New Arrivals

1 03 2009

Specs: OD 6+ @ 690-1300 nm, OD13 @808nm specifically. For when you have gratuitous amounts of energylaser_goggles





Prep

21 02 2009

Here is a 1 axis stepper motor robot (it’s just the x-axis of a reprap). I’ll use this to do a laser welding test… a straight line butt joint. This makes it easy to control speed and distance with Gcode.

1axis





Laser Safety Goggles

19 02 2009

For the record those OD3 @808nm laser safety googles are INSUFFICIENT for the power of this laser. I’ve ordered these glasses, which are OD 6+ @ 690-1300 nm, and are OD13 @808nm specifically. This is 10,000,000 X the protection of the OD3 glasses. They are also glass which can withstand a direct hit much better than polycarbonate. Shout out to my peeps.insufficient





Laser Welding

16 02 2009

So the next move is to attempt to laser weld two pieces of steel. Having computer controlled laser welding at our disposal will be indispensable for constructing the core (beginning with welding the lids to the chassis) and the vacuum chamber (welding the chamber itself, welding various feedthroughs). I think we have enough wattage to laser weld stainless steel, although at a slow rate.  However, we still need to focus the beam, which is especially challenging for diode lasers that produce a bar beam like this:

beam_shapeIn my research, I found the back story to the lasers I picked up. Looking at the beam path illustration, these units correct for some of the diode array’s problems with divergence and astigmatism, so the output of the diode is a rectangular beam that focuses to a 1.5 cm long line about 15 cm beyond the output aperture.  So we are working with a well columnated beam, but it’s rectangle, not a circle. 

I think the easiest route to a top hat beam would be to focus this bar beam into a single thick core multimode fiber optic cable which results in a perfectly circular Gaussian spot, and an easy way to deliver the beam to it’s target where it would pass through a simple circular focusing lens. Challenges include sourcing the correct fiber optic cheaply, cleaving the fiber optic correctly, and aligning and focusing the bar beam into the fiber optic. This process would benefit from a Laser_beam_profiler, so you can find the sweet spot with focus and alignment for max transmission through the fiber. 

Here is a good overview of the basics of laser welding, including weldability of various materials.





Fire the Laser!

13 02 2009

Today we will fire the danger laser! I have the plumbing for the water cooling working. For this we take a field trip to my friend Stuart’s shop. He has 240V mains and a variable power supply. Here are the lasers:

img_3205

The labels are a bit ambiguous for the electrical connection. Is the chassis the anode, and both leads on the top the cathode? I think this must be the case. Poking around with an electrical multimeter, I find there is almost no resistance between the two terminals on top. But when you test between the either of the terminals and the chassis you get a different resistance depending on the direction of the test, which is from the diode’s electrical bias.

img_3206

 

We will be testing these current limiting power supplies (originally from NASA)

img_3207

Here is the full setup.

img_3224

Bucket of distilled water for the heat exchanger (we must have run this at too high a voltage, you can see it melted a little):img_3234

And the verdict? Success! Here is a video of the setup, and a video of the trial run.img_3236





New Arrivals

30 01 2009

Got a bunch of gear in the mail this week:
img_3144

laser safety goggles, tuned to the 808nm infrared of the cutting laser. Here is the spec sheet. These are model EP-5, so they have OD3. OD5 is ideal for the power range we are working in, but OD3 is INSUFFICIENT  better than nothing. To be on the safe side, I plan to only operate the power lasers in an opaque enclosure. 

img_3155A variety of lenses for shaping the beam path.

img_31571

Pretty.

img_3158Same lens.

 

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Tiny Tiny beam splitter. 

img_3146An finally the new geared motor for the new pinch pulley extruder, with the perfect timing belt pulley on it’s end.





Lasers

24 01 2009

Just received 3 650nm 5mW laser module.3.2V to with lens 650 nm.

I got these to a) play with and b) learn about beam paths:

img_3126

These are safe as long as you don’t look directly into the beam:

img_3122








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