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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 guys 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

5 Replies

user
ptkrf (author)2015-07-29

If you are trying to do that with image source being your phone, I have to disappoint you by saying that it is not possible. Firstly because phone screen doesn't provide enough light (keep in mind that same luminance is being stretched to entire room - even smallest projectors have HID lights) and the other reason is lens equation - this means it would have to be huge in all dimensions.

If your LCD can be made transparent (remove built in backlight), you could add a point light source very close behind it and a big (in diameter) piece of lens in front of it and make a proper projector (that is simplified version of how actual projectors work)

Hope I helped.

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user
pucksurfer (author)2015-07-24

I would think that you could achieve it by doing the same as others but use a flat lens?

Or, I would think it would work if you just used a regular lens and then turned it around.

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user
rickharris (author)2015-07-23

Find an old removable camera lens this will give you a good start.

look at some of the projector projects here.as well.

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user
seandogue (author)2015-07-23

Well, for playing and experimenting, you could grab a pair of binoculars or one of those inexpensive telescopes, etc, and turn them around for your optical chain (ie, object on small side, image from large side)

After all, that's the basic trick to reducing. Reverse a magnifier.. And by using something like a pairof binoculars or a small scope, all the major adjustments are already handled for you by using a pre-made optical path.

Lighting your object-of-interest might be tricky, but you can look up existing overhead projector tech to see how that's accomplished.

Good luck

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user
Downunder35m (author)2015-07-23

Be patient, stick to one topic for the same problem ;)

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