Scannermax 506s

[Galvonaut]

Didn't know you were after a graphics solution Keith.

No worries. Also after beams but don't really require massive angles for them. Some 506s wouldn't go amiss though.

[Pangolin]

Hi Keith,

As I said, we actually have a few lenses that do what you need, and do it really well. One of them is being reviewed by AVI right now on a real dome. If we like what we see, then that lens will be a relatively inexpensive option, and one we can deliver within a few weeks. If we think that the divergence increase is too much, then we have an alternative design that we know is super-duper fantastic, but it will take a bit longer to bring to market, because we'll have to develop a lens barrel for it. That means design, machining, etc.

Regarding the scanners themselves, we did our own comparison between Compact 506 and DT40, since that was a topic of discussion on another thread. You can see our video here:
http://www.youtube.com/watch?v=8iWjpz2YEO0

Bill

[Bradfo69]

Nice video Bill. Thank you!

[Galvonaut]

Hi Keith,

As I said, we actually have a few lenses that do what you need, and do it really well. One of them is being reviewed by AVI right now on a real dome. If we like what we see, then that lens will be a relatively inexpensive option, and one we can deliver within a few weeks. If we think that the divergence increase is too much, then we have an alternative design that we know is super-duper fantastic, but it will take a bit longer to bring to market, because we'll have to develop a lens barrel for it. That means design, machining, etc.

Regarding the scanners themselves, we did our own comparison between Compact 506 and DT40, since that was a topic of discussion on another thread. You can see our video here:
http://www.youtube.com/watch?v=8iWjpz2YEO0

Bill

I look forward to hearing more news

Just watched the video on the other thread - Nice results!

Keith

[planters]

Bill,

Thanks a lot for the video. There is so much useful information provided with a video demonstration. For example, the layout of your mounting block is now obvious. Something I have noticed in aligning projectors is the inevitable deterioration of a hard won RGB far field spot to a wider far field line. The scanned line width is never as good as the static beam even when the beam path includes the scanner mirrors ( off, non-scanning). I have always attributed this to a combination of tracking errors and mirror surface distortion under G loading. In both the test patterns and the show the 506 seems to produce sharper lines that are sometimes more obvious and sometimes less. To be fair, do you agree? And if you do, can the effect of the laser sources be isolated to demonstrate this more effectively or predictably?

Larger laser sources (larger beams require larger scanner mirrors) will more likely be used at larger distances and the need for lower divergence will be greater. EMS and Nutfield both changed to fused silica (from what I do not know) to enhance their mirror stiffness ostensibly to allow a thinning (lightening) of their mirrors. What is not discussed is the quantitative effect of mirror stiffness (ie silicon) on the mirror itself. Certainly, if high enough scanning speeds can break a mirror then something short of that has to be undermining a high quality, low divergence laser beam.

[mixedgas]

Mirror photo this afternoon before I ship the system back. You WILL be impressed.

Steve

[Pangolin]

In both the test patterns and the show the 506 seems to produce sharper lines that are sometimes more obvious and sometimes less. To be fair, do you agree?

Hehe, I will always agree that our stuff looks better than anyone else's. This may seem boastful or arrogant but it's not meant to be. Everything about our scanners is DESIGNED. There isn't a single part that is used unmodified and off the shelf. Even the bearings are made special just for us and just this morning, I got off the phone with a lubricant manufacturer who will be custom-blending lubricants just for us.

But to speak precisely to your topic, what you're talking about is called "dynamic stiffness" and yes, this plays a dramatic role in what opticians call the "resolution" of the image. If the beam becomes spread out just as a result of your scanning action, then "resolution" has become decreased. When designing resonant scanners (which typically have far higher torques) the designer actually STARTS with the mirror, to ensure dynamic stiffness is there, and then works outward on the mechanics to hold such a sufficiently-stiff mirror in the first place.

The work we have done in the field of rotor dynamics (mentioned and shown on my video) speaks to essentially the same thing, but in two dimensions.

EMS and Nutfield both changed to fused silica (from what I do not know) to enhance their mirror stiffness ostensibly to allow a thinning (lightening) of their mirrors.

I don't know of anyone else who has done the degree of study we have on the effect of mirror thickness on overall rotor dynamics. Remember, the mirror is not "in a vacuum". The mirror is mounted to a rotor. One thing we show is that it doesn't matter how thick (or almost how thin) the mirror is on a scanner with a long rotor (or small-diameter shaft), resonances will happen at a similar frequency. The mirror may dominate rotor dynamics (and dynamic stiffness) in certain scanners, but not others.

And -- again, it may sound boastful or arrogant -- but I haven't seen either of the two companies you mentioned above do any real engineering. I haven't been inspired or impressed by even so much as a single thing that these other companies have done. And finally, I believe that the work we do can't even be compared to the work that these other guys do. If you (the reader) thinks this sounds arrogant, I understand and even agree, it sounds arrogant. But if you visit both companies (as Steve has), look at our parts under a microscope, and see the degree of real engineering that goes into these products, then you'll understand what I'm talking about.

Regarding Fused Silica, that's the material we have always used when we use optical glass. But Fused Silica as compared to what? BK7? As far as I know, at least in the distant past EMS used mirrors made from something called Sodalime glass, made by Knight Optical in UK (because that's their standard material). It's not as stiff, and it's also heavier (but much less expensive than Fused Silica).

