Digitally Surfaced PALs (Free Form) Clarified

[Dave_Guevara]

I've just recently started too get a grip on this subject. Conventional PAL design involved a bunch of designers thinking up a lens design on a drawing board and an artist crafting a clay mold from which glass molds of a front surface design could be cast. The clay mold by this time cost millions of dollars and was to valuable to be used in manufacturing. Thus, this glass mold would be the one the final lens was cast from, the lens now being a second generation casting. With reapeted use, the quality and accuracy of the lens coming of these glass molds would decrease until it was replaced with a fresh mold, creating inconsistency in the process.
With the application of CNC machines, digital lathes that are controlled by computers and can consistently carve out the same lens, the clay mold was removed from the process and a new level of accuracy and consistency could be acheived.
Computers can also be used in the design process of the lens, that's where we get into free-form design. Within programs running on supercomputers a model of the human eye has been created to predict how rays of light will behave after passing through a lens and hitting the back of the eye. These programs can be used to optimize a lens design to control unwanted astigmatism and reduce periphrial distortion to the theoretical limits of progressive lens design.
Now some companys are using this technology to create a better PAL design but one that is still just one consistent design for all prescriptions. Others are using this to integrate their one cookie cutter design with the patients prescription and using the digital lathe technology to carve a PAL in the back of an otherwise single vision sperical lens offering a wider channel by getting the addition closer to the eye and a smoother power shift. The culmination of all this, what only few (one that I know of for sure) companys offer is a computer designed backside PAL customized to the patients prescription, the desired fitting height as well as the frame choice. This design can push the distortion into areas that get edged off the lens, offer any focal length desired where ever in the lens it's needed and give clear vision edge to edge, eliminating the need for pointing your nose to see. Plus, any single vision blank available can have this custom design carved in the back of it.
So, when a company takes an old design and scans it into the computer this only means that you'll get a more consistent version of that design and that a computer has verified that the back surface is properly aligned with the front producing a more consistent and accurate but not neccisarily better design.
When they use free-form design optimization you get a PAL designed with the latest advancment in our understanding of visual habits and the human eye.
When they take free-form design and combine it with the patients Rx you get the best version of that design for your patient.
But, when they design a unique PAL specifically for that application, that patient, that Rx, you get the latest technology in restoring perfect sight.
The future is now, it's just to pricey for every patient.

[Darryl Meister]

With the application of CNC machines, digital lathes that are controlled by computers and can consistently carve out the same lens, the clay mold was removed from the process and a new level of accuracy and consistency could be acheived.

Although I agree with much of your post regarding the potential visual benefits of true free-form-enabled customization for the wearer, I think you are overstating the consistency of the free-form surfacing process. While a properly calibrated generator may be able to replicate fairly complex surfaces, at least without rapid changes in surface features, the kinematics of the soft lap polishing process will not "automatically" produce complex lens surfaces of consistent, repeatable quality. Moreover, while a cast lens may not exactly replicate the lens design due to factors such as shrinkage, it is easy to verify the quality of cast lenses by inspecting a limited number of measurement points, once the mold has been validated. This is not the case with free-form surfacing, which can result in low and medium spatial frequency "form" errors distributed across different regions of the lens surface -- at least without sufficient process engineering.

[HarryChiling]

Although I agree with much of your post regarding the potential visual benefits of true free-form-enabled customization for the wearer, I think you are overstating the consistency of the free-form surfacing process. While a properly calibrated generator may be able to replicate fairly complex surfaces, at least without rapid changes in surface features, the kinematics of the soft lap polishing process will not "automatically" produce complex lens surfaces of consistent, repeatable quality. Moreover, while a cast lens may not exactly replicate the lens design due to factors such as shrinkage, it is easy to verify the quality of cast lenses by inspecting a limited number of measurement points, once the mold has been validated. This is not the case with free-form surfacing, which can result in low and medium spatial frequency "form" errors distributed across different regions of the lens surface -- at least without sufficient process engineering.

I am glad some one else is mentioning the polishing process. This is where most the inconsistencies in FF comes from. Forget how accurate the design is when it comes out of a finley tuned generator it still has to go on the polsher and conformable laps stil need to apply pressure and pressure is not applied evenly on a a surface such as a deformed conicoid.

