On 20 Oct 2014 04:55:43 GMT, "DoN. Nichols"
wrote:

On 2014-10-20, Larry Jaques wrote:
On Sun, 19 Oct 2014 20:03:29 -0400, "Carl Ijames"
wrote:

The sparks travel that fast, yeah, that's what I meant :-). Guess I
shouldn't post while watching football. The Giants just finished losing to
Dallas, and I'm not doing any math, so maybe I'm safe from typos and mental
misteaks (:-)) this time. We have a 1200 W Amada CO2 laser at work, but it
dates from the 80's and moves the sheet, not the laser head, so it isn't
nearly as impressive as current tech.

Perhaps not, but 1200w is nothing to scoff at. I wonder why they
moved the work instead of the cutter, though...

Possibly the laser tube (glass or quartz for CO2, I believe) was
too fragile to accept the acceleration. It is possible to design more
durable tubes, but they probably didn't back then. :-) I'm not sure what
the window material would have to be for CO2 -- perhaps something like
Irtran -- I forget what wavelengths it worked well at. I do remember
lenses for far infrared imagers being made from either silicon or
germanium crystals.

Let's see -- Nd/Yag lasers were about 1.06 uM (1064 nm) (very near to
red), and I think that CO2 was closer to 10.6 uM

Also -- depending on the size (mass) of the head, it might be
easier to move the workpiece. :-)

One possibility would be prisms or first-surface reflectors to
take a horizontal light beam parallel to a support beam, and move the
reflector to turn the beam down from the horizontal to impact the
workpiece. (And, of course, each reflection introduces more potential
positional error, so how precise was this beastie, anyway?)

Enjoy,
DoN.

As Carl said, it was the mirrors and alignment that were the issue.
You have the wavelengths about right but they're not an issue. The
fiber lasers that have been mentioned, and which are the real speed
demons in thin stock, produce the same wavelength as the Nd/Yag types.

The next big thing is the direct-diode lasers, which are being used
for welding and cladding already, but not much -- yet -- for cutting
sheet and plate. They're coming soon.

--
Ed Huntress