freeform prism

**Ory** · 10-04-2006, 08:09 AM

This thread is partially suggesting a solution to drk's other thread and exploring the capabilities of freeform lenses.

If we can provide a gradual progression of power in a PAL, why not a gradual increase in prism as well? Would this horribly affect the optics of the lens?

So basically I'm proposing a lens that has 0^ at the fitting cross and X^ at the reading area, with a smooth increase from 0 to X. Freeform people? Is this a pipe dream?

**Jacqui** · 10-04-2006, 08:26 AM

Should work

**FVCCHRIS** · 10-04-2006, 03:56 PM

If possible, could this be a solution for the occassional patient who needs prism correction only at near, or for those anisometropes who had the cosmetics of a progressive "ruined" by a slab-off line???

**Ory** · 10-04-2006, 04:10 PM

Ok, so if it is possible, the next question is how difficult would this be to do? I'm not sure how complex the system is for freeform design. Is it simply a matter of punching a few buttons, or would this be a long design process?

**Jacqui** · 10-04-2006, 04:13 PM

Originally Posted by FVCCHRIS

If possible, could this be a solution for the occassional patient who needs prism correction only at near, or for those anisometropes who had the cosmetics of a progressive "ruined" by a slab-off line???

With the freeform slabs that we see here, there is no line, rather just a blending. All the work is done on the minus side rather than the plus.

**Jacqui** · 10-04-2006, 04:14 PM

Originally Posted by Ory

Ok, so if it is possible, the next question is how difficult would this be to do? I'm not sure how complex the system is for freeform design. Is it simply a matter of punching a few buttons, or would this be a long design process?

Depending on the Rx it could be either. Since you brought this up, I've been thinking that it could, with some work, replace some Franklin bi's.

**Jim Mush** · 10-04-2006, 05:11 PM

Originally Posted by Jacqui

Depending on the Rx it could be either. Since you brought this up, I've been thinking that it could, with some work, replace some Franklin bi's.

It wont work. You would be changing the actual curve and power. Good idea. It just aint gonna work. You can do it all at once, like a slab.

**Dave Nelson** · 10-04-2006, 05:50 PM

What about horizontal prism at near? I know very little about freeform technology, but in theory at least, a geometric configuration for a near only base in/out exists, but would manufacturing it be feasable? Or would it simply look like a highly decentered exec?

**Jim Mush** · 10-04-2006, 06:50 PM

Originally Posted by Dave Nelson

What about horizontal prism at near? I know very little about freeform technology, but in theory at least, a geometric configuration for a near only base in/out exists, but would manufacturing it be feasable? Or would it simply look like a highly decentered exec?

That would work I believe same as slabs. The slabs I've seen are smooth but sudden changes in prism. As opposed to conventional slabs with a sharp line. In the pre freeform days, you could not get a fuzzy lins slab past the opticians. I just know the gradual prism thing wont work. That equates to the same thing as a curve change. In theory, a lens is nothing more than a stack or series of prisms.

OH! Crap. Here I am posting. Crap. Sorry Steve!

**Jacqui** · 10-04-2006, 07:55 PM

Originally Posted by Dave Nelson

What about horizontal prism at near? I know very little about freeform technology, but in theory at least, a geometric configuration for a near only base in/out exists, but would manufacturing it be feasable? Or would it simply look like a highly decentered exec?

This is actually what I was talking about. It would take some doing, but I think it's possible. It would look like a decentered exec.

**Jim Mush** · 10-04-2006, 08:30 PM

Originally Posted by Jacqui

This is actually what I was talking about. It would take some doing, but I think it's possible. It would look like a decentered exec.

A blended exec. Probly best to do with a blended rd. No sharp lines with this system.

**Jim Mush** · 10-04-2006, 08:36 PM

The biggest hurdle with this system is that a major lens manufacturer is threatening to sue anyone that creates any program to grind progressives. Guess who? I'd have had one a long time ago but the manufacturers of the equipment seem not to want to have anything to do with grinding progressives. If that sounds negative, it aint my vibes.