Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

LPF Donation via Stripe | LPF Donation - Other Methods

Links below open in new window

ArcticMyst Security by Avery

# Pumping a Ruby Rod

#### BowtieGuy

##### 0
LPF Site Supporter
Wow, that's a pretty impressive "quick" calculation, and a lot of needed energy! :yh:

##### 0
Show off! Cool though.

#### vortish

##### 0
I forgot that Styro knows just as much as Kaiser on the subject. Sorry Stryro

#### Rivem

##### 0
Wow, that's a pretty impressive "quick" calculation, and a lot of needed energy! :yh:

That is a pretty quick calculation in the context of upper level mathematical sciences. Some of the electromagnetic calculations using Maxwell's equations around antennas get crazy. Not looking forward to going back to that after a semester off. Not to mention finishing the math degree side.

Good job though styro! Maybe there are pulsed LEDs that would fit the bill and be more efficient than flashlamps, but their cost would likely be prohibitive.

Last edited:

#### styropyro

##### 0
^ Yeah it really isn't that bad of a calculation in the scope of upper level courses. Five years ago that would have looked like alien writing to me. I remember taking a math test that was 3 questions, 3 hours long. I filled at least 10 pages and there were almost no numbers. I ended two classes short of a math degree. And yeah...calculations with the EM field can get nasty quickly.

#### Seoul_lasers

##### 0
ughhh...now I'm just procrastinating...

A quick calculation shows that to reach total inversion in the rod, (doped 0.05% by mass Cr3+ and pumping with 400nm at 100% efficiency) you need 3854W of INPUT for every cubic centimeter of ruby rod. You need to be at half that to reach the threshold of lasing, but once it starts lasing you need to pump in even more energy to make up for that lost by the crystal.

So...you probably won't be doing that with LEDs. There's a reason those lamps for pumping ruby rods are operating in the megawatts when firing!!

Some work has been done with pumping a very small synthetic ruby with a 405nm laser diode for CW use ~2009. The output was very tiny, but it did lase none the less. :can:

Last edited:

##### 0
I used to be able to handle math which looked like that, been three decades now. DPSS ruby has been made, 2009. LED, I doubt that will ever happen unless a very tiny piece.

#### Mosc007

##### 0
Thanks for all the input.

Looks like I will keep looking around for a Flashlamp or 2 that would be usfull to pump it.

#### Mosc007

##### 0

One of them might be ok. But I will have to check the length of my Ruby Rod. Also have to look closely at the tubes rating. It varies by a large amount. Most are only useful for 10-50 Joules. At least two of the ones you linked to have a good rating.

Interesting they need a small inductor in series to limit the current rise time. Didn't know that with high power xenon tubes.

Last edited:

#### Mosc007

##### 0
This is so tempting. It has popped up on EBay. Never seen one on there before.

#### styropyro

##### 0
Interesting they need a small inductor in series to limit the current rise time. Didn't know that with high power xenon tubes.
Still gonna recommend this book. https://www.ebay.com/itm/Solid-Stat...id=2137676&hash=item3ad4a5fb1d:i:252675750685 Even if you don't know the math to derive the laser rate equations, that does not mean that you won't find the stuff on flashlamp parameters and cavity design super useful.

But yeah the inductor is important. If the lamp fires too fast for a given energy you will degrade its lifetime.

As a separate note you have to make sure the entire rod is pumped by the lamp. Ruby is a 3 level laser system, so if you only pump a portion of it, the unpumped portion will just absorb the output.

#### Mosc007

##### 0
Still gonna recommend this book. https://www.ebay.com/itm/Solid-Stat...id=2137676&hash=item3ad4a5fb1d:i:252675750685 Even if you don't know the math to derive the laser rate equations, that does not mean that you won't find the stuff on flashlamp parameters and cavity design super useful.

But yeah the inductor is important. If the lamp fires too fast for a given energy you will degrade its lifetime.

As a separate note you have to make sure the entire rod is pumped by the lamp. Ruby is a 3 level laser system, so if you only pump a portion of it, the unpumped portion will just absorb the output.

Thanks for the link. For the price i just ordered that book. I was aware that the whole Rod needs pumping. The chamber is one of the difficult parts to manufacture.

Thats one reason that link i posted on EBay is so tempting. Rod, Lamp and water cooled pump chamber. He also has a new lamp available. I need to ask if mirrors are included. I suspecf they might be internal or silvered Rod ends.

Last edited: