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Thread: non liner analog modulation

  1. #1
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    Default non liner analog modulation

    Hello
    I got a cheaper analog control 532nm laser but find the modulation voltage is far from liner , is this because it's a DPSS or did I get a shit quality laser?

    https://www.ebay.com/itm/Analog-sign...kAAOSwGtRXyOLv

    aside from just going to a diode laser are there better affordable green dpss lasers, I like the 532nm green but the non liner modulation is annoying and I dint know if that just the fault of the cheap laser? It is in a Lumia build so fast response time is not needed.

    any one know of a DPSS that has a more reliable linearity or is that just inherent with DPSS lasers
    Polk SDA SRS, Parasound HCA 3500, Luxman M117, Onkyo 504, 7.62X39, sometimes a ball on a string is the greatest of toys for us nonhuman types. oh and some lasers, lots of lasers

  2. #2
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    Default

    Wow...for the Price you bought an DPSS Laser you cant fill the Tank of your Car here in Germany :-)

    Short : You bought the ceapest Chinese Crap which was to get.

    Good DPSS use 2 TEC Controller to set Temperature of Diode and KTP. All you got is one fan and a PWM Driver.

    The Current/Power Ratio of a DPSS was never linear. Above his Idle Current he starts to Output some light but the most Power you got is in the upper Current Range.

    Where to buy good one ? HmmÖ Showlaser - DPSS maybe LasEver or something like that Level. Be sure that the Driver is a Linear Regulator, no PWM IC.
    Greetings
    Guido

    www.mylaserpage.de

  3. #3
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    You should be able to use show software to correct it somewhat. But as Guido was implying without it being a well regulated build in thermal control and driving current, it's never going to be linear. This is why green diodes are such a big deal, why blue diodes were such a big deal. 473nm was worse and way more expensive!

    And I've bought cheap chinese "analogo" drivers, some are PWM that can't be dimmed while scanning for poka-dots and others that use LED drivers that only modulate in about 5 steps from 0.3V-1.3V. While that's kinda sorta working, it's about as good as you can expect for the price.

  4. #4
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    cool, thanks for the info, I have a few DPSS that have two TEC's and an analog driver that I think may have analog control or can modded for that, my other green DPSS is a monster class 4 beast (I was hired to realign that thing and ended up just buying it, we found out the hard way that it can't be used on the road, it falls out of optical alignment with vibration , it's happy to just sit on a table and do it's thing) and it has two TEC's as well in a future build I will try that.

    I suspected a single TEC would suck just not to this level..

    The smaller two TEC lasers are by Crystalaser and I can't find pump diodes for them so over the years I am down to 3 and they are all running at end of life, the pump is at full power for 25mw out, I am told they use an A-mount pump and can't find replacements.

    My preference is 532nm green over the 520 green but for one projector I am making I switched to a 520nm after I ran into this characteristic, was hoping it was just the cheapness of the laser.

    Thankyou for the info


    Draco
    Last edited by Draco; 02-01-2019 at 18:12.
    Polk SDA SRS, Parasound HCA 3500, Luxman M117, Onkyo 504, 7.62X39, sometimes a ball on a string is the greatest of toys for us nonhuman types. oh and some lasers, lots of lasers

  5. #5
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    All of the analog 532nm lasers I've owned over the years (mostly from quality manufacturers) were non-linear. They typically had a plateau or even a drop in power in one or two areas. With software that allowed you to create linearity adjustment curves with several points, you could compensate for this for the most part. The very low end was always that terrible jelly-beaning (dashes of on/off or brighter/dimmer) though. Thankfully, bright people came up with laser diodes to replace these faulty technologies for the greens and blues. I'm still waiting for an affordable solid state yellow, though!

    -David
    "Help, help, I'm being repressed!"

