Maxyzmodules 225mW RED module

[steve-o]

Well you wanted that devil smiley and you got it Doc

Since I do beam-shows only and no graphics I wonder how much of a difference it would be..
(fat beam w/ lousy divergence-could re-collimate it though, right?)

I do have the Marconi^2 setup though and loving it...
Now if I had both

Just wondering who the manufac of the 900mw diode is.

[The_Doctor]

Well you wanted that devil smiley and you got it Doc

Hell yes, I even rifled it from another forum and showed it in PM to Spec, I think. He liked it, so there it is... Said it was cute.

Re maker of that diode, me too. Bet it COSTS in one-off quantities though, that's the main reason I never played with high power multimode types.

Beam shows NEED a fine beam. If you're doing graphics, you can make the focal point good on the screen, up to a point, but in beam shows, you need a fine beam at all lengths for a sharp bright display. Multimodes with big divergence are no fun at all, even if they start bright, the weakening along the length as they diverge gives an overall impression of weakness and slackness. It's just not what people go to see lasers for... They might be useful in a limited case though, when you want power and very long range, like a fixed display beam. Two of those (100:1 polarisation, you'll have noticed) would get nearly 2 watts after a beam combiner, and a beam enlarger would make a collimated beam that starts out big, but will still be very visible after a few miles with light mist or smoke. Good for open air festivals.

[steve-o]

Yeah I noticed the 100:1 and thought cube

and I see your point about the beam strength far-field for beam shows.

[buffo]

Adam,
Who sells 900mW 660nm multimode laser diodes??

Well, Lasever does, for one. Although I'm sure there are other manufacturers that do so as well.

But looking at the head in the picture on that E-bay listing, it sure looks like a Lasever design. Add to that the fact that Aijii sells a lot of Lasever gear, and I'd just about bet that it's a Lasever unit.

Adam

[The_Doctor]

Lasever's spec sheet is a mess. What kind of spatial mode is TE? Looks like someone started to write TEMxx and fell asleep midway. Not sure how they can specify any mode in a multimode diode, either. And what kind of diode needs a TEC to stabilise it if it's not needed for critical wavelength matching? Looks like someone took a DPSS spec sheet and butchered it badly to try to fit a simple diode laser. The case looks like a DPSS, but I bet it isn't. 635 nm and 660 nm are typical of diode lasers, but not of DPSS lasers. And unless it's being pushed WAY too hard, no diode is going to be spec'd for 5000 hours, when it's easy to get 20000 hours or more out of them.

Whether that spec sheet is the result of incompetence or deliberate misdirection, I don't know, but it's either one or the other, or both. And it won't stop happening unless people question it more closely before buying.

Edit: I'm not sure, but I'm guessing that Aijii and Lasever are getting heads from the same source and Lasever are mounting them inside their standard DPSS cases. Aijii's spec sheet is better, and both probably derive from another, common source. That's just a guess though, based on a feeling that neither of them is sourcing to the other, and on the assumption that if Lasever were the real source, their spec sheet would be better, whereas Aijii's has info that Lasever's sheet (Buffo's link) could not supply (no mention of multimode in that one). I know that LambdaPro made heads that could be bought by other firms for making their own modules and PSU's, so if a firm is willing to do this with DPSS modules, it might be willing to do it with simpler diode-based heads. Aijii's also mentions a TEC for 'stabilising' too though. That is something needed for a DPSS. I don't know what purpose it can have in a direct diode laser. Arguably you could keep the temperature constant to allow hard diode drive without destruction if it gets cold, but you still need a feedback circuit and a sensor AND a TEC. It would be simpler (and more effective) to monitor temperature and adjust the diode's drive current directly. Ok, a long post, but if people can't get their heads round this, they'll always be ripe for this kind of daft and woolly specsmanship. In this case it's so bad it's not easy to tell what kind of laser is being sold unless you DO get your head round it, so think about it before buying.....

[buffo]

Lasever's spec sheet is a mess.

True. True. But you can say that about a lot of things that are made in China. Lasever is not the only company that needs better documentation for their products. It's a common problem, and one of the things you trade-off in order to get the (much) cheaper price.

Not sure how they can specify any mode in a multimode diode, either.

Umm... Like TEM11, or TEM01, maybe? I agree though, it looks like the guy got started typing that line and then fell asleep.

And what kind of diode needs a TEC to stabilise it if it's not needed for critical wavelength matching?

Just guessing here, but perhaps a high power diode that tends to drift downward slightly in output wavelength when it gets hot? Not to mention that a TEC would keep the thing from overheating when producing nearly 1 watt of power. Seriously, have you never heard of TEC-cooled direct injection diodes? I have, and I'm not talking about the expensive lab models that need frequency stabilization either... TEC cooling isn't unheard of in diode lasers.

The case looks like a DPSS, but I bet it isn't.

