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I was adjusting the position of our projector to allow for bigger prints to be generated. I encountered a problem that at larger distances, our prints are not seeming to adhere as desired.

Does the inverse square law of light apply to DLP projectors?

I am aware that the inverse-square law only is 100% applicable when you have a point as your light source. But I assume close to the same holds constant for other real world light sources.

Unless DLP projectors compensate for distance with their power output. Is this the case?


Cross-Post: @ Physics.SE

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  • $\begingroup$ I am currently troubleshooting this. Running a print right now with the law applied. So far it seems much more solidly adhered. $\endgroup$ – DMrFrost Jun 29 '17 at 21:32
  • $\begingroup$ I got pretty decent adhesion with a longer layer times. Im guessing that this is indeed the case. $\endgroup$ – DMrFrost Jun 29 '17 at 22:15
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    $\begingroup$ I'm voting to close this question as off-topic because it has been cross-posted at physics.SE and is probably more suitable there. $\endgroup$ – Tom van der Zanden Jun 30 '17 at 8:16
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    $\begingroup$ While this question would probably be quickly answered over at Physics.SE, I believe the content is best suited for 3DPrinting.SE. @TomvanderZanden we need to broaden our spectrum of questions regarding other 3D Printer types and draw in more experts. Our site currently has a strong hold on FDM printing to accommodate advanced questions, but I don't feel that we're there yet in other 3D printing types. So, I'm leaving this question open in hopes to encourage more questions about DLP printers. $\endgroup$ – tbm0115 Jul 2 '17 at 18:16
  • $\begingroup$ @tbm0115 This question has already been cross-posted (verbatim) on Physics.SE and gotten good answers here. Having the same question exist on two different SE's is not good. See here for a meta discussion. This question could possibly be salvaged by turning it into a more 3D printing specific question. However, allowing substandard questions in a hope to attract more experts is counterproductive. Experts are attracted by interesting, high-quality questions. $\endgroup$ – Tom van der Zanden Jul 2 '17 at 19:32
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Yes, of course it does. The same amount of light is being spread across a wider area, so there's less light per area. Once you're past a few 10's of filament diameters, a point source is a highly accurate representation of most light bulbs. Even more so when there's a lens setup that causes the light to go through a point focus.

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  • $\begingroup$ Thanks, I just wasn't sure if projection software for stereolithographic printers was set up in a way that compensated for this falloff by boosting power. $\endgroup$ – DMrFrost Jun 29 '17 at 23:20

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