decan an 808 and add a DPM?

[Cyparagon]

With the small mass of a pointer, you'd probably get only a couple seconds before those TEC temperatures start to fluctuate because they cant get rid of the heat fast enough, which means your power will go all crazy and drop like a stone.

Spyder II anyone? :

 

[chaosfourever]

So where can I get some good but cheap green crystals?

 

[ElektroFreak]

Snoctony sells some on his ebay page here: http://cgi.ebay.com/Nd-yvo4-Ktp-Glu...5|66:2|65:12|39:1|240:1318|301:1|293:2|294:50

but the best place to get them is from dead green lasers from your own collection. Snoctony also sells individual discrete crystals, so you could experiment with those later on..

 

[suiraM]

Cheap and good is mutually exclusive.

You can get good performance out of Susie's discrete crystals, which for the gain crystal are 3x3x2mm for the 1% Nd:YVO[sub]4[/sub] crystals, and 3x3x1mm for the 2% Nd:YVO[sub]4[/sub] crystals. She also has SHG crystals, specifically the 2x2x5mm KTP and 2x2x10mm LBO, both DBAR coated.

You will want some sort of output coupler, but you can get one off eBay for a decent price. However, a suitably coated crystal can also be had, if enough people were to be interested that a custom run can be split down to a reasonable item cost. The main hassle remaining after that is aligning the crystals and fine tuning the pump beam, which is why lots of people go for the DPM crystals and low power.

Also, of course, the more power you want, the more pump power you need. And more pump power isn't all that cheap, particularly for end face pumping (though, as a neat trick, you can sometimes increase the efficiency with an etalon on the pump diode). For an eBay source, sinolasers have 20W bars for $100 or so, but the optics will set you back a fair bit, too, if you want to use it properly and lack the tools and skills to fiber couple it yourself (in which case it's unlikely you'd ask about the more basic things here).

 

[ElektroFreak]

[highlight]Cheap and good is mutually exclusive[/highlight].

You can get good performance out of Susie's discrete crystals, which for the gain crystal are 3x3x2mm for the 1% Nd:YVO[sub]4[/sub] crystals, and 3x3x1mm for the 2% Nd:YVO[sub]4[/sub] crystals. She also has SHG crystals, specifically the 2x2x5mm KTP and 2x2x10mm LBO, both DBAR coated.

You will want some sort of output coupler, but you can get one off eBay for a decent price. However, a suitably coated crystal can also be had, if enough people were to be interested that a custom run can be split down to a reasonable item cost. The main hassle remaining after that is aligning the crystals and fine tuning the pump beam, which is why lots of people go for the DPM crystals and low power.

Also, of course, the more power you want, the more pump power you need. And more pump power isn't all that cheap, particularly for end face pumping (though, as a neat trick, you can sometimes increase the efficiency with an etalon on the pump diode). For an eBay source, sinolasers have 20W bars for $100 or so, but the optics will set you back a fair bit, too, if you want to use it properly and lack the tools and skills to fiber couple it yourself (in which case it's unlikely you'd ask about the more basic things here).

As a general rule, you're right. Cheap and good rarely mix... except, it seems, when you're talking about cheap chinese DPMs. Real world experimentation has shown that the cheap DPMs from cheap chinese modules almost always boast very high efficiency. This isn't guesswork talking here. Several members of the forum including myself have built lasers using these DPMs and have had excellent results. Sure there are better quality crystals out there, but why pay extra $$ if you're getting great results with something nearly free?

 

[suiraM]

Define excellent results?

Which pens have the best crystals?

And how consistent are the results with these?

 

[ElektroFreak]

By excellent results I mean that I've seen efficiencies of 25% and above in some of my experimentation, and Wannaburn has done even better than that..

There is some variation, of course. Not every crystal set I have does that great, but the majority do. I've gotten upwards of 50mW of green from 300-350mW of pump power using tiny DPMs ripped from 5mW DX lasers.

Susie's modules have very efficient crystals. If you end up with one of her modules that has died, I highly recommend pulling the DPM.

 

[suiraM]

Thanks for the info and the suggestion.

 

[mauswiesel]

Sorry to bump, here is my copy of my post in the thread of Group buy of Susie.
In one word, 808nm@532nm can be done with an efficiency of 50%, in maximum.

Here is the graph from Mike for the Stenkat 808nm 200mW diode
"I ran this diode later at 400 mA (270 mW) for a life test."

I made some research about the optical conversion efficiency of 808@1064 with Nd:YVO4 and 1064@532 with KTP.

(from Casix)Recently, over 30 W of TEM00 output power was achieved by using a-cut Nd:YVO4 and pumped by 60 W fiber coupled diode lasers. The optical conversion efficiency exceeds 50%.

Potassium Titanium Oxide Phosphate (KTiOPO4 ), or KTP, is an efficient nonlinear optical crystal in the visible to infrared spectral region with relatively low cost. It has large nonlinear coefficient. The effective nonlinear optical coefficient of KTP deff at 1064nm is more than 1.5 times that of BBO. It's damage threshold is near 1 GW/cm2 for 1 Hz 10 ns pulses at 1064nm. However, it is now limited to moderate to low power applications due to it's gray-tracking problem.

[FONT=verdana,helvetica,arial,geneva]Advantage[/FONT]

• [FONT=verdana,helvetica,arial,geneva]Efficient frequency conversion(1064nm SHG conversion efficiency is about 80%)[/FONT]

These conversion efficiency can drop dramatically if the temperature is not controled. So 50% for Nd:YVO4 and 80% for KTP can be obtained for moderate temperature.


We know that olike module can do 140 mw(120-150mw version) of pure 532 nm with a 350 mA current.
i'm supposing that the pump diode in the olike module is the same than the Stenkat one, so at 350 mA, the graph of Mike say that the output of the diode is nearly 236 mw.
Supposing that the Efficiency is for both crystal 50% & 80%, i obtain an output power of 532 nm at 95 mW... which is far from the reality (about 140 mW).

1)It can't be the same diode as stenkat.
We obtain 140 mw of 532 nm. With both 50/80 efficiency for crystal, this tends to have a pump power of 808 nm at 350 mW .

i see on others websites that some 200 mw diode, if extrapoled can do 300 mW at 350 mA as .3lite say, or exactly at 370 mA (http://www.uocnet.com/pdf/LD/U-LD-80C044D-preliminary.pdf)

So 350 mW is a little too much, it seems to be 300 mW pump diode. The only explanation is that the efficiency of Nd:YVO4 is higher than 50 %. As the pump power is a "low power" compared to the 60W pump of casix, the efficiency could be higher than 50%, i guess 60%.

With a 300 mw diode and efficiency of both crystal at 60/80, it give an output of 144mW of pure 532 nm.

im a little surprised. I have always thought that the conversion efficiency was 35/40. Was wrong.
So this little module are great.

 

[ElektroFreak]

As crystal manufacturing techniques and purity get better, so does the efficiency. This will continue until green DPSS is replaced by green diodes (I can't wait!!).. Then we'll be talking 80-90% efficiency (mA in => mW out).