Re: [CAD_CAM_EDM_DRO] Re: Laser specs ? optics ?

turbulatordude wrote:

>--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@...> wrote:
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>
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>>I run the laser with a
>>pulse generator at a 1:1000 ratio,
>>so it doesn't harm my eyes.
>>
>>
>
>
>I don't understand what the pulse does, nor how that would have any
>effect on your eyes.
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>

Diode lasers are very non-linear devices. If you turn the current down,
they become
LEDs, and spread the light broadly around. When you turn up the current
above
the lasing threashold, the beam becomes much more defined and aimed forward.

So, when setting up the optics, you can't just dial the current down
until it is eye-safe.
Pulsing the laser on for .1% of the time at normal lasing current allows
me to get
right in there with a magnifier, but not fry my retina. Looking
directly into a
5 mW laser, or at a highly focussed spot from one, is not safe to the eye!

>I guess that before too much more, I should look into some sort of
>safety glasses. The laser beam is an IR diode. Any suggestions ?
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>
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In my case, I was using 670 nm visible red lasers, so there was no
problem with seeing
the beam, or being struck accidently by an invisible beam or
reflection. But, I had to
make the intensity eye-safe to set it up.

>Also, since IR is not visable to the naked eye, any suggestions on how
>to 'see' it so as to help with lenses and alignment and all that ?
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>
>

I thought we were talking about laser pointers. Those would be
"pointless" if
they were IR. (sorry, that one was too easy!) You ought to get an
Edmund Scientific
Optics catalog, and maybe Melles Griot, too. They have enormous amounts
of info in
them. Edmund has 4 catalogs, I think, but you want the Optics one.
They have
safety, lenses, lasers (don't buy lasers from them, they are $$$$ crazy)
and all the
paraphernalia you'd ever need. The Melles Griot catalog is not for the
basement
experimenter, but it gives you an idea what the pros use. Edmund and others
should have IR detector cards that you illuminate under fluorescents for
a couple
of minutes, then it will light up in a dark room when hit by IR. But, I
don't
think you can do fine focussing with them.

Jon