Scanner Adjustment

[planters]

I'm trying to optimize some 30K scanners and have read thru a number of tuning guides. Typically , it seams that tuning is being performed at 8-20 degrees optical angle ( base to vertex of 1/7 to 1/3 radian). I am typically displaying at 40 degrees. Do I set the software to scan at 40 degrees, but at a lower frequency, say 24K, for lack of a better choice and do the Benner walk by dropping the gain then upping the gain in order to optimize? Or do I set at 20 degrees and 30K, optimize tuning and just live with the image degradation when set at 40 degrees? Which is better?

[mixedgas]

Which test pattern? The one with the large box around the ILDA test pattern or the ILDA test pattern only?

That is one of the major differences between 8 and 20.

I usually tune at 8' per the scanner spec and then drop the scan speed as I open the angle.
That is on older amps.

I then bounce between the large 10x10 grid, the ILDA patterns, and the Laser Media pattern, then run a hand rotoscoped complex animation, then again, and again, and again.


Steve

[planters]

I am using the 12K pattern without the extra large box. I had assumed that the angle applied to the outer frame on this image and not to the circle/box couple. After rereading the tuning instructions, I'm not so sure anymore.

I usually tune at 8' per the scanner spec and then drop the scan speed as I open the angle.
That is on older amps.

So, after tuning to the smaller angle it is better to adjust the speed down while watching a test pattern set to the desired angle than to tune initially to that same desired angle. That seems a little surprising (not that I'm doubting you) that the resonances,inertia etc will maintain a stable relationship as the speed is changed. This would certainly be more convenient than retuning for each venue. Do I understand you correctly?

[norty303]

Are you doing beam or graphics shows?

I ask, because if its just beams then it's not a complex issue. Set up your scanners at their rated scan speed (30k is usually fine) at 8deg using the pattern/s. Once you have them set up, simply open up the scan angle to max in the software, and maybe drop the speed a bit (I scan all my beams at 18-20k regardless).

I can't think of a single situation (other than tuning) where I've ever thought to measure the scan angle. They simply go as wide as they can. If I'm doing any sort of graphics/lissajou projection, then I make sure the angle is appropriate - but I do it by feel and intuition - you sort of 'know' what is going to be ok, and what isn't. Playing around with angles and patterns at home where you can hear the scanners will give you a really good 'feel' for what they are happy with. Watching for curly edges/corners and other oddities are also usually good visual clues about whether you are near a limit or not.

The only time I've ever adjusted a driver size pot is when size matching 2 sets of scanners in matched pairs of projectors. Otherwise they stay 'full out'.

[mixedgas]

For the ILDA pattern only, not the one with the confusing outer extra box, its 8 degrees from the outside of the aggregate patten, You do not measure the circle in the square.

Its approx 20' for the outside of the big boxed pattern.

For beam shows, we tune the scanners for graphics per the standard, and then crank up the scan angle and slow down the scan rate, again, as Norty says, by "feel" till it looks the best it can. Thats the "Art" part of the artistic part of laser shows..

Steve

[planters]

That works and makes good sense. Thanks.