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Thread: Big green modules for projection: OPSL vs DPSS? ~10W to ~15W

  1. #21
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    Quote Originally Posted by sbk View Post
    Honestly, I wouldn't advise you Viasho. I had quite bad experiences with the reliability of their 4W heads in the past
    Oh wow, we must have been really lucky then. We had 3-4x 8W heads year ago and they were all great.

    Quote Originally Posted by Humphry View Post
    Will try to see if I can combine two with PBS instead of having them in separate projectors.
    My opinion... don't cheap out on a PBS... 20W is a huge amount of power, and a few percent loss in any cube is quite a lot of thermal energy. Do you trust the glue that's holding the glass together!
    A cheap one may work, but for how long? This might just be me being over cautious though

    Good quality standard PBS from a known manufactuer with proper testing + damage threshold data:
    https://www.thorlabs.de/newgrouppage...ctgroup_id=739

    Higher power PBS cubes (probably overkill for your needs!):
    https://www.thorlabs.de/newgrouppage...tgroup_id=6055

    Both of those cube type do not use glue and are optically contacted.

    Quote Originally Posted by Humphry View Post
    Anyone have a contact for Vaisho? I cannot find their website.
    I don't have an email address to hand, but the contact we dealt with was Frank Wang.
    http://en.viasho.com/

    All the best,
    Dan
    - There is no such word as "can't" -
    - 60% of the time it works every time -

  2. #22
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    Quote Originally Posted by danielbriggs View Post
    Oh wow, we must have been really lucky then. We had 3-4x 8W heads year ago and they were all great.
    Ok nice to hear, maybe they had a short bad period once and then improved. Mine was bought back in 2011, 4W heads, and they did around 3.3-3.5W already out of the package.

    Since I switched to OPSL 8W 532nm heads and they are still running up to spec since 2012, hope they will last very long time like this

  3. #23
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    Thanks for the tip on the PBS Daniel. Will make sure it can "handle the heat".

    Quote Originally Posted by sbk View Post
    Since I switched to OPSL 8W 532nm heads and they are still running up to spec since 2012, hope they will last very long time like this
    Sbk where did you obtain your 8W OPSL units and how much were they? If you would prefer not to say publically would you mind PMing me?

  4. #24
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    Quote Originally Posted by Humphry View Post
    Sbk where did you obtain your 8W OPSL units and how much were they? If you would prefer not to say publically would you mind PMing me?
    First one was from Kvant (with HB-Laser driver), second one from RTI (own RTI driver, very small footprint). Prices you can expect somewhere under 10k€ (+-2k), but it strongly depends on the current USD exchange rate and your actual discounts/volume by each manufacturer...

  5. #25
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    Hi Humphry.

    I just wondering what you need for your project.?
    Is it a single low divergence beam or do you need the beam to be thru scanners ? Because it makes a huge diffence what you are able to do with the divergence then, Vs a single beam you can collimate up to a 10 or more mm beam to get a really low divergence.
    We have many laser over the years, Jenlas, CNI DPSS and of cause the best coherent 10W green OPSL. Then 10W OPSL is a selected type, it do a 4.5 - 5mm beam with only 0.5mrad beam. That is great for long distance beam(s).
    Then jenlas do a great beam but they also have been repaired more than one time over a 3-5 years periode with less than 500 hours, But generally then do a great job 3mm beam around 0.7 - 0,8 mrad for the 5W model (D2.10) forget the D2.8 8 watt version, bad beam spec.
    Depending on how much you have for the project. I will look at a OPSL 10W or go the diode way 8->32W(possible more) Green module. Johan (edison) can do that power for you with a good divergence less than <1mrad for a 5mm beam, But of cause if you don't need scanner in front of the beam you could easy get a <0.5mrad or less with a bigger beam.

    Pic attached is 1 km distance 10W OPSL 5mm beam with 0.5mrad
    Click image for larger version. 

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    Last edited by Laserpower; 07-03-2018 at 00:45.

  6. #26
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    Hey Laserpower,

    Thanks for your thoughts.

    We have already pushed the size of the initial beam coming out of the laser module to 8mm for best divergence (we have discussed with the manufacturers CNI about this). Our max scanner mirror size is for an 8mm beam. We have been offered the following specs on a 10W 532nm DPSS laser module by CNI:
    10mm 0.55mrad
    8mm 0.8mrad <------- Our choice
    6mm 1.05mrad
    4mm 1.4mrad

    They confirm we can indeed combine with PBS and waveplate. So we can achieve 2x 10W 532nm DPSS resulting in 20W 532nm with 8mm beam at 0.8mrad divergence (at half the price of an 8W OPSL, I might add). What do you all think? This even leaves budget for some nice blue. I assume a 20W diode system is going to cost much more than this.

  7. #27
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    Hey Fabian, don't rush with the CNI DPSS yet. I didn't realize for good divergence even DPSS has to be somewhere around 8mm for 0.8 mrad.
    At this point, why not go with a pure diode 520nm module? It will last longer and you could ask Atenlaser what beam diameter you could get for that divergence. Even if the pure diode diameter was 10mm you could easy get a 10mm aperture 506 scanner for good price.
    You could also ask Goldenstarlaser if they can icnrease their beam diameter for their 10W pure diode green from 6mm to 8mm or 10mm by decreasing the divergence which for 6mm is 1.2 mrad. http://goldenstarlaser.com/index.php...product_id=437
    I haven't tried their green modules specifically but the 10W RGB modules have worked fine for my beam shows. Just ask them if they PBS combine in the module.
    They have a 15W module as well. http://goldenstarlaser.com/index.php...product_id=536

    520nm is admittedly a little bit dimmer than 532nm but at the same time lower wavelengths tend to travel better in the atmosphere.