  6. #6
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    Colors safe IRIS. Fixes all this....just saying....

    i bought dhom 500mw years back. It modulates just fine. It was about 500.00. They exist. Still diodes are far better but not for beam quality. Diodes are cheaper and more stable. I found an opsl green on eBay that does 100mw and is 530mw. Few still left. Seems a real nice option for low power. The beam is 0.1mm! Tem00. Perfect perfect. Just lower power. Look up opsl on eBay.

    https://www.ebay.com/itm/PL530-Osram...QAAOSwEUdcDVhx

    here is 525nm green diode. Thatís getting pretty close. https://www.civillaser.com/index.php...x&cPath=24_304

    donít forget in most software you can blend a little blue or red in to move the apparent color around.
    Last edited by kecked; 02-03-2019 at 06:43.

  7. #7
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    Quote Originally Posted by kecked View Post
    Colors safe IRIS. Fixes all this....just saying....

    i bought dhom 500mw years back. It modulates just fine. It was about 500.00. They exist. Still diodes are far better but not for beam quality. Diodes are cheaper and more stable. I found an opsl green on eBay that does 100mw and is 530mw. Few still left. Seems a real nice option for low power. The beam is 0.1mm! Tem00. Perfect perfect. Just lower power. Look up opsl on eBay.

    https://www.ebay.com/itm/PL530-Osram...QAAOSwEUdcDVhx
    Did you test it with a meter to determine if it had plateaus? Also, I've never seen a 532nm that didn't jellybean at the very low end. In any case, a tiny 520nm diode as opposed to a big 532nm/473nm DPSS with TECs and tiny fans screaming away? No contest, IMO. That said, my 473nm DPSS units had beautifully tight beams. Definitely blowing away the 450nm/473nm single mode diodes.

    That green you found is intriguing. Its half the price of a single mode 520nm diode and has about the same output. I wonder how challenging it would be to combine two in this configuration.
    "Help, help, I'm being repressed!"

  8. #8
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    Quote Originally Posted by dkumpula View Post
    Did you test it with a meter to determine if it had plateaus? Also, I've never seen a 532nm that didn't jellybean at the very low end. In any case, a tiny 520nm diode as opposed to a big 532nm/473nm DPSS with TECs and tiny fans screaming away? No contest, IMO. That said, my 473nm DPSS units had beautifully tight beams. Definitely blowing away the 450nm/473nm single mode diodes.

    That green you found is intriguing. Its half the price of a single mode 520nm diode and has about the same output. I wonder how challenging it would be to combine two in this configuration.
    Didnt measure it and itís in a box. You want? I have two of the opsl units. Steve and I are playing with them to see if we can bend their wavelength. Combining should be easy but I didnít measure polarization yet. I also have a full factory built rgb unit. R and b are single mode diodes. Have not put power to it yet. Grab them as once gone thatís it per the seller. I think these were engineering samples for a cell phone based video projector. I was struck by the 530nm color and itís opsl the forbidden fruit of laser. If I ever win the lottery my next beast will be fourcolor opsl with saturns and iris and final spatial filter. What about 100k?

  9. #9
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    Quote Originally Posted by kecked View Post
    Didnt measure it and itís in a box. You want? I have two of the opsl units. Steve and I are playing with them to see if we can bend their wavelength. Combining should be easy but I didnít measure polarization yet. I also have a full factory built rgb unit. R and b are single mode diodes. Have not put power to it yet. Grab them as once gone thatís it per the seller. I think these were engineering samples for a cell phone based video projector. I was struck by the 530nm color and itís opsl the forbidden fruit of laser. If I ever win the lottery my next beast will be fourcolor opsl with saturns and iris and final spatial filter. What about 100k?
    Thanks for those links, Kecked. I ordered a couple of those OPSL greens and couple of the RGB modules with the OPSL greens today. They are dirt cheap, so I'm sure I can work them into something cute.
    "Help, help, I'm being repressed!"

  10. #10
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    Quote Originally Posted by dkumpula View Post
    Thanks for those links, Kecked. I ordered a couple of those OPSL greens and couple of the RGB modules with the OPSL greens today. They are dirt cheap, so I'm sure I can work them into something cute.
    If it works well I maycombine one rgb unit with my 506 scanners but the source I already have that logsquared made me is still going strong so no real point.

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