Grid Test Pattern

[Insanity]

Having spent a lot of time this week tuning 3 sets of scanners, I finally found out what the Grid Test Pattern is / can be used for

As far as I recall, it was not mentioned in Buffo's very handy tuning guide, but it has been a while since I read through it... I guess that shows how many sets of scanners I have tuned...

I used it to set the damping on the scanners. The grid should be perfect when your damping is set correctly. So when tuning, look at the edges of the pattern. Low frequency damping will adjust the angle of the squares round the edges and high frequency damping adjusts the positioning.

So, if your HFD is set too high, the edge squares will be outside the grid and too little they will be inside the grid. If the boxes are leaning into the grid (like on the edges of the X axis in the photo) you need to add a little more LFD, if they are leaning out of the grid, you need to add a little less...

As with all adjustments when tuning scanners, take it easy.. Especially with HFD... You don't want to send your scanners loopy...

I always found one of the longest most fiddly jobs was getting the bottom line under the green box in the ILDA 12k Pattern to be straight and in the right position (ie; not pointing up or down), which is also done with damping... But using the Grid Pattern made the job much easier...

Excuse the photo, my camera couldn't keep up as this was scanning at 40k....

Cheers
Mark

[buffo]

As far as I recall, it was not mentioned in Buffo's very handy tuning guide

You are correct, Mark! It is not mentioned in the tuning guide at all. I've used the grid test pattern after tuning is completed, as a means of checking the performance of the scanners, but I've never used it to try and tune with. Guess I need to give that a shot and see how it goes!

I always found one of the longest most fiddly jobs was getting the bottom line under the green box in the ILDA 12k Pattern to be straight and in the right position (ie; not pointing up or down), which is also done with damping... But using the Grid Pattern made the job much easier...

Have you tried tuning with the blanking disabled? On page 7 of my tutorial there are some pictures that show what the ILDA test pattern looks like when you can see the re-trace lines. And the one that runs diagonally from the middle of the pattern down to the bottom edge is *very* useful for tweaking both LF and HF damping.

Note that it's easier if your tuning is already fairly close before you turn off the blanking. At least that's been my experience.

Adam

[Insanity]

Have you tried tuning with the blanking disabled? On page 7 of my tutorial there are some pictures that show what the ILDA test pattern looks like when you can see the re-trace lines. And the one that runs diagonally from the middle of the pattern down to the bottom edge is *very* useful for tweaking both LF and HF damping.

Note that it's easier if your tuning is already fairly close before you turn off the blanking. At least that's been my experience.

Adam

I did try that this time and it worked very well, all my scanners are tuned perfectly this time... For once in my life, I'm a very happy laserist

Mark

[allthatwhichis]

For once in my life, I'm a very happy laserist

Mark

The dual frequency blues didn't do it huh?

[Insanity]

The dual frequency blues didn't do it huh?

Yeah, you got me... They do make me *very* happy...

Mark

[Doc]

Its also handy for matching the X/Y size of multiple scan sets.