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After the optic has been mounted in an optical mount and placed as close as possible to the amplifier end of interest, fire the head of interest at the normal operating pump voltage. After the head has been fired, remove the optic mount and look carefully for any signs of water on the optic surface that was facing the amplifier rod.
Test optic and mount placed as close a possible to the end of the amplifier head of interest.
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With the oscillator/seed beam completely off, fire just the head of interest. After firing, remove optic mount and inspect:
Test optic clearly shows signs of water discharged after firing head.
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- Follow steps 1-2 mentioned above
- Place covers in front of all SHG crystals that could be negatively affected by potential water spray, as the following steps require disconnecting and draining water from the amplifier heads.
SHG crystal removed and covered during process involving potential water spray
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4. Using the Oring spanner wrench, remove the brass retaining nut from the amplifier head by turning wrench CCW.
5. Remove Delrin thrust washer. It may be useful to use a piece of tape to help in pulling the washer away from the head.
6. Remove the Oring using a sharp tool that can pierce the Oring so that the Oring can be pulled off of the rod and way from the head.
7. Install new Oring. The use of a small blunt-ended tool such as the end of a 5/64 ball driver will be necessary in order to press the Oring over and around the rod and between the rod and the stainless collar holding the rod. Try to press the oring so that it is seated as uniformly as possible, but using care to not press to hard, which could result in a puncture or cut into the new Oring.
8. Clean the end of the rod surface as best as possible. Since the diameter is 2", multiple swipes with a clean sheet of lens tissue before each swipe will be necessary. Take the time and patience required to do a thorough job. Acetone is best as an initial cleaning solvent to remove the bulk dirt and grime that may have accumulated followed by multiple swipes using methanol.
9. Clean the new replacement Delrin thrust washer and insert it into the amplifier head and carefully push it up against the Oring. Install the brass retaining nut and tighten snuggly using the spanner wrench to compress the Oring. Use care not to over tighten.
10. Reconnect water connections for input and output of amplifier head. This may require the head to be re-located back to the original position before dis-assembly. If so, be sure to secure the head as accurately as possible to the original position using the indexed plates that should have been installed.
11. Return the master key to the LSS and set the appropriate mode that will allow the amplifier head cooling units to turn on so that leak checks can begin. It's recommended that splash shields be used before enabling amplifier head cooling in the event that there is a significant leak that could spray on optical surfaces at or right after cooling unit turn on.
12. Enable the cooling unit. It may take 5-10 turn-on attempts before the amplifier cooling supply sufficiently primes the amplifier head and begins to flow without turning off. Observe both ends of the repaired head ASAP to see if there is any sign of leaks. If no leaks, continue to let the cooling unit run for an hour while checking for leaks periodically during that time.
13. Prepare to fire the amplifier head. Use the test technique of placing an old, damaged optic close to amplifier head ends prior to firing and verifying that there is not any water that has discharged from the head after firing. Operate only the amplifier leg that was repaired
14. If no water is detected on the optic, proceed as normal with operating the system at full energy. Operate only the amplifier leg that was repaired to confirm that the camera image of the 527nm is as expected with no sign of spatial distortion due to water discharge (shown below).
