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Quadrant pyroelectric detector for femtoseconds laser pulse detection

Discussion in 'Electronic Design' started by Mathieu G, Aug 24, 2009.

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  1. Mathieu G

    Mathieu G Guest


    I would like to design the electronics to use the Eltec 4202 quadrant
    pyroelectric detector ( datasheet: ) to detect the position of a
    ~100fs pulse width 1kHz repetition rate pulsed laser beam.
    I would like to resolve each peak with the amplified signal to be within

    Yet I am unfortunately no expert in electronics, but willing to learn!
    I would greatly appreciate if someone could help me define the basic
    design to reach my goal, please.

    Best regards,
  2. Nemo

    Nemo Guest

    Mathieu G writes
    Hi Mat,

    one of the key problems you will have is: light travels just a fraction
    of a mm in 100fs. This could make it very difficult to design - there
    will be many layout and component problems. For example, if 0.03mm is
    significant, thermal expansion of the components. Most people find it
    hard to design things that work well at just a few hundred MHz, ie where
    the signals are about the same size as a PCB, because you get unexpected
    reflections and interactions at this size scale. So, you need really
    expert advice here. (I see you have already been sent to Phil Hobbs - I
    asked him some questions myself recently.)

    Some things to consider:

    - Is this a one-off item, or do you want to make many of them? If more
    than one, the assembly needs to be designed well enough to be

    - What frequency is the laser light? This may affect choice of materials
    in your optical assembly.

    - What sources of optical and electrical interference will be present? A
    shielded (ie, metal) box would be best against electrical
    interference... you will probably want an optical filter to allow only
    the laser light through and cut out daylight.

    - A pyroelectric detector is not ideal for detecting fast signals. It
    has too much capacitance.

    - What is your development budget? You may end up needing some expensive
    specialist items.

    This does not sound like a beginner's project.
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