Optics - Close Proximity Focus

[Cuddly Ninja]

Hello,

I am currently working on a project for fun which involves me being able to view a small monitor inside of a pair of glasses; the monitor will either be on the left or the right. I have successfully constructed the hardware side of things and all I have left to do is make the screen focusable in close proximity to the eye. Originally I was going to try and create a mirror system to try and get 'it' far enough away from the eye to be in focus (I think that is how commercial ones do it) but I was wondering if it could also be done with a convex lens. As far as I understand your eye has a limit to which it can contract the crystalline lens which means you cannot focus directly in front of you, with a powerful lens are you able to get the focal point closer to your eye and thus focus on the screen?

Thank you for any help and if my theory is correct where would I go about buying such a lens?

Thanks!

 

[Cyparagon]

Yeah, the rest of the world uses a convex lens in front of the screen. I'm not sure of the specifics though.

 

[Cuddly Ninja]

Yeah, the rest of the world uses a convex lens in front of the screen. I'm not sure of the specifics though.

I thought they had one screen in the middle and mirrors to make distance, oh well. I am not able to find any lenses which are 5cm in diameter and have >10mm focal length, I am not sure what that would look like...

 

[Cyparagon]

Even if you have mirrors, you can't cram more than a few inches of "depth" into something that fits on your head. Ever try to stare at something a few inches away for an hour? I bet it gives you a monster headache.

1mm FL? Wow, no. No, I really don't think it's that short. Grab a few lenses and experiment.

 

[Cuddly Ninja]

Even if you have mirrors, you can't cram more than a few inches of "depth" into something that fits on your head. Ever try to stare at something a few inches away for an hour? I bet it gives you a monster headache.

1mm FL? Wow, no. No, I really don't think it's that short. Grab a few lenses and experiment.

Sorry, I meant 10mm.
So 10 - 30 mm

 

[Soren]

I took a magnifying glass and some strong prescription glasses (for myopia) and put them together. The convex lens allows you to focus closely, and the concave corrects for that. Together, they allow you to focus on anything between the lenses, while also focusing on your surroundings. Here's a diagram:

Just don't get dust in there.