Announcing: "The Radiator"

[lasermaster1977]

I'll Bet the person who asked the original question will probably never ask the forum again, NICE JOB GUYS!

learning is a forever process and is catching

[Lasertize]

my bad guys,
8 years ago when Adam (buffo) recommended to me to buy pangolin software and hard ware to power my Chines 800mw RGB laser projector, he became the one I would go to for questions on setting up and trouble shooting my QM2000 net box and software settings. one of my q's were "I am having lines were I am not supposed to. " he suggested that I reduce the scan rate of my projector via the LD2000 software under settings that my Kpps was to high, being new to the laser projectors I didn't know what Kpps was so I asked him and at my best recall remember Kpps was a number times 1000 passes per second,now that was 8 years ago I obviously remembered wrong on the proper termanology of pps, now thanks to this discussion, that is forever corrected and I will never use the foul word "passes" again! Now I'm going to stand in the corner for a hour nose pressed tight, hands pressed on my butt with a nice pain full lean in to the corner. This should reinforce what I have learnt as I recite my goesintas and probably my spelin!

[lasermaster1977]

my bad guys,
8 years ago when Adam (buffo) recommended to me to buy pangolin software and hard ware to power my Chines 800mw RGB laser projector, he became the one I would go to for questions on setting up and trouble shooting my QM2000 net box and software settings. one of my q's were "I am having lines were I am not supposed to. " he suggested that I reduce the scan rate of my projector via the LD2000 software under settings that my Kpps was to high, being new to the laser projectors I didn't know what Kpps was so I asked him and at my best recall remember Kpps was a number times 1000 passes per second,now that was 8 years ago I obviously remembered wrong on the proper termanology of pps, now thanks to this discussion, that is forever corrected and I will never use the foul word "passes" again! Now I'm going to stand in the corner for a hour nose pressed tight, hands pressed on my butt with a nice pain full lean in to the corner. This should reinforce what I have learnt as I recite my goesintas and probably my spelin!

Aw shucks, just when I became convinced there must be true meaning and purpose for the phrase "passes per second" in the laser entertainment world. <It could even be associated with drinking in bars!>

And by the way...why don't we spell "with" like "wyth"? It works just the same. OK, now talk amongst yourselves.

are we having fun yet?

[Lasertize]

Ya I thought of the bar thang too in my passed Navy days, have passed out many times per second all over the world but now that to has passed at last!

[Lasertize]

notice I did not use the word passes! sh-t back to the corner!

[tertior]

So 400htz is 24 kpps?like 111 bpm corresponds to 1.85 Hz for example. Are we ok? I save you how many mph are in lbs thanks all if i am not wrong

[Lasertize]

So 400htz is 24 kpps?like 111 bpm corresponds to 1.85 Hz for example. Are we ok? I save you how many mph are in lbs thanks all if i am not wrong

yep, she be perfect, your math is good, just wear sunglasses when traveling, the light will weigh heavily in thought changing the pulmonary rhythm,
collected velocity piles on the pounds=67520 mph 0.0000e+0 lbs

[lasermaster1977]

yep, she be perfect, your math is good, just wear sunglasses when traveling, the light will weigh heavily in thought changing the pulmonary rhythm,
collected velocity piles on the pounds=67520 mph 0.0000e+0 lbs

nyet

think about it...the math result is perfect for dividing 24,000 by 60...the result of 400 is not "Hertz" but rather 400ppm.

another way to look at the math, given scanners capable of 24Kpps is to say "what is the most points an image can have to draw it 60 times a second or 60 Hz. answer: 400 points.

