding bandwidth and diode voltage

    For your circuit you need a very low noise voltage reference, to get reliable results...in either case.

    Klaus
    Please don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



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    Re: How to they calculated resolution of the photodiode

    Quote Originally Posted by KlausST View Post
    Hi,

    It seems you want to measure SNR.
    Define the bandwidth of interest...use an appropriate filter.

    Instead of the 10k series resistor (which will degrade AC performance) I'd use a TIA combined with filter.
    This gives more defined results especially regarding bandwidth and diode voltage

    For your circuit you need a very low noise voltage reference, to get reliable results...in either case.

    Klaus
    Thank you as per your suggestion i have made a circuit PFA, used an opamp as buffer circuit and LM358 as input reference. Do i need filter(I don't have any idea)? or is this configuration is enough.

    Planning to varying the LED intensity using potentiometer and simultaneously measuring the LED intensity using bifurcated optical fiber connected between OP560C and Thorlabs powermeter (as a standard device)

    Click image for larger version. 

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    Re: How to they calculated resolution of the photodiode

    your micropower supply (LM385) will provide, at best, about 70 uA (micro, 10^-6)
    in the green wire above the 5V label

    the op-amp, MCP602 requires 230 uA quiescent current

    the photo-transistor op560C has an on state current of 1 mA (milli 10^-3)

    i think your circuit is significantly under-powered

    i recommend a TL431 instead of the LM385
    you'll have to change the feedback resistors R1 and R2
    and you can reduce R3 to about 47 ohm and 1/2 watt



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    Re: How to they calculated resolution of the photodiode

    I want to measure the resolution of this photodiode op560c when it connected to the 16 bit ADC (NI-DAQ)...
    Resolution will depend on the original signal strength.

    You need to look into the noise specifications. The user has to decide the acceptable signal to noise ratio. If you are passing the photodiode output to a DAC, then the input signal must be much over 2^16 times the noise level so that you can get the 1 bit (LSB) resolution.



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