varying brightness with single color DPSS green

Discussion in 'Lasershow Designer 2000' started by dceremuga, May 20, 2005.

  1. dceremuga

    dceremuga Member

    Forgive my ignorance on the technical portion. I just have a question.

    I have a 350mw Lambda Pro DPSS laser with blanking. I am also using a catweazle II setup with X/Y scanners.

    I notice that if I pull up a single beam, I can watch the beam and the brightness is not steady, it will even appear to flicker from bright to dim, etc. If I unplug the blanking connector, the beam is then FULL intensity without any variance. I also get full intensity if I unplug the connector to my QM board on the back of my computer.

    I'm not quite sure where my problem is?

    One last question, what is the proper way to make a single beam in LD2000. I know just clicking and making a dot is not the proper way. I've searched the help files but can't find any help :)

    Once again, if my question doesn't make sense, I'm sorry. I am just trying to get everything "RIGHT".

  2. aricha

    aricha Well-Known Member

    Disconecting your catweazel driver ground from the QM ground can help but it is also the way your laser is working some are not good for our needs

    you can make a dot by a single click with the point tool
    then you go to the main menu : SFX - Renumber and give it 500 points

    good luck
  3. Pangolin

    Pangolin Staff Member

    Hi Guys,

    Your laser problem may be caused by a ground as Aricha suggested, or it may be caused by the lack of a ground. Let me ask you a dumb question. Did you follow the strong recommendations in our help file and on our web site about the proper way to connect a single-color laser to the system (including connecting the respective negative color output to pin 25)?

    Regarding a single beam, you may use the technique that Aricha mentioned, but I usually use one of the drawing tools (point, line, etc.) and then use the "find point" tool, click on the point, and then press and hold CTRL+A for "add point". This will increase the number of points. You may use this technique for those instances where you have more than one "beam" in a single frame. I am not quite sure I would go as far as 500 points as Aricha mentioned, but something in the neighborhood of 80 to 150 points should be fine...

  4. dceremuga

    dceremuga Member

    Guys, thanks so much for the information about a single beam.

    I'm not at home, so I'm guessing. I have pins 16 and 25 together for the negative and pin 3 for the positive. About the grounding. Are you saying to not have those pins connected to the catweazle driver board? That makes sense since I am not using a blanking scanner.

    I'm learning as I go. I have read everything supplied with Pangolin, help files, and the support files. I try not to come in like a noob needing handheld. Just a laserist like yourselves trying to get things right.

  5. dceremuga

    dceremuga Member

    Ok. i'm getting a little confused. I've read the darned documentation till my head hurts.

    I have pins 3 and 16 controlling my blanking. That is all that my laser needs to work, it is either on or off. the problem is that I am getting variable levels of beam intensity with only using the blanking. If I unplug the blanking from the back of my laser, the beam is always full intensity throughout a show, regardless of color, but of course it is messed up without the blanking. My setup should be a no brainer. I have trained LD2000 that I am using a single projector with blanking.

    I notice variable intinsity when different colors are used in a show being played back. Once again, I am only using the scanning and blanking options of the board. I am in total using.

    pins 1 and 14 for my X scanner
    pins 2 and 15 for my y scanner
    ping 3 and 16 for blanking
    Of course I have the ground connected to the catweazle board.

    So, I believe I'm not getting my full voltage to my blanking??? I don't know.

    How can I tell LD2000 that everything should be 1 color and full intensity?

    If you see some holes, PLEASE help.
  6. dmxlaser

    dmxlaser Member

    Hi David,

    When I read your posting it seems like everything is connected OK.
    I think the problem is the perception and/or the board's training.

    As you say that during show playback the intensity of the colors change. This should be correct if the color projected is programmed as a dark color. Some shows use light and dark colors and thus will your laser project these variations in different intensity.

    If you want everything to be either on or off ( full on or full off ) then I suggest you adjust the pallette during training where the 100 % slider is fully open, the 50 % slider is set to 100 % and the 0 % output ( blanking ) slider is set to 0 %. This will have as an effect that the laser will either be fully on or fully off, nothing in between.

    If this is not what you're aiming at, I might have misunderstood your questioning.