    If you don't need the beam to be scanned even a laser bar or an array of bars taken from a video projector might work for your needs.
    https://www.ebay.com/itm/New-Nicha-5...IAAOSwP4FaIRBN

    https://www.youtube.com/watch?v=IzUoe-9bKa0
    https://www.youtube.com/watch?v=OVNGHliB0GE
    https://youtu.be/JMFep9n0izQ?t=7m29s

    This does require some DIY though.

    Beware of photos taken of outdoor lasers. Usually they are very overexposed and make any light source appear several times brighter than in reality.
    Last edited by piydadorto; 07-03-2018 at 01:01.

  8. #28
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    Hi again.

    Is it some thing there need to run many hours in a instalation ?

    Have been working alot over the years with DPSS lasers. There a + and - about DPSS. Then must importend thing about the system is the Diode and the Crystal "must" have it's own TEC, so all is hold total in place in temperature. And normally CNI only have cooling, but it's nedded with heat and cooling in the electronic. I know they have option to pay alittle more and get a Heat and cool driver for many systems. So Heat and cool is a must.
    Living hours is another thing. all 3w+ CNI i had have seen never last over +500 hours. But can have been unlucky.
    Service: you must expect some service on DPSS. You need to readjust the TEC's temp. over time to keep full spec power out of the lasers. General i would say OPSL and Diode systems also need service but i would say DPSS is still more service required.

    If it's only a short time installation less than 500 hours use go for the CNI's. But if it's something you need to be sure it runs for longer time. I would go for some better sources, but of cause all comes down to the money you can use for this project.
    Last edited by Laserpower; 07-03-2018 at 02:56.

  9. #29
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    Hi Laserpower (what is your actual name?)

    Your time is really appreciated, thank you.

    Our temps are pretty moderate here. Maybe 20 deg c minimum at night. Do you think TEC is necessary?

    We are not going to be doing many hours on the system, its actually only for 2 minutes of official show display haha. But of course use in the future must be considered.
    I have a CNI 5W and I am really happy with it. Great divergence and still over spec 5 years later. That being said, it's probably only got a few hundred hours on it.

    Another reason for DPSS is the beam just seems so much cleaner to me. I have seen the Goldenstar modules and they are not good at all for graphics in my opinion - without a spatial filter it all seems so fuzzy. Even the lightspace modules don't come close to a 5W CNI DPSS when you are throwing far distances. It's night and day in my opinion.
    Another thing is the actual spot size, and thermal shift of all the diodes - mirco changes seem to just occur, which might be acceptable for 2 or 4 diode setups, for 10 it compounds any tiny changes. So I don't think a chinese solution for diode is really going to cut it - I feel it's either chinese DPSS, or European multi diode. I can get the 20W DPSS system mentioned above for something like $5,000. I have not got a cost on green diode, but have asked Jordi to let me know his thoughts via email.

    As I type I am sitting in a film studio shooting a Bollywood scene for an airline. Love my job!

    All the best. Fabian.

  10. #30
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    Quote Originally Posted by Humphry View Post
    Our temps are pretty moderate here. Maybe 20 deg c minimum at night. Do you think TEC is necessary?
    With a DPSS laser, you have two competing thermal targets inside the cavity, which is why you want 2 separately controlled TECs.

    The pump diode gets hot (as all diodes do when they are running hard), and it really wants to be cool. So you need a TEC on the pump diode to cool it down. Even with lower power DPSS designs (just a few watts), the TEC on the pump diode is a must to keep the diode temperature in spec.

    The other thermal target is the doubling crystal. As a general rule, these non-linear optical elements perform best when they are hot. For KTP, you want the crystal to be between 40 and 60 degrees C. So now you need a second TEC to heat the doubling stage.

    Some cheaper Chinese DPSS designs (especially those that were under 2 watts) simply used a single TEC and dumped the heat from the pump diode into the doubling crystal. Eventually waste heat built up inside the case, and that was radiated through the bottom of the module to the baseplate. This worked OK, but it wasn't optimal.

    Higher power DPSS designs all have dual TECs, and for *very* high power DPSS lasers you may need to tweak the temperature settings on those TEC controllers to get maximum power. The efficiency of the doubling stage is highly temperature dependent, so if you are off by a few degrees you can see a marked decrease in output power.

    I have seen the Goldenstar modules and they are not good at all for graphics in my opinion - without a spatial filter it all seems so fuzzy.
    Those modules can't come close to the performance specs you listed earlier. (.8 mrad is hard to beat!) But implementing a spacial filter is actually quite simple, and not very expensive either. If your only complaint is the "fuzzy" nature of the beam, I would suggest installing a Keplerian collimator with a pinhole spacial filter at the focal point between the two lenses. You can easily clean up the trash around the outer edges of the beam this way.

    I can get the 20W DPSS system mentioned above for something like $5,000.
    That doesn't sound too bad. If they can guarantee the power, diameter, and divergence numbers, that might be the way to go.

    I have not got a cost on green diode, but have asked Jordi to let me know his thoughts via email.
    Jors can certainly build you a custom laser to meet your specs. I've spoken with him before on other projects, and he's really sharp! Some of the designs he has posted here on PL are astounding. So, yeah, it would definitely be worthwhile to at least discuss the possibility of a one-off build from his shop...

    As I type I am sitting in a film studio shooting a Bollywood scene for an airline.
    Priceless!

    Adam

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