RPL laser "dual beam" issue = wasted power demo

[Benm]

Re: RPL laser "dual beam" issue = wasted power dem

not everytime a company uses non-disclosure is it for a sinister reason. they probably just don't want everybody knowing how their patented product works.

If its actually -patented- there would be no problem finding out how it works - a trip to the patent office would suffice.

On the other hand, it could be a trade secret, but as things go it'll probably be revealed by someone actually taking the product apart and analyzing its inner workings... as seems to be happening here.

As for the actual product: It does what is promised in terms of output power and mode, so even if half of the power would be wasted by shining it onto the enclosure, customers still don't have any reason to worry or complain. It's like buying a car advertised at 200 hp, that actually delivers 200 hp while the engine could generate 250 by software modification alone... it's a product with, well, interesting possibilities.

 

[Aseras]

Re: RPL laser "dual beam" issue = wasted power dem

well I'll say I guess the majority of the dual beam is caused because the crystals are not touching either physically or bonded. There's a 1-2 mm gap in there between the plate the ktp is in and the plate the vandanate is in.

the crystals are very high quality. I chipped the ktp and nd:yv04 and took it up ( to the other building here ) to my gf who has a NMR and mass spec and it went to UCF for IR spectroscopy this week too.

I can guess the doping and other materials based on the plots of nmr and IR spectra.

 

[Aseras]

Re: RPL laser "dual beam" issue = wasted power dem

If its actually -patented- there would be no problem finding out how it works - a trip to the patent office would suffice.

On the other hand, it could be a trade secret, but as things go it'll probably be revealed by someone actually taking the product apart and analyzing its inner workings... as seems to be happening here.

you don't patent trade secrets, you keep the secret, but you also have a hard time protecting that and if someone reverse engineers it you can loose your advantage.

As for the actual product: It does what is promised in terms of output power and mode, so even if half of the power would be wasted by shining it onto the enclosure, customers still don't have any reason to worry or complain. It's like buying a car advertised at 200 hp, that actually delivers 200 hp while the engine could generate 250 by software modification alone... it's a product with, well, interesting possibilities.

This happens a LOT. often a product significantly outperforms it's original planned abilites due to process imporivements and further refining and tweaks from prototype to production. It's readily apparent in computer chips and a bit less in cars. Often you detune things for a safety margin and to meet spec and orders for a certain spec.

 

[Milos]

Re: RPL laser "dual beam" issue = wasted power dem

well I'll say I guess the majority of the dual beam is caused because the crystals are not touching either physically or bonded. There's a 1-2 mm gap in there between the plate the ktp is in and the plate the vandanate is in.

the crystals are very high quality. I chipped the ktp and nd:yv04 and took it up ( to the other building here ) to my gf who has a NMR and mass spec and it went to UCF for IR spectroscopy this week too.

I can guess the doping and other materials based on the plots of nmr and IR spectra.

Thank you for taking time and disecting this issue, as well as your own RPL!!!
You da man Aseras !!

I would love to see a picture if you have, of the guts, as I own RPL myself.
Performance of my unit is by far the best green hand held I tested or read about, and I believe there is a good reason to design crystal setup the way they did.

Question:
Is the main heat in RPLs absorbed by the body and heat sink up front mainly generated by this second beam hitting the "wall" ?

 

[Deleted member 10578]

Re: RPL laser "dual beam" issue = wasted power dem

Hi Milos,

Good question.
This would depend on the color of the material on the inside of the cavity where this "other beam" is projected. You need to remember that the beam is not like a blow torch. There isn't any heat in the beam of light itself, the heat is created by the absorption of that light. If the inside area where this beam is striking is dark/black in color, then I would expect heat to be produced; however if the area is fairly reflective like bare aluminum (silver), then very little heat would be produced from that beam.

 

[pseudonomen137]

Re: RPL laser "dual beam" issue = wasted power dem

Hi Milos,

Good question.
This would depend on the color of the material on the inside of the cavity where this "other beam" is projected. You need to remember that the beam is not like a blow torch. There isn't any heat in the beam of light itself, the heat is created by the absorption of that light. If the inside area where this beam is striking is dark/black in color, then I would expect heat to be produced; however if the area is fairly reflective like bare aluminum (silver), then very little heat would be produced from that beam.

Well, actually considering the pinhole is the only exit to that front portion, it doesn't matter that the inside isn't dark. The extra beam isn't just gunna hit the aluminum, its gunna bounce around in there till all of it is absorbed one way or another. There's no where else for the energy to go after all, and it'd still only take a few passes for the aluminum to absorb the majority of its energy. So basically, within the front, you're getting a good 200mW+ of heat generated any way you look at it.

However, consider that against all the other heat produced: There's a 2W pump in there that's probably no more than 35% efficient. That means the pump alone is giving you a few watts of excess heat to worry about, and then you're likely getting another watt+ from the crystals (assuming the pump is outputting 2W and you're getting <1W of green between the stray and main beam). So in that context, the heat from the stray beam looks pretty insignificant eh?

