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I recently bought some cheapish laser parts off of EBay: 1.8mmx63.5mm 0.5% Nd, 0.5% Cr YAG rod ($25), 3x3x20mm LBO ($35), 20W Spectra-Physics diode bar ($36). Can these parts be put together into some sort of reasonable DPSS laser given mirrors and enough work, or have I squandered my money on useless parts?
Yes, I know its a pain in the ass to build a DPSS. But I'm stubborn and want to give it a try :p
Well then I commend you for your ambition. Do you have links to the ebay lsitings for what you bought? It would be good to know more about these bits.
But my first thought is, I'm not sure if that rod can be pumped with that bar you bought. I need to do some more reading.
http://www.repairfaq.org/sam/laserfaq.htm
Rod: http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWNX:IT
Bar: http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWNX:IT
I don't have a listing for the LBO since it was a second chance offer.
Quoting wiki:
YAG doped with neodymium and chromium (Nd:Cr:YAG or Nd/Cr:YAG) has absorption characteristics which are superior to Nd:YAG. This is because energy is absorbed by the broad absorption bands of the Cr3+ dopant and then transferred to Nd3+ by dipole-dipole interactions.[3] This material has been suggested for use in solar-pumped lasers, which could form part of a solar power satellite system.[4]
Is phi and theta marked on the KTP crystal? The crystal must be cut for a specific wavelength and coated correctly. You can download SNLO and put in theta and phi, plus wavelengths for a given crystal material and find out what is going on.
www.as-photonics.com/SNLO.html
Is the pump diode 808 to 810 nanometers?
Steve
You will need also Output coupling mirrors for the rod...I may have an extra set somewhere....I will try and locate them. Have you considered cooling the rod? Thermal expansion rates? It can be mounted into a clam-shell style block and still side pump it. JDSU end pumped their smaller greens....but it was a lot smaller rod. I think Junktronix had some smaller rods with brewster cut ends....negating the use of the mirrors.
@mixedgas: The LBO is coming in the mail, so I can't say anything about it yet. The fact that it's LBO and not KTP worries me a bit :( The diode claims to be a 808nm pump diode. Is there any way of checking?
@MechEng3: I have big TEC thermal-pasted to a gigantic heatsink that should be capable cooling the rod. I'm still missing mirrors (the OC should be HR1064/HT532, right?)
you can check the specs of the diode. if it is 808nm +-3nm you are pretty much ok. if it is 808nm +-10nm maybe you should reconsider its suitablity for your application
i think i have one of these brewster cut junktronix yag rods. in case you reconsider your design and can't locate anything at that time, send me a pm and i'll dig around to find it. i got an yvo4, so i won't be needing the yag rod
(looking for ktp 1064/532 coated and all now... and a pump diode...)
The diode specs are rather hard to find.
It is a DW20-50319-Q12; I'm not even sure which manufacturer anymore. The seller claims it is Spectra-Physics, but another Ebay listing mentions a Coherent bar of the same model :( It doesn't help that it hasn't arrived in the mail yet either.
Fortunately, used diode bars don't cost very much :) And there are some pretty interesting underspec (but still quite usable) Coherent bars on Ebay right now.
All the parts I ordered arrived today :) Does anyone know where exactly the diodes are located in a diode bar module? I see a row of golden stripes near the aperture, and I'm worried those are the diodes, in which case I should probably be very very careful not to hurt them.
Hmm...one of the stickers on my LBO crystal says "THG". Is there any fundamental difference between SHG and THG crystals?
Also, LBO is hygroscopic and needs to be protected from moisture in the air, right?
Yes it will degrade and grey track or simply split if it is left to air....got a couple of those. The LBO is in a mount? Have you calculated the mode volume of the rod vs. the SHG? You will need to verify the coatings as you mentioned THG. This may be THG for a much lower wavelength...300-ish nm. But unless you have the OC for that wavelength it won't lase. Keep us posted...your resonator layout is a V fold of sorts I take it?
Yeah, my resonator is a V-fold. If I use a THG crystal for SHG will terrible things happen, or will it still lase with lowered efficiency?