    Good luck and be carefull !

  7. dceremuga

    dceremuga Member


    I have done EXACTLY what you mentioned through the Palatte training. Of the 3 sliders (I'm not where I can see what exactly they are), the first two I put to 100%, the bottom to 0%. This made 2 of the 3 lines appear, and properly. Your post just helps to check off another thing I have done correctly. I am wondering if my blanking voltage is not reaching the correct voltage to give full intensity. I may have to do some voltage checking or go through the pain of replacing my DB25 cable to see if that is the problem. I am using a 25 foot high quality, sheilded cable. Not a el'cheapo radio shack job :)

    So far I can't find fault in my wiring or setup of LD2000. It is interesting that I see some comments in the QM2000 message board of some people mentioning issues the same as mine.
  8. Pangolin

    Pangolin Staff Member

    Hi dceremua,

    I do see one thing that you have not quite right. Yes, you connect your laser between pins 3 and 16, but you should also connect pin 16 to pin 25. This may or may not make a difference in your case, but you can try it.

    The last thing might be that the laser is not a very good laser... This is sadly the case with many lasers. They are fine when the beam is not modulated, but when you start to modulate the beam, actually you are also unintentionally and inadvertantly modulating heat within the laser cavity. This heat modulation can cause many effect including a dramatic drop in power. I have also seen a phenomenon that I call "jelly-beaning" -- where the projected laser imagery does not appear as a solid line, but instead appears as a bunch of jelly beans, all lined up to create the line. There are very brief "cuts" in the lines of projected imagery and sometimes this jelly bean appearance can actually walk around the images.

    If you have an external function generator, you can test my theory by exciting the modulation input with a function generator and use different frequencies and see what happens to the beam and the power. I would almost be willing to bet that this is what is happening with your system.

  9. dceremuga

    dceremuga Member

    Hello Bill,

    I have completely rewired the system. I have tied 16 to 25 and have the connections of pin 3 and pins 16/25 connected very close to the laser.

    I don't think it made much of a difference at all. I have notice that the general brightness of the laser shows seems visually brighter. I really cleaned up the wiring and made sure everything is sheilded nicely.

    I still think the QM2000 does have some minor issues with the blanking voltage/signal.

    BTW, I don't get the "jelly bean" affect on solid lines, my images are smooth and the blanking seems precise. I'm very happy with the image quality, just the brightness that bothers me.

    I get much better brightness out of some of the "beam shows" than I do with graphic shows.
  10. Pangolin

    Pangolin Staff Member

    Hi dceremuga,

    OK, then your problem becomes more mysterious... I would not be so quick to blame the QM2000 and in fact, you can test your own theory. Note that, even though you have a single color laser, you do not necessarily need to use the Blanking output. You can use the RED output, or GREEN output, or really almost any output. In certain circumstances, you can even tie multiple outputs together PROVIDED THAT YOU TRAIN THE SYSTEM PROPERLY (this is an advanced technique and I would only want experienced LD users who really understand the color system to do this).

    In any event, I guess one thing you can do is to try a different output or two and see if that makes a difference. If it does not make a difference, then this pretty much rules out any problem with the QM2000 board. At that point I would suggest that you seek the advice of a more-experienced user or dealer with test equipment including a scope and fast photodetector. If you can tell me your geographic area, then I can recommend such a user or dealer in your area.

    Best regards,

    William Benner
  11. luminavp

    luminavp Active Member

    We also have a 350mw lambdapro unit. We noticed that without the blanking plugged in, the laser output was very stable after warmup, and sat aroudn 350-360mw. With blanking plugged in (analogue blanking btw), and with a 5v signal, the most power we got out was 120mw. We noticed turning it up a little past 5v increased the power a bit more, however we didn't want to damage anything. We have since sent the laser back to lambdapro for repair, and its come back fine.

    Basically I believe the issue is more likely to lie within your lambdapro psu. I don't think their blanking circuits work too well basically. Someone else I know in england bought a 300mw lambdapro dpss, that did 420mw when 5v was put into the analogue input....

    Have you tried running the blanking input off a 5v supply/potentiometer to rule this out ?