Question about 50W laser pointers

Discussion in 'After Hours Lounge (Off Topic)' started by andrew markworthy, Jul 22, 2008.

  1. andrew markworthy

    Joined:
    Sep 30, 1999
    Messages:
    4,762
    Likes Received:
    11
    I got a 50W laser pen off ebay. It was under £6 (i.e. under circa $12). I need one once every blue moon for lecturing work and this will fulfil the job perfectly - the light is bright enough to be seen, the pen is compact, etc, etc.

    Anyhow I got an email from a prospective ebay buyer - does this pen burst balloons. light matches, etc? If not then, according to this buyer, it can't be a true 50W pen. Out of curiosity, I tried to light a match with it and couldn't.

    Physics ain't my strongpoint - should all 50W lasers be able to do this?

    [Beyond intellectual curiosity, I'm personally not bothered - all I wanted was a green laser pointer and that's what I got; its strength is of zilch interest (in fact, I wouldn't want something that could generate that much heat for use in front of an audience)].
     
  2. Steve_Tk

    Steve_Tk Cinematographer

    Joined:
    Apr 30, 2002
    Messages:
    2,833
    Likes Received:
    1
    So you're saying you don't want a laser pointer that can also be used as a ray gun? Are you crazy!?
     
  3. andrew markworthy

    Joined:
    Sep 30, 1999
    Messages:
    4,762
    Likes Received:
    11
    I must confess that there is the occasional student I might like to apply it to, but since they could do the same to me ...

    I suppose a Star Wars type shootout might be a little more entertaining than Statistics 101 on a wet Monday morning, but I fear that it wouldn't go down well with senior management.
     
  4. Jay Taylor

    Jay Taylor Supporting Actor

    Joined:
    Sep 8, 2000
    Messages:
    830
    Likes Received:
    1
    Location:
    Oklahoma City
  5. andrew markworthy

    Joined:
    Sep 30, 1999
    Messages:
    4,762
    Likes Received:
    11
    I knew it was a mistake entering my name as Auric Goldfinger. [​IMG]

    Being serious for a moment - yes, quite right, the laser I've got is supposedly 50mW, not 50W.
     
  6. Jay Taylor

    Jay Taylor Supporting Actor

    Joined:
    Sep 8, 2000
    Messages:
    830
    Likes Received:
    1
    Location:
    Oklahoma City
    Okay, here are two of the posts from the thread at that link:

    1. Try a lens, 50mw isn't that much power to burn, especially if you have wider beam diameter. A lens should focus it good enough to smoke black plastic things.

    2.
    TheMafioso wrote:Hmm where can I buy a lens?

    any lens will work....magnifying glass....lens out of some old binoculars...even a woman's make up mirror that magnifys.......
     
  7. DaveF

    DaveF Moderator
    Moderator

    Joined:
    Mar 4, 2001
    Messages:
    17,499
    Likes Received:
    1,382
    Location:
    One Loudoun, Ashburn, VA
    Real Name:
    David Fischer
    Your pen is DEFINITELY 50 milli-watt; a "pen" laser is not 50W [​IMG] That would approach industrial cutting tool power.

    Andrew you want to be extremely careful with that and not operate it without protective eyewear for you and anyone in the area. A 50mW laser is extremely bright -- that's about 50-times brighter than the laser pointers used for academic presentations -- and can cause permanent eye damage.

    It's a Class IIIb laser: at work we don't do engineering work with a laser that powerful without a safety review by our laser coordinator, an approved operating procedure, a safety perimeter in the test area, and approved safety glasses.

    You might find this OSHA page helpful. TABLE III:6-4 notes the general health hazards of different lasers.
     
  8. Dennis Nicholls

    Dennis Nicholls Lead Actor

    Joined:
    Oct 5, 1998
    Messages:
    8,820
    Likes Received:
    315
    Location:
    Boise, ID
    Real Name:
    Dennis
    [​IMG]
     
  9. andrew markworthy

    Joined:
    Sep 30, 1999
    Messages:
    4,762
    Likes Received:
    11
    I always am, and as I said, I use it rarely. Generally when lecturing the students get the lecture notes well in advance and are told to print them out and bring them to lectures. I rarely use a projected display because all that ever happens is that as soon as you put one up, half the students are too busy copying it down to listen to what you're saying. About four times a year I 'have' to use a display and need a pointer. The standard ones are too weedy for the job. And I never *ever* 'play' with pointers, not even the weedy ones.

