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2.5 Watt 532nm Laser for 400 dollars, what do you think?

Alaskan

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I bought this 532nm 2.5 watt laser on ebay for 400 dollars, I have not received it yet, sharing the info in case you might be looking for something like this yourself.

Lightwave Halfnote Green Laser Module w Heatsink 532nm 2 5W Tested Working | eBay

Here is a link to an old post on this kind of unit which was selling for over 3K here on LPF a few years ago: http://laserpointerforums.com/f39/fs-lightwave-half-note-2-5w-532nm-system-43243.html - To make these play you need a 10A TEC driver for the baseplate, a 1.5A TEC driver for the KTP and a 20-25A diode driver for the pump diode.




LATE EDIT Sunday August 10th: I found a thread on this unit here which answered all of my questions in my posts below: SELLING Any interest in Lightwave Half-Note laser(s)?
 
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upaa27

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Nice laser. Did the seller say how much it has been used? It might fall apart really quickly on ya if you got it for only $400.
 

Alaskan

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No, I don't know. He has eight more of them. I am sure they have time on them, maybe lots. So far, he is accepting 400 dollar offers on them. From what I've read in the post I linked to (above) from a member here a few years ago, these are easy to work on, easy to change out the 20W DPSS diode or even replace it with a 40W IR source/driver. I happen to have a dozen of the same type of 20W 808nm bar lasers this unit uses :)


I posted this here to get some feedback if anyone else happens to have one as well as to let members know they are available on ebay at far less of a price than I expected to find something like this. The seller doesn't have a high current power supply unit to test at full power, according to his listing the most he could push them at under constant current to make sure they lase was about 7 amps, near threshold. That's the only guarantee he gives, that they will lase but doesn't know the full output power they can produce other than the specification. If he is being completely truthful then maybe these are still good for over 2 watts of output.
 
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Pi R Squared

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It sounds too good to be true, but if it really does 2.5W then you got a good deal.

Alan
 

Alaskan

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Yea it does, most of the time too good to be true is just that, hoping this is an exception. On the ebay sale they say not to go past 10 amps of current but according to the old LPF post I found from someone selling one of these here (Although with a 40W bar) the unit needs at least 20 amps of current to produce full output at about 2.5 watts CW.

EDIT: (Half a day later) I found this feedback in the sellers records for the same item a few months ago:

Good ManGod Bless Him but Halfnote NEEDS aprox 20A for 2.5W,poss.langu. barrier Buyer:
c***x ( 80Blue star icon for feedback score in between 50 to 99)
Apr-01-14 15:49 Feedback conversation
Lightwave Halfnote Green Laser Module w/ heatsink 532nm 2.5W Tested Working (#331133272631)

Late EDIT: I borrowed some photo's from Junktronix sale of the same units last August, a year ago, but just learned he has some of these for sale at 500 dollars each he is taking to the SELEM meeting. I didn't know he had any left, he isn't showing them on his ebay sales or web site that I can find yet. If Junktronix has these, I'd buy from him due to his reputation and I am sure, full power output testing of what he sells. This sellers units might be just fine, they lase at 7 amps indicating the diode is good to fire that low but they don't have a power meter.








Sunday August 10th update: I found an old thread which answered all of my questions here: http://www.photonlexicon.com/forums/showthread.php/20403-Any-interest-in-Lightwave-Half-Note-laser(s)?highlight=halfnote



 
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Alaskan

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I have an update: The unit arrived and works fine, the only real challenge is the KTP; making a feedback loop driver for the KTP so it is kept at the right temperature, without that the output is 10 percent of its full capability. There are wires leading to the KTP which is sitting on what appears to be a small TEC. I've seen KTP ovens to keep the crystal temperature in the sweet spot, but this one appears to only use a cooler to keep the temperature right. I didn't know you had some crystals which need to be cooled, others which need to be heated... Any comment on that? This is all new to me.

That's the catch and why the price is low, it won't play by just hooking up wires to 2 VDC for the laser diode and 12 VDC for the main and KTP TEC's. Even so, you can pay two to three times the price from other sellers for the same thing.
 
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Cyparagon

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You're forgetting that TECs can heat as well.

Send a lowish curren to the TEC. Watch for a peak in the green output, and take note of what appeared on the thermistor/thermocouple/whatever at that point, then repeat the process for the other TEC polarity. google temperature controller and build it to keep it at that temperature.
 

Alaskan

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I did forget! & thanx for suggestion, I'm on it now. It would sure be nice if I had a manual for this thing but the seller doesn't provide schematics, at the very least I could use some pin-out info for the ribbon cable. I don't understand why a seller who had a dozen of these wouldn't go to the trouble of getting that info for buyers. I wouldn't list something like this on ebay without it.
 
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DashApple

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Well the diode will like to be around 20C ( maybe 25C centre wavelength ) , lower temps may give gain in power but will push it away from 808nm .

To get the best output you can , run the KTP TEC at a set temperature that produces the most green ( KTP likes to be warmish ) I had a DPSS that liked the KTP to be at 25C .

Then slowly adjust the diode temperature till you reach max power then you can then move to the KTP and repeat , the idea is to get the diode as close to 808nm as possible then get the KTP to its happy place aswell .

