Page 1 of 2 12 LastLast
Results 1 to 10 of 12

Thread: Measuring Scan Angle....

  1. #1
    Join Date
    Jun 2007
    Location
    Lake Geneva, WI.
    Posts
    2,704

    Default Measuring Scan Angle....

    Hi Everyone,
    Is their a simple mathematical equation for measuring the scan angle of my galvos by the distance from the scanners to the projection and width and/or hight of a test pattern?
    Thanks!
    Adam

  2. #2
    mixedgas's Avatar
    mixedgas is online now Creaky Old Award Winning Bastard Technologist
    Infinitus Excellentia Ion Laser Dominatus
    Join Date
    May 2007
    Location
    A lab with some dripping water on the floor.
    Posts
    9,350

    Default

    Quote Originally Posted by 300EVIL View Post
    Hi Everyone,
    Is their a simple mathematical equation for measuring the scan angle of my galvos by the distance from the scanners to the projection and width and/or hight of a test pattern?
    Thanks!
    Adam
    The data is in lookup tables on the Pangolin Web site, with math examples

    Steve

  3. #3
    Join Date
    Oct 2006
    Location
    Central Florida
    Posts
    7,067

    Lightbulb

    Love, peace, and grease,

    allthat... aka: aaron@pangolin

  4. #4
    Join Date
    Jul 2005
    Location
    Lancashire UK
    Posts
    1,379

    Default

    Rob ( stanwax ) posted a fantastic scan angle chart,

    just pop it 30cm in front of your scanners .... and easy indication of scan angle

    see here ...

    http://photonlexicon.com/forums/showthread.php?t=4544

    hope this helps


    Karl

  5. #5
    Join Date
    Jun 2007
    Location
    Lake Geneva, WI.
    Posts
    2,704

    Default

    Thanks for the help guys! I like Karl's option the best. Gonna have to go to the local print shop to have them do A3 paper though, I only have 8.5" X 11" here.
    Thanks Again!
    Adam

  6. #6
    Join Date
    Oct 2006
    Location
    Central Florida
    Posts
    7,067

    Lightbulb * taken from Pangolin's site "http://www.pangolin.com/userhelp/scanangles.htm"

    Dude, the math is easy. I think. I have a small room, it is 136 inches to my wall, and my image width is 31 inches. Defintly try Rob's card, but if you really need it "now", just do the math.

    * W is 31 inches and D is 136 inches. First, multiply D times 2 to get 372. Then, W (31) divided by 2*D (372) is 0.0833. Next, look in the table below, to find the closest angle which has a tangent of 0.0833. This is 5 degrees (at 0.0875). We have just found the half-angle of scanning; the actual peak-to-peak angle is twice this, or 40 degrees. Thus, the desired scan angle A is about 10 degrees

  7. #7
    Join Date
    Jun 2007
    Location
    Lake Geneva, WI.
    Posts
    2,704

    Default

    Quote Originally Posted by allthatwhichis View Post
    Dude, the math is easy. I think. I have a small room, it is 136 inches to my wall, and my image width is 31 inches. Defintly try Rob's card, but if you really need it "now", just do the math.

    * W is 31 inches and D is 136 inches. First, multiply D times 2 to get 372. Then, W (31) divided by 2*D (372) is 0.0833. Next, look in the table below, to find the closest angle which has a tangent of 0.0833. This is 5 degrees (at 0.0875). We have just found the half-angle of scanning; the actual peak-to-peak angle is twice this, or 40 degrees. Thus, the desired scan angle A is about 10 degrees
    Hey,
    Yeah, the math is not that hard but I still suck at it. It's a real deficiency since I'm such a science geek. I like the chart since i can make changes and adjustments fairly quick without having to re-measure and calculate.
    Thanks!
    Adam

  8. #8
    Join Date
    Oct 2006
    Location
    Central Florida
    Posts
    7,067

    Question

    What do you mean, measure and re-calculate? Just tune em till they won't tune any bigger at 30K... right?

    I like to run the 30K pattern, the real small looking one, at 100% when tuning. I am not sure this is the best thing to do, but it always worked out... the three or so times I have done it. Adam, buffo, tuned my DT40s up when I got them, but they were doing fairly well to start with. He only used the 12K pattern at 29% at the end. I just viewed the 30K pattern at 100% and it is actually smaller than the 12K patter at 29%. I think I am running at 1o degrees, so that may be why.

  9. #9
    Join Date
    Jun 2007
    Location
    Lake Geneva, WI.
    Posts
    2,704

    Default

    Quote Originally Posted by allthatwhichis View Post
    What do you mean, measure and re-calculate? Just tune em till they won't tune any bigger at 30K... right?

    I like to run the 30K pattern, the real small looking one, at 100% when tuning. I am not sure this is the best thing to do, but it always worked out... the three or so times I have done it. Adam, buffo, tuned my DT40s up when I got them, but they were doing fairly well to start with. He only used the 12K pattern at 29% at the end. I just viewed the 30K pattern at 100% and it is actually smaller than the 12K patter at 29%. I think I am running at 1o degrees, so that may be why.
    Yes, However I plan on writing a review on my new galvos and want to provide data on the scan angle at different speeds. I plan on running them at 30K but I want to see what it can do accurately at 20K, 40K and 50K.
    Thanks!
    Adam

  10. #10
    Join Date
    Jan 2006
    Location
    Akron, Ohio USA
    Posts
    1,754

    Talking

    I hate to throw this in there, but......

    You REALLY need to know math and understand a fair amount of the history of computer aided laser display to even begin to understand what the original ILDA 12K and 30K scan test is really all about. I don't get it, but anyway.......

    It's a weird thing to describe, and I bet there are others out there who might do better, but...

    That pattern is all about driving your scanners to their absolute max with a minimal set of coordinates (to make the circle). It relies heavily on the fact that scanners have mass and can be driven to a real limit of accurate swing between reasonable coordinates in both axis. That accuracy will ultimately fall off at a predictable rate, after that frequency limit is breached.

    That's all cool! But my question is, how does that translate into a reasonable quantified value like "radians per second"?

    James.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •