Laser-wave to CNI Compare Test

[bridge]

Hi Adam
Very pleasure to see you are join.
yes, I am sure you are the profession, each time I carefully reading what you reply. they always tell me what we need more working to improve our unit, although many times you are not indicate Laser-wave, but I really thanks you, you tell us what to do , how to do better.
thanks for you always good information and detail anylyse.
Best regards!
Bridge

[Pitts]

HI Guys..

Good to see you in on this Adam... I guessed you have been watching it.

I totally agree with you in what you have written very informative as usual.

In a way you have started to quantify my "waffle" which is what I hoped may happen from some of you experienced guys.

I do suggest that we work up a specification sheet for a "minimum" DPSS laser system suited for our show work.
If we do this then the manufacturers , whom, as pointed out seem to have taken some liberties in "off loading" some their sub standard units overseas will have no choice but to have met that spec. (or bear the consequences of having failed to meet a reasonable specification)
This gets us away from "oh I'm happy with this manufacturer or that one etc" Thats like saying Ford always make a good car... maybe, maybe not.
Manufacturer branding loyalty is part of the mix but not the only part... "like brand X are always good" etc... maybe, maybe not !

Like audio its in the eye (ear) of the beholder.. what is to one member a thing of sheer beauty may be a pile of crap to someone else. Therefore emperical evidence is of limited value to us and should be used with great caution when spending thousands of dollars.
In my work I crawl all over audio specification sheets all the time.. many of our amplifiers are of high quality manufacture BUT they all have hidden traps... know how to read the spec sheets and you can pick it up most of the time.

I also agree very strongly with you that many of these issues I have seen (which is small compared to you guys but at almost 100% partial failure for me [other than the Maxys which have been fine], that's not good).. these issues are really ones of being very lax on final quality inspection OR worse and I hope this is not the case, "lets just dump this crap down to NZ or wherever".. they must learn to fix this problem.

OUR MEMBERS ARE NOT A DUMPING GROUND FOR POOR QUALITY CONTROL.

So whether one thinks we should have to do a specification order sheet or not how about we work one up. Lets cover the essentials at least so the inexperienced can order their lasers at least knowing what it is they need to get. (whether they get it from their supplier is what in part this is all about)
No use just ordering a Greenie at 500mw... God knows what you would get.

The good thing at least is that the manufacturers are on here now maybe they will get the message and help us to define this as well. After all they have the professional engineers who should be able to advise the correct specifications to obtain a good suitable light show system.
So how about it Bridge, CNI, and Frank give us your input on what you see as an acceptable specification that you could meet on every order while keeping cost within reasonable bounds..

Cheers

Ray
NZ

[buffo]

Hi Adam
Very pleasure to see you are join.
many times you are not indicate Laser-wave, but I really thanks you, you tell us what to do , how to do better.

Hi Bridge;

I don't have a lot to say about Laser-Wave lasers because I've never owned one, nor have I done any tests on them. However, I must admit that I have spoken with several members here that have purchased lasers from you, and so far they seem very pleased with the performance.

I do appreciate your efforts to participate here in the forums, as well as your pledge to make your lasers better.

Good to see you in on this Adam... I guessed you have been watching it.

Yeah, I've been watching it for a while now. Plus after the discussions we had while you were visiting us here in the states, I've been thinking about some of the problems you had with your CNI unit and how that *should* have been resolved. (You got a raw deal, in my opinion.) This thread might be just the thing that prevents someone else from going through what you did.

I do suggest that we work up a specification sheet for a "minimum" DPSS laser system suited for our show work. If we do this then the manufacturers , whom, as pointed out seem to have taken some liberties in "off loading" some their sub standard units overseas will have no choice but to have met that spec. (or bear the consequences of having failed to meet a reasonable specification)

You have a point there. It would serve as a defacto standard that *every* laser manufacturer should be able to meet. I guess I'm just frustrated that we, the end users, have to spell out these things. I would expect that the manufacturers would have been more proactive on this.

But no matter. If we develop the list, then at least the manufacturers will understand exactly what we need. Of course, we may still get stuck with a laser that doesn't meet the specs... Then you're still forced to ship the laser back to China to get it repaired. (Maybe we should include some language in the spec that deals with returns?)

Lets cover the essentials at least so the inexperienced can order their lasers at least knowing what it is they need to get. (whether they get it from their supplier is what in part this is all about)

Hmmm.... Something like a "PhotonLexicon-Approved Laser List"? That might be interesting. I agree that it would certainly help out new members that might otherwise purchase a laser that doesn't work well for a laser show enthusiast.

The good thing at least is that the manufacturers are on here now maybe they will get the message and help us to define this as well. After all they have the professional engineers who should be able to advise the correct specifications to obtain a good suitable light show system.

