Fun with a Ruby laser Rod [pic heavy]

[Peter Zeboroff]

Hi, I also have a Ruby Rod which is 120mm long and 6.5mm wide and in excellent brand new condition. I took some photos of it and a few of the Dielectric 30mm wide by 10mm thick Ruby Laser mirrors which are also brand new and in excellent condition.The mirrors are HR=99% Reflective and the OC=55% Reflective

 

[ultimatekaiser]

Looks like a good one to me. If it has no scratches or chips in the faces, and is clear and monocrystalline when you look through it with no bubbles or deformities or anything, then it should be fine to use. 240mm x 15mm is quite large. The diameter might make it a bit challenging to pump. You'll need some fairly beefy lamps or a good cavity probably. Usually rods that large would be water cooled, which greatly complicates things. But if you're only doing one shot at a time with long cooling periods in between, it should be ok to do convection cooling. Ruby is very poor at conducting heat, and it's made worse by the fact that you have to mount it with as little touching the rod as possible, so you get no dark spots. Finding a lamp with a 240mm arc length would be pretty expensive potentially. You'll want to use xenon as your gas preferrably....Optimally you want a linear lamp with the same arc length as the rod. Helical lamps work but they can make hotspots. the 120mm is probably going to be easier to work with. most people that make hobby ones do 2-3" ones but obviously one can't be picky these days. That rod looks similar in size to my larger one, but i'd have to check, but I think it was the same, 6" and not sure on diameter. someone salvaged it from a broken laser and sold it to me. I kinda wish they'd thought to save the whole cavity and lamps and everything.

The mirrors look great, I'd have to test them to know if they're suitable though. I have a few HRs, but not sure if I have any OCs left. that's kinda where i'm stuck personally in my case. Might just have to use one of my older etalon style OCs instead of a dedicated mirror. It works, but not quite as effective.

 

[Peter Zeboroff]

Looks like a good one to me. If it has no scratches or chips in the faces, and is clear and monocrystalline when you look through it with no bubbles or deformities or anything, then it should be fine to use. 240mm x 15mm is quite large. The diameter might make it a bit challenging to pump. You'll need some fairly beefy lamps or a good cavity probably. Usually rods that large would be water cooled, which greatly complicates things. But if you're only doing one shot at a time with long cooling periods in between, it should be ok to do convection cooling. Ruby is very poor at conducting heat, and it's made worse by the fact that you have to mount it with as little touching the rod as possible, so you get no dark spots. Finding a lamp with a 240mm arc length would be pretty expensive potentially. You'll want to use xenon as your gas preferrably....Optimally you want a linear lamp with the same arc length as the rod. Helical lamps work but they can make hotspots. the 120mm is probably going to be easier to work with. most people that make hobby ones do 2-3" ones but obviously one can't be picky these days. That rod looks similar in size to my larger one, but i'd have to check, but I think it was the same, 6" and not sure on diameter. someone salvaged it from a broken laser and sold it to me. I kinda wish they'd thought to save the whole cavity and lamps and everything.

The mirrors look great, I'd have to test them to know if they're suitable though. I have a few HRs, but not sure if I have any OCs left. that's kinda where i'm stuck personally in my case. Might just have to use one of my older etalon style OCs instead of a dedicated mirror. It works, but not quite as effective.

Hi, Both of the Rods are in absolutely perfect brand new condition without a single mark of internal distortion of any kind and the mirrors are also in the same perfect condition.. The only thing I am not certain of is the chromium content or how to accurately calculate how many joules of input energy I will require to reach threshold. Do you have any photos of exactly what the etalon style OCs are? I fully intend on having a 2 or 3 piece aluminum housing milled for me that will hold the Rod and the lamps since I definitely intend on having it fully liquid cooled, even though I am not after a high repetition rate. I have talked to a guy who states that he may have access to two 12.000 joule each flash lamps that are around 18 inches long with a arc length exactly what I require but two of those lamps will have an extremely high input power rating and that is where I run into issues since I am on a very limited income and the vast number of capacitors needed is quite a bit beyond what I could possibly afford. E bay has 5000 joule flash lamps supposedly but they are probably 40 years old or more and perhaps even gassed out by now. Do you have any idea how long a flash lamp will last if new but not used? Will they gradually lose their vacuum or gas mixture? Even though I have been extremely interested in Ruby Lasers and building one since I was a young kid in the 60s, now that I am actually on a path to hopefully eventually put one together and produce those extremely powerful laser pulses, I am finding there is a great deal of issues in actually constructing a working device that does not instantly blow up on the first pulse.

I have put out many calls for any kind of help in this endeavour over many years and you are the first person that actually replied and I am greatful for any assistance you are able to provide.

 

[Peter Zeboroff]

One thing I forgot to say is I intend on trying to pump the 120mm by 6.5mm Ruby Rod with high power blue leds and possibly also high power ultra violet as well. Apparently if enough input energy is used from the array of leds or even laser diodes, it is possible to achieve a deep red continuous low power beam from a small Ruby Rod and that is something that would be extremely interesting to see so I intend on giving it a shot. I already have around 500, 3 watt deep blue leds for a start. I will keep everyone posted once I actually start assembling that one or when I start the main build of the High power Ruby Laser.

 

[ultimatekaiser]

i’ve personally never tried doing a CW Ruby but it requires extreme cooling to do, in order to depopulate it fast enough. it would be interesting to try with a little tiny block of ruby though. i’m betting if you had a tiny sliver of it like would be found an a DPSS laser, Multi stage tec cooling would probably be enough if you had enough pump power. it would be pretty challenging though. There was a company that made a commercial CW Ruby, but it never took off. I imagine that’s how they did it via something similar.

Ruby is a three stage laser instead of a four stage so you can’t technically ever truly get a continuous wave output, at least not without any fluctuations. But you can kind of create a very stressful low output cw if you can get the chromium to depopulate fast enough.

 

[Peter Zeboroff]

Hi, I found an article several months ago in which they used a ruby crystal that was 8.6mm long and 3mm in diameter and they pumped it with either a violet or blue laser diode and were able to achieve a deep red, low power continuous beam from the Ruby Crystal. The beam was a few milli watts but just the thought of pumping a synthetic solid state Ruby Crystal with another solid state semi conductor laser crystal has a very nice ring to it and in articles related to that one, it was stated that even regular blue or violet or possibly even green high power leds should be able to work provided the input power was high enough. Even though I do not expect to have any real success in this experiment, It will be interesting to see what the Ruby Rod I have will do when I pump it will a killi -watt or more of Light from what I expect is going to be a very large and definitely impractical high current led array with as yet to be determined light wave guides to direct all the light possible from the led array. Once I actually start building this thing,I will be taking photos just incase there is something of interest to come out of this experiment. I also have even smaller Ruby rods that are the 45mm long by 3.5mm in diameter if the 120mmby 6.5mm in diameter turns out to be impractically large which is what I actually expect.

 

[ultimatekaiser]

Yeah I’ve always wanted to try doing it. Theoretically it should be doable but you would have to have someone who can fabricate things for you, which I don’t have. Theoretically you could just make a cavity that is tec cooled, and pump a tiny ruby with huge leds or laser diodes of the appropriate wavelength. You could still do high power pulse regimes with it too, but youd need a very good driver system, which would likely have to be custom and therefore you would have to have some degree of electrical engineering to make something fast and reliable enough. It’d take some significant design work.