Dave, thank you for that well informed post.

[AWTECH]

I am glad some one else is mentioning the polishing process. This is where most the inconsistencies in FF comes from. Forget how accurate the design is when it comes out of a finley tuned generator it still has to go on the polsher and conformable laps stil need to apply pressure and pressure is not applied evenly on a a surface such as a deformed conicoid.

Dave, thank you for that well informed post.

Comments on polishing and inconsistancy are not the same for all freeform processing. So such a general statement is not appropriate. Creating the surface determines the amount, if any polishing is needed. A few facts to consider: The same generator can create different qualities of surfaces. The cutting standards used in production also determine the amount of polish requires.

A diamond tool may be used by one manufacturer with a very small chip for more cuts than another manufactuer. (a 3 micron chip in the tool will produce approx 3 micron rings). Also consider all lenses then receive approximately a 4 micron thickness of hard coating.

Harry: I think one reason you are upset with many direct surfacing lenses that are being produced is your desire for knowledge about these products. This combined with direct surfacing lens producers unwillingness to part with more informaiton has cause you to jump to some incorrect conclusions. In our case we have a number of confidential processes and we do not choose to share these. The fact is the lenses we produce in almost all cases offer the patients better vision than conventional molded lenses. We have enough satisfied customers to know this is true. I think if you check with dispensers who have despensed large numbers of good designed individualized lenses the conclusions will not support claims that these type of lenses are not better.

[HarryChiling]

A diamond tool may be used by one manufacturer with a very small chip for more cuts than another manufactuer. (a 3 micron chip in the tool will produce approx 3 micron rings). Also consider all lenses then receive approximately a 4 micron thickness of hard coating.

Harry: I think one reason you are upset with many direct surfacing lenses that are being produced is your desire for knowledge about these products. This combined with direct surfacing lens producers unwillingness to part with more informaiton has cause you to jump to some incorrect conclusions.

You mean cut to coat and everyone is not doing this, if it hits the polishers and the surface is a deformed conicoid or any other surface other than sperical that needs to have comformable laps then it is a FACT the surface wll lose some accuracy (it may be negligable, but it will lose accuracy to the intended design) are manufacturers factoring this into their desings sure they are, but it doesn't mean they all are or have. Their is nothing innacurate about the inconsistencies in pressure being applied by conformable laps, that's one of the reasons why they are smaller in diameter than a hard lap.

And you are mighty correct saying that it does upset me that a manufacturer wants me to sell a product that they will shroud with secrets.

INCORRECT CONCLUSIONS, that's bold buddy, lucky I like you.:D Their is nothing incorrect abotu an opinion or reason for me to not use a product. I can't reiterate the same thing over and over again, but I'll try one last time in laymans terms.

I NO SELLY WHAT I NO KNOWY. :D

It seems that there are many on this thread alone reiterateing the same thing in different ways. Allen their are ways of provideing education about your product without divulgeing trade secrets or proprietary secrets.

[AWTECH]

Harry Said:

You mean cut to coat and everyone is not doing this, if it hits the polishers and the surface is a deformed conicoid or any other surface other than sperical that needs to have comformable laps then it is a FACT the surface wll lose some accuracy (it may be negligable, but it will lose accuracy to the intended design) are manufacturers factoring this into their desings sure they are, but it doesn't mean they all are or have. Their is nothing innacurate about the inconsistencies in pressure being applied by conformable laps, that's one of the reasons why they are smaller in diameter than a hard lap.

You are assuming the type of polishing I am doing. You are also assuming that non-hard lap polishing can not maintain a consistant surface. I don't think you have worked with any non hard laps. If I am wrong please correct me. You may have seen machine manufacturers explaining their soft laps to you, but developing this type of technology requires a great deal of time and equipment development. Controlling a diamond cutting tool to move in multiple directions involves very complicated development also. These two process have to work together.

I won't give specifics but we have developed a method to produce the designs without any significant loss of accuracy.

The design loss of accuracy maybe greater for some methods than others. I can assure you that our loss of accuracy from intended design, due to the process of polishing or hard coating, has much tighter tolorences possible than the tolorences from one fining pad to another. What is the tolorence for thickness of the paper you order for your polishing pads? What is the tolorence for the fining material? I doubt that you spec. these items like this.

We do spec all items used in our process and measure our accuracy. We had to know this for us to be able to develop our processes.

Again I respect your passion for your profession but it is not good science to say something is not accurate when you have no first hand experience with the processes you are saying are not accuate. I think the accuracy you see as being probable is not a factor in the production of good quality lenses. I see a lot more merit in your effort to want more knowledge of the actual design differences.

[AWTECH]

Dave_Guevara said:

But, when they design a unique PAL specifically for that application, that patient, that Rx, you get the latest technology in restoring perfect sight.
The future is now, it's just to pricey for every patient.

I agree with your conclusion Dave regarding the possible use of individualized lenses. I see you are in Europe and this technology has been on the market about two years ahead of this technology here is the US.

The results the patients have when trying these new individualized digitally surfaced high quality designs speaks for itself. I have spent some time with optical retailers in Europe last year who were dispensing high quality individualized lenses and they confirmed to me the success rate was very high.

[HarryChiling]

Wow, Allen you elluded to a process that doesn't require polishing, which is cut to coat or whaever the jargon is for it today. I never said that is what you are doing or that I know your process. By the way I did actually see a LOH generator and polisher in action I was their about 4 hours watching the thing work it's magic and the technology is impressive.

You seem to think that if a person doesn't have first hand experience with the specific equipment you use that they don't understand it. The equipment is nothing fancy, it is the processes and the tight control of these processes that are what give these lenses theleel of accuracy every manufacturer is gloating about. I KNOW THAT EVERYONE DOESN'T HAVE A CLUE WHAT THEY ARE DOING. That includes the manufacturers, some are still refining their processes, yet they are selling what they could some day be able to do with their equipment today. The average optician isn't going to know better.

In your case you use the SEIKO products, which means you are licensing the technology from SEIKO and a lab that uses the SHAMIR lenses licenses their technology form SHAMIR. And so on and so forth. I have a copy of Adobe Illustartor on my home PC, it doesn't make me a graphic design artist. In your case and in many others the lens desing you license is where the ideal performane comes from, your process and machines are supposed to make sure that the design is transfered as accurately as possible to the lens blanks. Are SEIKO lenses good sure I will even for sake of arguement say they are the best, but if your process doesn't accurately reproduce that int he lens blank then I get crap anyway. Also as Darryl mentioned and I have mentioned in previous posts the ANSI doesn't differentiate from a FF progressive and a traditional progressive. So even with the FF equipment you can provide the same level of inaccuracies than a traditionally processed lens.

Here is what you can provide that will make me consider a FF product. What tolerances to the finished product do you hold yourself to? Here are some specifics I would be interested in knowing:

Warpage? (ANSI )
Surface Astigmatism in the Distance zone? (ISO ) (since your surface incorporates the prescription and design on the same surface are you holdng yourself to the ISO tolerance on surface astigmatism or are you opting to try and meet the ANSI's total power tolerance)

Here is a quote from the tech bulletin on the ANSI change from 99 to 05:

The two significant changes in ANSI Z80.1-2005 are justified

from a manufacturing capability point of view and also from
a consistency viewpoint.
The effect on the lab should be a significant decrease in
rejects thereby improving delivery time and cost containment of
prescription prices.

The decrease in visual acuity on the wearer should be negligible.

One of those significant changes was the tolerance on progressive lenses and their cylinder tolerance. It went from 0.12D to 0.16D not a significant change but a change none the less.

Here is another quote for you:

Another paper by Judith Perrigin, et al, “A Comparison of

Clinical Refractive Data Obtained by Three Examiners” reported

the repeatability of refraction on 32 subjects was 98% within +

0.50 D (American Journal of Optometry & Physiological Optics, Vol

59, No 6)

Within that's a significant amount of power, but if only 2% of people can be effected by a power difference of 0.50D what niche is it that gets filled by a more accurate progressive especially one that's shrouded in secrecy?

I know that ANSI is the minimum tolerance but every lab that I do business with will meet or exceed this. I have seen NO LABS with documentation that they will do better than this tolerance so that's what I hold all labs to.

[AWTECH]

Harry Said:

In your case you use the SEIKO products, which means you are licensing the technology from SEIKO and a lab that uses the SHAMIR lenses licenses their technology form SHAMIR. And so on and so forth.

Harry: Your conclusion is true for most labs. ICE-TECH is not a traditional lab. We do offer the Seiko lens digitally surfaced PAL products, but we also offer the ICE-TECH line. This is not licensed from Seiko. ICE-TECH is a very small lens company not a lab. We happen to have a lab to produce our products. The traditional labs in this industry are set up to produce many products from many lens companies.

I think it is best if our customers think of us as another lens vendor who exclusively offers digitally surfaced products. In addition to our own ICE-TECH products we also offer the Seiko Succeed PAL products.

You said you have seen the Loh equipment in action and refer to it as, nothing fancy. I think you would find as I did after taking delivery of all of the equipment for digital surfacing necessary to start manufacturing lenses, that I now understood the process. That was my first mistake, and I have a good background in machine design and custom tooling manufacturing. What you begin to understand after a few months of working with the equipment is all of possible permutations and combinations for the production of lenses. The speed and feed of the tools, the tools used. What angle do you want on the finish tool?, what angle do you want the finish tool to feed into the lens? This goes on and on and on. So in a nutshell many of the issues with individualized lens production have to do with R&D time with specific equipment. On top of all of this there are three basic softwares involved to produce an individualized lens.
1-The machine control software.
2-The lens design software.
3-The data entry and lens and lab management software
All of these are designed by different companies. Now the lens manufacturers are trying to get their design software to work with all equipment manufactures software and all lab management software.
VCA is just now establishing standards. Unfortunately until you work with all three of the above you don't even know what standards to attempt to set.
As an example: Loh produces there individualized lenses using a lathe type cut. With any lathe type cut you have a center point issue. (That is the center is not turning, so how do you avoid a dot on the center of the lens). With the Opto Tech equipment they do not use this lathe method but rather a milling process that does not have a center point issue. (there are other issues for this type). Then there are the use of motion control and spindles. Using a standard controller such as that the Loh and Opto Tech and Schneider use the machine tool manufacturer is also in another software trap. As the controller manufactuer does not release the source code.

The equipment vendors sell equipment saying all you need is the lens companies software to product freeform lenses. It is just not as simple as described.

As you know we developed a great deal of our own software, using many outside the industry sources for help, and this has allowed us to compet with other digitally surfaced lens designers.

I will try to address your other issues at some point. I am short of time tonight.

You do ask some of the most knowledgeable questions I encounter about our technology. I too love the

[AWTECH]

Deleted due to duplication by mistake.

Sorry

[AWTECH]

Deleted due to duplication by mistake.

Sorry

[AWTECH]

Harry said:

Within that's a significant amount of power, but if only 2% of people can be effected by a power difference of 0.50D what niche is it that gets filled by a more accurate progressive especially one that's shrouded in secrecy?

As one example of the improvement for the patient consider:
full side to side far vision vs. a Y of some kind for far vision.

Another: a 30% wider corridor

Another: is a reading area with no skew distortion.

I believe if we worked together in our facility you would be the first one to push the benefits of this technology, unless the patient could not afford the cost of the benefit.

I am working on the refraction issue but it is not a cost effective solution yet.

[lensguy]

Being from canada, I think that the largest problem with some of these local "freeform" producers (other than what has been stated) is no one with the exception of Nikon has the proper tools to properly analyze the entire lens surface.

this back side process has so many things going on that using a lensometer to check only the optical center is not enough.

I once had an issue with a Rodenstock Impression lens, everything was perfect in the lensometer, patient had had them previous and stated he "couldnt see through the lens". I had the rep come in and see the patient.

the conclusion was we ordered the exact same lens, looked perfect (same) in the lensometer and patient felt it was totally different than the first pair. "best set of progressives I have ever had..........again".

this is so much different than a consistant (molded front surface) not much can go wrong with 1 or 2 simple curves on the back, but when all the progressive properties are on the back how do you measure and / or controll that without the equipment IN YOUR LAB ?????

