decan an 808 and add a DPM?

^ Also, I did say that the process is 20-30% efficient [highlight]at best[/highlight]. At best means under optimal conditions using high-quality crystals.

So you don't read property.

"add a cheap DPM from a cheap chinese green laser "

.3lite said:

So you don't read property.

"add a cheap DPM from a cheap chinese green laser "

Click to expand...

"cheap" china sets work better than you think

WannaBurn said:

[quote author=.3lite link=1240424407/0#17 date=1240591394]So you don't read property.

"add a cheap DPM from a cheap chinese green laser "

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"cheap" china sets work better than you think [/quote]


I had like about twenty green laser pointers from china, like 4-5 different types, can't remember, and all had the same crystals set as my picture shows (first one).

^I've had the best luck with "cheap chinese" DPMs myself. The crystal quality tends to be quite good, and the cavities are quite efficient. Generally, the quality of so called "cheap chinese" lasers are getting better all the time.

I also have a large collection of crystals from various chinese modules, both pointers and labbys, and they range in size from 1x1x2.5mm to 2.5x3x5mm and some are glued, while others are optically bonded.

I have a 473nm laser that is doing better than 10% efficiency... (2W pump power, 250mW out)

25% shouldn't be hard to get out of a green at all. I have one that is 700mA to the pump, so probably around 550-600mW (estimate) pump power and it's doing 200mW...

.3lite said:

[quote author=ElektroFreak link=1240424407/0#10 date=1240515425][quote author=chaosfourever link=1240424407/0#9 date=1240512649]so if i use a DPM from a 20mw then i should use 500mw of 808nm to get 500mw of green?

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No. The process of converting the 808 to green is only about 20-30% efficient at best. That means that on a good day you'll typically see 100-150mW of green for 500mW of 808 pump power.[/quote]

Show then those crystals which have that effectivity, never saw such crystals, never in green pointers f. example from ebay, so let's say ten percent.

@topic
So all you can get from 500mW is about 60-50mW, which means about ten percent of effectivity, it's quite good, but remember, if you pump more you get better effectivity.

Anyway, here's two of my crystals, one from green laser today (it was said 50mW I believe) and the second which propably can hold 2W+- of input power.

[/quote]
what did you get the larger crystal set from?

HumanSymphony said:

[quote author=.3lite link=1240424407/0#14 date=1240582859][quote author=ElektroFreak link=1240424407/0#10 date=1240515425][quote author=chaosfourever link=1240424407/0#9 date=1240512649]so if i use a DPM from a 20mw then i should use 500mw of 808nm to get 500mw of green?

Click to expand...

No. The process of converting the 808 to green is only about 20-30% efficient at best. That means that on a good day you'll typically see 100-150mW of green for 500mW of 808 pump power.[/quote]

Show then those crystals which have that effectivity, never saw such crystals, never in green pointers f. example from ebay, so let's say ten percent.

@topic
So all you can get from 500mW is about 60-50mW, which means about ten percent of effectivity, it's quite good, but remember, if you pump more you get better effectivity.

Anyway, here's two of my crystals, one from green laser today (it was said 50mW I believe) and the second which propably can hold 2W+- of input power.

[/quote]
what did you get the larger crystal set from? [/quote]

I've bought it from one guy, he was pumping a 2W LD into it and worked fine (of course any shit can't be on surface of the crysal, it will burn it). I have two of them, cost me 30$ each.

In future I believe I will build some custom DPSS laser, but first need to get some c-mount diode with atleast 1-2W of power.

so might this have a good DPM?
http://www.dealextreme.com/details.dx/sku.10094

^I wouldn't expect anything too impressive from a 5mW module.. Try and go for something a bit more powerful. The way I've collected my crystal sets is to wait until one of my cheaper laser fails, then pull the crystals. If you have any higher powered (100mW and up) DX-type pointers they would make decent crystal sources.

chaosfourever said:

so might this have a good DPM?
http://www.dealextreme.com/details.dx/sku.10094

Click to expand...

Check out my pictures, It's the first one.

Its so tiny

GooeyGus said:

I have a 473nm laser that is doing better than 10% efficiency... (2W pump power, 250mW out)

25% shouldn't be hard to get out of a green at all. I have one that is 700mA to the pump, so probably around 550-600mW (estimate) pump power and it's doing 200mW...

Click to expand...

So you could have a 250mW blue portable that would have the same heat issues and battery life as an RPL If that's possible , why don't they make and sell those?

Gus is drawing many watts with the TEC. The overall heat and overall current go way up, but not the pump diode. If you take all power factors into consideration, and not just the pump power, he's getting far less efficiency. But that doesn't matter too much on something that runs from mains.

Cyparagon said:

Gus is drawing many watts with the TEC. The overall heat and overall current go way up, but not the pump diode. If you take all power factors into consideration, and not just the pump power, he's getting far less efficiency. But that doesn't matter too much on something that runs from mains.

Click to expand...

Exactly. Blue lasers require RIDICULOUS temperature stability. If I turn the TEC's off, mine wont even make 5mW of 473 and it has a lot of metal inside to heat sink to. Pretty huge difference in power temperature can make. The TECs really dont have to work too hard but it's still way too much power draw to be in pointer form. 2A draw for the diode alone, then add in the current draw for the TEC's, probably another amp or two (also at a higher voltage than the 1.8V the diode needs), then add in all the losses in the diode and tec driving circuitry and it just isn't very feasible to have in hand-held form. It could be done with a few 18650's, but another problem is that you have no where for your heat to go. The lab lasers have a thick aluminum base plate, and are supposed to be on a metal platform for further heat sinking. 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.

If you just want it to look as bright as possible, you don't really want to run it in CW operation. Put it in a TEC assembly, with a temp of 25C or less, and start to slowly scan a beam across the surface (beam waist just inside the crystal) until a certain point is found where the Nd:YVO[sub]4[/sub] crystal starts to Q-switch itself. Then you will have an order of magnitude higher pulse power, with little increase in heat. Measure the pulse rate, and use a higher LD power than the crystal can take in continuous operation, then fiddle with pulse shapes for the LD output to figure out what will give the same pulse power as continuous pumping. Then you turn up the power of the pump pulses.

The pulse rate should be above the flicker-fusion threshold, and thus seem like a solid beam. Don't try modulating an overpowered LD unless you know what you're doing.