If you don't mind me asking , what was shipping on the module ,

Power supply for testing id just use parallel linear regulators , even it its just for testing .
 
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Jmillerdoc

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Pretty cool. I recently did a group buy with Goldenstar for a "1.5w" 532 for around $460, we got three of these units and the lowest of the three is outputting 2.7w and the highest is just over 3w. Driver and everything you need to laze is included. Retail is right around $500 IIRC. Although this is a pretty cool unit, if you need that kind of power and don't want to have to "DIY" it, check out the 1.5w 532 lab at GS.
 

Alaskan

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Thanks for the suggestion to get the thing running well, I'd have this thing hooked up and going except I'm working 12 hour days and traveling this week. The shipping was just under 30 dollars to Alaska, I also bought a 3W Jenlas unit from the same guy, hope to have time to test it soon.

The price on the GS is great, I wonder what the duty cycle is though?
 

Alaskan

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Indefinite as far as I know, it is a fan cooled unit. I have run it for well over 15 minute straight without any issues.
WOW...I wish I knew about the GS 532nm earlier.

Edit: Can you post photo's?

Edit again: I finally have a manual for the halfnote laser, given to me by the kindness of a member on the Photonlexicon forum: http://photos.imageevent.com/qdf_files/technicalgoodies/experimentersfolder/irandlightwavecommunications/irledandlaserproject/Lightwave DPSS.pdf
 
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lwrnce

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Hey Laserproject,

Nice laser. I just won an auction on one from the same seller a couple of days ago. But now I dont know what im gonna do with it. I certainly dont have a laser power meter that goes to 2.5w let alone the required power supplies I intend to build the power supplies but that will take me forever so I have no way to find out if its outputting the rated (or at least near) 2.5W. I heard the seller has several more of them and would be willing to trade it out if its not making full power.

Thanks for the Link to that manual that should come in very handy.

I don't know, even with the good buy I got, I may still end up selling it.

I look forward to seeing how it goes for you. Hope you keep us posted. :)
 

Alaskan

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Hi, if I could just get things set up at home to wire my own unit up I'd be happy, my wife has me on too many honey-do projects right now. I have the power supplies needed, the power meter, even a couple of TEC controllers if I want to wire them in to keep the KTP crystal and laser diode at temperature but haven't set up to do it yet. I did try it without monitoring the KTP temperature and it put out green, but only 300 mw. I shouldn't have even done that, did that before I learned if the KTP crystal isn't kept at the right temperature, you can possibly damage something if adjusting the voltage high enough to allow a lot of power output from the 20W 808nm laser diode that can damage the crystal cavity it drives, maybe even the KTP itself if it isn't tuned to resonance by being at the right temperature? I still have much to learn about them.

I bought at 25 amp constant current adjustable power supply from the same seller fairly cheap, I think under 200 with shipping. You might look into getting one from him to drive the diode with.

Here's what needs to be controlled:

1. The temperature of the 808nm IR laser diode to keep it at 808nm, lower or higher temperature than specified on the unit and it won't be.

2. The voltage and current to the 808nm laser diode (limited current so you can't over drive it).

3. The temperature of the KTP crystal as written on the unit (via its little TEC which is wired backwards to heat it, instead of cool it) so it will be "tuned" to the right temperature for an efficient conversion, otherwise they are inefficient.

There are standard 10K monitor thermisters on the diode as well as the KTP crystal and you can just monitor their individual resistances with a volt meter to make sure your diode and KTP crystal are at the right temperature, using a chart to convert resistance to temperature. A TEC controller can do that for you and adjust the Thermo Electric Coolers (wired backwards if used to heat instead of cool) to keep things at the right temperatures but they aren't cheap if designed for lasers. I bought a expensive Wavelength Electronics MPT Series MPT5000 Temperature Controller (5 amp capable for $50 on ebay, hundreds if new) to control the KTP crystal temperature and a cheap 10A capable Chinese temperature controller for 10 dollars to control the laser diode temperature via its TEC wired to cool which might not keep the diode at the correct temperature well enough with this cheapo unit: http://www.ebay.com/itm/321465614249 -

The specifications on the Chinese unit seem good but so much of their stuff doesn't meet their own specs I just don't know. For ten dollars I thought I'd try it, a "real" TEC controller capable of 10 amps for a laser, if such exists, could not be found on ebay when I last looked (I seldom buy my laser toys outside of ebay except for DTR's LPF online store). Keeping the KTP on temperature is more critical so I bought a fast loop controller for automatic control of its temp., the laser diode temp, I think might not be so difficult due to the large mass of the heat sink it has.

I'm betting the KTP can be kept at the right temperature manually by monitoring its thermister and adjusting the current as needed to its heater, but better to wire it up with a controller which gets its control feed back from a thermistor for automatic control.
 
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DashApple

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The Die4Chill if you can at all find one , is a nice tec controller , its just a " Bang ' Bang " type controller but it will keep the temperature pretty close ,

Its 10A , 12V rated and uses a 10K thermistor input , it can be built aswell as the circuit is available someplace .
 
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