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Photodiode Daylight elimination

Discussion in 'LEDs and Optoelectronics' started by chippevijaya, May 3, 2013.

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  1. chippevijaya

    chippevijaya

    8
    0
    May 3, 2013
    Dear friends,
    I am developing a IR Laser receiver. for that i have chosen QSD2030F photo-diode(Peak sensitivity λ = 880nm, and specified daylight filter), from fairchild, And i have connected this to a high speed transimpedance amplifier, opa380.

    Here the problem comes in picture, whenever i have taken this module to outdoor environment, under sunlight, there is a dc-offset and it is completely high(up to 5VDC, entire is working on 5V). So i am unable capture the pulses of laser that fired on it. the QSD2030F is showing having daylight filter option, but it is not working under daylight.

    In indoor condition the DC-offset is as low as, i can capture the pulses.

    Is there any idea that to eliminate the daylight effects, and my module will work under sunlight.

    Please help me...
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Investigate a magic component which blocks DC yet allows an AC signal to pass...
     
  3. JMW

    JMW

    90
    3
    Jan 30, 2012
    Early heat seeking guided missiles suffered from the same problem. They would lose lock on the target and target the sun.
     
  4. chippevijaya

    chippevijaya

    8
    0
    May 3, 2013
    thanks for your suggestion steve
     
  5. glewis721

    glewis721

    49
    1
    Apr 30, 2013
    so from what i understand the sunlight is so bright thar it is over-riding the laser pulses, no? well if that is the case, then mabe you could build some sort of sunlight shield, like a sun visor.

    or if than doesn't work you could make a box aroundthe reciver, and leave a hole in the side that is just large enough for the laser to shine through.

    hope this helps! =D
     
  6. chippevijaya

    chippevijaya

    8
    0
    May 3, 2013
    Thank you, i did this by using particular wavelength filter. It works well under sunlight, but it is more expensive(approx 200$). I don' want to use this, for that i choose the photo-diode with built-in daylight filter(somehow better than normal photo-diodes, but under direct sun all are one) i am experimenting on it.
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    If my first suggestion wasn't helpful, consider seeing if you can select an appropriate biasing for use in bright sunlight.

    Once you've determined that, see if you can make this value determined by the average of the recent ambient light levels.
     
  8. chippevijaya

    chippevijaya

    8
    0
    May 3, 2013
    Steve, appropriate biasing for what case either photodiode or amplifier. will you explain me clearly.

    I think i achieved a step in this problem, i have connected photodiode cathode to 5V and anode to transimpedance amplifier, a variable resistor other end grounded, a capacitor other end grounded. with the help of this adjusting resistor i can adjust the dc-offset of the daylight output to near by zero, my guess the dark current are reducing.
    But still need to work to make my sensor to work in all types of sunlight(day-dawn-dusk).
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Draw a circuit diagram of what you have now.
     
  10. chippevijaya

    chippevijaya

    8
    0
    May 3, 2013
    Here you find the attachment,
     

    Attached Files:

  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Why is the capacitor there?

    Wouldn't it be better to AC couple your signal?
     
  12. chippevijaya

    chippevijaya

    8
    0
    May 3, 2013
    Photodiode Amplifier problem

    Dear friends,
    I am trying to develop a photodiode receiver circuit as shown in figure. When i placed this in under sunlight the output voltage level is shifted(DC-offset) is happening.
    Is there any possibility to reduce the offset of the voltage and try to pull near to zero. This is happening due to photodiode is receiving the sunlight components and turned to high.
    Please help me in this.
     

    Attached Files:

  13. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,496
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    Jan 21, 2010
    The answer was given in post number 2 and amplified in post number 11.

    Please don't start multiple threads for the same problem.
     
  14. chippevijaya

    chippevijaya

    8
    0
    May 3, 2013
    Capacitor is just for fine pulse shape.....
    It is not that much important...

    Can you a have any circuit idea to solve the level shift in signal....
     
  15. chippevijaya

    chippevijaya

    8
    0
    May 3, 2013
    Both the threads are different, see the questions one is for daylight elimination and other is to remove level shift in op-amp.....if anyone solved it will help in solving my problem.
    And try to understand problem and give any solutions, thats why i am posting in forums.
     
  16. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,496
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    Jan 21, 2010
    They are both the same problem.

    signal source -- capacitor -- amplifier

    This fixes both (I say both...)

    Note that you may need to provide a DC bias for the input of your amplifier
     
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