Mylar film vendors

[FI marco]

Thanks!

I think there are many applications like e.g. car driving simulators (they are used in Holland for driving lessons) or some types of gaming that could use a ‘low cost’ collimated display solution. The only systems that are available at the moment are the very big & expensive ones. That probably has to do with patents as you mentioned…

Our mirrorcell was first designed in Solidworks (CAD), we did some calculations regarding the virtual image size, eyepoints, minimal mirror radius, backscreen radius etc. We also did a raytrace simulation in 3D studio Max to see if the image generated by the mirror was as we expected it to be.
The next step was to have the mirror cell cnc milled by a company that specializes in making large objects from Styrofoam. Our mirrorchamber was produced out of high density Styrofoam. We coated it to make it airtight.

As we haven’t received our Mylar yet, and still need to construct the projection screen etc. we’re not 100% sure if our system is going to work or not…
We are planning to use a differential pressure sensor toc ontrol our mirrorshape. We’ll be using one of our own I/O modules to control the sensor and vacuumpump.

Marco

[Roland]

Hi Marco,

The styrofoam screen looks like a nice way to get lightweight complex dimensions.

With good tools and guides, styrofoam (or the denser variant like roofmate) can be heat-cut with thicker steel wire shapes, to get hollow spherical shapes.

I had been thinking about a small (single seater) collimated setup for my 3DoF cockpit:
Maybe a stupid idea, but if you would have this spherical (or parabolic) hollow shape cut into the stryrofoam structure, would it be possible to make the mylar screen from many strips of mylar, glued into the spherical hollow shape? If done neatly, I think you could end up with a decent mirror, without needing the vacuum system.

Just an idea...

[FI marco]

Hi Roland,

I'm not sure if that would work. When you apply mylar (or any other type of mirrorfoil) directly onto a surface, I think that would only work if that surface is absolutely 100% smooth. Even the smallest dust particle between the mylar and the surface would create a considerable deformation on the image. It would also be very hard to apply the mylar without any wrinkles in it. One of the advantages of using a vacuum behind the mirrorfoil is that it smoothes out all the wrinkles.

So, if you can create a 'mirror' smooth surface to apply the mylar onto that would be great, but it's very hard to do...

Gr,
Marco

[geneb]

Marco is being polite. It's _impossible_ to do. Mirrors of the optical quality REQUIRED by collimated display systems must have an accuracy measured in *angstroms*.

I understand you guys want to avoid the hassle of building a mirror cell and doing the whole vacuum thing, but you need to understand that you cannot do it by coating a surface with mylar. You'd have to be half blind and currently suffering from a concussion in order for it to look right. The kind of perfection a vacuum formed mirror can achieve is right up there with multi-million dollar machine ground telescope mirrors.

Marco, I really, really hope that styrofoam is insanely strong stuff. I say this because if it's not, you're going to collapse it as soon as you draw the Mylar into position. If I remember correctly, Wayne calculated a compressive force of about 3500lbs along the top edge of the display we built, which is about half the size of yours.

g.

[FI marco]

I always try to be polite , but I must say I have to agree wih your explanation.

We still have to test the styrofoam mirrorcell but we are waiting for the Mylar to arrive. We did however test it with cheap mirror foil that was about 2 mil thick and put a fair amount of vacuum behind it (yes, 2 mil is too much thickness and very hard to apply) The styrofoam seemed to hold ok. As the mirrorcell is high density styrofoam it is very 'shape consistent' and pretty strong. We also reinforced the upper and lower edges with an extra 'ring' made out of wood. Lets hope it is enough...

Gr,
Marco

[geneb]

Wayne & I used 1mil and it works great. I worry that the .5mil you've ordered may be too delicate to work with. The commercial outfits use 1mil as well.

I think it's insanely cool that you've got a monolithic mirror cell like that. Awesome job.

g.

[Roland]

Thanks guys,

Always good to reflect an idea with the experts. I was half expecting this answer. So getting a decent collimated display really needs the mylar vacuum thing.

Adding this on top of a moving platform will make things even more complex, and I really doubt the tensioned mylar mirror construction can withstand the accelerations of a fast moving platform, as it would require an extremely rigid construction.

I guess the 2-DoF platform action that Marco shows in his video maybe just OK, as it does not produce very fast heave movements of touch-down and turbulence.

Even the commercial 737 6DoF I experienced, I did not really feel the fast G's that my little 3DoF motion cockpit is generating. Maybe on purpose to avoid tearing the mylar mirror?

[FI marco]

@ Roland: you're right, it never hurts to ask. At least you got a clear answer If you could heat-cut styrofoam very precise it maybe is possible to make a small vacuum mirror chamber for your system. The biggest problem with a fast moving motion system like you have would be the construction that holds the beamers & folding mirrors etc. because of the obvious mass and height of the system...

@ Geneb: You might be right about the Mylar thickness, 0.5 mil is very very thin (and delicate) It will be a challenge to get it placed... The advantage might be that if we get it applied right there's less vacuum needed to form the right shape I hope. Good thing is that we didn't run over our 'experiment' budget yet, so we can always try the 1 mil version later if 0.5 doesn't work. I'll try to post some pics here with the results when we got the Mylar in.

Thanks,
Marco

[max2770]

I'm curious as to what is the black part of your design made of, as it requires air to pass through.

[crashdog]

Hi Marco,
seco-sign.de could have what you're looking for. I can't see the thickness of their mirror foil. But the sizes are up to 9m X1.80m
I'm gonna start building a collimated visual for my MD80 MD80 Flight simulatorsimulator soon. Your approach looks quite good. I could be interested to know more about how you build it.

Regards,

Gery