Epic CVL Projector Build Thread

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Output coupler
the output coupler is not a part that you need to buy from oxford. basically any normal and not reflective window glass is good enough (as used during normal house construction, with approximately 4% reflection at the resonator side). When the glass is noth thick enoug to fit into the holder, you can use O-rings to fix it into position (or wathever you have available for).

A correct output coupler is more precise flat (does not matter with approx. 5mrad divergence) and has the outlet side antireflection coated (which gives about 10% more in output power).

Do the first test with such a plain piece of window glass and when the laser is running then you can go and buy a expensive one for the last watts of output.

But for the Brewster windows, you need the thick quartz glasses, regarding strength and temperature resistance.

before your first power up

I repeat my answer in another post from a 10W Oxford because both systems are identical in the basic mechanical and electrical construction

- check al least if enough oil is in the vacuum pump (or replace it because of the age)

- check the tube for vacuum leaks. often old O rings are dead and give leaks. With leaks, the laser does not work.
you need to close the gas inlet, open the valves of the gas flow, and to power up the vacuum pump.
when the system was on air for a long time, let the pump run forat least 3-4 hours.
check the vacuum on the gauge. after swithing off the pump, the pressure should rise up maximum 1-2 mbar / hour
when the pressure rises faster, then the system has a leak, most time the O-rings on tube end and on the brewster windows are old and hard
to see the gas flow use figure 8.1 in chapter 8 of the manual

- check the thyratron tank and clean it out when you can see any dirt into the oli or on the bottom or on the HV components
when necessary, pump the oil out of the tank. a old fuel pump from a car is perfect for that job
clean the tank and all components, and be very patient when tighten the connections of the big (blue) condensators,
let the oil go through a sieve when necessary, or better, replace it as soon as you see as the laser works
use gloves when handling the oil

HV safety
- the Oxford lasers haves a dump switch to discharge the capacitors after switching off of the HV. But it is alway a very good practice
to check the voltage on the capacitors with a HV probe and to short it with an additional labor cable.
There are 3 points to check
- at HV supply in the PSU
- in the thyratron tank
- peaking capacitors at the tube end
In case there is a bad connection, the dump switch must NOT BE ABLE TO DISCHARGE ALL OF THEM !!! Keep this alway in mind.

After this few points, you can go to the normal start procedure described in the manual.

broken tubes
the storage temperature must be some degrees under the freezing point.
the glass tube and the inner cooling jacket tube have only about 5mm of space. some water rests in the cooling jacket of the tube and
get frozen and expand so much, as the inner tube of the jacket bent toward the tube and cracked the tubes.
so be care with storing the laser in a non heated environement.
i still have a quotation for new tubes from oxford for a really fair price, but i need some parts more. both systems have near 2000 hours on
its first thyratron so i like to replaces the thyratrons too to become reliable systems. and the electrodes looks very poor.
in the past the costs for 2 tubes and 2 thyratrons are more a i like to spend but it is planned now to do it this year.

scematics
i have 2 binders wit the original Oxford paperwork, one is user manual, the other is service manual. some 100 pages total. as i bought the documents
from Oxford, there was no pdf available. As i have seen in another post, you have received pdf files from Oxford. It would be cool to know what is included there
so i have less work to scan the rest.

Andi

[dsli_jon]

^^ Wow, how... 'Epic'.. ..would be very-cool to see you guys 'collaborate that thing to-life'.. ..@ J, I know this nutty guy that has a fair-bit of shop-space and 3Ø and tools and such..
Oh, and oil-resistant chem-gloves..

Tracking-mode: Set..
j

[mixedgas]

Jonathan, I found a place that offered me good neon at 225$ a tank for 35 litres and about 70$ in shipping. Since I will need to restore some henes soon, I was hunting. Pm me for his phone number.

Steve