Optical experts here? Question about biconvex

[Alaskan]

Maybe an uber dumb question, but what are the requirements for a lens to be able to focus to infinity so I don't have a close in focal point? I have some lenses made for cutting with a close in focal point, is there a way to use one of those to focus the beam to infinity?

Forgive me the glaring hole in my understanding, I'm missing something here and have fallen and can't seem to get up on my own to find the answer yet. Can someone please offer me a hand up on this one? I even scrounged around at Edmund optics looking for something on this, the answer is probably pitifully simple!

 

[The Lightning Stalker]

If the beam is coming to a focus, the infinity point will be closer to the diode. I don't know why this works,
but it does. As the lens moves closer to the diode, the focal point moves farther away and eventually goes
to infinity, closer still will give a highly divergent beam with no focal point. Most lenses will work, as long
as the lens is wide enough to capture most of the raw output at the infinity point. I imagnine that some
lenses are so strong that it hits the can before reaching infinity, but that would be a very strong lens.

 

[Alaskan]

Thanks, I can see what is happening now, even though I don't really understand why, maybe if I did I'd have to pull out my calculator. By the way, what is that a photograph of for your avatar?

 

[The Lightning Stalker]

That is what happens to an LBO crystal when it has absorbed atmospheric moisture. They have to be
sealed inside the laser with a dessicant or else they will go bad.

 

[Alaskan]

"Where, now, is the way by which the light distributes itself" - Job 38:24

Some say the ether, but that has never been proven to exist, others say it is there, but difficult to detect. An interesting property of light is its timelessness, to light, time does not exist, it goes forward frozen in time to itself, an interesting property. An interesting book on light is God at the Speed of Light: the melding of science and spirituality by T. Lee Baumann. While I am far from religious, extremely distanced from such organizations, I still find this book very fulfilling on a spiritual level.

 

[lazeristasUVISIR]

The lens without specs can be useful or useless
It should be a great piece glass for collecting a sun light and burning wood LOL

As for the shape: as it was mentioned it can have a shape of the best form shape. You might figure out radii of the surfaces in several ways. Try guess a refractive index and see if they would match with best form specs.

The lens could come from a larger optical system like a big objective with several lenses to reduce aberrations. Then radii would not match best form.

As for aspherical surfaces - I doubt - a size is really big and to start messing up with two curved surfaces is $ $$$ $$$ unless you have those $$$ to burn for a good reason.

err, what is your not philosophical question?

 

[Alaskan]

Thanks, I haven't done anything with the big lens since I received it, as far as trying to characterize it. I was hoping it could be used as part of a IR beam expander but am learning it is so huge, to expand a beam that far isn't so practical, in terms of the parts needed. Perhaps if it were on the end of a long enough tube so that a beam expander lens output size would match it, as it expanded, if far enough away, it could work for me. I'm still learning about the possibilities with it but my big challenge right now is finding a beam expander input lens which can take a lot of power at 808nm from a FAP laser diode and not finding anyone who is willing to help engineer it for me yet.

The ""Where, now, is the way by which the light distributes itself" - Job 38:24" post was in response to The Lightning Stalker having used that in his signature, thought he might like reading the book I referenced..