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Thread: help identify this retroreflective material

  1. #11

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    Yes, sounds perfect. Thank you.

    By the way, how are such retro reflective screens rated? Viewable angle and gain level? Or is there more specs?

    EDIT: By the way for anyone interested the sheet itself can be PVC, polyester, TC (Tetron Cotton) and although don't know probably others as well.

  2. #12
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    "There also has to be a reason fo the grey color of the fabric and some required properties for it for proper reflection..."
    Yes, the index of refraction of the glue needs to be different than the glass. You just have to be an extrovert.
    "There are painters who transform the sun into a yellow spot, but there are others who, with the help of their art and their intelligence, transform a yellow spot into the sun." Pablo Picasso

  3. #13

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    So several sellers contacted me about retro reflective sheets.
    One said he has 3 types with reflective coefficientents : R>270, 380 and 500.
    Anyone know for a video projection use, should one aim for a bigger number or lower? No idea how this translates to screen gain.

  4. #14
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    According to this article, the key is it needs to create directional reflective instead of secular reflection. It also compares it to the reflective strips on trainers, which makes Greg's link sound like a possible solution:

    https://www.gamersnexus.net/guides/2...ng-glasses-pax

  5. #15

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    Glass beads used in these sheets bounche the light back almost 180 degrees unlike a mirror which bounces the light at an angle.
    That said they have a property called "reflective coefficientent" and different sellers sell retro reflective sheets with glass beads with different reflective coefficients. Dont know if the number should be higher or lower for a better high gain video projection screen.

  6. #16
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    Same way a rainbow works critical angle refl3ction/refraction. Look up double rainbow.

    No idea on scale. Guess higher number smaller bead. Smaller retro angle but brighter in retro area. No such thing as free lunch. If it’s brighter it’s narrower. I could look up the physics it this feels right.

    https://www.google.com/patents/US2980547

  7. #17
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  8. #18
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    Nov 2008
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    Other question

    https://en.m.wikipedia.org/wiki/Silver_screen

    Explains screen types

  9. #19

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    Thank you, but to warn others the wikipedia page seems outdated and could use some citation and reference. Glass beads are way smaller than each individual pixel, I've never heard of retro reflective screens having a resolution issue. Also glass beads preserve polarization as well which the wikipedia article seems to hint only works with metallic surfaces.

    I guess I'll take both high and low reflective coefficient retro reflective sheets and compare the two.

  10. #20

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    Got various chinese retro reflective polyester sheets delivered today. In my experience all are pretty good and the 500 reflective coefficient one produces twice as bright looking projection than a 1.0 gain screen although the brightness drops too much starting at around 20 degrees from the projection. But for my use case is perfect. If you want one yourself post a RFQ in alibaba for "retroreflective polyester sheet with 500 RC"

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