Long-wavelength infrared diodes

Discussion in 'General Electronics Chat' started by steinar96, May 15, 2010.

  1. steinar96

    Thread Starter Active Member

    Apr 18, 2009
    239
    4
    Has anyone seen retailers selling these types of diodes. I'm making a passive infrared detector as part of a indoor security system. Human peak infrared emission is at around 12 micrometer wavelengths.
    Almost all diodes i come across are peaking at around 950nm with upper half bandwidth at 1050 nm which is far from the spectrum i'm seeking.

    I would like to do this passively. If i can't find proper passive infrared diodes for 12um i assume i'll have to change my system to an active system with pinging infrared radiation. But that's slightly more complicated.

    Anyone run across these types of diodes capable of pointing me in the right direction ?
     
  2. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    You need to look for PIR sensors or Passive Infrared Sensor,


    Quote from Wikipedia:

    B. Morse
     
  3. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    1,015
    69
    These are available, but it is often cheaper to buy a ready built PIR module than just a sensor.

    PIR elements detect body heat. They must have a matching infra-red lens so the infrared patterns from people etc. appear as focussed spots on the sensor surface. It's the focussed patterns moving across the sensor segments that allow the movement detection to occur.

    If you look closely at the front body of a commercial PIR module, you will see it's a fresnel lens.

    PIR device:
    http://uk.farnell.com/murata/ira-e712st3/pir-high-light-immunity/dp/1006207

    This is a lens to suit.
    http://uk.farnell.com/murata/iml-0636/fresnel-lens-for-pir/dp/1006208
     
  4. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    there are some available at sparkfun, and even radio shack that are perfect to include in your own project....

    [​IMG]

    There is even one from sparkfun with a built in uc based on a Zilog mpu, and another based on the MSP430F2013 uc.


    B. Morse
     
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