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Registered Member #2040
Joined: Fri Mar 20 2009, 10:13PM
Location: Fairfax VA
Posts: 180
Cool! That's exactly what I was looking for. Looks like I'll give the cheapies a try. I'll get a 60% and a 70% since the ad I saw was for a set. That will let me experiment a little to see what this one likes.
That looks like a book that I should have, I'm going to have to check it out, thanks.
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
I am not sure who you got them from, but I got a pair off ebay for not much and they arrived looking very nice, AR coated on the back side, etc. Unfortunately I don't have the tools to measure the surface flatness, or time to measure the transmission, but I would say for $15 a piece they are well worth it :)
Good luck with your project, although I will say you really need to find some way to measure the laser power that is more repeatable then looking at the smoke cloud.
Registered Member #2372
Joined:
Location:
Posts: 62
I wouldnt worry about the quality of the cheap optics. Like someone else said, unless you are dealing with high intensity it wont be a concern. If they are AR coated you wont notice a difference, most of the time with more expensive stuff that is what you are paying for anyways. I have worked in a few laser labs and there is a huge premium that you will pay for "top quality" stuff and in some cases the newport stuff was worse than the cheap thorlabs stuff. Also we bought most of our polarization optics from china because it is like 1/4th the price.
Registered Member #2040
Joined: Fri Mar 20 2009, 10:13PM
Location: Fairfax VA
Posts: 180
... wrote ...
Those pics look a lot better than your earlier images, definitely 10s of joules available there.
I love the pieces of glowing metal bouncing across the floor
What is the largest size hole you can do in a single shot? (diameter)
Yeah I agree; I thought those flying metal bits were just too cool!
For a penny I might be able to get a sowing needle through after one shot, but just barely if so.
I've been doing some more reading about laser induced fusion. One of the things the researchers learned with Shiva (a multi KJ Nd:glass laser for those who don't know) is that the 1060nm IR couples strongly with the plasma produced on the surface of the fuel pellet. This leads to less energy absorbed by the fuel pellet and more wasted in heating the plasma. This is one of the reasons they frequency triple the beam to 351nm. I'm wondering if that is the reason for the less than spectacular performance on the black plastic I was shooting up earlier.
As for why the laser had a scorch mark on the shutter from before but won't produce one now, there might be a simple explanation. The original power supply had a multi tap inductor to change the pulse shape for drilling or welding at different power levels. It could be that someone set it up for the least inductance and then preceeded to crank the charge up all the way for a very short high power pulse. Who knows though. I might have access to a power meter in a few days at which point I will know for sure what is going on with this thing. As for now I'm fairly impressed with it.
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"Joules" the 60J ND:Glass laser