But when you "do the math" on all of these materials, the real difference in the actual application between Fused Silica (which is the most expensive and thus rarest used), BK7 and Sodalime Glass, the actual and tangible difference is negligible. We use the most expensive, best, and stiffest because we always want the absolute best performance possible. The topic of cost rarely comes up when we are discussing parts with vendors.

What is not discussed is the quantitative effect of mirror stiffness (ie silicon) on the mirror itself.

This was discussed, or at least alluded in my video. Silicon is anywhere between twice and four times as stiff as Fused Silica (depending on the angle of stress) while being negligibly heavier. So silicon is a clear winner as a mirror substrate. But silicon is harder to process and more expensive. Even setting cost aside, you need to actually find companies who can do the job well and consistently. Because of this, I've only seen us and Cambridge using it up until now.

Bill

[planters]

Bill,

Not to sound arrogant, but as you know, I know all this. Yet, to paraphrase... "it does NOT go without saying", it IS useful to specify these interactions. However, what I was alluding to is that like the video where the effect of twisting and bending and tracking errors must be present, would it be possible to demonstrate this? I'm not sure to what extent the line widths for the different patterns and scanners were effected by camera focus and zoom (there was a fair amount of this) and laser focus.

Without thinking this through too thoroughly, what about the sharp corner of a pattern (for X and Y) with a single color diode to avoid DPSS modulation delays? Mount the camera on a tripod and ramp up the speed to reveal dynamic effects. Repeat for the other scanner. What do you think?

[Pangolin]

Hi Planters,

Yes, it's clear from your own past videos that you know your stuff too! On lines being scanned, what you're talking about could only be caused by:
1) flatness of the mirrors themselves
2) dynamic stiffness of the mirror -- mirrors that are so thin, that torsional forces on the mirror actually cause them to twist while scanning, thus spreading out the beam.
3) a general lack of stiffness in the entire system

Regarding my point number 1, we pay a lot for mirrors, and I suspect others pay much less. This is an area where you get what you pay for...

Regarding my point number 2, the fact that our shafts are 50% larger than everyone outside the USA (and 25% larger than those inside the USA) coupled with the fact that we actually support the back of the mirror helps dramatically in this area.

Regarding my point number 3, this is something even we had to learn. When creating the Saturn 1, we actually created a scanner whose entire system inertia was only 0.008 GM*CM2. When we projected images with it, what we noticed was that the corners actually looked fatter. When we used a tiny and tightly-focused laser, we found that the beam actually wasn't coming to a stop on the corner but rather was drawing a tiny circle and squiggling around. Once we discovered this, we re-visited scanners made by other companies and surprisingly (or perhaps not surprisingly) we saw exactly the same thing, especially scanners made by the two manufacturers you mentioned above. It was this discovery which stopped us in our tracks, and encouraged us to hire a guy from Boeing who does rotor-dynamic analysis as a living, and help us to fully understand this. It is a result of his work that we re-endineered all of our products. Now you won't find squiggles or wiggles in any of our products, and things come to a complete stop on the corners.

In many cases, a fat laser beam can mask what's happening on the corner, and hide problems. When I am doing work on our scanners, I actually use a focused, single-color laser beam for this purpose. In the side-by-side video, it was impossible because already the point was to compare two full-color projectors (each laser having a different divergence and beam diameter). We were trying, as much as possible, to have as good of a side by side comparison as we could.

By the way, "tracking error" is a term used in servo design. It only means the amount of TIME between the command signal and position signal. I doubt that "tracking error" (at least in servo terminology) has anything to do with what you're seeing. After all, "tracking error" is actually always present even when scanning very slowly, and should be substantially similar in all 30K scanners, regardless of who they're made by.

Without thinking this through too thoroughly <snip> What do you think?

Hehe. What I think is that we've already done a thorough analysis of this. For everyone else, it's possible for people to Google "resonant frequency of cantilever beam" and similar topics and see for themselves on sources like Wikipedia that when you make a mirror 1mm thick, it has far better characteristics than when you make a mirror 0.7mm thick. When you increase the diameter of a shaft by 50% it actually makes the shaft more 5 times stiffer! All of these things should be understandable after doing a bit of reading on the internet...

And lastly, I think no matter what we do, some people will always have questions. Already on another thread here on PL, we have a guy doubting that the tests were performed correctly and consistently, or questioning the role that camera angle or shutter settings played in the test. I think no matter what we do, there will always be doubters and such. So we only present the physics behind what we're doing, and let people come to their own conclusions...

Bill

[kecked]

Well with that said. Loved the video by the way. If I am successful in adapting planters spatial filter and some telescopes, those fine lines will be available without ion. So your scanners are going to be required not just desired to show a good image. As the laser gets better it will show more and more. I noticed the image on my 6215s bobbles around slightly. At first I though it was ripple from the power supply or a ground issue but I ruled that out. There is definitively and repeatabley something askew in the way these scanners are working. I noticed it most on the grid pattern with wide scan angles (how wide well the image is about 7-8'square and my projector is 15 feet from the wall). It shows up with the r g b w dancing around ever so slight and a slight ripple in lines. From a distance you don't notice but when up close you do. I'm definitively going Saturn once they come out.