If this can happen at Rodenstock from Germany (only once), how can I trust a method of sending a few samples every month or even week overseas to ensure the quality is still consistant??
this should be checked on every lens, there are too many Variables.

please help me understand this!

[AWTECH]

Lensguy said:

I think that the largest problem with some of these local "freeform" producers (other than what has been stated) is no one with the exception of Nikon has the proper tools to properly analyze the entire lens surface.

This back side process has so many things going on that using a lensometer to check only the optical center is not enough.

You have a very valid point. I don't know how many producers of freeform lenses have the equipment to properly check each lens but I would agree in general it is not that many.

At ICE-TECH Advanced Lens Technologies we have the equipment to map each lens and compare the results to the design. We are one of the smaller lens companies but I think our technology approach to these products is superior to most digitally surfaced producers.

[bhess25]

ok this is annoying the crap out of me...we all want to know more about the lenses, and your just trying to sell us on them. so far all ive seen is icetech this and icetech that, im sure you guys have a good lens even though noone will ever know because you wont tell us anything except how to buy them, listen we not only want but need to know more. Im one of those people that has to believe in a product by knowing specifics in order to sell it, im not willing to take the risk of waisting what little money i have to let a patient try them and worry about them asking for a remake or even worse, refunding. I see it like this, if your not willing to tell us anything, stop trying to sell them untill you are. You should understand how unfair this is to all of us when we just want to know certain things so that we know weather or not we can trust this technology. Or just give me another lolipop....30% wider corridor!!

[AWTECH]

ok this is annoying the crap out of me...we all want to know more about the lenses, and your just trying to sell us on them. so far all ive seen is icetech this and icetech that, im sure you guys have a good lens even though noone will ever know because you wont tell us anything except how to buy them, listen we not only want but need to know more. Im one of those people that has to believe in a product by knowing specifics in order to sell it, im not willing to take the risk of waisting what little money i have to let a patient try them and worry about them asking for a remake or even worse, refunding. I see it like this, if your not willing to tell us anything, stop trying to sell them untill you are. You should understand how unfair this is to all of us when we just want to know certain things so that we know weather or not we can trust this technology. Or just give me another lolipop....30% wider corridor!!

Sorry I offended you: I think most of our customers are satisfied with the amount of information we give. The fact that the patients have great success is important. If you are not personally interested because I don't supply enough information that is your choice. To bash the company is unfair to our company.

For my information: How would evaluate a plot of specific lens if I did supply it to you? What equipment do you have to check lenses? I think you are asking for information that not specific and if provided you may not have the ability to use it.

For example: If I you had an x,y,z surface data point file of a PAL of any freeform lens, how would you evalute this design? Knowing the front surface, the center thickness and the point file is all of the information you would need to compare one design vs. another. Do you have anyway to use this information?

[bhess25]

can you point out where i "bashed" your company?....i said "im sure its a good design"...and im not willing to sacrifice my relationships with my patients over something i dont know, and am not being told enough about....secrets dont sell very well.

[AWTECH]

can you point out where i "bashed" your company?....i said "im sure its a good design"...and im not willing to sacrifice my relationships with my patients over something i dont know, and am not being told enough about....secrets dont sell very well.

This is what I am referring to:

ok this is annoying the crap out of me...we all want to know more about the lenses, and your just trying to sell us on them. so far all ive seen is icetech this and icetech that, im sure you guys have a good lens even though noone will ever know because you wont tell us anything except how to buy them, listen we not only want but need to know more.

We provide as much or more information as most lens companies. Like I suggested. If you had all of the information via x, y, z data points what would you do with it?

Give me a list of the information you think is important.

For our customers we will offer a 3D plot of the exact lens. We are not a large company and do not have the capacity to respond to lengthy requests from potential customers. We offer our products with a full patient satisfaction warranty. With no down side for our customers I don't really understand why a few people think we need to provide data they have no ability to use. The fact is if the most of the patients are extremely pleased with the results why do you need more information?

