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Laser, a quality issue? — Parallax Forums

Laser, a quality issue?

rwgast_logicdesignrwgast_logicdesign Posts: 1,464
edited 2012-12-16 14:19 in General Discussion
So I purchased some 5mW red laser modules cheaply off ebay, they finally arrived today. The things start turning in to a blob after maybe 8 ft or soo... is this just cheap lasers or what? Ive taken lasers out of cheap junk items before and they all work well in a focused beam at 20ft plus

Comments

  • ElectricAyeElectricAye Posts: 4,561
    edited 2012-12-15 22:19
    How big is your blob at 8 feet? Does the tip have a rotating focuser or some other optical cover?
  • rwgast_logicdesignrwgast_logicdesign Posts: 1,464
    edited 2012-12-16 11:16
    I would say its quarter sized at 8ft. Its just a plain laser diode

    http://item.mobileweb.ebay.com/viewitem?itemId=140800296661&index=2&nav=SEARCH&nid=57232683175

    the pne i pulled out of junk looks exactly the same just a little bigger, like i said it stays a pinhole well over 30ft.
  • xanatosxanatos Posts: 1,120
    edited 2012-12-16 12:25
    I can't be sure from the photo, but they -look- like they have collimating optics. If they do it's likely they need the forward collimating lens turned to make the beam less divergent.

    If they do NOT have optics... they need some. Raw laser diodes can have very divergent beams and require collimating.

    Dave
  • rwgast_logicdesignrwgast_logicdesign Posts: 1,464
    edited 2012-12-16 14:15
    :/ well these were a waste im sure the price and effort of optics isnt worth the hassle.

    Can anyone recomend a supplier of resonably priced lasers with whatever i need to get a decent beam.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2012-12-16 14:19
    If the blob is quarter-size at eight feet, the module probably has a collimating lens. From the photo, it looks like the housing is two-piece, so try screwing the front part back and forth to see if anything changes. Or, if it's not threaded, there may be a setscrew you can loosen to slide the lens barrel back and forth.

    -Phil

    Addendum: By the way, I've had good luck with laser modules from DealExtreme.
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