- Joined
- Mar 27, 2008
- Messages
- 478
- Points
- 28
Over the last few months I have been very busy with college, and I never got around to running my argon laser. I ran it a lot over last summer and about the start of September was when I put her away for a while. Well I never got around to using it until after Christmas. And man was that ever a mistake!
Around new years I pulled her out of the dusty corner of my bedroom and plugged it into the special 20amp socket I had installed specifically for my baby. I turned on the power and the fan came on. I adjusted the foam lining around the base of the fan, put on my safety goggles, set the current to 8 amps and turned the key. The passbank cooling fan came on and I waited the usual 30 seconds for the cathode to heat up. And then it began to start...
.... click
.... click
.... click
Nothing. The start pulse just kept firing, nothing else. I took off the goggles. No laser action, no sustained discharge. "Well, it's been a while, I'm sure it will start soon." 10 minutes later and still nothing happening. Oh crap.
Its winter here, so I took the laser head off and put in the shed. -8 degrees C should cool the tube and lower the pressure enough to start, right? I brought it in the next morning and tried again. Still no joy. Well, now what? The pressure is still to high. Alright, lets make it colder. The tube is made of BeO, which is a kind of ceramic, it should be able to take a big thermal shock when it does start, right?. So I took a quick drive down to the local chemistry supply store and bought 7 pounds of crushed dry ice (only $50, plus I had some left over!). I packed the laser and a thermometer in the dry ice, packed the dry ice into a box, packed the box into styrofoam and packed that into another box. I the took the whole thing and left it in the shed again. Came back the next morning. I check the thermometer, it was off the scale on the low end. Sounds good, lets do this! I brought the whole thing back inside, quickly removed the laser and wired up the power supply. I threw on the safety glasses, and flicked the power switch. The fan came on. Turned the key. Waited 30 seconds. The lights dimmed, the fan slowed, my life flashed before my eyes and the thing started to lase. I backed away, shocked that I actually managed to get it working. I left it. I didn't touch a thing for three hours. Then I came back and turned the current down to 6 amps. I left it for another three hours.
There are a few things to consider here. I needed to use dry ice to cool the tube to get it to start because I had left it so long, and worse yet, after I cooled it I brought it into the warm house and then started it. The thermal stress on the tube alone going from -60 to 5000 degrees C should have killed it. But even WORSE, the moisture in the air condensed on the laser head. The laser head running at 100 volts and 8 amps. If that moisture had condensed on the wrong place I could have been looking at a dead laser, a dead power supply, a dead laser AND power supply, or if I was touching it at the wrong time, a dead me.
So for God sakes people run your damn argons once in a while!
Around new years I pulled her out of the dusty corner of my bedroom and plugged it into the special 20amp socket I had installed specifically for my baby. I turned on the power and the fan came on. I adjusted the foam lining around the base of the fan, put on my safety goggles, set the current to 8 amps and turned the key. The passbank cooling fan came on and I waited the usual 30 seconds for the cathode to heat up. And then it began to start...
.... click
.... click
.... click
Nothing. The start pulse just kept firing, nothing else. I took off the goggles. No laser action, no sustained discharge. "Well, it's been a while, I'm sure it will start soon." 10 minutes later and still nothing happening. Oh crap.
Its winter here, so I took the laser head off and put in the shed. -8 degrees C should cool the tube and lower the pressure enough to start, right? I brought it in the next morning and tried again. Still no joy. Well, now what? The pressure is still to high. Alright, lets make it colder. The tube is made of BeO, which is a kind of ceramic, it should be able to take a big thermal shock when it does start, right?. So I took a quick drive down to the local chemistry supply store and bought 7 pounds of crushed dry ice (only $50, plus I had some left over!). I packed the laser and a thermometer in the dry ice, packed the dry ice into a box, packed the box into styrofoam and packed that into another box. I the took the whole thing and left it in the shed again. Came back the next morning. I check the thermometer, it was off the scale on the low end. Sounds good, lets do this! I brought the whole thing back inside, quickly removed the laser and wired up the power supply. I threw on the safety glasses, and flicked the power switch. The fan came on. Turned the key. Waited 30 seconds. The lights dimmed, the fan slowed, my life flashed before my eyes and the thing started to lase. I backed away, shocked that I actually managed to get it working. I left it. I didn't touch a thing for three hours. Then I came back and turned the current down to 6 amps. I left it for another three hours.
There are a few things to consider here. I needed to use dry ice to cool the tube to get it to start because I had left it so long, and worse yet, after I cooled it I brought it into the warm house and then started it. The thermal stress on the tube alone going from -60 to 5000 degrees C should have killed it. But even WORSE, the moisture in the air condensed on the laser head. The laser head running at 100 volts and 8 amps. If that moisture had condensed on the wrong place I could have been looking at a dead laser, a dead power supply, a dead laser AND power supply, or if I was touching it at the wrong time, a dead me.
So for God sakes people run your damn argons once in a while!
