CNI GLP-589 noob review

[qumefox]

Here's some views of one of these I hope nobody else ever has to see. heh. I however don't remember mine being pulsed though. At least for the short time it actually worked. It was a 1mW version as well. It's also the laser that put me off on participating in glenn's CNI group buys anymore.

 

[Johnyz]

Strange observation -

Long story short, someone shipped me a 473nm GLP that was meant to be shipped to zdarkazn. Before I forwarded the package along to its rightful recipient, zdarkazn allowed me to power it up and test it. In the process, I noticed that it too was pulsed.

What is that ?

Personally, I'm not sure whether I like / hate the effect that has. My eyes are really sensitive to pulsed light sources. Some car tail-lights drive me nuts because they use pulsed LEDs. I'd be curious to know the rationale here.

(wrong statement removed) As Tech Junkie has already said, pulsing allows the diode to pump out more mW's (avearge) and may make the crystals last longer, since they aren't seeing all the power all the time.

Actually, all switched laser drivers (basically all that contain a little inductor/coil) are pulsed. It's very fast though. Out of the couple IC's I am looking at now, it's 1.6MHz, 2.5MHz and 3.5MHz. I might try to make a pulsed driver, after we finish this little boost driver shortage issue, so the hobbyist can make use of the "pulsed" rating found all over the diode datasheets.

 

[qumefox]

Actually no.. The doubling (or summing, in this case) crystals need pump photons to operate. No photons in, no photons out. It continuing to operate, even for a microsecond, after the pump was removed would mean it's creating energy from nothing. Which isn't possible.

And also pulsing a diode only allows higher peak power.. Average power will stay about the same since as you increase power, you decrease duty cycle at the same time.

My guess is these are pulsed due to either needing more pump to drive the crystals than the pumps can put out CW, or because of thermal issues.. or both.

I know I tried to transplant the cavity of my defunct 589 into a new housing (using properly focused IR even. It was one of the 'non-working ebay 473nm housings), and I never managed to get squat out of it. So either the cavity alignment on mine was borked, which is why it never worked well to begin with, or 2W of 808 wasn't enough pump to drive it.

 

[rhd]

In my head, qumefox's critique makes sense. At a very basic level, if the crystals continued to output photons when the pump was off, then we wouldn't SEE the broken output of 473 that was the basis for my observation about the output being pulsed in the first place.

 

[aryntha]

I have a GLP-589 1mW (that does 7-9) and it is *not* pulsed. Same exact batch as Qumefox's. None of my PGL 589's are pulsed either... Maybe newer GLPs are.

My first GLP 473 was pulsed, a later one I got was CW. My first PGL 671 was (is) pulsed, my more recent one is CW.

So I'm not sure what the criteria is. And, we are talking "speed of light" here, so, no; "pump off = laser off".

EDIT: Much like Qumefox's situation, I took my GLP-589 out today and it is dead. Camera shows that the IR emission is still working, so the pump diode at least seems to be 'alive' (but perhaps not lasing). Seems to be drawing 100mA off a CR2 that's doing 3.5v. IR being emitted, but not in a beam.

Not too happy with this... and not too happy with CNI's track record lately. Hopefully the OP will have better luck.

 

[Wolfman29]

I am falling in love with the yellows and ambers on the spectrum... anyone have any advice when it comes to buying one of these that *won't* fail?

 

[qumefox]

Stay away from the 'pens'. I never really liked them due to really short battery life anyway. If you want a yellow, and want it to work, and get good support.. Order from laserglow. Yes it's the most expensive option, but it's also about the only one that's guaranteed to get you a good working laser the first time.

And aryntha. 100mA current draw sounds WAY too low. Even figuring a 1% efficiency, which I don't think these are even that high, Your talking about needing at least 100mW of pump to get 1mW out After driver losses etc you'd still be looking at more current draw than you were seeing.. Plus.. These use C-mount pumps, so they're likely at minimum 1W pumps. If they were less it seems like a 9mm diode would have been easier than lathing c-mounts down to fit in a pen like they did.. Sounds to me like you have a driver or connectivity problem. Which means it's likely fixable... IF you can get it apart without destroying it.

