Re: 405nm AR glass lenses - fit AixiZ FEELER
IgorT said:
[quote author=Jimmymcjimthejim link=1212842385/480#497 date=1225312554]
If the lens is going to be just like the Meredith one, wouldn't that mean that the diameter of the beam is going to be wide?
Oh, and what is NA?
Umm, what do you mean wide? The AixiZ acrylic lens has a FL of 7.3mm. The Meredith has a FL of 4.6mm. That's a BIG difference! I was actually hoping for something like 5.7mm. 5.7mm and 7mm dia allows for a high enough NA, but isn't too short a FL, so focusing would work better.
I tested a Meredith with a red, and it makes a beautiful round beam, not too thin, but noticably thinner than AixiZ. If you go even thinner than that, focusing becomes very hard. At a distance, the focus is just too spread out. Not to mention, that divergence increases dramatically.
With a PHR and a Meredith, the beam is also thinner, however a PHR has a thin but wide output. The Meredith makes a thinner beam, but it also collects more light - more of the fast axis. The result is a beam, that looks even flatter, than usual. But that's because of the diode output, and becausee of the fact, that the Meredith collects all of it. Every high NA lens will do this.
The only way to create a round beam from a flat output diode is to clip it with a low NA lens. The AixiZ has such a low NA, that it makes a PHR output oval, even tho it's not. The only way to create a super thin round beam is to use a short FL lens with a low NA. Low NA means losses. We want max power.
Well, there is another way to make a beam round - corrective optics, like an astigmatic lens, or a special lens, that first collimates the fast axis to give it the same divergence as the slow axis, and then collimates both into a thin beam. But those lenses can not work in a rotary system. If you turn such a lens just a little, it will distort the beam instead of making it rounder.
In any case, the Meredith makes a red beam noticably thinner and it looks very round. But a PHR beam looks almost as wide as AixiZ, only flatter. With a better blu diode, the beam will be more like a red beam, altho it will still be slightly fatter. It would take two different lenses, to give both a red and a blu the same beam diameter.
The third lens has an eveen shorter FL, so it will compress the beam further, but it will make focusing harder and divergence higher. With a PHR it will still be flat tho. That's because the PHR is a weird low power diode, almost multimode.
In any case, i only really know what lens #2 will look like. Not the other two. I will need to test them. That's why i paid for them - to get to see the final results! So let's do the testing first, and then we can decide what we want.[/quote]
Wow, Thanks for the info!!!
I never had any experience with the Meredith glass lens, so I don't know much about it.