That case shouldn't surprise you at all. There are numerous examples of direct injection red diode lasers installed in exactly that same case. Have a look at this thread for pictures of the insides of two different PL members' projectors that have direct injection red lasers mounted in that very style of head enclosure. Just because the same case is also used for DPSS lasers doesn't mean that it can't be used for a direct injection diode.

And unless it's being pushed WAY too hard, no diode is going to be spec'd for 5000 hours,

I'd say that nearly 1 watt of multi-mode optical output might qualify as "pushing the diode hard..." As for the 5000 hour rating - I actually own two solid state lasers that are spec'd for 5000 hours of use. Says so right on the data sheet. Of course, they will probably last 5 times that long, but the spec sheet only says 5000 hours. Maybe they're just playing it safe?

Aijii's also mentions a TEC for 'stabilising' too though. That is something needed for a DPSS. I don't know what purpose it can have in a direct diode laser.

That doesn't mean there isn't a reason for it that you haven't considered. At a minimum, I can think of two (and I'm not even in the business of building or selling lasers): Keeping the diode cool to prolong it's life, and keeping the diode cool to keep the output frequency close to 660 nm, rather than letting it get hot and fly away to 670 nm or higher. A TEC could accomplish both goals rather nicely. (And if Aijii is using it, there has to be a good reason, else why include it?) I suppose we could ask him...

you still need a feedback circuit and a sensor AND a TEC. It would be simpler (and more effective) to monitor temperature and adjust the diode's drive current directly.

No, not really. If you do that, it means when the diode gets hot you have to lower the drive current to keep it from overheating and your power output goes down. Adding a feedback circuit and a sensor doesn't increase the cost of the TEC significantly, but having a working TEC means you can keep the diode running at full power at the specified wavelength for long periods without overheating and damaging the diode. Sounds like a reasonable application of a TEC to me.

Don't get me wrong: I do think that they should be more up-front about the multi-mode beam profile, and that their spec sheet should be re-written to more accurately reflect the details of this laser. Truthfully, I'm not sure that I'd be willing to buy one of these things without more information - maybe even a hands-on review from someone I trusted.

Nevertheless, I think you're going a bit far when you accuse them of outright fraud simply because you don't understand why the head has a TEC in it, or why the head looks like a DPSS laser. Maybe a question to the seller on E-bay would provide some answers?

Adam

[The_Doctor]

It's a common problem, and one of the things you trade-off in order to get the (much) cheaper price.

No matter how little I might spend, I still need to know what I'm getting for my money. The first rule of business is to describe the goods properly if the customer isn't in a position to view them directly before buying.

Seriously, have you never heard of TEC-cooled direct injection diodes? I have, and I'm not talking about the expensive lab models that need frequency stabilization either... TEC cooling isn't unheard of in diode lasers.

Of course. I've even announced maybe twice here somewhere that I'll be doing it myself, in one post claiming that it makes better sense to cool the diode as directly as possible with the smallest possible cooler to avoid waste. I was disagreed with by Yadda, if I recall right. My point is that this isn't for 'stabilisation'. That is needed only in DPSS tuning. A gross drop in temperature of a red diode, to try to increase visibility by shortening the wavelength, is NOT stabilisation.

Just because the same case is also used for DPSS lasers doesn't mean that it can't be used for a direct injection diode.

Agreed. I have no problem with that, it's a good idea, saving on the effort and resources needed to be different just for the sake of it. But when using the same standard box, it become even more important to specify the contents properly so the potential buyer has no reason for confusion other than their own carelessness or lack of learning.

Of course, they will probably last 5 times that long, but the spec sheet only says 5000 hours. Maybe they're just playing it safe?

Maybe, but MTTF estimates for direct injection diodes have steadily risen over the last few years. It might make sense to lower this to specify a system that introduces other complications, such as a DPSS where heat can affect crystals, but to do it for a direct diode laser where the only significant stress is from either excessive current or a weakness in the driver's protections especially in the modulation circuit suggests a lack of full duration testing. While 10000 hours is over a year (417 days) a company that has been selling for years should have been able to test one for that long, or if not, could stay within maker's specified limits to get their longer MTTF spec transferred to their own product. It's reasonable to assume that by lowering the MTTF, they're hedging their bets as you say, but it's also reasonable to assume that overdriven diodes are the reason why, especially as much of the market values raw power over beam quality. Even a more complex DPSS is usually specified for 10000 hours. It's usually only the inferior fan cooled DPSS's that get specified for 5000 hours or less. This is well known to many here, and on eBay, it's been common advice for at least 5 years now. So, when a seller of a direct diode laser feels a need to be cautious with a MTTF spec while neglecting other details, I think people should look VERY closely at exactly what is being offered.

That doesn't mean there isn't a reason for it that you haven't considered. At a minimum, I can think of two (and I'm not even in the business of building or selling lasers): Keeping the diode cool to prolong it's life, and keeping the diode cool to keep the output frequency close to 660 nm, rather than letting it get hot and fly away to 670 nm or higher. A TEC could accomplish both goals rather nicely.

