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Thread: Scan Angles....

  1. #1
    Join Date
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    Default Scan Angles....

    Hi Guys,

    Before I start, I'd just like to say Hello to you all. I'm new to the forums!

    Right, that's got the formalities out of the way...

    I've recently purchased a Laserworld Pro 1600 RGB Laser and Pangolin Quick Show. I've got to say I'm more than happy with this setup as I use it for Mobile Disco's etc etc... However, I'd like some advice on Scan Angles. From my research, would I be right in thinking that the ILDA test patterns are based on an 8 degree scan angle. Therefore to set my Scan speed in Quick show correctly, I could set up my laser so the distance to the projection is say 20 metres, with a projection size of 3 metres. From the Laserworld online calculator this would give me a scan angle of 9 degrees. I could then set the Scan speed in Quick Show to produce the best ILDA test pattern. Also, would I be right in thinking that I could adjust the Projector settings in QS, specifically the "Size and Position" of the projected image to quickly set the 'magic' 8 degree Scan Angle??

    I've read that the Scanners in this laser would produce upto 40kpps @ 4 degrees, so would I be better off 'tweaking' the settings/distance to projection/image size to be as close to 4 degrees as I can?

    Ultimately, I don't want to over stress the scanners, but I'd like the animations to be as smooth as possible.

    If I've a) not made myself clear or b) sounded like a complete balloon then do please let me know and I'll be more than happy to supply more details.

    Thanks in advance, Oh, and I hope you all have a wonderful 2017.

    Kind Regards,

    Cadders

  2. #2
    Join Date
    Jan 2006
    Location
    Charleston, SC
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    2,147,489,446

    Thumbs up

    Quote Originally Posted by cadders View Post
    Before I start, I'd just like to say Hello to you all. I'm new to the forums!
    Hello Cadders! Welcome to PhotonLexicon.

    would I be right in thinking that the ILDA test patterns are based on an 8 degree scan angle.
    Correct. When adjusting (tuning) the scanner amps, you want to be scanning at 8 degrees or less. Once everything is tuned correctly, however, you can scan nearly all graphic images much wider than 8 degrees. In fact, many scanners can even scan the ILDA test pattern at greater than 8 degrees. But the tuning spec specifies a minimum of 8 degrees. Note that the ILDA test pattern is specifically designed to have sections that are difficult to display properly, so it's more of a "worst case" scenario than an example of a typical ILDA frame from a graphics show.

    Therefore to set my Scan speed in Quick show correctly, I could set up my laser so the distance to the projection is say 20 metres, with a projection size of 3 metres. From the Laserworld online calculator this would give me a scan angle of 9 degrees.
    Close enough. 9 degrees at 20 meters distance would produce an image exactly 3.14 meters square. 8 degrees would be 2.8 meters square at the same distance. But yeah, you're in the ballpark, and it's not crucial to be dead-on.

    I could then set the Scan speed in Quick Show to produce the best ILDA test pattern.
    You can do this, but you will be limiting your scan angle. What I suggest is doing exactly what you've proposed, but then double the final value for size in quickshow. So if you are adjusting the size up and up, and when the ILDA test pattern starts to distort you find that you are at 21 on the size setting, then make your maximum setting double that amount, or 42. This is a very conservative starting point that will still give you a somewhat reasonable angle to work with.

    Note also that it's important to define what we mean when we say the ILDA test pattern "starts to distort". What you want to look at is the center circle. It should just be touching the sides of the center square at 8 degrees. As you keep increasing the scan angle, you will reach a point where the circle won't get much bigger, so it appears to pull away from the center square. (Technically it's the square getting bigger while the circle doesn't, but you see what I mean...) If you keep going up on the size, you will also notice that the circle itself will start to pull apart and resemble a spiral.

    The point where the circle just starts to pull away from the square is the nominal limit for the ILDA test pattern. When you get to this point, double your size setting and you should be good to go. The ILDA pattern will look terrible once you double the size setting, but all the other images should still look fine. (Remember: the ILDA test pattern is abnormally difficult to display by design.)

    Once you've done this, run a few shows and look at the images. If you see artifacts like rounded corners or pronounced overshoots, then back off on the size setting a few ticks and try again. But if they look fine, then you're golden.

