# working to understand virtual images

I'm starting to understand how to use lenses a bit more, but I'm still pretty lost.

I'm building a project that's extremely similar to this one with the implementation. I think my biggest challenge has been the unfamiliar terminology. When it came down to the lens, this DIY talks about how it turned out to be a lot of trial and error, but I'd really like to have it down to a formula and I'm hoping someone can help me with this!

Where my build differs...My LCD sits flat, facing up and will need a lens very close to it because there won't be a lot of space between the LCD and the reflective film that is angled at 45 degrees. The image then travels into the eye while creating a virtual image on that film. My previous post explained that I need my virtual image to be in focus at a much further distance so that my eye could see it while looking through it. Currently I have a very rough prototype without any lens(es) in place.

So far I'm gathering my variables as....

• Dimensions of the LCD
• Distance from the LCD to the lens
• Type and curve of the lens (each type looks like it'll have a new formula if it'd even work)
• Distance from the lens to the reflective film and my eye
• And based on those things, the focus distance of the virtual image. (or how far the image on my LCD would "appear" at)

I've found a lot of images that illustrate how this would work, but I haven't been able to find much to come up with an actual formula to figure out what kind of lens or lenses I should use, their focal lengths, and what type, or how I should position them relative to the LCD. I know this is a stretch, but I'm hoping someone might be able to help me come up with such a formula.

I'm still learning but I don't feel like I'm close enough to do this on my own yet.