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using a UV LED as a detector

Discussion in 'Electronic Design' started by Peter Lynch, Sep 4, 2007.

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  1. Peter Lynch

    Peter Lynch Guest

    The plan is to build some sort of meter for measuring the UV light
    intensity from the sun. Now I'm not talking about UV-indexes or any sort
    of medical/lab-quality measurements, just a hobby level goofing around
    project.
    I know that a normal LED can be used "backwards" as a detector, so
    one option I'm considering is to use an ultraviolet LED, with emmissions
    around 395 nm as the detector. I realise it will probably detect
    normal light too, but hopefuly with a bit of experimentation using LEDs
    of different colours I can take this into account.

    Has anyone got any experience of this kind of thing and in particular
    will a uv LED actually detect at long-uv wavelengths?

    Pete

    ...........................................................................
    .. never trust a man who, when left alone ...... Pete Lynch .
    .. in a room with a tea cosy ...... Marlow, England .
    .. doesn't try it on (Billy Connolly) .....................................
     
  2. AZ Nomad

    AZ Nomad Guest

    Why don't you just use a proper sensor?
    They can be had for around $20:

    http://www.mouser.com/search/Produc...O18virtualkey63510000virtualkey718-PC1-2-TO18
     
  3. I experimented a bit with LEDs as detectors, and found that,
    generally, only wavelengths shorter than they emit are
    detected. You might have to use a blue LED to detect long
    wave UV. The problems you might have include low detection
    efficiency, and packaging material that absorbs UV.
     
  4. Al

    Al Guest

    Check out:

    http://www.electronicdesign.com/Articles/Index.cfm?AD=1&ArticleID=15980

    and

    http://www.iscid.org/forrest-mims.php

    Forrest Mims is the guru on the subject.

    Al
     
  5. Peter Lynch

    Peter Lynch Guest

    ..... and, sadly, another $33 shipping to --------+
    |
    |
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    ...................................................|.......................
    .. never trust a man who, when left alone ...... V .
    .. in a room with a tea cosy ...... Marlow, England .
    .. doesn't try it on (Billy Connolly) .....................................

    However, John holds out some hope that a blue/UV LED will detect at
    shorter wavelengths. I guess I'll pick up a variety of LEDs and do a
    bit of playing - see what I come up with.

    As I said, it's only a hobby project. If nothing comes of it at least
    I'll have learned something and had fun in the process

    Pete
     
  6. I think this short wave blue (428 nm) would be an
    interesting candidate:
    http://www.avagotech.com/assets/downloadDocument.do?id=2549
    They should be responsive to 380 nm.
     
  7. Tom2000

    Tom2000 Guest

  8. I ran across some related links, and discovered that Digikey
    sells a a couple small GaN UV detectors.

    http://www.cinstrum.unam.mx/~martha.rosete/Leds.htm
    http://nina.ecse.rpi.edu/shur/Tutorial/GaNtutorial3/index.htm
    http://media.digikey.com/pdf/Data Sheets/Photonic Detetectors Inc PDFs/PDU-G106B-SM.pdf
    http://www.advancedphotonix.com/ap_products/pdfs/PDU-G105A-SM.pdf
     
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