Well, Bridge from Laser-Wave seems to be willing to participate. And CNI has at least one representative present in the forums as well. David Wu from Lasever used to log in here on a regular basis, but I haven't seen him much lately. And of course, Frank from Viasho is usually around as well. If they're all willing to keep an open mind and discuss this issue, maybe we can make some progress.

I'm game.

Adam

[allthatwhichis]

Now it gets really intersting...

[Pitts]

Quote:
I do suggest that we work up a specification sheet for a "minimum" DPSS laser system suited for our show work. If we do this then the manufacturers , whom, as pointed out seem to have taken some liberties in "off loading" some their sub standard units overseas will have no choice but to have met that spec. (or bear the consequences of having failed to meet a reasonable specification)
You have a point there. It would serve as a defacto standard that *every* laser manufacturer should be able to meet. I guess I'm just frustrated that we, the end users, have to spell out these things. I would expect that the manufacturers would have been more proactive on this.

But no matter. If we develop the list, then at least the manufacturers will understand exactly what we need. Of course, we may still get stuck with a laser that doesn't meet the specs... Then you're still forced to ship the laser back to China to get it repaired. (Maybe we should include some language in the spec that deals with returns?)

Quote:
Lets cover the essentials at least so the inexperienced can order their lasers at least knowing what it is they need to get. (whether they get it from their supplier is what in part this is all about)
Hmmm.... Something like a "PhotonLexicon-Approved Laser List"? That might be interesting. I agree that it would certainly help out new members that might otherwise purchase a laser that doesn't work well for a laser show enthusiast.

Thanks Adam..
Now were talking..
If we get this "form" setup we should be able to at least minimise the number of problems.
It should also stop their current strategy of "if you had asked we could have done" message. (OK .. so now we have a list so we did ask !!!)

Also if we see a manufacturer that consistantly over time unable to produce a good product to the spec then we will soon know who are the "good" guys and who aren't.

In our endevours though we need to remember that this should maybe be a "minimum" list, not in number of spec's factors on the list but in being reasonable in our technical expectations.
There is no point in trying to turn this into a full blown scientific DPSS laser that NASA would be proud of and that no one can afford.
eg
Power = 1000mw
Divergence = .00003 mrad
Analogue - blanking - 100Khz
Etc etc

No one could afford it.. if they could in fact make it.

Lets hope the manufacturers take up the offer to contribute to our product list specs.

Cheers

Ray
NZ

[CNI LASER]

Hello Guys.
I broke the test now.
Thanks for your help and tests,and point´s what to do.
Phil

You can do what you want,but please only do the fare comments.All the laser lovers all customers only need the true result.

[bridge]

Hi Bridge;

I don't have a lot to say about Laser-Wave lasers because I've never owned one, nor have I done any tests on them. However, I must admit that I have spoken with several members here that have purchased lasers from you, and so far they seem very pleased with the performance.
I do appreciate your efforts to participate here in the forums, as well as your pledge to make your lasers better.

First of all, thanks , Adam, although you still not have Laser-wave unit and didn't do any review about Laser-wave, I must thanks for you contribute to the PL forums,you are warmhearted to help anyone here. because of your profession, I read many topic about you, give me most impression is "color blance", be honest, many people here not know the exact RGB rate for blanking white lasers, also including Bridge, thanks for your exact analyse. about the color blanking, I 'd like communication with you later, if you 'd like. yes, also many other threads about lasers, be honest, still now, I don't know what you are doing? but you knowledge about lasers, optics always shame our laser manufactory.

Well, Bridge from Laser-Wave seems to be willing to participate. And CNI has at least one representative present in the forums as well. David Wu from Lasever used to log in here on a regular basis, but I haven't seen him much lately. And of course, Frank from Viasho is usually around as well. If they're all willing to keep an open mind and discuss this issue, maybe we can make some progress.

So how about it Bridge, CNI, and Frank give us your input on what you see as an acceptable specification that you could meet on every order while keeping cost within reasonable bounds..

good idea, Adam,pitts, the only question is who will be the coordinator? Adam, maybe you will like.
Best regards!
Bridge

[buffo]

There I go again... Me and my big mouth!

OK - I'm willing to head this up. I'll need lots of input from other folks though. I've only got one perspective on these specs, and that's not a good way to develop a list of minimum specs.

But to start, I'd like to think that we can all agree that beam aberations are a definite no-no.
So requirement #1 should be a TEM00 beam with a gaussian profile at all power levels. Agree?

Requirement # 2 should probably say something about beam diameter and divergence... Here I'm open to suggestions. My gut feeling would be to spec the diameter at 3 mm or less at the aperture, with a divergence of 1mrad or less. But I'm open to suggestions.

