# Ideas for small image projector (flashlight size, maybe bigger)



## _hAxel (Dec 2, 2012)

I'm am starting a project where I would like to be able to project an image(a QR code, 2D Barcode) from a small handheld device. Preferably flashlight sized, maybe a bit larger and I'm trying to collect ideas. It doesn't have to be any thing awesome, just be able to project the QR code onto a surface (not far away) and the QR code be able to be read by a scanner/reader. I am thinking about trying to make something using a piece of transparency film with the code printed on it and a light source behind it, but I was wanting to see if any one else had any ideas or input on my current idea. Thanks.


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## AnAppleSnail (Dec 2, 2012)

Where do you want this to be visible?

Outdoors? Budget is a few thousand USD (kilowatt short-arc lamp with projector lenses would do it).
Indoors or at night? More doable.

The compact method is, "An aspheric lens projects forwards whatever image is at its focal point." With a plain LED, this will be an image of the phosphor layer. You can either put a mask after the lens, or figure out a way to make a lit image of your 'logo.' Cree uses the second method for their 'flair' at job fairs: They have a handheld spotlight to project their logo all over.


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## _hAxel (Dec 2, 2012)

AnAppleSnail said:


> Where do you want this to be visible?
> 
> Outdoors? Budget is a few thousand USD (kilowatt short-arc lamp with projector lenses would do it).
> Indoors or at night? More doable.
> ...



It would be indoors, projected against a table top (or other surface nearby).


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## lightdelight (Dec 2, 2012)

Here is a projector I put together that works with most p60 hosts. Not the most efficient, pretty, or easiest to use, but it works good enough for many of my uses. Lenses are from a telescope eyepiece. You will want something with a short back focal point. If you are using a transparency and working at a fixed distance that will be a lot easier because you won't have to build a focusing mechanism.




IMGP8005 by ectro, on Flickr


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## _hAxel (Dec 2, 2012)

lightdelight said:


> Here is a projector I put together that works with most p60 hosts. Not the most efficient, pretty, or easiest to use, but it works good enough for many of my uses. Lenses are from a telescope eyepiece. You will want something with a short back focal point. If you are using a transparency and working at a fixed distance that will be a lot easier because you won't have to build a focusing mechanism.
> 
> 
> 
> ...




I hadn't thought about using a lens from an eyepiece, thanks.


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## DIWdiver (Dec 4, 2012)

That might work for camera-type readers, but laser scanners won't even see the projected image, only the surface beneath it.


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