    Also, would I be right in thinking that I could adjust the Projector settings in QS, specifically the "Size and Position" of the projected image to quickly set the 'magic' 8 degree Scan Angle??
    That is where you adjust the scan angle, yes. And once you know what the number is, you can usually double it and still get good images. Depending on the type of scanners you have and the complexity of the ILDA frames you are displaying, you may be able to go even wider, but 2X is a very conservative starting point that should be OK for virtually any scanner set.

    I've read that the Scanners in this laser would produce upto 40kpps @ 4 degrees, so would I be better off 'tweaking' the settings/distance to projection/image size to be as close to 4 degrees as I can?
    Probably not. My guess is that the scanners have already been tuned for 30K. Thus, they should be able to display the most difficult images (including the ILDA test pattern) at a minimum of 8 degrees. So dropping down to 4 degrees won't make it any better - it will just make it smaller.

    Now, if you plan to run the scanners at 40K speeds (to help reduce flicker), then you would want to perform the above steps at that 40K scan rate to find the new scan angle limit and set your size accordingly. (It would be best if you actually re-tuned the scanners for the new 40K speed, but it's not strictly required.) And because you will be running the scanners faster, you will definitely end up with a greatly reduced scan angle. I suspect the ILDA test pattern will probably start falling apart at around that 4 degree mark...

    Ultimately, I don't want to over stress the scanners, but I'd like the animations to be as smooth as possible.
    Listen to your scanners. A soft, high-pitched whine is OK, but a high-pitched screeching squeal is not. Also, monitor the heat they are producing. If they are getting very hot (hot enough to burn your finger), then consider dropping the scan angle. If they are hot *and* squealing, you've got a big problem!

    That being said, most scanners can handle at least a little abuse. If you bring up an image and it looks terrible (image is distorted and nearly unrecognizable) and you hear the scanners howling, back off on the scan angle and try again.

    Note also that you can trade scan speed for scan angle (and vice-versa), although it's not a linear relationship. But if you find that your images flicker excessively, you can drop your scan angle way down and then bump up the scan speed to see if you can smooth things out. Just make slow, careful steps and watch (and listen) for changes along the way.

    As an aside, I strongly urge you to try to attend a Laser Enthusiast's Meeting in the near future. I know there is one in Surfleet (UKLEM) in April, but there is also a Dutch-LEM coming up later this month. Attending one of these events (or better yet, both!) will really give you a good handle on how everything works, and you can also learn how to tune your own scanners. Plus you'll meet some really amazing people, get to watch some killer laser shows, and in general you'll have an awesome time. Can't recommend this highly enough though: LEM's are where you go to learn while having fun.

    Best of luck to you!

    Adam

  3. #3
    Join Date
    Dec 2016
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    Nr Norwich - UK
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    Hi Adam,

    Thanks very much for you well explained reply. That's made a lot of sense to me, and I really do appreciate you taking the time out to explain. I'll have a shufty at the UKLEM and see If I can make it.

    Kind Regards,

    Lee

  4. #4
    Join Date
    Jul 2009
    Location
    The Netherlands
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    1,473

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    Quote Originally Posted by cadders View Post
    Hi Adam,

    Thanks very much for you well explained reply. That's made a lot of sense to me, and I really do appreciate you taking the time out to explain. I'll have a shufty at the UKLEM and see If I can make it.

    Kind Regards,

    Lee
    Hi Lee,

    you should definately try and come over to the UKLem. I started visiting the UKLems back in 2007 or 2008 and learned a lot there, while having fun.
    There are some very electronic savvy dudes over there that can explain, teach and demonstrate all about lasers, scan angles etc.
    All while having great fun.

    the UKLem , organised by Jim (smogthemog on this forum) inspired me to organise the DutchLEM (very nice of Buffo to mention both UKLem and Dutchlem!)
    Jim is really putting lots of efforts in having the best LEM experience in the UK. It's a nice hall, it's also possible to stay over at the hall.
    And the indian food on saturday is legendary !
    a few times back we setup a table and ate in the hall with lasers projecting overhead. It was a cool laser diner!

    I booked hotel last month, looking forward meeting you there (yeah i am the crazy Dutch guy that is coming over for almost 10 years now to UK twice a year ...)

    Make sure not to miss it !

    Kind regards,
    Dimitri
    Last edited by hobbybob; 01-11-2017 at 04:59.
    I didn't fail !
    I just found out 10,000 ways that didn't work.

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