Requirement # 3 (for me, anyway) would be the power stability. Say, no more than a 10% change in power (plus or minus 5 %) during operation at any given power level. (This is assuming that the laser supports analog blanking.) What do you think?

Requirement # 4 would be the blanking spec. This, in my opinion, is one of the most crucial areas, and perhaps the one that many manufacturers have not been paying enough attention to. As I posted earlier, A good start might be something like the following:

1) The blanking signal is assumed to be a square wave signal with a 50% duty cycle. (That is, the laser is only on for 50% of the time.)

2) The power of the laser reaches 90% of full power (or 90% of whatever power level is selected, in the case of an analog blanking unit where the blanking signal is somewhere in the middle of the range) within the length of a single blanking pulse when the blanking signal goes high. (For a 10Khz blanking laser, this would mean the laser reaches 90% of full power in 50 microseconds or less.)

3) The power of the laser falls to zero within the same time period (or faster) as in # 2 above when the blanking signal goes low.

4) During operation, blanking the laser at any speed or duty cycle up to it's rated maximum (in Khz) will not adversely affect the beam quality. (This means no mode hopping, no artifacts, no noise, and no power fluctuations greater than 10%.)

Now, we could simplify this to simply state that for a 10Khz blanking rating, the laser must reach 90% of the selected power within 50 microseconds, and for a 20Khz rating it much reach 90% of the selected power within 25 microseconds. (Basically, just the part in red above.)

The 4 steps quoted above really detail the test requirements needed to verify that the laser meets the spec anyway. But maybe it should be included in the document. Comments? Are these specs too loose? To stringent? Personally, I'd like my future lasers to meet the 20Khz (25 microsecond) blanking spec. Hell, Marconi's Maxyz modules are guarenteed to work at 50Khz, and have been successfully tested to 120Khz!

Requirement # 5 might want to say something about beam height and mounting holes. How about a baseplate that will mount to a standard US optical table (1/4x20 holes on 1 inch centers as well as a metric table #10 holes on - what? 2 cm centers? I don't know what the metric standard is.) How about a spec that states the beam height will always be 40 mm off the baseplate, plus or minus 5 mm? (Or is that not so important to people?) How about a spec that states that the beam must be parallel to the baseplate within so many tenths of a degree?

Requirement # 6 might deal with extra devices attached to the head or the driver board. Things like a manual shutter, a heat sink, fans... What is the consensus here? (Personally, I like a large, passive heat sink on the driver board, no fans, and a manual shutter on the head. But I'm open to suggestions...)

How about a requirement # 7 that deals with warranty returns. Things like, "If the item is siezed by customs and the form was filled out correctly, it's not the users fault." These are important issues when you have a high power laser that fails and you need to send it back. You can't tell me that a $4000 laser has to be sent back because it sometimes winks out is now worth just $100. It still has value, even if it's broken. But declaring it as a $4000 laser triggers excessive fees. A work-around needs to be found for this problem.

Requirement # 8 might deal with meeting the specs of specific government regulations. Here I'm mostly concerned with the CDRH Accession number, though there may be regulations from other countries that I'm not aware of that would apply as well. (Comments?)

This is just a start, but I think it's a frame work that we can work within... We can add more items, edit these, or even delete some. So lets start talking about it!

Adam

[allthatwhichis]

They look OK to me...

[tocket]

I agree that blanking specs is very important and something the manufacturers need to work on. You left out one important issue however; linearity. This can fairly easily be analyzed from a statistical point of view by fitting it to a linear function y = kx + m. By normalizing the data (setting the maximum optical power and voltage to 1) we can get a set of conditions that apply to any laser with analog modulation. Ideally the offset (m) should be 0 (this means the laser will start emitting at any voltage higher than 0) and
the slope (k) 1. You also need to look at the residual. Stating that the residual may at no point be larger than 0.1 and the standard deviation for k must be less than 0.05 would weed out any lasers that cannot handle analog blanking in a linear fashion.

The other related issue is that of power fluctuations due to blanking. Zoof seems to be very familiar with this issue. I have also noticed it in my laserwave, so I suspect many manufacturers have a problem with this. You did mention it in your requirement #4, but only briefly. Here's my take on how to analyze it.

Normally you would expect a beam's power to be a simple function of duty cycle (D) and analog blanking on-state voltage (V) like:
P=Pmax*D*V/Vmax

Since there are two variables in this problem it becomes more complex to analyze. A fairly simple way of doing it is to pick 10 points on the surface spanned by D and V, measure actual power at those points and compare to the ideal function above. By requiring that the measured value is within 10% of the ideal we can assure ourselves that the handles analog blanking properly.