[Lasertize]

nyet

think about it...the math result is perfect for dividing 24,000 by 60...the result of 400 is not "Hertz" but rather 400ppm.

another way to look at the math, given scanners capable of 24Kpps is to say "what is the most points an image can have to draw it 60 times a second or 60 Hz. answer: 400 points.

yes i saw the math as relevant to pps/ppm
so providing that "i save you how many MPH is Lbs"
the better answer to this is "what is half of two plus two?"
and why is the speed of light only relative to one but constant to all?
all about perspective or point of view!
this has been fun

[mixedgas]

30Kpps after some bench tests corresponds to a roughly 2400 Hz small angle bandwidth response at the very small angle in the circle of the test pattern,. As you open up the scan angle or deflect a portion of an image very wide, that frequency response falls off like mad in a non-linear way. The 2400 Hz number is not part of a standard, but it is something an Engineer friend of mine worked out from some oscilloscope measurements made while scanning the test pattern.

Wide angle jumps are slow, small angle jumps can be fast. The galvo shaft has inertia, and takes time to respond. It has resonances that can cause bending mode failures and/or bearing failures if the galvo is abused.


There is not a linear relationship between PPS and displayable abstract Cycles per Second, that is dependent on scan angle and the galvo's non-linear frequency response. The galvo is, in simplest terms, a complex low pass filter with several integrals, and with several shaft resonances.


So, say you have an 1000 data point frame, at 30,000 PPS your time for one complete point is 1/30,000 = per point time in seconds, is 3.33 x10-5 seconds..., thus one 1000 point frame is completely scanned every .0333 seconds.
While your DAC is updating at one sample every 3.33 x 10-5 seconds, your scanners are following, integrating and filtering that waveform mechanically to produce an image. Actually in many cases they are vastly lagging behind the waveform. 30Kpps does NOT equal 30 Khz scanner response.


PPS is simply used to tune to the galvo amp to a common response to the standard test frame at a specific angle , so that images from different users are interchangeable.

So 30Kpps means the galvo can be given a point update rate of 30,000 points per second while scanning the ILDA test pattern at 8 degrees.

ILDA rated speed is related to making the feedback and PID loop tuning of different scan system hardware consistent, so artwork is interchangeable. Along the way it became a marketing point, as the first widely used feedback galvo system was 12K PPS, then 20Kpps, then 24Kpps, then 30Kpps, and a few systems have went faster. So for a long time the standards were 12K and 30K, and finally the Asian copies of scanners became less expensive, so most users have a 30K scan set.

Very little of this relates to how an abstract console behaves. In fact, with a console, one has to be careful not to stress the scanners with fast waveforms. You listen to the scanners, monitor their temperature, monitor their current draw, and keep the scan angles small when using a console, as the first thing the clone galvo manufacturers removed from the galvo amps was the "coil temperature calculator" circuit that protected the galvanometer scanners from overheating.

Only two manufacturers of scanners publish a scanner response vs frequency curve table, which is a complex data table set that might tell an engineer a few things, but tells an artist basically nothing.

The ILDA test method was a compromise designed by a panel of very bright people to allow laser show companies to interchange images by tuning the hardware to a common response standard using the display controller. It was NEVER intended to convey the complex response of a galvo scanner. PERIOD. So we tune the scanner amplifiers to produce a certain pattern to the eye with the vector data updated at a defined rate at a certain angle. Then we can interchange images without having to "pull points" at each location for each scan pair, as it was in the beginning.

Attached is the theoretical state-space model of a galvo scanner before closing the loop with the tunable feedback network.
Kind of hard to express that concept to a gifted artist who has never had an engineering controls class and or calculus.
The ILDA test pattern is a compromise between art and engineering. It was never intended to fully model the system response.

The circle in the square pattern in the center of the ILDA standard can be thought of as a means of measure of the small angle frequency response. But more importantly, since the X and Y mirrors are different sizes, it lets us match the slower response of the larger Y mirror to the smaller X mirror by slightly detuning the faster X mirror's control system. Strange as that may seem, it is needed to ensure I can send a show file to Beijing from Akron and know the person half way around the work see almost exactly the same images I see here.



Hope that helps, it is a simple approximation of what happens in a complex servo system.

Steve