 

[Wolfman29]

Damn. I just want the wavelength -.- If only I could find a 589/593.5nm equivalent of the "defective" 473nm labbies from eBay for $45!

 

[qumefox]

Will never happen. The only reason those are cheap is because they're surplus scavenged out of medical equipment.

And even if a source did turn up, I doubt you'd find it priced cheaper than $50/mW just due to the fact it's a 'rare' wavelength.

 

[Wolfman29]

(Really just hoping for 1-2mW anyway.)

Yeah, that's really unfortunate -.- Guess I will have to wait till I am an adult and making enough money to be able to blow $800+ on a laser.

 

[qumefox]

(Really just hoping for 1-2mW anyway.)

Yeah, that's really unfortunate -.- Guess I will have to wait till I am an adult and making enough money to be able to blow $800+ on a laser.

Same here :na: Though hopefully you'll be well off enough you can afford expensive lasers heh. I'm not

That GPL that died has been my single most expensive laser i've bought.. And it lasted roughly a week before it quit completely and took 9 months to actually show up.. Any other situation I would have sent it back to CNI but eh. .I wasn't in the greatest of moods that week. WHen I get other projects taken care of i'll likely see what the highest power cmount 808 I can find is and try again to get yellow out of mine ramming as much pump in it as I can. If I can get any yellow out of it at all hopefully I can tweak the cavity well enough I can get a few mW out of it again, even if it'll be a labby then instead of a pointer.

 

[Wolfman29]

Yeah... well, I plan on being a professor, so hopefully they make enough money to support my laser addiction.

I understand how one makes a green 532nm... because the primary emission of Nd:YVO4 is 1064, right? But I don't understand how to make other wavelengths.

 

[qumefox]

With 532nm, two 1064nm photons are combined into one higher energy 532nm photon. You have to remember that ND:YAG and ND:YVO4 both lase at other lines other than 1064nm. The 1064 us just the strongest. The others are weaker. Other wavelengths are created by using the weaker secondary lines of these materials.

It's the same with 473nm as it is with 532nm, except it's the 946nm line that's used. Same with 457nm. It doubles the 914nm line.

With the yellows.. It's a little different. There are two lines lasing at once in the cavity that get summed as they're combined into a single output. In 589nm lasers, I think it's 1064nm and 1319nm that are combined, and in 593.5, it's 1064nm and 1342nm. Yellows are so expenisive due to the higher cost of materials, but mostly due to the fact they're very low efficiency and alignment is super critical.. Meaning they take longer, and more skill, to actually build, and I imagine they have a fairly high QC failure rate as well.

One thing i've never really understood is why solid state laser alignment is still a 'hands on' thing. It seems to me that the technology exists for the process to be automated and get less rejects as well as a higher part turnout count.

 

[Wolfman29]

So how do you get two lines lasing at once in the cavity? And what kinds of crystals are used in this process?

 

[qumefox]

The coatings on the optics determine what lases in the cavity. However it's not possible to have all possible lines a material can lase at lasing at once, since they will steal energy from each other and be intermittant. Actually some 593.5 lasers have this problem, with the dominant 1064nm line robbing the 1342nm line of all it's energy.. When this happens.. Usually when the lasers are cold from what i've heard.. They just output 532nm heh.

As far as what the non-linear crystals are used. I know 532nm is generally KTP, 473nm is either BBO or LBO.. Beyond that, I don't really know. The lasing medium is typically either ND:YAG or ND:YVO4

 

[Wolfman29]

Oh. That's interesting. So that's how multi-line argons work? I thought that solid-state systems could only lase at one wavelength?

And what determines what wavelengths a lasing material can lase at?