Many of the verifications in this industry are legacy related. Example: If you verify the Rx in one spot on the lens for far vision to the Rx and you want the patient to have a good intermediate, how would you verify the patient looking 10 degrees to the left in the intermediate zone?

We produced many wrap around progressive before we were able to make the 34 mm engravings with any engravings. We told our customers to ask the patient to put the glasses on and if they had any problems they could return them without any charge. We only had a few returns and all were from incorrect seg height being given to us.

This technology works and produces lenses with excellent vision for the patient. The Rx can be verified via the compensation provided by us. Other than this verification you would need additional very expensive equipment.

The information about freeform lenses in the trade publications is primarily generated by the equipment manufacturers, since the lens manufactures are currently producing all of these lenses in house except for Seiko and Shamir. It is not as simple as the equipment manufactures present this.

[Opticaldeals]

Seiko Succeed is a 100% back side(internal) digital cut
Hoya Lifestyle ID is a front side digital mold with a back side digital cut.

[TLG]

Hoya Lifestyle ID is a front side digital mold with a back side digital cut.

Another active thread differs with your information, suggesting that the front and back are both cut with digital technology. I'm not saying you're wrong 'cuz I don't know. Click here to view the other thread

[AWTECH]

Another active thread differs with your information, suggesting that the front and back are both cut with digital technology. I'm not saying you're wrong 'cuz I don't know. Click here to view the other thread

If I remember correctly the Lifestyle ID and the Hoya ID are similar but different in that the Lifestyle ID was a molded front and the Hoya ID was digitally surfaced on both sides. I am not 100% sure this is the case. I think the logic was a way to offer a similar product for slightly less money.

[TLG]

If I remember correctly the Lifestyle ID and the Hoya ID are similar but different in that the Lifestyle ID was a molded front and the Hoya ID was digitally surfaced on both sides. I am not 100% sure this is the case. I think the logic was a way to offer a similar product for slightly less money.

My bad, I thought it was a reference to the same lens. The other thread was not referencing the LifeStyle ID. I stand corrected :hammer:

[Fezz]

If I remember correctly the Lifestyle ID and the Hoya ID are similar but different in that the Lifestyle ID was a molded front and the Hoya ID was digitally surfaced on both sides. I am not 100% sure this is the case. I think the logic was a way to offer a similar product for slightly less money.

After a seminar, reading the literature, grilling the sales reps and territorry managers, this is what I believe as well. The LifestyleID uses a standard molded front(digitally surfaced mold) and "Free-Form" digital surfacing on the back surface. The ID requires free-form surfacing on both sides of the lens.

[HarryChiling]

Amazingly someones listening to what is being asked:

Questions you shoud ask regarding any new digitally surfaced product

1. Other than increased precision and optimization of optics, how does this PAL design benefit from digital surfacing vs. traditional surfacing?
2. Is this PAL desing personalized to the patient? If so, what measurements are required and how do they inform the design?
3. Is this PAL design customied (e.g. to frame size or task)? If so, how are the customized features determined?
4. Is this PAL wavefront optimized? If so, can you demonstrate an actual improvement in the wavefront produced by the lens?
5. Can you provide clinical analysis to show an actual benefit to patients? If so, were the studies conducted on wearers and who conducted the research?
6. Where are the lenses manufactured? What processes are in place to ensure the quality and consistency of the end product?

Now the way I word things are no where near as eloquent and to the point as these questions are and it's a shame to see that it was again the large manufacturers that stepped up to the plate and demanded we ask questions, too bad the independents are missing the boat on an opportunity to inform their customers and really reel them in on these newer FF produced designs.

Again a different approach of transparency is what I see as a benefit to sellign this product nd apparently someone else sees it too, Pete if this was your idea or doing you may have just won me over. I will be calling my Varilx rep to get a hold of the clinical data.

[TLG]

Harry,
Another thing I thought was really cool about that ad is that the first sentence states "...I can't help but begin this months installment by talking about some comments I've read on Optiboard.com..."

It makes me think...
1.) What we have to say here CAN make a difference in our industry.
2.) Never stop asking tough questions and never back down because someone wants to offer easy answers that don't necessarily address industry-wide issues.
3.) What a great advertisement for our board. Hopefully it will help to inspire new membership.