I'm still waiting for mirrors (Laser Ben said he'd PM me some time soon). I also have 2 more 20W bars now :) MOAR POWER!!!
MAKE SURE YOU PURCHASE SAFETY GOGGLES THAT COVER 808, 1064, and 532 at Optical Density 6.
Crystals For Type I NLG SHG of 1064nm (Nd:YAG)
Theta 90 Deg 14 Deg Coatings S1, S2: AR1064/532nm
Crystals For Type I CPM SHG of 1064nm (Nd:YAG)
Theta 90 Deg Phi 0 Deg Coatings S1, S2: AR1064/532nm
Crystals For Type II CPM THG of 1064nm (Nd:YAG)
Theta 42 Deg. Phi 90 Deg. Coatings S1, S2: AR1064/532/355nm
The above are from the Newlight Photonics Website.
Judging from those crystal angle differences, No. certainly not with any decent conversion.
You can download SNLO, select LBO and plug in the theta/phi numbers, to find out.
LINK:
http://www.as-photonics.com/SNLO.html
The third harmonic is a product of the fundamental and second
harmonics.
Thus THG is a signal mixer, not a signal doubler.
MAKE SURE YOU PURCHASE SAFETY GOGGLES THAT COVER 808, 1064, and 532 at Optical Density 6.
We talk you out of a KTP and you decide to build one anyways?
You will need 2 power meters, a IR visualizer, a Qswitch, a 1064 nm polarizer for diagnostics, and a alignment laser, plus 1064 only optics to figure out the thermal lensing to get that going. The crystal will need a oven, and the diode and rod will need cooling. Better add in a milling machine. That is going to be quite a chunk of change.
MAKE SURE YOU PURCHASE SAFETY GOGGLES THAT COVER 808, 1064, and 532 at Optical Density 6.
Steve
I have goggles that are OD8 at 532 and OD7 at 808 and 1064.
As for 1064-only optics, I think I can borrow them from my (currently non-functional due to lack of chiller) arc-lamp pumped YAG.
This LBO crystal seems to be a mystery crystal, as the box it is in does not appear to be its original box (I just noticed the crystal is 3x3x20 and the box is for a 3x3x10 crystal :p).
I have TECs for cooling and heating the rod, diode, and crystal.
Speaking from past ventures in building things like this......He is barking up somewhat a very tall tree here with this stuff. It would be much easier to locate a Melles or another large frame laser to try and repair or rebuild....you are setting out to damage a lot of things if you are not ready to spend a lot of time absorbing theory on this. I would hope that you do have eye protection...OD6 at least like Steve said. I have constructed an indirect viewing cabinet with a LCD tv for the monitor...light proof cabinet...no worries at all with this. The laser chamber with a cheap camera works and helps to keep dust out with internal filtration. That way if you fry the CCD just toss it. Can't replace eyes like that. Bottom line...be careful. Tiny dust particles on the diode facet will destroy it...and optics get these nasty looking black spots from burnt dust on them, ruining the coatings...get the picture? Just be as clean with everything as possible...then clean off with your choice of inert gas. Look at a diode facet with a 10X scope or better...then you will see...photon emissions attract dust...from everywhere. But you have parts...I understand the quest.....BTDT..still have the laser in parts again somewhere in a box...Yag rod...mirrors and 2- 40 watters...it destroyed a new 5 x 5 x 8mm KTP .....even at threshold it was a tad much.
Blarg, I cannot find this crystal's original use (SHG or THG). Is there some easy way too figure out, or should I return this crystal and get another one that is marked?
Quote:
Originally Posted by bwang
They are oriented for cutting using X-rays.
The only easy way involves a working laser designed for the crystal.
The not so easy way needs a variable power, 1064 nm, Qswitched laser and perhaps a crystal oven.
Steve
More thought has caused me to realize that my design needs to be built around the mirrors I have available.
My new design is a linear cavity: HR1064-YAG-HR532-LBO-HR1064. The HR's are not AR532, but they transmit green well.
My question is, will it work if the HR532 is not AR coated for 1064 nm?