    To be honest, I'm not sure that the pointer I've got is even 50mW. I got out my reading glasses last night (I really should use them more - something about denying the onset of presbyopia, I guess [​IMG]) and what I took to be an ink smudge before the 50mW on the label on the pointer is a 'less than' sign in about 2 point font. Methinks it may be a rather more modest powered pen. However, it's still brighter than a standard pointer.
     
  10. DaveF

    DaveF Moderator
    Moderator

    Joined:
    Mar 4, 2001
    Messages:
    17,499
    Likes Received:
    1,382
    Location:
    One Loudoun, Ashburn, VA
    Real Name:
    David Fischer
    WIth the increase of wisdom, comes the decrease of vision. [​IMG] (So I wrote in the intro to my thesis.)

    A standard Class IA laser pointer (< 4 mW) will not cause permanent eye damage without unreasonably prolonged exposure and are safe public use. But I agree -- if this is what you're saying -- that they were a step backwards in ways from other pointers: old professors with shaky hands create quite the laser light show, but do little to actually draw attention to the specific point of interest.
     
  11. Marianne

    Marianne Supporting Actor

    Joined:
    May 18, 2000
    Messages:
    855
    Likes Received:
    0
    DaveF, what is the strength of those laser guns used in stores? Sometimes they leave them in a position where they shine in your eye if you happen to walk into the beam.
     
  12. Scott McGillivray

    Scott McGillivray Supporting Actor

    Joined:
    Sep 20, 1999
    Messages:
    860
    Likes Received:
    5
    Ah crud...I was SO excited that something like a 50W laser was available to the public!

    *mumble*....stinking "milli" watt....no fun....*grumble*
     
  13. Jay Taylor

    Jay Taylor Supporting Actor

    Joined:
    Sep 8, 2000
    Messages:
    830
    Likes Received:
    1
    Location:
    Oklahoma City
  14. DaveF

    DaveF Moderator
    Moderator

    Joined:
    Mar 4, 2001
    Messages:
    17,499
    Likes Received:
    1,382
    Location:
    One Loudoun, Ashburn, VA
    Real Name:
    David Fischer
    Very low power. They're in the power class that won't cause harm unless you stare into them for over 15 minutes without blinking [​IMG] Your blink reflex naturally protects from this sort of beam the same way it protects from bright reflections on a sunny day.
     
  15. Marianne

    Marianne Supporting Actor

    Joined:
    May 18, 2000
    Messages:
    855
    Likes Received:
    0
    I thought so, but it is a bit perturbing when one happens to shine in your eyes.
     
  16. Dave Poehlman

    Dave Poehlman Producer

    Joined:
    Mar 8, 2000
    Messages:
    3,813
    Likes Received:
    0

    Great! I can shoot my office coworkers with my barcode scanner and not have to worry about it! They're going to think I'm so funny!
     
  17. andrew markworthy

    Joined:
    Sep 30, 1999
    Messages:
    4,762
    Likes Received:
    11
    Given that my annual anonymous feedback nearly always contains several comments along the lines of 'it's just like being taught by Stephen Fry', I might be in serious danger of wrecking my image. [​IMG]
     
  18. DaveF

    DaveF Moderator
    Moderator

    Joined:
    Mar 4, 2001
    Messages:
    17,499
    Likes Received:
    1,382
    Location:
    One Loudoun, Ashburn, VA
    Real Name:
    David Fischer
    I forgot the other piece of critical advice: Never look into laser with remaining good eye.
     
  19. BrianW

    BrianW Cinematographer

    Joined:
    Jan 30, 1999
    Messages:
    2,562
    Likes Received:
    29
    Real Name:
    Brian
    I recently had to write firmware for a handheld, finger-trigger laser scanner like those used in POP applications. Of course, it had the usual warning label about how you should NEVER look directly at the laser. But the warning label was printed on the lens inside the shroud. Reading the warning label required you look directly into laser light source!

    Nincompoops.
     

Share This Page