Projector characteristics

This is the place to discuss DLP projectors, UV Lasers, Galvanometers, LCD screens and similar display devices. Also discussed are optics in general.
jkao
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Re: Projector characteristics

Postby jkao » Sun Mar 08, 2015 3:49 pm

Yeah, I don't think that power is the limiting factor for DLP projectors. I think the main thing is the clarity of the optics. The description of "functions without modification" generally refers to the optics, not the UV brightness. DLP projectors generally all throw out UV, the modifications are to the lenses so that they can focus down to a suitably small area (e.g. 25-100 micron resolution, which would requiring being able to focus the projector down to a size ranging from 192mm x 108mm to 25mm x 14mm). Any projector that can't focus to a picture at least as small as 192mm x 108mm would be fairly useless for printing.

Additionally, many projectors have aspherical optics so that rather than being centered on the image, the projector is at the bottom of the image. This can make it impossible to put the entire printable area in the same focus; some part is always fuzzy (for instance the Acer 6510BD's top corners will always be fuzzy when the center and bottom are in focus, it's said that Vivitek projectors, like the D535 used in the B9Creator or the D912HD can project an image that is sharp throughout, at the cost of requiring lens modification to enable it to focus small enough).

Optics are also the least exciting when it comes to planning, since you can't really assess a projector's optics until you have it in hand, and it's very difficult to photograph the focus issues that are obvious when the projector is in front of you. However, I believe that this is, by far, the most important characteristic to assess.

In the end, you can always use longer exposures to work around issues of power, but optics will be a hard limiting factor that cannot be corrected in software.

Steve Baker
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Re: Projector characteristics

Postby Steve Baker » Sun Mar 08, 2015 8:48 pm

Ah, OK.

So I've been a graphics programmer for 30 years - geometric distortion issues are something I understand well and know how to correct for. Focus, I agree would be tough to fix because you're going to need weird lenses that might be tough to find.

But I'm concerned about long exposures - my main interest in going this route is the possibility of being able to make a bunch of small objects at the same time on a larger bed, and to be able to cycle the steps quickly so I can use this to make things in low-volume massed-production (thousands of parts in a week).

If there a place I can read about all of these issues so I can get caught up on this tech? I hate to ask a gazillion "obvious" questions on a forum like this while I absorb the essentials.

jkao
Posts: 45
Joined: Sun Jan 04, 2015 5:42 am
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Re: Projector characteristics

Postby jkao » Sun Mar 08, 2015 9:23 pm



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