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DIY Small Image Projector PLEASE HELP!! Answered

Hi there,

This site seems quite informative but still couldn't find what I am looking for, I really hope you can help me.

I am actually trying to achieve the exact opposite of what most people try to do with their DIY projector builds. I am trying to make a "small image" projector.

I have tried using all kinds of combinations of focal calculations but cant seem to get the result that I am looking for. I will be honest with you, I am very new to this and still acquainting myself with it.

I want to build a projector that can project an image as small as 10mm across to as large as about 50mm - 70mm across without loss of image clarity. I also want to be able to project the image from a short distance, up to maybe 300mm away. I will use a 7" LCD (1280x800) and want to be able to build this projector no larger than an A4 size sheet of paper.

is this achievable? if so, how would I go about building it? would you be able to give me any advice, ideas?
 
Any ideas are welcome as my head is about to explode :-(
 
Cheers
Jon

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user
Downunder35m (author)2015-07-23

Ok, do you use a real projector or do you base it on the 7" display?
In a projector the display panel is tiny to allow for small size optics.
If you use a 7" for that you are looking at a quite complicated setup.
a) The light source needs to placed so the entire display is illuminated evenly.
b) The light should pass at a 90° through the display, or at least close to it.
Otherwise you already need to copmpensate through optics.
c) On the output side you need a lens system to focus down from the 7" to your desired size - again quite hard in good quality.

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killerjackalope (author)2015-07-23

Something like this might be the answer, I'm guessing that these focus down ok, not sure about the optics but it'd be a cheap starting point.

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