 

[Aseras]

Re: RPL laser "dual beam" issue = wasted power dem

The laser runs just as long without all the crystal assembly removed as it does with it. The heat almost all comes from the pump diode. The crystal set doesn't appeat to get very hot, although I did stick a leadlight MCA on top of the diode on "1" (~550mw ) and I got a nice green beam and the little copper heatsink got so hot I have a blister on the tip of my finger when I went to pick it up and remove it. It got that hot in maybe 10 seconds. Mostly because a fair bit of the beam was hitting the copper and being absorbed.

I have somehting I may try I have a flir unit I can use, BUT I'm afraid the IR coming out of the laser might fry it. I don't want to ruin a $6k tool I need. I'm gonna try and see what I can do with it. I wish I'd done some before and after pics now.

 

[Nordhavn]

Re: RPL laser "dual beam" issue = wasted power dem

I find Asers' explanation makes very good sense.


I DO wish two beams could be combined. That would be a quick way of almost doubling the power of current diode/crystal set abilities that are already available to us.

This was the intention of the video and original post. I would like to let everyone know that I'm not trying to slam the design or Optotronics. These are good lasers for the intended audience. Mine has been holding up well. The thing to remember is these lasers do NOT use MCA's. I believe the beams can most definitely be combined as I have a 3W Melles Griot that produces a pair of beams and I have a combiner that produces a single beam. Combining the beams will make the unit larger (possibly hercules sized!) but the increase in power and decrease in divergence (the output beam would be larger) could be worth it for those wanting really long range! It's not a project for the novice either.

 

[pseudonomen137]

Re: RPL laser "dual beam" issue = wasted power dem

I keep seeing mention of combining the beams. Can someone please explain how they intend to do that? I am under the impression its hardly even possible.

 

[laserrod]

Re: RPL laser "dual beam" issue = wasted power dem

Edit: Thanks ASERAS!!
This is a coolest thread yet!
Just been reading/skimming this for 30min..
Sorry if I missed something wrote already.

1. How good is the polarization of each beam?  

2. If you combine the beams using the polorization method then does the product beam become random polarized? Polarized beams steer with less loss.

3. Can beams be combined using reverse bifringance?

4. Would crystal ends cut a brewster angle solve the problem?

5. Is bifringence: the property of a off axis twin image to the main axis image and also known as fast axis and slow axis? (light travels slower on the twin off axis image?)

6. Does this waste beam go through the OC and Coll. lens too? Using it then would be easier then. EDIT: No it doesn't


MMMMMMMMMMM

Why not just retrofit the housing with a aux apperture & beam steer mirror for 2 beam laser projector or for a parallel companion main beam?
(Waste not, what you have available.)

Drill out your RPL & Prometheus? Ha HA

DGM [smiley=beer.gif]

 

[ixfd64]

Re: RPL laser "dual beam" issue = wasted power dem

This is a very interesting thread.

However, I find it hard to believe that 50% of green light is wasted. It's often agreed that KTP crystals have a maximum efficiency of about 35%. Suppose that a high-quality laser's KTP crystal has an efficiency of 30% and an IR saturation limit of 2W. It should output around 600 mW of green light. We've seen RPLs operate at around 550 mW, so I highly doubt that 50% of the green light is wasted.

 

[john_lawson]

Re: RPL laser "dual beam" issue = wasted power dem

I think I'll buy a RPL now that I read this

 

[Ace82]

Re: RPL laser "dual beam" issue = wasted power dem

Very interesting thread, i'll be keeping an eye on this, learning lot's off new things

Sorry LPF members, this post is way off topic. Fear and Loathing in Los Vegas. Awesome!

 

[Ace82]

Re: RPL laser "dual beam" issue = wasted power dem

Some chefs or cooks don’t wish to expose their personal recipes as some love sharing them on TV. Even fast food companies have their “secret sauce”. You know, it’s just the thing that makes them unique.

As far as quality issues on the RPL’s, what does the 12month warrantee have to say about that? It’s obvious that they’re confident that their design is effective. As for today’s most practical way of making a 532 green laser, it undergoes certain steps to achieve the intense green beam peaking our human eye’s sensitivity. If you want a powerful laser to blow missiles out of the sky, IR might be the way to do it.

Until there is a DPSS laser diode at 532nm, these “side effects” are inevitable. There are other ways of creating green lasers, but I don’t think the common hobbyist or researcher could afford them.

I’m sure all current DPSS 808nm diode green lasers are capable of better utilizing its power, it just wouldn’t be 532nm green! But what’s the purpose of an invisible laser pointer?

P.S. Not knocking the insanely powerful IR lasers, just sticking up for today’s most economically feasible 532nm green lasers.

 

[FreeBee]

Re: RPL laser "dual beam" issue = wasted power dem

I have it on my DX true 50.

But, the problem is only present if the laser is still cold. Once it warms up a bit it pops normal.

 

[john_lawson]

Re: RPL laser "dual beam" issue = wasted power dem

if its not broken don't fix it my rpl 260 is a very nice unit Jack is #1