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Metrologic ML855 HeNe Laser

Discussion in 'Electronic Repair' started by [email protected], Sep 10, 2013.

  1. Generally, a confocal FP is best since it greatly simplifies alignment.

    For the HeNe, the mirror Radius of Curvature (RoC) of both mirrors needs
    to be less than about 50 mm so that the Free Spectral Range (FSR, or
    mode spacing of the FP) is larger than the gain bandwidth of the
    HeNe red transition.

    One of the FP mirrors is then mounted on a piezo transducer (PZT) and
    the FP is scanned rather than the laser. The PZT can be the beeper
    element from a digital gizmo or less than $2 from Digikey. :)

    More info at: http://www.repairfaq.org/sam/laserlia.htm#liasfpi

    --
    sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
     
  2. Guest

    OK you may like this, I have only a few youtube videos.

    I'm sending a diode laser into a confocal cavity, (20 cm mirrors)
    with the cavity length set maybe 1cm short, so all the modes, don't all fall at the same wavlength. I'm then scanning the laser wavlength, and have abare CCD camera (no lens) pointing into the back end of the cavity. This video has mostly just the even modes* but the others show both odd and even..

    George H.
    *if you get the laser 'smack dab' down the middle you lose 'most' of the odd modes.
     
  3. I assume you are seeing a combination of the laser modes (if not single
    longitudinal mode) and the off-axis cavity modes. It may be possible to
    determine the spectrum of the diode laser from the video but that's above
    my pay grade. :)

    --
    sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
     
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