Of course there can be reasons any of us haven't thought of, so if the reason is clear to the maker but not to the buyer, wouldn't the maker be shouting it from the rooftops? When a maker spends time, money and effort to add something, they usually need to get paid for it, and will state in detail whatever they think will convince the potential customer of the validity of the extra feature they're being charged for if they buy. Reaching for the standard DPSS spec sheet line of 'stabilisation' only makes sense if it IS a DPSS. Cooling to prolong life appears to make sense, but does it, on these terms? A diode is NOT specified for deep cooling, so why not just use a good thermal coupling to a decent heatsink, if you don't need to lock to a constant temperature for wavelength matching to a crystal? Good heatsinking alone would solve the problems you raised, and do it better than a TEC, too. It takes a LOT of temperature change to make the wavelength drift much. It's only critical when wavelength matching crystals, far less so when adapting it to human visual perception.

If you cool with a TEC to get a shorter wavelength, you also need to monitor the diode temperature to stabilise the output power, as facet damage is a far more likely cause of death than thermal or overcurrent damage to the gain medium is. In this case, the TEC isn't a cause of stability, but a potential cause of INstability requiring feedback between diode temperature and diode drive current (Trying to stabilise the output power by changing the diode temperature instead of the diode current is an inferior method, far harder to design well, and less accurate, more risky). If current stabilisation is what is happening in that laser, fine, but they should say so. Or say nothing, if they choose. I think they should not just borrow a spec sheet line that looks familiar and misuse it in a different context like this.

No, not really. If you do that, it means when the diode gets hot you have to lower the drive current to keep it from overheating and your power output goes down.

This is the main reason why most if not all sellers (and makers) insist on a good solid heatsink. The range of temperatures that a good baseplate will go through is far less than a diode would if it was not firmly coupled to that heatsinking base plate. A TEC is an added complication, it's as likely to add heat to the stable base, and if there is no reason a TEC must be used, it's preferable not to use it. People have advised fan cooling instead of TEC's for laser modules in threads here, for the same reason. Power loss due to current compensation will only be noticeable if it changes temperature by several tens of degrees C, and no well-clamped diode is going to do that.

Don't get me wrong: I do think that they should be more up-front about the multi-mode beam profile, and that their spec sheet should be re-written to more accurately reflect the details of this laser. Truthfully, I'm not sure that I'd be willing to buy one of these things without more information - maybe even a hands-on review from someone I trusted.

Exactly. I agree totally with that. I want to be able to trust the maker and the seller though. It's amazing what a decent maker of binoculars will tell you, a whole crash course in fine optics with detailed diagrams. Binocular buyers, on the whole, are far less tech-savvy than laser buyers, so why are we being sold short? I learned what 'clear aperture' and 'numerical aperture' means from a binocular seller, but I had to work far harder to learn anything about lasers, and a lot of that did come from directly questioning sellers. When asking sellers, it helps to have some grounding anyway, as without it, it's hard to ask good questions, and even harder to understand detailed answers, so the wise seller will volunteer good details, as it's their best chance of winning a deal when other seller's don't. I sold a few lasers I built on eBay on the strength of that, and had no complaints. I might have overdone the detail even, but no-one ever complained about that either.

Nevertheless, I think you're going a bit far when you accuse them of outright fraud...

If I'd pinned them with that and no other possibility, I'd agree, and I'd not state such a thing unless I had direct proof, and then I'd confine the claim to that instance. What I said was that there is a possible continuum of misdirection and carelessness that is making these woolly spec sheets appear. All a maker has to do to avoid the possible misdirection issue, is to avoid being careless. Unless, they really want to misdirect, that is, but that would be another issue. If those that care become less careless, it will be easier to see who's doing what, because we'll have better direct guidance from more sellers and makers. I had a look last night to see what precedents there were for confusing DPSS wavelengths with direct diode wavelengths. I didn't take notes, but I saw that some firms were careful. CNI notably so. The more that new kinds of diode laser proliferate, the more important this is going to be.

[cruch]

Hi folks,

I just received the single version of maxyzmodules 225mW
Was I surprised?? OHHYEAH...sooo bright beam alot of power in there.

I am looking forward to my dual setup!

Thanks marconi!

[jsalopeck]

i added only one of the maxyz modules and it is bright... nice deep red... hopefully next week i can add in the second one i have... i was shocked to see the single one almost hang with my 200mw 532nm lasever!

[marconi]

Ah thanks guys...

Glad it got there in ok shape and you like it..thought you would.

The post has been moving rather slow lately.
Looks like they are re-organizing and renaming rates and methods.
GEM is no longer..its called Expess Mail International now..hmmm

I dont see why any of this would impact how fast the mail moves but maybe
thay are all in a meeting dunno.